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Lake Qinghai

Lake Qinghai Drilling1

Lake Qinghai Scientific Drilling Project

An Zisheng, Ai Li, and Song Yougui Institute of Earth Environment, Chinese Academy of Sciences

Steven M. Colman University of Minnesota-Duluth

Lake Qinghai in the People’s Republic of China covers 4400 km2 on the northeastern margin of the Tibetan Plateau, at an elevation of 3194 m (Fig. 1). The lake is extremely sensitive to changes in climate because it lies in a critical transitional zone between the humid climate region controlled by the East Asian monsoon and the dry inland region affected by westerly winds. Three major atmospheric circulation systems affect its climate: (i) the winter monsoon, induced by Siberian high pressure and associated high latitude ice cover, (ii) tropical moisture from low latitudes, carried by the East Asian summer monsoon, and (iii) climatic changes in the North Atlantic region, the effects of which are inferred to be transmitted via the westerlies. A study of drill cores from the lake and the surrounding area is critical for understanding the climatic, ecological, and tectonic evolution of the area, including the development of the East Asian monsoon system and its relationship to major global atmospheric circulation.

Lake Qinghai Drilling

Figure 1. Satellite photograph of Lake Qinghai with sketch map of drilling sites.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Lake Qinghai occupies a closed tectonic depression, or piggy-back basin, on the upper plate of a major, active thrust fault. The basin is bound to the north by the Qilian Mountains, which constitute the northeastern margin of the Tibetan Plateau. The lake basin thus is intimately related to the active tectonics of the Tibetan Plateau. Seismic-reflection data show that the lake sediments are tectonically deformed in some parts of the basin and largely undeformed in other parts, where they should record at least the timing of regional tectonism. The seismic surveys indicate that the shallow lake is underlain by northern and southern sub-basins and that the southern sub-basin contains a continuous stratigraphic sequence of unconsolidated sediments more than 700 m thick.

Scientific Objectives

The overall scientific objectives of the project include:

  • To obtain an improved understanding of the late Cenozoic environmental history of the Lake Qinghai region and the development of the East Asian monsoon climate
  • To understand the Late Cenozoic tectonic evolution of the Lake Qinghai basin and the growth of the northeastern margin of the Tibetan Plateau and its effects on regional climate
  • To correlate Lake Qinghai environmental records with other regional and global paleoclimatic records to obtain a better understanding of the connection between regional climatic change, the development of the East Asian monsoon system, prevailing westerlies, and, ultimately, the evolution of global climate

Drilling Campaign

After several weeks of delay caused by poor weather and a regional outbreak of bird flu, drilling operations began in late July 2005 and continued to early September. The drilling was conducted from a barge with the Global Lake Drilling 800 m (GLAD800) coring system (Fig. 2), the modular ICDP drilling platform and drilling system operated by Drilling, Observation and Sampling of the Earth’s Continental Crust (DOSECC, Inc.). DOSECC’s coring operations were supported by the Qinghai Geology Survey and scientists from the Xi’an Institute of Earth Environment of the Chinese Academy of Sciences (IEECAS). The sediment cores were described initially onboard by observing through the plastic core liners and examining core-catcher samples. The maximum 1.5-m-long core segments were scanned for geophysical properties with a GEOTEK instrument at a shore base that was occupied throughout the drilling operations. In total, 324 core runs for 548 m of drilling acquired 323 m of core at an average recovery rate of 59%.

The upper few tens of meters of sediment were mainly gray clay and silty clay. Core recovery was excellent in this upper part of the lake bed, and these cores will serve for the planned high-resolution study of climatic changes extending through much of the last glaciation. The sediment below the clay-rich upper section was mainly rather fine-grained, unconsolidated sand with only a few clayey layers. The character of these sandy units plus the persistent rough wind and wave conditions experienced during the drilling operation greatly hindered the recovery of good cores. The principal investigators thus decided to postpone the proposed 700-m drilling for a future campaign and to focus on obtaining high-quality, overlapping cores of the upper 30–50 m of relatively fine-grained sediment at several sites (Fig. 1). Hole 2C penetrated the deepest (114.9 m), and the cores from this site may provide paleoenvironmental information through the late Quaternary.

Concurrently with offshore drilling, an onshore site was drilled successfully on Erlang Jian on the southeastern shore of the lake (Fig. 1) using Chinese equipment. The drill rig was deployed to its maximum drill string capacity, allowing coring down to 1108.9 m, with an average recovery of more than 90%. Comparisons to outcrop exposures suggests that the lowermost sediment recovered sediments with a maximum age of late Miocene. The onshore drilling was conducted by the Qinghai Geology Survey, in collaboration with the IEECAS. All drill cores were shipped in refrigerated trucks to the IEECAS in Xi’an, China for storage at 2–5°C. So far, about sixty scientists from China, Japan, Europe, and North America have expressed interest in participating in upcoming studies. The principal investigators (Z. An, S.M. Colman, G. Haug, P. Molnar, and T. Kawai) and the science team held a planning and sampling meeting in May of 2007 in Xi’an, China. Preliminary results of a wide variety of paleoenvironmental proxy analyses were presented at a special session on Asian monsoon history at the American Geophysical Union meeting in December of 2008.

Read more about Lake Qinghai scientific core drilling services project at ICDP.

Lake Qinghai Drilling1

Figure 2. The GLAD800 drilling system being towed away from the dock to the first drill site, Lake Qinghai, China.

Acknowledgements

About 500 scientists, engineers, and technicians from the People’s Republic of China and abroad worked at and visited the drilling sites, mainly from the Chinese Academy of Sciences, the Ministry of Science and Technology of China, the National Science Foundation of China, the China Meteorological Association, the ICDP, and several universities and research organizations, as well as local governments. China Central Television and other TV stations and newspapers gave enthusiastic attention to this scientific research. They are all thanked for their contributions.

 

 

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Lake Malawi

Lake_Malawi Drilling Project

Lake_Malawi Drilling Project

Lake Malawi scientific core drilling project, located in Malawi, a 2005 project that was NSF, ICDP-funded.

LAKE MALAWI DRILLING PROJECT

East African Rift System, Malawi, Tanzania, Mozambique

The top scientific objective of the project was to obtain a continuous, high-resolution (annual-decadal) record of past climates in the continental tropics over the past ~800 kyr. Other primary scientific objectives of the drilling program intersect several fields, including extensional basin evolution and neotectonics, evolutionary biology, and the environmental background to human origins. The critical role of the tropics in driving global circulation is widely recognized, but the climatic linkage between tropical Africa and the high latitudes at decadal-centennial through orbital timescales, has yet to be established.

Read more about the Lake Malawi scientific core drilling services project at ICDP.

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Chesapeake Bay Impact Structure

Chesapeake Bay Impact Scientific Core Drilling Services

The ICDP-USGS Chesapeake Bay Impact Structure Deep Drilling Project

Gregory S. Gohn  U.S. Geological Survey

Christian Koeberl  University of Vienna

Kenneth G. Miller Rutgers University

Wolf Uwe Reimold Humboldt University

The Chesapeake Bay Impact Structure Deep Drilling Project is a joint venture of the International Continental Scientific Drilling Program (ICDP) and the U.S. Geological Survey (USGS). Project activities began with a planning workshop in 2003 that was attended by 63 scientists from ten countries. In 2004, a funding proposal to ICDP was accepted, and the USGS authorized additional drilling funds. The NASA Science Mission Directorate, ICDP, and USGS provided important supplementary drilling funds in November 2005 that permitted coring of the deeper part of the impact structure. Studies of post-impact sediments were supported by the U.S. National Science Foundation (NSF), Earth Science Division, Continental Dynamics Program.

Chesapeake Bay Impact Drilling

Figure 1 – Chesapeake Bay drilling locations.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

The late Eocene Chesapeake Bay impact structure (CBIS) is buried at moderate depths beneath continental-margin sediments in southeastern Virginia, USA. It is among the largest and best preserved of the known impact structures on Earth (Poag, et al., 2004; Horton et al., 2005). The CBIS consists of a ~35 to 40-km diameter, strongly deformed central crater surrounded by a ~25-km-wide, less deformed annular trough. Therefore, the full diameter of the structure is ~85 to 90 km. The Eyreville coreholes were drilled into the deepest part of the central crater, as determined from pre-drilling seismic surveys. This structure is perhaps unique among known impact structures as a locality where impact effects in a shallow-marine, rheologically layered, silicic target can be addressed by core drilling. Also, it is the source of one of only four known tektite strewn fields on Earth, the North American tektite strewn field (Koeberl et al., 1996).

 

Chesapeake Bay Impact Drilling1

Figure 2 – Drilling pad setup, including driller’s trailer (left) and USGS office (right)

Drilling Operations

Site preparations began in July 2005 at Eyreville Farm in Northampton County, Virginia, USA, and deep coring operations were conducted during September-December 2005. DOSECC, Inc., was the general contractor for the deep drilling operations, and Major Drilling America, Inc., was the contract drilling company. Two connected coreholes were drilled (Table 1). Eyreville corehole A was drilled to a depth of 940.9 m. Problems with swelling clays and the repeated loss of mud circulation led to deviation from Eyreville A to a new corehole, Eyreville B, at 737.6 m. Eyreville B was drilled to a final depth of 1,766.3 m. The USGS, Rutgers University, and the Virginia Department of Environmental Quality conducted shallow coring operations in May-June 2006 to a depth of 140.2 m (Table 1). The final result was a continuously cored section from land surface to a total depth of 1,766 m (Gohn et al., 2006).

Geologic Section

Table 1. Cored sections in the Eyreville coreholes
Eyreville A: 125.6 to 591.0 m, PQ core (85.0 mm diameter)
  591.0 to 940.9 m, HQ core (63.5 mm diameter)
Eyreville B: 737.6 to 1,100.9 m, HQ core (63.5 mm diameter)
  1,100.9 to 1,766.3 m, NQ core (47.6 mm diameter)
Eyreville C: 0 to 140.2 m, HQ core (63.5 mm diameter)

 

A total of 1,322 m of crater-fill materials and 444 m of overlying post-impact sediments were recovered in the Eyreville cores (Table 2.) The cored crater section consists of five major lithologic units. The lowest unit consists of 215 m of fractured mica schist, granite pegmatite and coarse granite, and several impact-breccia veins. These rocks could be the autochthonous crater floor, but, more likely, they are parautochthonous basement blocks.

Above these rocks, 158 m of melt-bearing and lithic breccias are considered to be fallback and (or) ground-surge deposits. Above these breccias, a thin interval of quartz sand (22 m) contains an amphibolite block and other lithic clasts of centimeter to decimeter size. This sand occurs below a 275-m-thick granite slab, which is unshocked, and thus must have been transported at least 10 km from the rim of the crater during collapse of the transient cavity. The uppermost and thickest impactite unit consists of 652 m of deformed sediment blocks and overlying sediment-clast breccia. This unit contains clasts of target sediments and crystalline rock, as well as a small component of impact melt, and it is interpreted to represent late-stage collapse of the marine water column and its catastrophic flow back into the crater.

In the post-impact section, the upper Eocene interval consists of silty clays that were deposited in deep water (~200-300 m). There is a major facies shift from the Eocene clays to glauconitic Oligocene sediments that are associated with a >5 myr hiatus that may be attributed to a combination of eustatic fall, tectonic uplift, and sediment starvation. The lower Miocene strata also are highly dissected and thin. Sedimentation rates increase dramatically in conjunction with another facies change to fine-grained biosiliceous middle Miocene sediments. A ~13 to 8 Ma was followed by deposition of shelly, sandy upper Miocene and Pliocene strata. The Pleistocene section consists of two paralic sequences.

 

Table 2. Generalized composite geologic section for the Eyreville cores (Gohn et al., 2008).
0 to 444 m Post-impact sediments
444 to 1,096 m Sediment-clast breccias and sediment blocks
1,096 to 1,371 m Granite slab
1,371 to 1,393 m Lithic blocks in sediment
1,393 to 1,551 m Suevite, melt rock, lithic breccia, cataclasite
1,551 to 1,766 m Schist, pegmatite and coarse granite, impact-breccia veins

 

Research Program and Selected Preliminary Results

The project has wide ranging scientific goals that include studies of impact processes and products, post-impact continental margin tectonics and sedimentation, hydrologic consequences of the impact, and the effects of the impact on the microbial biosphere (Gohn et al., 2008). International science teams established at the planning workshop began the research phase of the project in March 2006 with a sampling party at the USGS National Center in Reston, VA. About thirty project scientists from seven countries attended the sampling party, and over 1,800 samples were marked for future study. These samples were in addition to hundreds of samples collected at the drill site for hydrologic and biologic study. Suevitic and lithic impact breccias were popular intervals for sampling, as well as the thin interval that records the transition from syn-impact to post-impact sedimentation.

The release of detailed research results began in October 2007 with 53 oral and poster presentations in three sessions at the Geological Society of America Annual Meeting. A 43-chapter volume of research results is nearing completion (December 2008) and a 2009 publication date is expected.

Hydrology

Major-ion and stable-isotope chemical analyses for >100 pore-water samples from the Eyreville cores yielded salinities of 40-64 ppt over most of the 1,322-m-thick section of impact deposits. Chloride and 18O values in the post-impact sediments show a steady trend with depth that indicates vertical mixing of fresh and saline waters. The Ca/Mg ratio increases regularly with depth, suggesting water-rock interaction related to increasing temperatures with depth. Overall, the pore-water chemistry suggests that much of the ground water in the central crater has been there since the impact, and that much of the brine was likely present in the target coastal plain sediments before impact.

Microbial biosphere

Microbiological enumeration and other methods, combined with geochemical data, suggest that three microbiological zones are present in the Eyreville cores. The upper zone (0-700 m) is characterized by a logarithmic decline in microbial numbers from the surface through the post-impact section across the transition into the upper layers of the crater-fill sediments. The middle zone (700-1,400 m) corresponds to a region of low hydraulic conductivity that may have been sterilized, in part, by the impact thermal pulse. A lack of culturable organisms and extractable DNA, and microbiological enumerations below the limits of detection, suggest that the middle zone is a biologically impoverished environment. The lowest zone (>1,560 m) coincides with fractured, hydrologically conductive schist, pegmatite, and granite. It has microbial cell numbers that are higher than the middle zone, and heterotrophic organisms have been cultured. These results support the hypothesis that impact events cause disruption to the subsurface biosphere that can result in well-defined zones of microbiological colonization linked to the process of impact cratering.

Read more about this scientific core drilling project at ICDP.

Representative References:

Gohn, G. S., Koeberl, C., Miller, K.G., Reimold, W.U., Cockell, C.S., Horton, J.W., Jr., Sanford, W.E., and Voytek M.A., 2006, Chesapeake Bay impact structure drilled, Eos Transactions, American Geophysical Union, v. 87(35), p. 349, 355.

Gohn, G.S., Koeberl, C., Miller, K.G., Reimold, W.U., Browning, J.V., Cockell, C.S., Horton, J.W., Jr., Kenkmann, T., Kulpecz, A.A., Powars, D.S., Sanford, W.E., and Voytek, M.A., 2008, Deep drilling into the Chesapeake Bay impact structure: Science, v. 320, p. 1740-1745.

Horton, J.W., Jr., Powars, D.S., and Gohn, G.S., 2005, Studies of the Chesapeake Bay impact structure—Introduction and discussion, in Horton, J.W., Jr., Powars, D.S., and Gohn, G.S., Studies of the Chesapeake Bay impact structure—The USGS-NASA Langley corehole, Hampton, Virginia, and related coreholes and geophysical surveys: U.S. Geological Survey Professional Paper 1688, p. A1-A23.

Koeberl, C., Poag, C.W., Reimold, W.U., and Brandt, D., 1996, Impact origin of Chesapeake Bay structure and the source of North American tektites. Science v. 271, p. 1263-1266.

Poag, C.W., Koeberl, C., and Reimold, W.U., 2004, The Chesapeake Bay Crater—Geology and Geophysics of a Late Eocene Submarine Impact Structure: New York, Springer-Verlag, 522 p., CD-ROM.

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Brazos River K/T Boundary

Brazos River, TX Scientific Core Drilling Company Project

Brazos River, Texas: Drilling the K-T and Chicxulub Event Strata

Gerta Keller Princeton University

 

Project Objectives

The main objective of this project was to drill the Cretaceus-Tertiary (K-T) transition in the Brazos River area in order to recover a series of cores that span the late Maastrichtian and early Paleocene, including the K-T boundary horizon, the sandstone complex (event strata) and the Chicxulub impact spherule layer. We reasoned that by recovering these three events in stratigraphic order, it could be determined whether there was a cause-and-effect relationship between the Chicxulub impact on Yucatan and the K-T mass extinction. The Brazos River area was chosen because K-T deposition occurred in a shallow shelf environment, sediments are undisturbed by tectonics and sediment deposition is among the most complete worldwide. The Brazos sequences thus held the potential to solve the current controversy over the age of the Chicxulub impact, the biotic effects and whether this impact caused the mass extinction.

Methods

DOSECC drilled in two localities and recovered three 75 m long cores spanning from the early through the late Maastrichtian. The cores were sampled and analyzed by an international team of scientists (US, UK, Germany, Switzerland, France, Israel, Egypt). Analysis included sedimentology, mineralogy, stable isotoes, PGE and trace element analysis (ICP-MS), biostratigraphy and quantitative faunal and floral analyses (planktic foraminifera, nannofossils, palynomorphs).

Results

The K-T sequences along the Brazos River of Falls County, Texas, provide the most important and critical information regarding the age and biotic effects of the Chicxulub impact outside of Mexico. New investigations based on outcrops and new cores drilled by DOSECC and funded by the National Science Foundation reveal a complex history of three tectonically undisturbed and stratigraphically well-separated events: the Chicxulub impact spherule ejecta layer, a sea-level lowstand event deposit (sandstone), and the K-T mass extinction (Keller, 2007; Keller et al., 2007).

The newly discovered Chicxulub impact spherule layer is the oldest of the three events and marks the time of the impact about 300,000 years before the K-T boundary (base of zone CF1), consistent with similar observations from NE Mexico and the Chicxulub crater core Yaxcopoil-l. Paleontological analysis reveals that the Chicxulub impact caused no species extinctions or any other significant biotic effects (Keller et al., 2008). The subsequent sea level lowstand resulted in deposition of a sandstone complex, which predates the K-T boundary by about 100,000 years.

Reworked Chicxulub impact spherules and clasts with spherules in this sandstone complex were eroded from the original impact spherule layer. The third event is the K-T boundary mass extinction, which in the new cores is 80 cm above the sandstone complex and clearly unrelated to the Chicxulub impact.

These data reveal that the Chicxulub impact and K-T mass extinction are two separate and unrelated events, and that the biotic effects of this impact have been vastly overestimated. The K-T mass extinction was likely caused by massive volcanism in India, which marks the second catastrophe at the end of the Cretaceous.

Project Grants

NSF EAR Drilling was supported by the US National Science Foundation’s Continental Dynamics Program and Sedimentary Geology and Paleobiology Program under NSF-EAR Grants 0207407, 0447171 and 0750664.

Brazos River, TX Drilling

Figure 1 – Gerta Keller and Jerry Baum examine cores from DOSECC drilling along the Brazos River, which recovered an expanded sequence with the K-T boundary 80cm above the sandstone complex with three reworked upward fining impact spherule layers at the base. The original impact spherule layer was discovered 65 cm below.

 

References:

Keller, G., 2007. K-T mass extinction and Chicxulub impact in Texas. J.South Texas Geology, Geol. Soc. Amer., XLVII (9), p. 15-44.

Keller, G. Adatte, T.. Berner, Z Harting, M. Baum, G. Prauss, M. Tantawy, A. A. and D. Stueben., 2007. Chicxulub Impact Predates K-T Boundary: New Evidence from Texas. Earth and Planet. Sci. Letters 255, 339-356.

Keller, G., Abramovich, S., Berner, Z., Adatte, T., 2008. Biotic effects of the Chicxulub impact, K-T catastrophe and sea-level change in Texas. Paleogeogr., Paleoclimatol., Paleoecol., doi:10.1016/j.palaeo.2008.09.007

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Valles Caldera

Valles Caldera Scientific Core Drilling Services

Deep Coring of the Valles Caldera: Obtaining a Long-Term Paleoclimate Record from Northern New Mexico

Peter J. Fawcett and John W. Geissman University of New Mexico

Fraser Goff and Jeff Heikoop Los Alamos National Lab

Scott Anderson Northern Arizona University

Short History

The goal of this project was to obtain and analyze a deep (~100 m) sediment core from a lacustrine sequence in the Valles Caldera, northern New Mexico. Our work focused on determining the paleoenvironmental record of long-lived lakes in the caldera and developing a paleoclimatic record for this part of northern New Mexico for a substantial part of the middle Pleistocene. The core was drilled by DOSECC in May 2004 with the CS500 rig, and achieved a total depth of 82.1m. Most of this material was lacustrine clay with over 99% recovery. Recovery of the basal sands and gravels at the base of the core was significantly less, but we did capture a basal tephra that allowed for a constraining Ar-Ar age date. The core, VC-3, was archived at the LacCore Facility at the University of Minnesota and initial core description and sampling was conducted there.

Questions to be Answered

The questions we hoped to address with core VC-3 pertained to the paleoclimatic history of northern New Mexico over much longer time periods than the many late Pleistocene to Holocene records that are available in the area. In particular, we hoped to develop a long-term Pleistocene record that would span a significant portion of the middle Pleistocene, including some of the longer interglacials with a similar orbital forcing to today (e.g. MIS 11). The goal here was to examine natural climatic variability under such conditions as an analog for future climate change in the southwest.

What Samples were Collected?

We sampled the lacustrine mud portion of the core at a resolution of ~20 cm for a total of several hundred samples. The gravels were not sampled in detail, but the 3-cm thick basal tephra was sampled almost completely.

What Did We Do to the Samples?

An Ar-Ar age date of 552 ± 3 ka was obtained from the basal tephra, constraining the base of the core to the middle Pleistocene. To develop the paleoclimatic record, the lacustrine mud samples were split for a number of different analyses, conducted at multiple institutions (UNM, LacCore, LANL, NAU, UMN-Duluth). These analyses included organic carbon, C/N ratios, d13C, d15N, magnetic mineral properties (magnetic susceptibility MS, anisotropy of remanent magnetization, ARM), XRD of clay minerals, ICP OES (destructive elemental analysis) scanning XRF (non-destructive elemental analyses), compound specific dD, Methylated Branched Tetraether (MBT – a new paleotemperature analysis), pollen and charcoal content as well as a detailed sedimentologic description of the entire core.

What Did We Learn?

The 82-m deep lacustrine sediment core from the Valles Caldera, northern New Mexico reveals details of climate change over two glacial cycles in the middle Pleistocene. Core VC-3, taken from the Valle Grande, has a basal 40Ar/39Ar date of 552 ± 3 kyr from a tephra associated with the eruption of the South Mountain rhyolite which formed the lake. A variety of proxies including core sedimentology, organic carbon and carbon isotopic ratios, pollen, scanning XRF analysis and a new paleotemperature proxy, MBT (methylated branched tetraether) content of soil bacteria reveal two major warm periods above the basal tephra which we correlate with interglacials MIS 13 and MIS 11. This chronology is corroborated by the identification of two geomagnetic field ‘events’ which are correlated with globally recognized events (14α and 11α). The lacustrine record terminates at ~350 ka when the lake filled its available accommodation space behind the dam of rhyolite lava. Thus, the entire core spans two full glacial-interglacial cycles in the middle Pleistocene.

Valles Caldera Drilling

Figure 1: DOSECC CS500 rig operating in the Valle Grande, Valles Caldera, New Mexico

MBT temperature estimates show average glacial temperatures in core VC-3 of -4oC, and average interglacial temperatures of +4oC, and the general trends are well corroborated by multiple proxies including interglacial/glacial pollen ratios and lacustrine organic productivity estimates (organic carbon and Si/Ti ratios from the scanning XRF). A temperature increase of ~9oC occurs during Termination V, the largest glacial termination in the Pleistocene. Multiple proxies from VC-3 show significant structure during the two interglacials present in the core (MIS 13 and 11). Three warm substages (~ 2oC warmer) are recognized within MIS 11 based on organic productivity (Corg, Si/Ti ratios), pollen taxa, elevated charcoal from fires, and the MBT temperature estimates. These warm substages appear to be a strong response to precessional forcing in the SW continental interior even though the amplitude of eccentricity-modulated precession was at a minimum during MIS 11. These results suggest that future climate change in the SW may be characterized by similar natural temperature variability on precessional timescales, superimposed on future anthropogenic warming. Intervals of mudcrack facies representing significant drought conditions occur during or just after the warmest phases of the two interglacials. This past coupling between warm temperatures and extended drought in the SW as a natural feature of long interglacials is consistent with recent predictions of extended Dust-Bowl-like conditions in the SW as a response to global warming.

Where We Able to Answer These Questions & Why Should Society Care?

As a result of the multiple analyses and collaborations in this project, we were able to address the questions posed prior to the drilling project. We have generated a long, high-resolution terrestrial paleoclimate record for the middle Pleistocene, including important reconstructions of the variability within two long interglacials (MIS 11 and MIS 13). As these periods represent possible analogs for future climate change in the southwest, society should be very interested, particularly as the paleoclimate record appears to support the recent prediction of extended Dust-Bowl-like conditions in the SW as a response to global warming. The record also shows how vegetation and charcoal has changed in response to past climate change, potentially showing how vegetation and fire regimes might respond to future climate change.

Valles Caldera Drilling1

Figure 2: Representative core sections of glacials (MIS 14, MIS 12) and interglacials (MIS13).

 

References:

* denotes graduate student author

Fawcett, P.J., Heikoop, J., Goff, F., Anderson, R.S., Donohoo-Hurley, L., Geissman, J.W., WoldeGabriel, G., Allen, C.D., Johnson, C.M., Smith, S.J., and Fessenden-Rahn, J., 2007, Two Middle Pleistocene Glacial-Interglacial Cycles from the Valle Grande, Jemez Mountains, northern New Mexico; New Mexico Geological Society Guidebook, 58th Field Conference, Geology of the Jemez Mountains Region II, 2007, p. 409-417.

Johnson, C.M.*, Fawcett, P.J., and Ali, A.S., 2007, Geochemical Indicators of Redox Conditions as a Proxy for mid-Pleistocene Climate Change From a Lacustrine Sediment Core, Valles Caldera, New Mexico, New Mexico Geological Society Guidebook, 58th Field Conference, Geology of the Jemez Mountains Region II, 2007, p. 418-423.

Donohoo-Hurley, L.*, Geissman, J.W., Fawcett, P.J., Wawrzyniec, T., and Goff, F., 2007, A 200 kyr lacustrine record from the Valles Caldera: Insight from environmental magnetism and paleomagnetism, New Mexico Geological Society Guidebook, 58th Field Conference, Geology of the Jemez Mountains Region II, 2007, p. 424-432.

WoldeGabriel, G., Heikoop, J., Goff, F., Counce, D., Fawcett, P.J., and Fessenden-Rahn, J., 2007, Appraisal of post-South Mountain volcanism lacustrine sedimentation in the Valles Caldera using tephra units, New Mexico Geological Society Guidebook, 58th Field Conference, Geology of the Jemez Mountains Region II, 2007, p. 83-85.

 

Presentations

November 2008   Quaternary and Environmental Sciences and Department of Geology, Northern Arizona University (Fawcett)

March 2008 Valles Caldera Trust Public Forum, Albuquerque (Fawcett)

November 2007 IGPP Climate Study Group, LANL (Fawcett)

September 2007 Department of Geosciences, UNM (Fawcett)

September 2007 Fall Field Conference of the Geological Society of New Mexico, Jemez Mountains (Fawcett, Goff)

June 2007 IGPP Board Meeting, Santa Fe (Heikoop)

 

Presentation with Published Abstracts

Cisneros-Dozal, L, Heikoop, J., Fessenden, J., Fawcett, P., Kawka, O, and Sachs, J., 2007, Mid-Pleistocene lacustrine records of carbon and nitrogen elemental and isotopic data from Valles Caldera, New Mexico, USA, Eos Trans. AGU 88(52), Fall Meet. Suppl., Abstract PP43B-1253.

Dodd, J.P., Sharp, Z.D., Fawcett, P.J., Schiff, C., and Kaufman, D.S., 2007, A laser-extraction technique for oxygen isotope analysis of diatom frustules, Eos Trans. AGU 88(52), Fall Meet. Suppl., Abstract B13A-0893.

Donohoo-Hurley, L. L., Geissman, J.W., Fawcett, P. J., Wawrzniec, T. F., and Goff, F, 2005, Environmental magnetic record of lacustrine sediments of the Valles Caldera, New Mexico, New Mexico Geological Society Spring Meeting, Abstracts with Program

Donohoo-Hurley, L., Geissman, J.W., Fawcett, P.J., Wawrzyniec, T.F., and Goff, F., 2005, Preliminary results of the environmental magnetic record of Pleistocene Valles Caldera sediments, New Mexico, Geological Society of America Abstracts with Programs, Vol. 37, No. 7, p. 453

Donohoo-Hurley, L.L., Geissman, J.W., Fawcett, P.J., Wawrzyniec, T.F., and Goff, F, 2006, An environmental magnetism investigation of the Pleistocene lacustrine sediments from the Valle Grande, New Mexico, New Mexico Geological Society 2006 Spring Meeting, Socorro, NM, Abstract volume, p. 17.

Fawcett, P J., Goff, F., Heikoop, J.,Allen, C.D., Donohoo-Hurley, L., Geissman, J.W., Wawrzyniec, T.F., Johnson, C., Fessenden-Rahn,J., WoldeGabriel, G. and Schnurrenberger, D., 2005, Deep coring in the Valles Caldera, New Mexico to obtain a long-term paleoclimatic record, New Mexico Geological Society Spring Meeting, Abstracts with Program.

Fawcett, P.J. Fawcett, Werne, J., Anderson, R.S, Heikoop, J., Brown, E., Hurley, L, Smith, S., Berke, M., Soltow, H., Goff, F., Geissman, J., WoldeGabriel, G., Fessenden, J., Cisneros-Dozal, M., and Allen, C.D., 2008, Coupled Warming and Drought in the American Southwest During Long mid-Pleistocene Interglacials (MIS 11 and 13), AGU Fall Meeting, 2008.

Fawcett, P.J., Goff, F., Heikoop, J., Allen, C.D., Donohoo-Hurley, L., Geissman, J.W., Johnson, C., WoldeGabriel, G., and Fessenden-Rahn, J., 2005, Climate change over a glacial-interglacial cycle during the middle Pleistocene: A long term record from the Valles Caldera, New Mexico, Earth System Processes 2, Calgary, Alberta, GSA Specialty Meetings Abstracts with Programs No. 1, p. 33.

Fawcett, P.J., Goff, F., Heikoop, J., Allen, Craig D., , Donohoo-Hurley, L., Wawrzyniec, T.F., Geissman J.W., Fessenden-Rahn, J., WoldeGabriel, G., and Schnurrenberger, D., 2004, Deep Coring in the Valles Caldera, Northern New Mexico to Obtain a Long-Term Paleoclimatic Record, EOS Transactions, American Geophysical Union, v. 85 T43C-1346.

Fawcett, P.J., Heikoop, J., Anderson, R.S., Donohoo-Hurley, L., Goff, F., Geissman, J.W., Johnson, C., Allen, C.D., WoldeGabriel, G., and Fessenden-Rahn, J., 2006, Two mid-Pleistocene glacial cycles from the Valles Caldera, New Mexico, 10th International Paleolimnology Symposium June 25-29, 2006, Duluth, Minnesota, USA, Abstracts Volume, p. 32.

Fawcett, P.J., Heikoop, J., Anderson, R.S., Hurley, L., Goff, F. WoldeGabriel, G., Geissman, J., and Allen, C.D., 2007, A long middle Pleistocene climate record (MIS 14 to 9) from lacustrine sediments in the Valles Caldera, New Mexico, Geological Society of America Abstracts with Programs, Vol. 39, No. 6, p. 270.

Fawcett, P.J., Heikoop, J., Anderson, R.S., Hurley, L., Goff, F., Johnson, C., Geissman, J.W., and Allen, C.D., 2007, Two mid-Pleisocene glacial cycles (MIS 14 to 10) from lacustrine sediments in the Valles Caldera, northern New Mexico, Abstract XVII INQUA Congress Cairns Australia; Quaternary International v. 167-168, p. 114.

Fawcett, P.J., Heikoop, J., Anderson, R.S., Hurley, L., Goff, F., Geissman, J.W., Johnson, C., WoldeGabriel, G., Allen, C.D., and Fessendeh-Rahn, J., 2006, Two mid-Pleistocene glacial cycles (MIS 14 to 10) from lacustrine sediments in the Valles Caldera, New Mexico, EOS Trans, 87(52) AGU, Fall Meet. Suppl., Abstract PP51B-1137.

Fawcett, P.J., Heikoop, J., Goff, F., Allen, C.D., Anderson, R.S., Donohoo-Hurley, L., Geismman, J.W., Johnson, C., WoldeGabriel, G., and Fessenden-Rahn, J., 2005, Climate change over a glacial-interglacial cycle from the mid Pleistocene: A lacustrine record from the Valles Caldera, New Mexico, American Geophysical Union Annual Fall Meeting. Eos Trans. AGU, 86(52), Fall Meet. Suppl., Abstract PP31A-1505

Fawcett, P.J., Heikoop, J., Goff, F., Anderson, R.S., Donohoo-Hurley, L., Geissman, J.W., Johnson, C., Allen, C.D., WoldeGabriel, G., and Fessenden-Rahn, J., 2006, A mid-Pleistocene glacial-interglacial cycle from the Valles Caldera, New Mexico, New Mexico Geological Society 2006 Spring Meeting, Socorro, NM, Abstract volume, p. 18.

Hurley, L., Geissman, J.W., Fawcett, P.J., Wawrzyniec, T., and Goff, F., 2006, An investigation of environmental magnetism of the Pleistoene Valle Grande lacustrine sediments, New Mexico, Geological Society of America Abstracts with Programs, Vol. 38, No. 7, p. 199

Hurley, L.L., Geissmann, J.W., Fawcett, P., Wawrzyniec, T., and Goff, F., 2007, Environmental magnetism of mid-Pleistocene lacustrine sediments of the Valles Caldera, New Mexico, Eos Trans. AGU 88(52), Fall Meet. Suppl., Abstract GP53B-1218.

Johnson, C.M., Fawcett, P.J., and Ali, A.S., 2006, Geochemical and mineralogical indicators of redox conditions of a mid-Pleistocene lake in the Valles Caldera, New Mexico, New Mexico Geological Society 2006 Spring Meeting, Socorro, NM, p. 23.

Johnson, C.M., Fawcett, P.J., and Ali, M., 2006, Geochemical Indicators of Redox Conditions as a Proxy for mid-Pleistocene Climate Change From a Lacustrine Sediment Core, Valles Caldera, New Mexico, EOS Trans, 87(52) AGU, Fall Meet. Suppl., Abstract PP51B-1143.

 

Valles Caldera Drilling2

Figure 3: Core VC-3 Stratigraphic section, Organic Carbon (%) in siderite free fraction, bulk magnetic susceptibility (SI x 10-6) and bulk sediment density (g/cm3). Age assignments are based on Ar-Ar dates, and correlation with geomagnetic field events and glacial terminations. MBT temperature estimates (in oC) and depths given in red, within the Organic Carbon plot.

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Lake Bosumtwi

Lake Bosumtwi Scientific Core Drilling Services Project

The 2004 ICDP Bosumtwi Impact Crater Drilling Project, Ghana

Christian Koeberl University of Vienna

Bernd Milkereit University of Toronto

Jonathan T. Overpeck University of Arizona

Christopher A. Scholz Syracuse University

The 10.5-km-diameter 1.07 Ma Bosumtwi impact crater was the subject of an interdisciplinary and international drilling effort of the International Continental Scientific Drilling Program (ICDP) from July to October 2004. Sixteen different cores were drilled by DOSECC at six locations within the lake, to a maximum depth of 540 m. A total of about 2.2 km of core material was obtained. 

Introduction and Geological Setting

Bosumtwi is one of only four known impact craters associated with a tektite strewn field. It is a well-preserved complex impact structure that displays a pronounced rim and is almost completely filled by the 8 km diameter Lake Bosumtwi. The crater is excavated in 2 Ga metamorphosed and crystalline rocks of the Birimian System; it is surrounded by a slight near-circular depression and an outer ring of minor topographic highs with a diameter about 20 km. The goal of the integrated drilling, rock property and surface geophysical study was to study the three-dimensional building blocks of the impact crater (delineate key lithological units, image fault patterns, and define alteration zones).

Lake Bosumtwi Drilling

Figure 1 – Location map with ICDP boreholes and seismic profile shown in Fig. 2.

Paleoclimatic Studies at Bosumtwi

Owing to its impact origin, Bosumtwi possesses several important characteristics that make it well suited to provide a record of tropical climate change. In order to gain greater insight into the role of the tropics in triggering, intensifying and propagating climate changes, scientific drilling for the recovery of long sediment records from Lake Bosumtwi was undertaken. Five drill sites (Fig. 1) were occupied along a water-depth transect in order to facilitate the reconstruction of the lake level history. At these five drill sites, a total of 14 separate holes were drilled. Total sediment recovery was 1,833 m. For the first time the GLAD lake drilling system (a system specifically constructed for drilling at lakes) cored an entire lacustrine sediment fill from lakefloor to bedrock.

 

The complete 1 Ma lacustrine sediment fill was recovered from the crater ending in impact-glass bearing, accretionary lapilli fallout. This accretionary lapilli unit represents the initial post-impact sedimentation and provides an important age constraint for the overlying sedimentary sequence. The initial lacustrine sediment is characterized by a bioturbated, light-gray mud with abundant gastropod shells suggesting that a shallow-water oxic lake environment was established in the crater. Future study of the earliest lacustrine sediment will address important questions related to the formation of the lake and the establishment of biologic communities following the impact. Most of the overlying 294 m of mud is laminated thus these sediment cores will provide a unique 1 million year record of tropical climate change in continental Africa at extremely high resolution. The shallow water drill sites consist of alternating laminated lacustrine mud (deepwater environment), moderately-sorted sand (nearshore beach environment) and sandy gravel (fluvial or lake marginal environments). These sediments preserve a record of major lake level variability that will greatly advance the present Bosumtwi lake level histories obtained from highstand terraces and shorter piston cores. All of the drill sites will be used to produce a basin-scale stratigraphic framework for the crater sediment fill.

Geophysics and Impact Results

The two impactite cores, LB-07A and LB-08A, were drilled into the deepest section of the annular moat (540 m) and the flank of the central uplift (450 m), respectively. Samples from these cores have been studied by more than a dozen different research teams from around the world. The first set of peer-reviewed papers resulting from this work has just been published in a special issue of the journal “Meteoritics and Planetary Science”, which contains 27 papers on various aspects of the impact and geophysical studies at Bosumtwi.

At both impactite holes, drilling progressed through the impact breccia layer into fractured bedrock. LB-07A comprises lithic (in the uppermost part) and suevitic impact breccias with appreciable amounts of impact melt fragments. The lithic clast content is dominated by graywacke, besides various metapelites, quartzite, and a carbonate target component. Shock deformation in the form of quartz grains with planar microdeformations is abundant. First chemical results indicate a number of suevite samples that are strongly enriched in siderophile elements and Mg, but the presence of a definite meteoritic component in these samples cannot be confirmed due to high indigenous values. Core LB-08A comprises suevitic breccia in the uppermost part, followed with depth by a thick sequence of graywacke-dominated metasediment with suevite and a few granitoid dike intercalations. It is assumed that the metasediment package represents bedrock intersected in the flank of the central uplift.

Major results include the complete petrographic and geochemical record of the impactite fill. Major surprises in this regard include the, in comparison to suevites outside of the crater, small impact melt component and the record of shock metamorphism in the clast content of suevites, which are both at variance with earlier numerical modeling results. Also, impact-related hydrothermal overprint seems to be limited. These examples suffice to illustrate that further research on impact structures, accompanied by numerical modeling, is required to solve these and other problematics. Impactite geochemistry has also revealed that the impact breccias and the Ivory Coast tektite compositions can be satisfactorily modeled as mixtures of the known Birimian-age target rocks (metasedimentary rocks and granitoids). The geophysical studies, calibrated against the petrophysical data retrieved from the drill cores, have allowed to develop much improved three-dimensional models for the crater volume.

Lake Bosumtwi Drilling1

Figure 2 – Seismic section with deep boreholes.

Deep drilling results confirmed the general structure of the crater as imaged by the pre-drilling seismic surveys. Borehole geophysical studies conducted in the two boreholes confirmed the low seismic velocities for the post-impact sediments (less than 1800 m/s) and the impactites (2600-3300 m/s). The impactites exhibit extremely high porosities (up to 30 vol%), which has important implications for mechanical rock stability.

The statistical analysis of the velocities and densities reveals a seismically transparent impactite sequence (free of prominent internal reflections). Petrophysical core analyses provide no support for the presence of a homogeneous magnetic unit (= melt breccia) within the center of the structure. Borehole vector-magnetic data point to a patchy distribution of highly magnetic rocks within the impactite sequence.

Prior to drilling, numerical modeling estimated melt and tektite production using different impact angles and projectile velocities. The most suitable conditions for the generation of tektites are high-velocity impacts (>20 km/s) with an impact angle between 30 and 50° from the horizontal. Not all the melt is deposited inside the crater. In the case of a vertical impact at 15 km/s, 68% of the melt is deposited inside the crater. Results of the numerical modeling agreed well with the then-available geophysical data, crater size, and the distribution of tektites and microtektites of the tektite strewn field. The now observed situation for breccias within and around the crater is very different from these model results. The predicted amount of melt is much higher than the meager amounts observed. Clearly, much more melt has been incorporated in the suevite ejected outside of the structure, in comparison with the low amounts measured in the within-crater suevite occurrences. The lack of a coherent melt sheet, or indeed of any significant amounts of melt rock in the crater fill, is thus in contrast to expectations from modeling and pre-drilling geophysics, and presents an interesting problem for comparative studies and requires re-evaluation of existing data from other terrestrial impact craters, as well as modeling parameters. This research project provided important new data and improved our understanding of global change and impact processes.

Lake Bosumtwi Drilling2

Figure 3 – Bosumtwi Project Coring Team aboard DOSECC’s GLAD800 drilling platform, R/V Kerry Kelts.

 

Read more about this scientific core drilling services project at ICDP.

Acknowledgments

This work was supported by the International Continental Drilling Program (ICDP), the U.S. NSF-Earth System History Program under Grant No. ATM-0402010, Austrian National Science Foundation (project P17194-N10), the Austrian Academy of Sciences, and by the Canadian National Science Foundation. Drilling was performed by DOSECC.

References:

Koeberl C., Milkereit B., Overpeck J.T., Scholz C.A., Amoako P.Y.O., Boamah D., Danuor S.K., Karp T., Kueck J., Hecky R.E., King J., and Peck J.A.

(2007) An international and multidisciplinary drilling project into a young complex impact structure: The 2004 ICDP Bosumtwi impact crater, Ghana, drilling project – An overview. Meteoritics and Planetary Science 42, 483-511.

Ferrière, L., Koeberl, C., Ivanov, B.A., and Reimold, W.U. (2008) Shock metamorphism of Bosumtwi impact crater rocks, shock attenuation, and uplift formation. Science 322, 1678-1681.

Nowaczyk N.R., Melles, M. and Minyuk, P., 2007: A revised age model for core PG1351 from Lake El’gygytgyn, Chukotka, based on magnetic susceptibility variations correlated to northern hemisphere insolation variations, Journal of Paleolimnology, 37: 65-76.

Secondary References:

Asikainen, C.A., Francus, P. and Brigham-Grette, J., 2006: Sediment fabric, clay mineralogy, and grain-size as indicators of climate change since 65 ka at El’gygytgyn Crater Lake, Northeast Siberia, Journal of Paleolimnology, 37: 105-122.

Berger, A. and Loutre, M.F., 1991: Insolation values for the climate of the last 10 million of years, Quaternary Science Reviews, 10: 297-317.

Brigham-Grette, J. and Carter, L.D., 1992: Pliocene marine transgressions of northern Alaska: Circumarctic Correlations and Paleoclimate, Arctic, 43(4): 74-89.

Brigham-Grette, J., Melles, M., Minyuk, P. and Scientific Party, 2007: Overview and Significance of a 250 ka Paleoclimate Record from El’gygytgyn Crater Lake, NE Russia, Journal of Paleolimnology, 37: 1-16.

Cherapanov, M.V, Snyder, J.A. and Brigham-Grette, J., 2007: Diatom Stratigraphy of the last 250 ka at Lake El’gygytgyn, northeast Siberia, Journal of Paleolimnology, 37: 155-162.

Dowsett, H.J., 2007: The PRISM paleoclimate reconstruction and Pliocene sea-surface temperature. In: Williams, M., et al., (Eds.) Deep-Time Perspectives on Climate Change: Marrying the Signal from Computer Models and Biological Proxies: The Micropaleontological Society, Special Publications, The Geological Society, London, 459-480.

Forman S.L., Pierson J., Gomez J., Brigham-Grette J., Nowaczyk N.R. and Melles, M., 2007: Luminescence geochronology for sediments from Lake El´gygytgyn, northwest Siberia, Russia: Constraining the timing of paleoenvironmental events for the past 200 ka, Journal of Paleolimnology, 37: 77-88.

Gebhardt, A.C., Niessen, F. and Kopsch, C., 2006: Central ring structure identified in one of the world’s best-preserved impact craters, Geology, 34: 145-148.

Glushkova, O.Yu. and Smirnov, V.N., 2007: Pliocene to Holocene geomorphic evolution and paleogeography of the El’gygytgyn Lake region, NE Russia, Journal of Paleolimnology, 37, 37-47.

Haug, G.H., et al., 2005: North Pacific seasonality and the glaciation of North America 2.7 million years ago, Nature, doi:10.1038, 1-5.

Juschus O., Preusser F., Melles M. and Radtke U., 2007: Applying SAR-IRSL methodology for dating fine-grained sediments from Lake El´gygytgyn, north-eastern Siberia, Quaternary Geochronology, 2: 137-142.

Layer, P.W., 2000. Argon-40/argon-39 age of the El’gygytgyn impact event, Chukotka, Russia, Meteroitics and Planetary Science, 35: 591-599.

Lisiecki, L.E. and Raymo, M.E., 2005: A Pliocene-Pleistocene stack of 57 globally distributed benthic ∂18O records, Paleoceanography, 20: PA1003, doi:10.1029/2004PA001071

Lozhkin, A.V., Anderson, P.M., Matrosova, T.V. and Minyuk, P.S., 2007: The pollen record from El’gygytgyn Lake: implications for vegetation and climate histories of northern Chukokta since the late middle Pleistocene, Journal of Paleolimnology, 37: 135-153.

Melles, M., Brigham-Grette, J., Glushkova, O.Yu., Minyuk, P.S., Nowaczyk, N.R. and Hubberten, H.W., 2007: Sedimentary geochemistry of a pilot core from Lake El’gygytgyn – a sensitive record of climate variability in the East Siberian Arctic during the past three climate cycles, Journal of Paleolimnology, 37: 89-104.

Miller, G.H. and Brigham-Grette, J. (lead authors) and 17 contributing authors, in press: Temperature and Precipitation history of the Arctic, Chapter 4, IN, Past Climate Variability and change in the Arctic and High Latitudes, CCSP Synthesis and Assessment Product 1.2, US Govt Climate Change Program. 201 pgs.

Minyuk, P.S., Brigham-Grette, J., Melles, M.M., Borkhodovev, V.Yu., Glushkova, O.Yu., 2007: Inorganic geochemistry of El’gygytgyn Lake sediments (northeastern Russia) as an indicator of paleoclimatic change for the last 250 kyr, Journal of Paleolimnology, 37: 123-133

Niessen, F., Gebhardt, A.C. and Kopsch, C., 2007: Seismic investigation of the El’gygytgyn impact crater lake (Central Chukotka, NE Siberia): preliminary results, Journal of Paleolimnology, 37: 49-63.

Nolan, M. and Brigham-Grette, J., 2007: Basic Hydrology, Limnology, and meterology of modern Lake El’gygytgyn, Siberia, Journal of Paleolimnology, 37: 17-35.

Nolan, M., Liston, G., Prokein, P., Huntzinger, R., Brigham-Grette, J. and Sharpton, V., 2003: Analysis of Lake Ice Dynamics and Morphology on Lake El’gygytgyn, Siberia, using SAR and Landsat, Journal of Geophysical Research, 108(D2): 8162-8174.

Nowaczyk et al., 2002: Magnetostratigraphic results from impact crater Lake El’gygytgyn, northeastern Siberia: A 300 kyr long high resolution terrestrial paleoclimatic record from the Arctic, Geophysical Journal International, 150: 109-126.

Nowaczyk N.R., Melles, M. and Minyuk, P., 2007: A revised age model for core PG1351 from Lake El’gygytgyn, Chukotka, based on magnetic susceptibility variations correlated to northern hemisphere insolation variations, Journal of Paleolimnology, 37: 65-76.

Salzmann, U., Haywood, A.M., Lunt, D.J., Valdes, P.J. and Hill, D.J., 2008: A new global biome 4004 reconstruction and data-model comparison for the Middle Pliocene, Global Ecology and Biogeography, 17: 432-447.

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Laguna Salada

Laguna Salada project, located in Mexico

Natural Variability and Climatic Change in the Delta of the Colorado River region

Laguna Salada project, located in Mexico

Juan Contreras, Arturo Martín-Barajas, and Juan Carlos Herguera Centro de Investigación Científica y de      Educación Superior de Ensenada

Ana Luisa Carreño Universidad Nacional Autónoma de México

The Salton Trough region of southern California and the Mexicali valley in north Mexico conforms the Delta of the Colorado. The delta of the Colorado provides with water to a population of more than 2.5 million inhabitants. The delta is so fertile that its agricultural output is the largest in Mexico; it also hosts the largest settlement of industrial complexes in the country. The combined production of those two economical sectors accounts for 1.5% of the gross domestic product of Mexico. Understanding of past climatic changes in the region is of vital importance because it can give us an idea of how the hydrological balance, specially the dynamics of the Colorado River, will be affected by global warming.

Colorado River Drilling

Figure 1 – Panoramic view of the drilling operations on the barren lakebed of Laguna Salada. The lake disappeared after the building and filling of the Hoover Dam in the 30’s.

Drilling in this basin also opens a window into the tectonic processes acting in the northern Gulf of California. Recovering sediment samples from the Laguna Salada basin will also help to characterize the mechanical response of the soil to shaking during earthquakes.

The delta of the Colorado River is an area of rapid subsidence due to extension along the San Andreas-Imperial fault system and high flux of sediments transported by the Colorado River. These areas, therefore, have a high preservation potential to store information of past climate events. In January 2004 DOSECC recovered 92 m of lacustrine sediments from two shallow boreholes drilled in Laguna Salada, and active sedimentary basin in northern Baja California, México. Laguna Salada occupies a semiclosed depression between the Sierra the Cucapá on the west and the Sierra de Juárez on the east. Our goal for drilling in this basin was threefold: (i) to document past climatic changes during the last glacial age and its transition to the present warmer climate, (ii) to document climate changes during the last two glacial cycles, and (iii) to document the vertical slip component of the Laguna Salada fault, which bounds the eastern margin of the basin.

Colorado River Drilling1

Figure 2 – Drillers emplacing downhole logging geophysical instruments. This picture, as well as brief note about the drilling operations, made into the Spanish edition of National Geographic Magazine.

Boreholes were drilled at the toe of the alluvial fans adjacent to the Sierra de Juárez and on dry lakebed close to the Sierra de Cucapá and the Laguna Salada fault. Recovery was in excess of 95%. Equipment used during the drilling operation included DOSECC Lake System (DLS) suite of coring tools and a modified CS-500 rig. The main tool employed for coring was a hydraulic piston core. The quality of the cores is excellent, being found millimeter-scale primary sedimentary structures preserved in the sequence.

Ten C14 dates in charred organic matter and plant remnants indicate the core spans ~50 Ka and sedimentation rates are in the order of ~0.7 mm/yr. We can resolve in the core, therefore, climatic variability at timescales ranging from Milankovitch forcing up to millennial to centennial periodicities imprinted at scales ranging from centimeters to meters. We have found, for example, that 0.7-2 mm-thick lamina group in bundles of 6, 25 and 50 cm. Intercalations of massive clay, gypsum and sand tend to form cycles of 50 cm and 100-120 cm. We also have identified evidences of abrupt climate changes.

At Milankovitch time scales we have identified cycles based on sedimentary facies in the core, color, granulometry, mineralogical composition and primary structures such as laminae, dissecation cracks, and bioturbation. Additionally, we obtained reflectivity of sediments every 5mm to 1 cm depending on the scale of the primary structures. The recovered stratigraphy consists of three sedimentary successions. The base of the core is characterized by laminae of silt and mud 5mm-1cm thick deposited during glacial stage 2 through the last glacial maximum. This ancient paleolake was characterized by moist conditions in which a water table prevailed year-round. Good preservation of laminae suggests that bottom anoxia was frequent phenomenon.

Colorado River Drilling2

Figure 3 – stratigraphic column of the LS04-1 core. It contains a description of the sedimentary facies recovered by the cores. Additionally, it shows the major climatic changes experienced in the region during the last 60 kyr.

During the last glacial maximum, moisture conditions changed drastically. Laminations are replaced by finely stratified sand and further upsection by repetitive packages 50cm-thick composed of coarse sand, brown mud, greenish silt and mud, caped by 5-10 cm of evaporites. These sediments were deposited in a continental sabka environment with intermittent freshwater input, as evidenced by the clear dissecation cycles.

The Holocene climate in the region also experienced major shifts. For instance, the Holocene thermal maximum is characterized by deposition of well-classified sand deposits with granulometry similar to that of modern dune fields. This is indicative of hyper-arid conditions. The second half of the Holocene, on the other hand, experienced a return to relatively more moist conditions. However, the hydraulic balance probably is close to null given the presence of evaporitic deposits intercalated with laminated mud and fine sand.

Laguna Salada project, located in Mexico, was a 2004 project that was CICESE-funded.

 

View related publication.

Colorado River Drilling3

Figure 4 – Core from Laguna Salada showing perturbed sediments by an earthquake of at least Mw 6.

 

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Hawaii Scientific Drilling Project

Hawaii Scientific Core Drilling Services

Hawaii Scientific Drilling Project (1991 – 2008)

D.J. DePaolo Lawrence Berkeley National Laboratory

E.M. Stolper California Institute of Technology

D.M. Thomas University of Hawai’i at Manoa

 

Hawaii Scientific DrillingThe Hawaii Scientific Drilling Project drilled and cored two holes in Hilo, Hawaii, the deeper reaching a depth of 3520 meters below sea level, and retrieved a total of 4600 meters of rock core; 525 meters from the Mauna Loa volcano and the remainder from the Mauna Kea volcano. The Mauna Loa core extends the continuous lava stratigraphy of that volcano back to 100 ka and reveals major changes in lava geochemistry over that time period. The Mauna Kea core spans an age range from about 200 to perhaps 700 ka and when combined with surface outcrops, provides a 700 ky record of the lava output from a single volcano. During the time covered by the lavas from the core the volcano drifted some 60 to 80 km across the melting region of the Hawaiian mantle plume, and therefore the HSDP rock core provides the first systematic cross-sectional sampling of a deep mantle plume. The geochemical characterization of the core, which involved an international team of 40 scientists over a period of 15 years, provides information about mantle plume structure and ultimately about the deepest parts of the Earth’s mantle. The study of the lava core, which still continues, has provided unprecedented information about the internal structure of a large oceanic volcano and the time scale over which volcanoes grow. The hole also provides an intriguing glimpse of a complex subsurface hydrological regime that differs greatly from the generalized view of ocean island hydrology.

Hawaii Scientific Drilling1Drilling conditions were favorable in the subaerial parts of the volcanic section, where coring was fast and efficient. The submarine part of the lava section, made up primarily of volcanogenic sediments and pillow lavas, proved considerably more difficult to drill. Some of the difficulties, and considerable additional expense, were due to pressurized aquifers at depth and a few critical mistakes made while setting casing. Even with the more difficult conditions, the project retrieved about 2400 meters of nearly continuous core from the submarine section of Mauna Kea. Overall the HSDP project was highly successful, even though the original target depth was about 20% deeper than the final hole depth. The project results answer important questions about oceanic volcanoes, mantle plumes, and ocean island water resources, but raise many more that might be addressed with further moderate-depth drilling in other Hawaiian volcanoes.

Read more about this scientific core drilling services project at ICDP.

Representative References:

Abouchami, W., Hofmann, A.W., Galer, S.J.G., Frey, F.A., Eisele. J., Feigenson, M. (2005): Lead isotopes reveal bilateral asymmetry and vertical continuity in the Hawaiian mantle plume. Nature 434:851-856 (14 April 2005); doi:10.1038/nature03402.

Büttner, G., Huenges, E. (2002): The heat transfer in the region of the Mauna Kea (Hawaii) – constraints from borehole temperature measurements and coupled thermo-hydraulic modelling. Tectonophysics, 371, 23-40.

DePaolo, D.J. and Weis, D. (2007): Hotspot volcanoes and Large Igneous Provinces. In Harms, U. et al., ed. Continental Scientific Drilling: A Decade of Progress and Challenges for the Future, Springer-Verlag, 366pp

DePaolo, D.J., Stolper, E.M. and Thomas, D.M. (2007): Scientific Drilling In Hotspot Volcanoes, McGraw-Hill Yearbook of Science and Technology, p. 203-205

Helm-Clark, C.M., Rodgers, D.W., Smith, R.P. (2004): Borehole geophysical techniques to define stratigraphy, alteration and aquifers in basalt. Journal of Applied Geophysics, 55(1-2):3-38.

Herzberg, C. (2006): Petrology and thermal structure of the Hawaiian plume from Mauna Kea volcano. Nature 444:605-609 (30 November 2006); doi:10.1038/nature05254.

Lassiter, J.C., Hauri, E.H. (1998): Osmium-isotope variations in Hawaiian lavas: evidence for recycled lithosphere in the Hawaiian plume. Earth Planet. Sci. Lett. 164, 483-496.

Li, X., Kind, R., Yuan, X., Wölbern, I., Hanka, W. (2004): Rejuvenation of the lithosphere by the Hawaiian plume. Nature 427:827-829 (26 February 2004) doi:10.1038/nature02349.

Lassiter, J.C., (2003) Rhenium volatility in subaerial lavas: constraints from subaerial and submarine portions of the HSDP-2 Mauna Kea drillcore. Earth Planet. Sci. Lett. V. 214, pp. 311-325.

Ren, Z-Y., Ingle, S., Takahashi, E., Hirano, N., Hirata, T. (2005): The chemical structure of the Hawaiian plume. Nature 436:837–840.

Ribe, N.M. (2004): Earth Science: Through Thick and Thin. Nature 427:793-795 (26 February 2004) doi:10.1038/427793a.

Sobolev, A.V. (2002): Hunting for Earth’s primary melts. Humboldt Kosmos 79/2002:19-20.

Sobolev, A.V., Hofmann, A.W., Nikogosian, I.K. (2000): Recycled oceanic crust observed in ‘ghost plagioclase’ within the source of Mauna Loa lavas. Nature 404:986-989.

Sobolev, A.V., Hofmann, A.W., Sobolev, S.V., Nikogosian, I.K. (2005): An olivine-free mantle source of Hawaiian shield basalts. Nature 434:590-597 (31 March 2005); doi:10.1038/nature03411.

Vahle, C., Kontny, A., (2005), The use of field dependence of AC susceptibility for the interpretation of magnetic mineralogy and magnetic fabrics in the HSDP-2 basalts, Hawaii. Earth Planet. Sci. Lett., V. 238, pp. 110– 129

Walton, A.W., (2008) Microtubules in basalt glass from Hawaii Scientific Drilling Project #2 phase 1 core and Hilina slope, Hawaii: evidence of the occurrence and behavior of endolithic microorganisms. Geobiology, 6, 351–364

Zimmermann, G., Burkhardt, H., Englehard, L., (2005): Scale dependence of hydraulic and structural parameters in fractured rock, from borehole data (KTB and HSDP). From: HARVEY, P. K., BREWER, T. S., PEZARD, P. A. and PETROV, V. A. (eds), Petrophysical Properties of Crystalline Rocks. Geological Society, London, Special Publications, 240, 39-45

HSDP2 Papers (G-Cubed):

Althaus, T., Niedermann, S., Erzinger, J. (2001): Noble gases in olivine phenocrysts from drill core samples of the Hawaii Scientific Drilling Project (HSDP) pilot and main holes (Mauna Loa and Mauna Kea, Hawaii). doi: 10.1029/2001GC000275.

Blichert-Toft, J., Weis, D., Maerschalk, C., Agranier, A., Albarède, F. (2003): Hawaiian hot spot dynamics as inferred from the Hf and Pb isotope evolution of Mauna Kea volcano. Geochem. Geophys. Geosyst. 4, doi: 10.1029/2002GC000340.

Bryce, J.G., DePaolo, D.J., Lassiter, J.C. (2004): Geochemical structure of the Hawaiian plume: Sr, Nd, and Os isotopes in the 2.8 km HSDP-2 section of Mauna Kea volcano. Geochem. Geophys. Geosyst., Vol. 6, Q09G18, doi: 10.1029/2004GC000809.

Chan, Lui-Heung, Frey, F.A. (2002): Lithium isotope geochemistry of the Hawaiian plume: Results from the Hawaii Scientific Drilling Project and Koolau Volcano. doi: 10.1029/2002GC000365.

Eisele, J., Abouchami, W., Galer, S.J.G., Hofmann, A.W. (2002): The 320 kyr Pb isotope evolution of Mauna Kea lavas recorded in the HSDP-2 drill core. doi: 10.1029/2002GC000339

Feigenson, M.D., Bolge, L.L., Carr, M.J., Herzberg, C.T. (2001): REE inverse modeling of HSDP2 basalts: Evidence for multiple sources in the Hawaiian plume. doi: 10.1029/2001GC000271.

Fisk, M.R., Storrie-Lombardi, M.C., Douglas, S., Popa, R., McDonald, G., Di Meo-Savoie, C., (2003), Evidence of biological activity in Hawaiian subsurface basalts. Geochem. Geophys. Geosyst. Volume 4, Number 12, 1103, doi:10.1029/2002GC000387.

Garcia, M.O., Haskins, E.H., Stolper, E.M., Baker, M., (2007), Stratigraphy of the Hawai‘i Scientific Drilling Project core (HSDP2): Anatomy of a Hawaiian shield volcano. Geochem. Geophys. Geosyst. Volume 8, Number 2, doi: 10.1029/2006GC001379

Stolper, E.M., DePaolo, D.J., Thomas, D.M. (1996): Introduction of special section: Hawaii Scientific Drilling Project. Journal of Geophysical Research, 101, B5, p. 11593-11598.

Walton, A.W. and Peter Schiffman, 2003, Alteration of hyaloclastites in the HSDP 2 Phase 1 Drill Core 1. Description and paragenesis: Geochemistry, Geophysics, and Geosystems, v. 4, # 5, Paper # 2002GC000368, 3I pp.

Walton, A.W., Schiffinan, Peter, and Macpherson, G.L., 2005, Alteration of hyaloclastites in the HSDP 2 Phase I Drill Core 2. Mass balance of the conversion of sideromelane to palagonite and chabazite, Geochemistry, Geophysics, and Geosystems, v, 6, #9 Paper #2004GC00903, 27 pp.

Walton, Anthony W., 2007, Formation, modification, and preservation of microbial endolithic borings in hyaloclastite from Hawaii: Clues for petrographic recognition of mictrorbial traces in basalt glass of any provenance and stage of alteration: Lunar and Planetary Science XXXVIII, 1975.

Walton, Anthony W., 2008, Petrographic examination of occurrence, associations, and behavior of microorganisms: Endolithic microborings in basalt glass from HSDP 2 Phase I Core, Hilo and Hilina Slope, Hawaii. Geobiology, v. 6, p. 351-364, DOl: 10.1 I I l/j.14724669.2008.00149.

Yang, H.-J., Frey, F.A., Rhodes, J.M., Garcia, M.O. (1996): Evolution of Mauna Kea volcano: Inferences from Lava compositions recovered in the Hawaii Scientific Drilling Project. Journal of Geophysical Research, 101, B5, p. 11747-11767.

Stolper, E.M., DePaolo, D.J., Thomas, D.M. (1996): Introduction of special section: Hawaii Scientific Drilling Project. Journal of Geophysical Research, 101, B5, p. 11593-11598.

Walton, A.W. and Peter Schiffman, 2003, Alteration of hyaloclastites in the HSDP 2 Phase 1 Drill Core 1. Description and paragenesis: Geochemistry, Geophysics, and Geosystems, v. 4, # 5, Paper # 2002GC000368, 3I pp.

Walton, A.W., Schiffinan, Peter, and Macpherson, G.L., 2005, Alteration of hyaloclastites in the HSDP 2 Phase I Drill Core 2. Mass balance of the conversion of sideromelane to palagonite and chabazite, Geochemistry, Geophysics, and Geosystems, v, 6, #9 Paper #2004GC00903, 27 pp.

Walton, Anthony W., 2007, Formation, modification, and preservation of microbial endolithic borings in hyaloclastite from Hawaii: Clues for petrographic recognition of mictrorbial traces in basalt glass of any provenance and stage of alteration: Lunar and Planetary Science XXXVIII, 1975.

Walton, Anthony W., 2008, Petrographic examination of occurrence, associations, and behavior of microorganisms: Endolithic microborings in basalt glass from HSDP 2 Phase I Core, Hilo and Hilina Slope, Hawaii. Geobiology, v. 6, p. 351-364, DOl: 10.1 I I l/j.14724669.2008.00149.

Yang, H.-J., Frey, F.A., Rhodes, J.M., Garcia, M.O. (1996): Evolution of Mauna Kea volcano: Inferences from Lava compositions recovered in the Hawaii Scientific Drilling Project. Journal of Geophysical Research, 101, B5, p. 11747-11767.

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Iceland Lakes

Iceland Lakes Scientific Core Drilling Services Project

Iceland Lakes Drilling Project

Gifford Miller University of Colorado

Aslaug Geirsdottir University of Iceland

DOSECC’s GLAD200 drilling system was used to target three Icelandic lakes, Hestvatn (HST), Hvítárvatn (HVT), and Haukadalsvatn (HAK), each with 10 to 12 ka years of sediment fill, averaging 1 to 2 m sediment per thousand years. From these collections, one PhD (J Black, Colorado HVT), and two MSc (H Hannesdottir, Iceland HST and Gudrun Eva Johannsdottir, tephra geochemistry) theses have been completed. Two additional theses (D Larson, Colorado HVT, PhD and K Olafsdottir, Iceland HAK, MSc) are in progress.

Major Findings

1) During the Holocene thermal maximum (9 to 5 ka) summer temperatures were up to 3 °C warmer than late 20th Century averages, and Iceland’s large ice caps were either absent (Langjokull), or greatly reduced (Vatnajokull).

2) Neoglaciation set in about 5 ka with the maximum snowline lowering during the Little Ice Age.

3) Summer temperature depression during the Little Ice Age was up to 1.5 °C below late 20th Century averages, producing the most expanded local glacier limits since regional deglaciation.

4) Laminations in the HVT sediment cores have been confirmed to be annual varves. Varve thicknesses have been determined in two cores back to 870 AD, and in one additional core back 3 ka BP, with confirmation from 5 historic tephras and one 14C-dated tephra (H3). Varve thickness provides proxies for glacier size (summer temperature) and precipitation at annual resolution over this time interval. Spectral analyses of these signals (Olafsdottir) is in progress.

5) A geochemical characterization of all major tephra deposited over the past 10 ka is nearing completion. Lake records provide a far more complete record of explosive volcanism in Iceland than does any other archive, especially for tephras older than about 6 ka.

 

Iceland Lakes Drilling

Figure 1 – GLAD200 drilling platform
being used to core Hvítárvatn.

Iceland Lakes Drilling1

 

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Soufrière Hills Volcano

Soufriere Hill Volcano

The CALIPSO Project at Soufrière Hills Volcano, Montserrat, BWI: Using Integrated Deformation Data to Constrain Magmatic Processes

Glen Mattioli University of Arkansas, Fayetteville

Barry Voight, Derek Elsworth, Dannie Hidayat Pennsylvania State University

Alan Linde, Selwyn Sacks Carnegie Institution of Washington

Peter Malin Eylon Shalev Duke University

Jurgen Nueberg University of Leeds

Steve Sparks University of Bristol

 

The “Caribbean Andesite Lava Island Precision Seismo-geodetic Observatory,” (i.e. CALIPSO) has greatly enhanced the geophysical infrastructure at the Soufrière Hills Volcano (SHV), Montserrat with installation of an integrated array of borehole and surface instrumentation at four sites. Each site has a Sacks-Evertson dilatometer, a three-component seismometer (~Hz to 1 kHz), a Pinnacle Technologies tiltmeter, and an Ashtech u-Z CGPS receiver with choke ring antenna. This sensor package is similar to that being installed at volcanoes in western North America as part of EarthScope.

 

Soufriere Hill Volcano

Figure 1. Aerial photograph to the southwest showing the scar from the 2003 massive dome collapse of SHV and its pyroclastic flow-created delta deposits. Photo by B. Voight.

CALIPSO sensors recorded the collapse of the SHV lava dome on Montserrat in July 2003, the largest such event worldwide in the historical record (Mattioli et al., 2004). Dilatometer data show remarkable and unprecedented rapid (~600s) pressurization of a deep source. Voight et al. (2006) inferred an oblate spheriodal source with average radius ~1 km centered at 5.5 to 6 km depth. An overpressure of ~1 MPa, was attributed to growth of 1-3% of gas bubbles in supersaturated magma, triggered by the dynamics of dome unloading.

Pyroclastic flows entering the sea may cause tsunami generation at coastal volcanoes worldwide, but geophysically monitored field occurrences are very rare. Mattioli et al. (2007) reconstructed the process of tsunami generation and propagation during the prolonged, gigantic collapse of the SHV in 2003 using a combination of strain, seismic, and GPS data from the CALIPSO array.

Soufriere Hill Volcano1

Figure 2. DOSECC’s CS500 drilling rig on-site at Soufrière Hills Volcano.

Mattioli (2005) also reported that periods of surface uplift recorded by GPS at SHV correspond to an inflating, and subsidence, to a deflating Mogi source. Inverted depths are between 6 and 13 km, with the recent observations favoring a deeper source, supporting a temporal evolution of the mid-crustal pre-eruption storage zone from 1995 to 2005. Elsworth et al., 2008 modeled the surface deformation and surface efflux records from 1995 through 2007 assuming a vertically stacked array of two chambers at 6 and 12 km depth. They concluded that despite the episodic nature of the SHV eruption, melt was supplied to the base of the magmatic system at nearly constant rate and that the lower chamber was largely responsible for the surface deformation.