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Lake Olorgesailie

olorgesaillie-scientific-drilling-project-2

Lake Olorgesailie Scientific Drilling Project on Climate and Human Origins

Project details extracted from The Smithsonian Human Origins Program.

 

Potts's American and Kenyan team of drillers and core-recovery experts undertook day- and night-time drilling

DOSECC Core Drilling Services Team drilled day and night.

Project Goal

The Smithsonian’s Human Origins Program team was led by Dr. Rick Potts in collaboration with the National Museums of Kenya and worked with DOSECC to obtain the first long climate core from an early human fossil site.  The goal is to better understand the climate environments connected with the origin of our species in Africa, along with the preceeding events.

The core was taken on a flat, grassy plain in the previously unexplored southern region of the Olorgesailie basin at the prehistoric site of Olorgesailie, located in the southern Kenya Rift Valley.  Previous excavations documented fundamental changes in the behavior of our early human ancestors over the past 500,000 years.  However, many tens of thousands of years of this period are missing due to the erosion of sediment layers visible above ground in the Olorgesailie region. Drilling allowed researches to recover sediment layers underground that preserve a complete, high-precision record of rainfall, temperature, vegetation, and environmental stresses – and how these changed over time – during the critical transitions involved in the origin and evolution of Homo sapiens.

Strategically-placed drill cores will capture the continuous, fine structure of the environmental record, which is vitally important in studying questions about changes in Earth’s climate, environment, and geological forces. The cores will allow sufficiently high resolution to study short-duration events and processes (e.g., seasonality, interannual change, volcanic episodes, tectonic events) and to see how these relate to environmental changes over evolutionary time scales that may have influenced the evolution of human adaptations.

Background

This project is part of the Smithsonian’s Human Origins Program and relates to the Hominid Sites and Paleo Lakes Drilling Project HSPDP.  This scientific drilling program drills ancient lake sediments in eastern Africa and other regions in order to obtain long climate records in the areas once inhabited by early hominins. This allows researches to better understand worldwide, regional, and local climate dynamics relevant to the time periods and the regions where human evolutionary change took place.  This allows us to explore the parallels and connections between environmental change and human origins

Results

From September 2 to October 4, 2012, the effort to recover the core was successfully carried out.  The core, lifted from two boreholes in segments 3-meters long, represents a detailed record of lake sedimentation.  Through the plastic liners in which the core was recovered, fine laminations of diatomite and clay lake deposits can be seen, along with inputs of fine silts and sands – all of which we believe capture the environmental dynamics of this region of the East African Rift Valley over approximately the past 500,000 years.

Two men wearing hard hat and safety vest pulling a long thin plastic tube of cored sediment from a metal casing

A 3-meter-long core is extracted in its plastic liner from the core barrel, which was brought up from the 30- to 33-meter level below ground.
close up view of a clear plastic tube containing banded layers of sediment core

The laminations visible through the drill core liner suggest that even changes in the annual seasons of rainfall and vegetation are preserved in this core.

The cores extend down to 166m below the ground surface, and provide evidence of the ancient lake that had not previously been visible but that we suspected must have existed in the drilling area.

Unexpected challenges in recovering these cores occurred, but all were solved so that the project started and was completed on time. These challenges included initial difficulties in getting drilling rods, core liners, and other critical supplies into Kenya, a rupture in the water pipeline in the closest town of Magadi, which was to supply the drilling water at no cost to the project, and damage to the drilling rods during the first several days of drilling due to our local team’s unfamiliarity with the specialized rods sent from the U.S. for this project. Project funding along with the expertise assembled at the drill site were instrumental in meeting and solving these challenges as they arose.

Future Study and Implications

The Olorgesailie team is excited about the results of the core drilling.  Knowledge gained from our two decades of study elsewhere in the Olorgesailie region imply that the layers of lake sediment in the cores represent the past 500,000 years in high-resolution.  We will employ direct methods of dating the volcanic tephra in the core.  If our current understanding of the age range is correct, the core will give us the most exact record of climatic stresses and ecological change in East Africa during four key chapters in human evolution:

  1. The earliest transition from handaxe technology to innovative technologies, including projectiles (i.e., being able to hunt at a distance); this transition is recorded at Olorgesailie between 500,000 and 300,000 years ago;
  2. The origin of the modern East African biota, which occurred in the same era;
  3. The origin of our species, around 200,000 years ago;
  4. An era of low population size or population crash in Homo sapiens in Africa 100,000 to 70,000 years ago, just prior to the global expansion of our species.

Investigating the environmental challenges of these eras will allow us to test and determine as best as possible how evolutionary processes of survival helped shape the human species.

The first of two steps in this project have been completed.  The ultimate goal is not only to recover the cores but to produce well-studied cores, which we believe will yield benchmark scientific papers in the study of human origins.  In late April 2013, Potts will assemble an international team of 20 to 25 scientists to open the cores, which will be housed at the international lake core facility, LacCore, at the University of Minnesota, Minneapolis.  At the week-long workshop, our scientific team will describe and sample the cores for detailed analysis, followed by 12-24 months of laboratory studies, project workshops, synthesis of results, and the writing of publications.

Support from the William H. Donner Foundation (New York); the Ruth and Vernon Taylor Foundation (Montana); and the Peter Buck Fund for Human Origins Research (Smithsonian) has been indispensable in enabling us to achieve the first step in this project.  Projects are also being planned by other research teams to try to recover ancient lake cores from other famous fossil sites in East Africa.

Four scientists crowd around a lab bench collecting samples from geological cores in long tubular trays.
Twenty-two researchers from around the world participated in the Olorgesailie core workshop. The team collected samples every 48 centimeters in order to carry out many different kinds of environmental analysis.

 

View National Research Council of the U.S. National Academy of Sciences issued a report on March 3, 2010, titled ‘Understanding Climate’s Influence on Human Evolution’

Read the NRC report on the National Academy of Science’s website.

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Snake River Plain

Snake River Scientific Core Drilling Project

Project HOTSPOT: Scientific Drilling of the Snake River Plain

John Shervais Utah State University

 

Project HOTSPOT: Scientific Drilling of the Snake River Plain held its inaugural workshop in Twin Falls, Idaho, on May 18-21, 2006 (Shervais et al 2006a). This inter-disciplinary workshop explored major science issues and logistics central to a comprehensive, intermediate-depth drilling program along the hotspot track. This was followed by two special sessions at Fall 2006 AGU dedicated to SRP drilling, and meetings at GSA Denver 2007 and Fall AGU in 2007-2008.

Snake River Drilling

Figure 1 – HOTSPOT Workshop excursion in southern Idaho, showing massive basalt flows with pillows at base.

 

The central question addressed by the workshop was: how do mantle hotspots interact with continental lithosphere, and how does this interaction affect the geochemical evolution of mantle-derived magmas and the continental lithosphere? Our hypothesis is that continental mantle lithosphere is constructed in part from the base up by the underplating of mantle plumes that are compositionally and isotopically distinct from pre-Phanerozoic cratonic lithosphere. Plumes modify the impacted lithosphere in two ways: by thermally and mechanically eroding pre-existing cratonic mantle lithosphere, and by underplating plume-source mantle that has been depleted in fusible components by decompression melting to form flood basalts or plume track basalts. The addition of new material to the crust in the form of mafic magma represents a significant contribution to crustal growth, and densifies the crust in two ways: by adding mafic material to the lower and middle crust as frozen melts or cumulates, and by transferring fusible components from the lower crust to the upper crust as rhyolite lavas and ignimbrites, leaving a mafic restite behind. We further hypothesize that the structure, composition, age and thickness of continental lithosphere influence the chemical and isotopic evolution of plume-derived magmas, and localizes where they erupt on the surface.

We know from studies of surface basalts and existing core that these differences reflect in part variations in lithospheric age, composition, and thickness, magma fractionation and recharge in crustal storage systems, and assimilation of older crust, as well as input from the deep-seated mantle plume and adjacent asthenosphere. Concrete scientific questions to be addressed within this context include:

  • How do the variations in magma chemistry, isotopic composition, and age of eruption constrain the mantle dynamics of hotspot-continental lithosphere interaction?
  • What do variations in magma chemistry and isotopic composition tell us about processes in the crust and mantle? To what extent is magma chemistry controlled by melting, fractionation, or assimilation of crustal components, and where do these processes occur?
  • Is the source region predominately lithosphere, asthenosphere, or plume? What are the proportions of each? Are there changes in the magma source/proportions at any one location along the plain through time relative to the position of the hotspot?
  • How does a heterogeneous lithosphere affect plume-derived mafic magma? Effect of crust-lithosphere age, structure, composition, and thickness on basalt and rhyolite chemistry, from variations in lava chemistry along the plume track.
  • What is the time-integrated flux of magma in the Snake River-Yellowstone volcanic system? Is it consistent with models of plume-derived volcanism, or is this flux more consistent with other, non-plume models of formation?
  • Can we establish geochemical and isotopic links between the “plume head” volcanic province (Columbia River Basalts), and the “plume tail” province (Snake River Plain) in the western SRP?

Rhyolites of the SRP are distinct from normal calc-alkaline rhyolites associated with island arc systems: they were very hot (850º-1000ºC) dry melts with low viscosity and anhydrous mineral assemblages. They produced very large volume (>200 km3) low aspect ratio lavas, vast (≈1000 km3) well-sorted, intensely welded ignimbrites and lava-like ignimbrites, and regionally widespread ashfall layers with little pumice. They are the youngest and best-preserved example of this type of volcanism, but the SRP eruptive centers are concealed beneath basalt. They have geochemical affinities to A-type/P-type granites and are common in other plume-related silicic provinces throughout the world. Major issues include:

  • Origin of the SRP rhyolites: crustal melting or fractional crystallization of mantle-derived basalt?
  • What are the volumes of the rhyolitic eruptions? What is the eruptive mass flux, and how does this vary with time, as the hot spot tracks across changing lithosphere? Related to this, how much plume-derived mafic magma is required to produce the rhyolites, and what does this tell us about total magma flux in the Snake River-Yellowstone plume system?
  • Do the rhyolites associated with the older western province differ from those of central and eastern SRP? Does the plume-crust interaction vary across a heterogeneous cratonic margin?

Snake River Drilling1

The formation of A-type granitic melts as dry melts of continental crust requires an external heat source capable of transferring immense amounts of heat to the crust – sufficient to form large volumes of high silica rhyolite with magmatic temperatures of 850-1000ºC. Determining the heat budget associated with these melts will be critical to our understanding of plume-continent interaction. In addition, the large volumes of rhyolite preserve a record of magma chamber processes that cannot be seen in surface exposures, but which are critical to understanding the origin and nature of these unique magmas. Proximal rhyolites will also provide a more complete record than distal rhyolites exposed outside the plain.

Major science issues of the paleo-lake Idaho component of SRP drilling include: (1) testing the hypothesis for the role of moisture transport to North America from the Pacific initiation of Northern Hemisphere glaciation; (2) examining the response of the Great Basin hydrological system to the Pliocene climatic optimum; (3) using the high resolution lacustrine records to infer the chronology of biotic recovery in both terrestrial and aquatic ecosystems in the post-eruption intervals following some of the largest explosive volcanic eruptions known; (4) resolving late Neogene record of biotic and landscape evolution in response to tectonic and magmatic processes related to SRP-Yellowstone hotspot evolution; (5) developing a “master reference section” for regional biostratigraphy and hence for sediments inter-bedded in basalts and rhyolites at other HOTSPOT sites.

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

Selected References:

Boroughs S, Wolff J, Bonnichsen B, Godchaux M, Larson P, 2005, Large-volume, low-δ18O rhyolites of the central Snake River Plain, Idaho, USA. Geology 33; no. 10; p. 821-824; DOI: 10.1130/G21723.1

Branney, M., Bonnichsen, B., Andrews, G., Ellis, B., Barry, T., and McCurry, M., 2008, ‘Snake River (SR)-type’ volcanism at the Yellowstone hotspot track: distinctive products from unusual, high-temperature silicic super-eruptions: Bulletin of Volcanology, v. 70, no. 3, p. 293-314.

Davis, O.K., Ellis, B., Link, P., Wood, S., and Shervais, J.W. 2006. Neogene Palynology of the Snake River Plain: Climate Change and Volcanic Effects. EOS Trans. AGU, 87(52), Fall Meet. Suppl., Abstr. V43D-08

Glen JMG, Payette S, Bouligand M, Helm-Clark C, Champion D, 2006, Regional geophysical setting of the Yellowstone Hotspot track along the Snake River Plain, Idaho, USA. EOS Trans. AGU, 87(52), V54-1698.

Graham, D W,
Reid, M R
 Jordan, B T
Grunder, A L
Leeman, W P
Lupton, J E, 2006, A Helium Isotope Perspective on Mantle Sources for Basaltic Volcanism in the Northwestern US EOS Trans. AGU, 87(52), Fall Meet. Suppl., Abstr. V43D-02.

Haug, G.H., A. Ganopolski, D. Sigman, A. Rosell-Mele, G.E.A. Swann, R. Tiedemann, S. Jaccard, J. Bollmann, M. Maslin, G. Eglinton, 2006, North Pacific seasonality and the glaciation of North America 2.7 million years ago. EOS Trans. AGU, 87(52), Fall Meet. Suppl., Abstr. V43D-08

Hanan, BB Shervais, JW, and Vetter, SK, 2008, Yellowstone plume-continental lithosphere interaction beneath the Snake River Plain, Geology, v. 36, 51-54. DOI: 10.1130/G23935A.1

McCurry, M, Hayden, K, Morse, L, and Mertzman, S, 2008, Genesis of post-hotspot, A-type rhyolite of the Eastern Snake River Plain volcanic field by extreme fractional crystallization of olivine tholeiite: Bulletin of Volcanology, v. 70, no. 3, p. 361-383.

Shanks, W.C., Morgan, L.A., and Bindeman, I., 2006, Geochemical and oxygen isotope studies of high-silica rhyolitic ignimbrites from the Snake River Plain and Yellowstone: Eos, Transactions, AGU.

Shervais, J.W., Branney, M.J., Geist, D.J., Hanan, B.B., Hughes, S.S., Prokopenko, A.A., Williams, D.F., 2006a, HOTSPOT: The Snake River Scientific Drilling Project – Tracking the Yellowstone Hotspot Through Space and Time. Scientific Drilling, no 3, 56-57. Doi:10.2204/iodp.sd.3.14.2006.

Shervais, J.W., and Hanan, B.B., 2008, Lithospheric topography, tilted plumes, and the track of the Snake River-Yellowstone Hotspot, Tectonics, 27, TC5004, doi:10.1029/2007TC002181.

Shervais, J.W., Vetter, S.K. and Hanan, B.B., 2006, A Layered Mafic Sill Complex beneath the Eastern Snake River Plain: Evidence from Cyclic Geochemical Variations in Basalt, Geology, v. 34, 365-368.

Shervais, JW and Vetter, SK, 2009, High-K Alkali Basalts of the Western Snake River Plain: Abrupt Transition from Tholeiitic to Mildly Alkaline Plume-Derived Basalts, Western Snake River Plain, Idaho, Journal of Volcanology and Geothermal Research, in press.

van Keken, P E
EM: Lin, S, 2006, Mantle-lithosphere interaction beneath the Yellowstone-Snake River province, EOS Trans. AGU, 87(52), Fall Meet. Suppl., Abstr. V43D-04

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Lake Van

Lake Van scientific core drilling service project, located in Ahlat, Turkey

Lake Van project, located in Ahlat, Turkey

Lake Van project, located in Ahlat, Turkey, a 2011 scientific core drilling services project that was ICDP-funded.

Lake Van in Turkey is an excellent paleoclimate archive comprising long high resolution annually laminated sediment records covering several glacial-interglacial cycles. The lake is situated on the high plateau of eastern Anatolia and has a surface area of 3,522 km2. Its maximum depth is 451 m and its length is 130 km. It is the fourth largest of all terminal lakes in the world and contains highly alkaline waters. (Photo ©:NASA)

See more about the Lake Van scientific core drilling services project at ICDP.

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Lake El’gygytgyn

Lake El'gygytgyn Drilling1

The Thrill to Drill in the Chill — 3.6 Million Years of Arctic Climate Change from Lake El’gygytgyn, NE Russia

Julie Brigham-Grette University of Massachusetts – Amherst

Martin Melles University of Koln

Pavel Minyuk Northeastern Interdisciplinary Scientific Research Institute (NEISRI) – Magadan

Christian Koeberl University of Vienna

 

After several years of preparation, pre-site survey work, and arduous logistical planning, Lake El’gygytgyn is now the focus of a challenging interdisciplinary multi-national drilling campaign as part of the International Continental Drilling Program (ICDP). With drilling initiated in Nov. 2008, the goal is to collect the longest time-continuous record of climate change in the terrestrial Arctic and to compare this record with those from lower latitude marine and terrestrial sites to better understand hemispheric and global climate change.

Lake El'gygytgyn Drilling

Figure 1 – Cross section of Lake El’gygytgyn showing drilling locations.

 

 

 

 

 

 

 

 

 

 

 

 

Coring objectives include replicate overlapping lake sediment cores of 330 m and 420 m length at 2 sites (D1 and D2 in Fig. 1; four cores total) near the deepest part of the lake. Coring shall be continued 300 m (D1) and 100 m (D2) into the underlying impact breccia and brecciated bedrock in order to investigate the impact process and the response of the volcanic bedrock to the impact event. One additional land-based core (site D3) to ca. 200 m in lake sediments now overlain by frozen alluvial sediments on the lake-shore will allow better understanding of sediment supply to the lake and spatial depositional heterogeneity since the time of impact. This latter drill site at the west edge of the lake outside the talik (unfrozen ground in an area of permafrost) will also be used for permafrost studies and be permanently instrumented for future ground temperature monitoring as part of the Global Terrestrial Network for Permafrost (www.gtnp.org/index_e.html). Drilling of the primary D1 and D2 sites will take place from February to the middle of May 2009 using the lake ice as a drilling platform. The project is using a new GLAD-800 drilling system modified for extreme weather conditions by Drilling, Observation and Sampling of the Earths Continental Crust Inc. (DOSECC). Moreover, the science and logistics involves close cooperation with the Russian Academy of Sciences (Far East Geological Institute-Vladivostok; and Northeast Interdisciplinary Scientific Research Institute-Magadan) and Roshydromet’s Arctic and Antarctic Research Institute-St. Petersburg.

In summer 2009, the cores will be flown by chartered cargo plane to St. Petersburg. Later they will be trucked to the University of Cologne, Germany, for sub-sampling starting in September by the international team and their students; the archive core halves will be shipped to the University of Minnesota LacCore Facility in the US for post-moratorium studies.

The impetus for deep drilling at Lake El’gygytgyn is largely based on field and laboratory studies carried out over the past decade. Seismic work in the lake and morphostratigraphic work in the catchment and surrounding region confirmed that the lake record is undisturbed, without evidence of glaciation or desiccation (Niessen et al., 2007; Glushkova and Smirnov, 2007). A 12.9-m-long sediment core retrieved from the deepest part of the lake in 1998 revealed a basal age of ~ 250 kyr and demonstrated, using a variety of proxies, the sensitivity of this lacustrine environment to record high-resolution climatic change across NE Asia at millennial timescales (Brigham-Grette et al., 2007; Melles et al., 2007; Nowacyzk et al., 2007; Forman et al., 2007; plus 7 other papers in same issue listed in supplemental references; Fig. 2). A 16.7-m-long sediment core taken nearby in 2003 dated to nearly 300 kyr and confirmed the reproducibility of the record (Juschus et al., 2007).

This research also showed that nearly every proxy can be systemically linked to changes in the duration of seasonal lake ice cover, regional temperature, and changes in hydrologic input driven largely by high latitude precessional cycles and feedbacks. For example, the magnetic susceptibility and sedimentology showed that perennial ice cover during glacial summers led to anoxia in the hypolimnion, which had a profound impact on the biogeochemistry at the sediment/water interface (Nowacyzk et al. 2007; Minyuk et al., 2007). Knowledge of the basin geomorphology and sedimentation processes informs us of likely changes in landscape weathering and sedimentation rates (Asikainen et al., 2007; Glushkova and Smirnov, 2007). We have also demonstrated that while gravitational sediment transport occurs in the basin, such events do not cause erosion of the continuous stratigraphy in the center of the lake where drilling is planned. Documenting the dynamics and controls on the lake’s seasonal ice cover (Nolan et al, 2003; Nolan and Brigham-Grette, 2007) has been key to understanding lake circulation and beach geomorphology. Moreover, this work has been critical to developing safety plans for ice thickening and engineering prior to drilling from the lake’s frozen surface.

 

Lake El'gygytgyn Drilling1

Figure 2 – DOSECC’s drilling platform on Lake El’gygytgyn, March 2009.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Our ability to inform policy makers about global/regional climate and related environmental change and its uncertainties depends on our capacity to understand the role of the Arctic region in modulating past periods of change under different climate forcing conditions. Of prime interest to the scientific community is determining why and how the Arctic climate system evolved from a warm forested ecosystem into a cold permafrost ecosystem between 2 and 3 million years ago. A continuous depositional record in this unique lake provides a means of capturing the mechanisms and dynamics of glacial/interglacial and millennial-scale change from this region over the duration of the “41 kyr world” and late Cenozoic “100 kyr world”. This record will then be compared with other long records from around the world, but especially the low latitude ocean records, to evaluate polar amplification, model systemic teleconnections and leads/lags relative to insolation forcing. This record will also provide insight as to whether rapid change events identified during the last glacial cycle are typical of earlier glacial periods. We hope to provide the science community with an understanding of the poorly documented regional sensitivity of the NE Asian Arctic to millennial-scale abrupt change (Heinrich and D/O scale) and interglacial warmth detected at global vs. regional scales, within the timeframe of the EPICA ice cores, long Asian loess and lake records, and comparable marine records. Climate modeling is also an important aspect of the program to allow these relationships to be evaluated systematically.

View more information at ICDP on Lake El’gygytgyn

Acknowledgements

The Lake El’gygytgyn Drilling Project is an international effort funded by the International Continental Drilling Program (ICDP), the US National Science Foundation Earth Sciences Division and Office of Polar Programs (NSF/EAR/OPP), the German Federal Ministry for Education and Research (BMBF), Alfred Wegener Institute (AWI), and GeoForschungsZentrum-Potsdam (GFZ), and the Russian Academy of Sciences Far East Branch (RAS/FEB). The leading Russian institutions include Roshydromet’s Arctic and Antarctic Research Institute (AARI), the Northeastern Interdisciplinary Scientific Research Institute (NEISRI) and the Far East Geological Institute (FEGI). The deep drilling system for Arctic operations was developed by DOSECC, Inc.

References:

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.

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.

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.

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.

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Lake Potrok Aike

Lake Potrok Aike scientific core drilling services project, located in Rio Gallegos, Argentina, a 2008 project that was ICDP, DFG-funded.

Lake Potrok Aike project, located in Rio Gallegos, Argentina, a 2008 project that was ICDP, DFG-funded.Lake Potrok Aike scientific core drilling services project, located in Rio Gallegos, Argentina, a 2008 project that was ICDP, DFG-funded.

The research initiative “Potrok Aike Maar Lake Sediment Archive Drilling Project” (PASADO) within the framework of ICDP addresses several key issues related to the evolution of maar craters, to quantitative climatic and environmental reconstruction, fire history, tephra and dust deposition and palaeosecular variation of the Earth’s magnetic field for the last several glacial to interglacial cycles. Moreover, dust and tephra records provide links to marine sediment archives and ice cores. Obtained reconstructions of climate variability have been compared to climate simulations from GCM’s to detect signals of climatic forcing.

Read more about the Lake Potrok Aike Scientific Core Drilling Services Project at ICDP.

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Andrill Program

Andrill Program scientific drilling

ANDRILL Program

Frank Rack University of Nebraska-Lincoln

 

andrANDRILL (Antarctic geological DRILLing) is a multinational collaboration comprised of more than 250 scientists, students, and educators from five nations (Germany, Italy, New Zealand, the UK and the US) whose objective is to recover stratigraphic records from the Antarctic margin using drilling technology deployed from ice shelf and sea-ice platforms. ANDRILL’s primary objective is to drill back in time to recover a history of paleoenvironmental changes that will guide our understanding of how fast, how large, and how frequent glacial and interglacial changes were in Antarctica. Future scenarios of global warming and climate change require guidance and constraint from past history that will reveal potential timing frequency and site of future changes.

Andrill Program

Figure 1 – Map of the Victoria Land Basin, showing the location of the MIS and SMS drillsites. Also shown are the locations of earlier drilling in the region as part of the Cape Roberts Project (CRP), and earlier drilling expeditions. The dark blue area represents the area covered by the McMurdo Ice Shelf, which is buttressed by Ross Island, while the lighter blue is the area covered by seasonal or perennial sea ice.

Operations and logistics for ANDRILL are managed by Antarctica New Zealand. The scientific research is administered and coordinated through the ANDRILL Science Management Office (SMO), located at the University of Nebraska-Lincoln. The overall international budget for ANDRILL is approximately $30 million US, with approximately $13 million US funding the activities managed by the ANDRILL SMO, which includes annual subcontracts with US academic institutions to provide services for each project, and funding for the participation of US scientists in ANDRILL and post-expedition research support through the ANDRILL US Scientist Support Program. The use of DOSECC tools by the ANDRILL drilling system was facilitated through the efforts of Alex Pyne, Victoria University of Wellington.

The McMurdo Sound region was the first area for Antarctic drilling under the ANDRILL banner; however, future target areas for scientific drilling are located all around the Antarctic margin. Because of the wide range of proposed drilling targets, individual drilling objectives are grouped into portfolios based on logistical requirements. The first drilling portfolio was the McMurdo Sound Portfolio, with two specific projects being funded in this portfolio, namely, the McMurdo Ice Shelf (MIS) Project (drilled in 2006) and the Southern McMurdo Sound (SMS) Project (drilled in 2007).

The ANDRILL Program successfully recovered a 1285m-long succession of cyclic glacimarine sediment with interbedded volcanic deposits, in its first season of drilling from the McMurdo Ice Shelf (MIS). The MIS drillcore represents the longest and most complete (98% recovery) geological record from the Antarctic continental margin to date, and will provide a key reference record of climate and ice sheet variability through the Late Neogene (~13Ma to present). The DOSECC sediment coring tools (Figure 3) were used to recover shallow subsurface sediments near the seafloor-water interface prior to the installation of the ANDRILL riser system using push-, gravity- and piston-coring approaches. The outcomes of these operational and scientific activities are included in the contributions to the ANDRILL MIS Project’s Initial Results volume in Terra Antarctica (Naish, Powell, et al., 2007). The initial results of the ANDRILL SMS Project were assembled for publication in Terra Antarctica in early 2009.

Andrill Program1

Figure 2 – The ANDRILL MIS Project drillsite, showing the drill rig and the integrated systems that contribute to its operation, including equipment storage and laboratory vans.

Specific science objectives of the McMurdo Sound Portfolio include:

  • Obtain high-resolution sediment cores that record major glacial events and transitional periods over the past 40 million years;
  • Determine orbital and sub-orbital glacio-climatic fluctuations that vary on 100,000, 40,000, and 20,000 year cycles (e.g., Milankovitch cycles);
  • Obtain a refined record of the onset and development of the East Antarctic ice sheet (EAIS) from 40 million years ago;
  • Identify how the Antarctic region responded to past episodes of global warmth;
  • Derive a detailed history of Antarctic Holocene environmental change at the end of the last glaciation (since the last glacial maximum at 20,000 years ago); and,
  • Test global linkages between climate changes in the Northern and Southern hemispheres.

In 2006-2007, the ANDRILL Program drilled to a record depth of 1284.87 meters below seafloor, through an access hole in the 85 meter-thick McMurdo Ice Shelf. This is the deepest sub-bottom penetration a drilling rig has ever reached in the Antarctic region, and it is the first time a geological drilling system operated through a floating ice shelf over nearly 900 meters of water. These successes are amplified by the recovery of more than 98% of the drilled interval as sediment cores that represent a nearly unbroken geological history of substantial glacial and climatic variation. Alternations of clastic-rich glacial sediment and diatomaceous marine sediment indicate a dynamic history of West Antarctica’s ice shelf /sheet advancing and retreating more than 50 times during the last 5 million years.

Andrill Program2

Figure 3 – DOSECC coring tools used at ANDRILL

A team of fifty-eight scientists, technicians, educators and support staff from United States, New Zealand, Italy and Germany spent three months in the Crary Laboratory of McMurdo Station providing the initial description and characterization of the recovered core. Their initial results document how Antarctic ice sheets behaved during periods of global warmth greater than the present day. Volcanic ashes, microfossils and paleomagnetic stratigraphy provide ages of the sediments and a means to compare this high latitude climatic history with that of other regions. Climate and ice sheet models will extend these results and provide guidance regarding potential response by the West Antarctic Ice Sheet and Ross Ice Shelf to future scenarios of global warming. Frequency and apparent speed of the retreating ice shelf, leading to interglacial and open marine conditions in the Ross Embayment, will be one focus of future studies on these cores.

The ANDRILL drilling season began in early October 2007 with the deployment of the drilling system and remote camp at the start of the SMS Project, which is co-led by Drs. David Harwood (UNL) and Fabio Florindo (Italy). Several UNL Department of Geosciences faculty members are part of the SMS team, including Drs. Chris Fielding, Tracy Frank, and Richard Levy, as well as UNL graduate student Eva Tuzzi. UNL undergraduate student Jake Carnes is participating in the Mackay Sea Valley seismic survey, which is related to future ANDRILL proposal development activities.

 

Selected References:

Armand L.K., Crosta X., Romero O. & Pichon J.-J., 2005. The Biogeography of Major Diatom Taxa in Southern Ocean Sediments: 1. Sea Ice Related Species. Palaeogeogr., Palaeoclim., Palaeoecol., 223, 93–126.

Bannister S. & Naish T.R., 2002. ANDRILL Site Investigations, New Harbour and McMurdo Ice Shelf, Southern McMurdo Sound, Antarctica. Institute of Geological & Nuclear Sciences, Science Report 2002/01, 24 p.

 

 

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Best Practices in the Development of Scientific Drilling Projects, Cohen & Nielson, 2007

Nielson: scientfic drilling company best practices

EXECUTIVE SUMMARY

Continental Scientific Drilling has an established record in advancing the earth sciences. The Continental Scientific Drilling Program was carried out in the U.S. between 1985 and 1994 and has been succeeded by the International Continental Scientific Drilling Program. Currently, projects of national and international interest are underway, and scientific drilling on continents and oceans is not as clearly separated as it once was. The process of developing a scientific drilling project, particularly one of international scope, is complex and both scientists and funding agencies need to understand the practical requirements that lead to success. In an effort to provide input to funding agencies concerning the scientist’s perspective of the proposal process and to provide a road map for scientists contemplating a scientific drilling proposal, DOSECC convened a workshop in May 2003 to address Best Practices in the Development of Scientific Drilling Projects. This report defines the stages from initial concept through the post-drilling activities, and presents recommendations that will be of interest for proponents of scientific drilling projects, particularly those that will have international participation.

 

 

 

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Lake Peten Itza

Lake Peten-Itza Scientific Drilling Project

The Lake Petén-Itzá Scientific Drilling Project (Proyecto Paleoambiental Lago Petén-Itzá)

Mark Brenner University of Florida

Lake Petén-Itzá lies at 110 masl in the lowlands of northern Guatemala. The lake has a surface area of ~100 km2 and a maximum depth ~165 m. It was targeted for drilling because it may be the only lake in lowland Central America to have held

water and preserved a record of paleoclimate/paleoenvironment changes through the last Glacial. Plans to drill Lake Petén-Itzá were formulated in the late 1990s. A joint Swiss-US team conducted seismic-imaging campaigns in 1999 (3 kHz pinger) and 2002 (airgun) that demonstrated the basin possessed thick lacustrine deposits. The seismic images were used to identify 6 primary and 4 alternate drill sites. Preliminary coring of Holocene sections was done in 2002 using a Kullenberg gravity corer. With seismic images (Anselmetti et al. 2006) and Holocene cores in hand (Hillisheim et al. 2005), a planning workshop supported by the International Continental Scientific Drilling Program, was convened in Flores, Guatemala in 2003. Scientists from 12 countries attended the meeting.

The Lake Petén-Itzá Scientific Drilling Project (PISDP) was undertaken to achieve three major objectives:

  • Develop a high-resolution paleoclimate reconstruction for the lowland neotropics extending well into, and perhaps beyond the last Glacial. Explore correlations between climate changes at this tropical, low-altitude site, and marine/terrestrial paleoclimate records from tropical and extra-tropical regions (e.g. Cariaco Basin, Greenland)
  • Investigate shifts in vegetation that accompanied climate fluctuations in the region during glacial and interglacial times. Evaluate responses of vegetation to natural (climate) forcing and later Maya land clearance
  • Study sediment biogeochemistry to gain a better understanding of mineral production in the water column and sediments of the lake, in response to changing hydrologic conditions.

 

Lake Peten-Itza Drilling

Figure 1 – Location of Lake Petén-Itzá, Guatemala.

 

 

 

 

 

 

 

 

 

 

 

 

 

Drilling was conducted by DOSECC in Lake Petén-Itzá between 3 February and 11 March, 2006 using the Global Lakes Drilling (GLAD800) rig mounted on the “superbarge” R/V Kerry Kelts. More than 60 people, including drillers, scientists, and students, participated in the field effort. Cores were retrieved at 7 sites in the lake, ranging in water depth from 30 to 150 m. A single core was collected at the shallow site (30 m), whereas three parallel holes were drilled at five sites, and five cores were taken at site PI-2 (water depth 54 m). In total, 1327 m of sediment were collected, with recovery at each site averaging between 86.3 and 94.9%.

Retrieved cores were analyzed in the field for magnetic susceptibility and gamma ray attenuation (density), using a multi-sensor core logger. Cores were ultimately shipped to the LacCore facility at the University of Minnesota for storage. Sampling parties visited Minneapolis in the summers of 2006 and 2007 to sample the cores and begin analyses. Composite Core PI-6 extended to 75.9 m below the lake floor and was chosen as the first candidate for study. The core was re-measured for magnetic susceptibility and gamma ray density at high-resolution. Next, core sections were opened, split, and imaged digitally, prior to sampling.

Core PI-6 represents ~85,000 years of continuous sediment accumulation, as determined from AMS 14C dating and tephra layers of known age. Pleistocene-age deposits possess alternating clay- and gypsum-rich sediments that reflect relatively wetter and drier conditions, respectively. Clay sections display higher magnetic susceptibility and lower density than gypsum deposits. Wetter times in lowland Central America were associated with interstadials and drier periods with stadials. Carbonate clays dominate the record from about 85 to 48 ka, suggesting relatively moist conditions. From 48 to 23 ka, the record displays wet-dry (clay-gypsum) alternations that resemble temperature inferences from Greenland ice cores and North Atlantic marine sediment cores, as well as rainfall reconstructions from the Cariaco Basin. A thick clay layer associated with the Last Glacial Maximum (LGM) chronozone (21+/-2 ka) indicates relatively moist conditions. This finding is at odds with previous inferences for arid LGM conditions in lowland Guatemala. The deglacial was marked by alternating moist and very dry conditions, with abundant gypsum precipitated from 18.0-14.7 ka, and 12.8-10.3 ka. Holocene conditions at 10.3 ka reflect increased rainfall and onset of more organic-rich sediment deposition.

Lake Peten-Itza Drilling1

Figure 2 – Drilling crew aboard the R/V Kerry Kelts (photo courtesy of ICDP).

Pollen analyses suggest 5 °C cooling at the LGM, at which time pine and oak co-existed with tropical forest elements in the region. Pollen data support geochemical analyses in pointing to times in the deglacial as the periods of greatest aridity. Changes in temperature/moisture availability throughout the deglacial (18-10.3 ka) are also being documented using stable oxygen isotope measurements on ostracod shells from the core.

 

Cores collected by the PISDP are providing the first well-dated, high-resolution records of Pleistocene climate and environmental change in lowland Central America. In addition to the preliminary information gleaned from core PI-6, investigation of ash layers in cores from site 7 suggest a >200 ka record was retrieved.

 

Findings of the PISDP of interest to a broad range of scientists, including paleoclimatologists, climate modelers, palynologists, biogeographers, sedimentologists, microbiologists, paleoecologists, and others. The public should also take interest, as the high-resolution paleoclimate records from the PISDP will provide information on the range of natural climate variability in the lowland neotropics prior to human impact.

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

References:

Anselmetti, F.S., D. Ariztegui, D.A. Hodell, A. Gilli, M.B. Hillesheim, M. Brenner, and J.A. McKenzie. 2006. Late Quaternary climate-induced lake level variations in Lake Petén Itzá, Guatemala, inferred from seismic stratigraphic analysis. Palaeogeography, Palaeoclimatology, Palaeoecology 230:52-69.

Bush, M.B., Correa-Metrio, A., Hodell, D.A., Brenner, M., Anselmetti, F.S., Ariztegui, D., Mueller, A.D., Curtis, J.H., Grzesik, D., Burton, C., and Gilli, A. In press. The Last Glacial Maximum in lowland Central America. In: F. Vimeux, F. Sylvestre, and M. Khodri (Eds.), Past Climate Variability from the Last Glacial Maximum to the Holocene in South America and Surrounding Regions. Developments in Paleoenvironmental Research (DPER) Series. Springer, Dordrecht, Berlin, Heidelberg, New York.

Escobar, J., D.A. Hodell, M. Brenner, J.H. Curtis. In prep. Climate change in the northern neotropics during the last deglaciation. Geology.

Hillesheim, M.B., D.A. Hodell, B.W. Leyden, M. Brenner, J.H. Curtis, F.S. Anselmetti, D. Ariztegui, D.G. Buck, T.P. Guilderson, M.F. Rosenmeier, and D.W. Schnurrenberger. 2005. Lowland neotropical climate change during the late deglacial and early Holocene. Journal of Quaternary Science 20:363-376.

Hodell, D.A., Anselmetti, F.S., Ariztegui, D., Brenner, M., Curtis, J.H., Gilli, A., Grzesik, D.A., Guilderson, T.J., Muller, A.D., Bush, M.B., Correa-Metrio, Y.A., Escobar, J., and Kutterolf, S. 2008. An 85-ka Record of climate change in lowland Central America. Quaternary Science Reviews. 27:1152-1165.

Hodell, D., Anselmetti, F., Brenner, M., Ariztegui, D., and the PISDP Scientific Party. 2006. The Lake Petén-Itzá Scientific Drilling Project (PISDP). Scientific Drilling 3: 25-29.

Hodell, D., Anselmetti, F.S., Ariztegui, D. Brenner, M., Curtis. J., and the PISDP Scientific Party. 2006. Preliminary results of the Lake Petén-Itzá Scientific Drilling Project. DOSECC News 4:5-6.

Hodell, D., Anselmetti, F.S., Ariztegui, D. Brenner, M., Curtis. J., and the PISDP Scientific Party. 2006. 1.3 km of sediment recovered by the Lake Petén-Itzá Scientific Drilling Project. DOSECC News 4:1-2.

Mueller, Andreas D.. 2009. Late Quaternary Environmental Change in the Lowland Neotropics: The Petén-Itzá Scientific Drilling Project, Guatemala. PhD Dissertation ETH No. 18349.

Abstracts:

Anselmetti, F.; Hodell, D.; Ariztegui, D.; Brenner, M.; Curtis, J.; Escobar, J.; Gilli, A.; Grzesik, D.; Kutterolf, S.; Mueller, A.D. 2008. The Peten Itza Scientific Drilling Project: A 200-ka record of climate change in lowland Central America. International Geological Congress. Oslo, Norway. August 2008.

Brenner, M., Hodell, D.A., Curtis, J.H., Escobar, J., Anselmetti, F.S., Ariztegui, D., Muller, A.D., Grzesik, D.A. 2008. Proyecto Paleoambiental Lago Petén-Itzá: nuevas perspectivas sobre el paleoambiente y paleoclima de Centroamerica. I Congreso Nacional de Cienagas y Lagunas. Medellin, Colombia. Sept 2008.

Escobar, J., Hodell, D.A., Anselmetti, F.S., Ariztegui, D., Brenner, M., Curtis, J.H., Gilli, A., Grzesik, D.A., Guilderson, T.J., Muller, A.D., Bush, M.B., Correa-Metrio, Y.A., Kutterolf, S. 2008. An 85-ka paleoclimate record from lowland Central America. Joint Assembly of the American Geophysical Union (AGU). Fort Lauderdale, Florida. May 2008.

Escobar, J., Hodell, D.A., Brenner, M., Curtis, J.H., Gilli, A., Anselmetti, F.S., Ariztegui, D., Grzesik, D.A., Mueller, A.D. 2008. Paleoclimate of lowland Central America during the last deglaciation. European Geophysical Union (EGU). Vienna, Austria. April 2008.

Hodell, D., Anselmetti, F., Ariztegui, D., Brenner, M., Curtis, J., Escobar, J., Gilli, A., Grzesik, D., Kutterolf, S., Mueller, A.D. 2008. The Petén-Itzá Scientific Drilling Project: A 200-ka record of climate change in lowland Central America. European Geophysical Union (EGU). Vienna, Austria. April 2008.

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Shaldril

SHALDRIL Project

U.S. Antarctic Program Shallow Drilling Project (SHALDRIL) Cruises Completed Using DOSECC Tools

  1. S. Wellner University of Houston
  2. L. Holloway ConocoPhillips

 

SHALDRIL (for SHALlow DRILling) is a project of the United States Antarctic Program aimed at developing and demonstrating a system to obtain drill core from the Antarctic continental margin. The concept behind SHALDRIL is to drill through the stiff glacial overburden that covers nearly all of the Antarctic continental shelf and has historically inhibited piston coring, in order to sample older deposits where they come close to the seafloor. In addition to being able to sample older lithified material, the system developed must also have the ability to sample soft sediment. SHALDRIL is designed to operate between the continental slope, where traditional drill ships typically work, and the fast-ice zone, where ANDRILL is best suited. The success of the SHALDRIL method is dependent upon having a mobile drilling platform, capable of operating in ice-covered waters, and a drilling system that can retrieve high-quality core during an extremely short operating window.

 

SHALDRIL Project

Figure 1- Nathanial B. Palmer with drill rig installed, SHALDRIL project, Antarctica

 

The History

In 1994, a workshop was convened at Rice University in Houston, TX. Fourteen scientists attended the workshop, which focused on new data from the continental shelf offshore of Seymour Island (Anderson et al., 1992; Sloan et al., 1995). There was strong consensus from the group that shallow drilling would yield key information about this critical region, the “Last Refugium of Antarctica.” The workshop participants also discussed drilling technology. In the final analysis, it was determined that the technology for SHALDRIL was not yet ready. A SHALDRIL committee was formed to monitor technical advances. The result of this work is several reports outlining different methods and techniques that might be utilized. In 2000, the SHALDRIL steering committee learned about improved drilling systems, including diamond coring, capable of drilling in water depths of several hundred meters and to core a few hundred meters beneath the seafloor. In 2003 a contract was signed with Seacore Limited (UK) to design and build a vessel specific drilling rig and to conduct the drilling operations for SHALDRIL. The rig was mounted over a small moonpool that was installed through the starboard deck of the RV/IB Nathaniel B. Palmer (Fig. 1).

The Campaign

SHALDRIL II was conducted in the northwestern Weddell Sea and the primary drilling targets were in the northern portion of the James Ross Basin, which contains one of the most complete Neogene successions anywhere in Antarctica (Anderson, 1999). Previous seismic investigations have revealed a virtually continuous succession of seaward-dipping strata on the continental shelf. The succession spans the late Eocene through Pleistocene.

Throughout both cruises the Seacore rig operated without difficulty and only minor adjustments were made to it between the cruises. The sampling tools for SHALDRIL I worked extremely well when taking push samples through soft Holocene sediments but were not so successful at getting through the stiff Pleistocene till. Thus, a change was made for the 2006 cruise to develop a modified set of sampling tools supplied to Seacore through DOSECC.

DOSECC Bottom Hole Assembly

The primary set of drilling hardware includes a suite of DOSECC tools that were designed to work within a common bottom hole assembly (BHA). The DOSECC tools were originally designed to operate with a drill bit with an internal diameter (ID) of 3.345″. However, for SHALDRIL, the bit throat was modified to accommodate a larger 3.85” ID. The larger throat would have allowed the Seacore piggy-back coring hardware (PBCH) to be deployed through the common BHA bit if material was encountered where high-speed diamond coring was required. This option was not deployed during the 2006 campaign. Since the time at any drill site was severely limited due to drifting ice, it proved important to have multiple tools fitting the same BHA in order to reduce tripping times to change the BHA.

Two coring assemblies and one non-coring tool were developed. These include an extended-nose spring-loaded corer and another DOSECC assembly known as the Alien corer. The extended nose corer is typically used for sediments after push or piston sampling is exhausted. The alien corer is similar to the extended nose corer but is designed to sample harder material and uses a triple core barrel inner tube assembly that is rotated in conjunction with the larger outer BHA. Due to increasing the bit and tools to accept the larger throat size in the primary BHA bit, all tools were then able to sample the same core size. The alien corer proved to be the tool used during the majority of the SHALDRIL II cruise. Sample recovery was high using this system. In addition, drilling through the subglacial and glacial-marine diamictons that form the overburden above most of the targeted strata was just as fast with the alien corer as with the non-coring tool (i.e., center bit installed in place of a coring assembly).

SHALDRIL Project1

Figure 2- Alien drill bit with glacial diamicton collected during SHALDRIL

Drill-in Bottom Hole Assembly

As noted above, the first hardware option allowed up to three sampling systems to be deployed through the same BHA. Others tools are available but were not part of the suite of tools purchased by Seacore for SHALDRIL II. Should hard rock be encountered at a very shallow depth where the common BHA bit cannot be advanced easily, a different operating system can be deployed. This hardware, which was originally developed at ODP and slightly modified for SHALDRIL, uses a robust five roller-cone bit and a one-cone center bit latched into its throat. The center bit is removable via wire line once the BHA has been drilled to depth to allow a clear passage for the PBCH to be initiated. This hardware was not deployed during SHALDRIL II.

The Results

During SHALDRIL II, the ice conditions along the existing seismic lines did not allow any of the proposed sites to be occupied in their exact locations. The ability to continue drilling into sections of the desired age was dependent on collection of new seismic data during the cruise. In effect, areas of open water were identified, then seismic data was collected and correlated, and then sites were selected and drilled before changes in ice conditions. Without this ability to follow the water, chances are none of the objectives would have been met.

While none of the planned sites were drilled, nearly all of the coring objectives were met by drilling in alternate locations. A total of five holes reached the targeted older material yielding samples from the Eocene, Oligocene, Miocene, and Pliocene, although only a few meters were recovered from any one hole due to being driven away by ice. Also during the SHALDRIL II cruise, a long Holocene core was recovered from the Firth of Tay that will complement other Holocene cores of the area, including that from Maxwell Bay collected during the 2005 SHALDRIL cruise. The only SHALDRIL drilling objective that was not met was to gain a continuous sample through a thick (80-100 m) grounding zone wedge deposit. This was simply not possible due constant problem of drifting ice. However, based on the samples obtained from the overburden at other sites, there is every reason to believe this would have been technically possible.

The Future

The sea ice conditions encountered during SHALDRIL II were the worst-case scenario, thick multiyear ice drifting at rates that were unpredicted. The fact that SHALDRIL is so mobile enabled us to improvise and overcome severe sea-ice conditions and exploit alternate sites, proving the efficacy of the “drill and run” strategy. The drilling and sampling system is capable of penetrating up to 20 meters of glacial overburden and sampling older strata within 24 hours time. Core recovery in partially lithified sedimentary material is quite good (greater than 80%). The fact that success was found in more ice, and thus much shorter windows for drilling, than predicted will allow future SHALDRIL plans to be made for a much broader set of conditions. We hope that this is the beginning of a long program of drilling from icebreakers in the Antarctic.

Acknowledgments

We thank the crew of the NBP and the dedicated staffs at Raytheon Polar Services Company and Seacore for helping to make SHALDRIL possible. We are supported by NSF Office of Polar Programs grant ANT-0125526 to John Anderson (Rice University), in collaboration with P. Manley (Middlebury College), S. Wise (Florida State University), and J. Zachos (University of California Santa Cruz.)

References:

Anderson, J.B., S.S. Shipp, and F.P. Siringan (1992), Preliminary seismic stratigraphy of the northwestern Weddell Sea Continental Shelf, in Y. Yoshida, K. Kaminuma, and K. Shiraishi (Eds.), Recent Progress in Antarctic Earth Science, Terra Scientific Publishing, Tokyo, 603-612.

Sloan, B.J., L.A. Lawver, and J.B. Anderson (1995), Seismic stratigraphy of the Palmer Basin, in A.K. Cooper, P.F. Barker, and G. Brancolini (Eds.), Geology and Seismic Stratigraphy of the Antarctic Margin, American Geophysical Union, Antarctic Research Series, 68, 235-260.

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Plate Boundary Observatory

Plate Boundary Observatory2

The Plate Boundary Observatory Borehole Strainmeter Network

Meghan Miller and Mike Jackson UNAVCO

Plate Boundary Observatory

Drilling PBO borehole B005 near Port Angeles, WA

One of the objectives of NSF funded geodetic component of Earthscope, the Plate Boundary Observatory, is to capture the continuous three-dimensional deformation field across the Western United States plate boundary. To accomplish this, the observatory consists of a suite of instruments which when combined have the ability to measure strain transients with deformation rates of milliseconds out to decades. The observatory, installed by UNAVCO, was completed in October 2008 and consists of over 1100 permanent GPS stations and 74 borehole strainmeter installations. Borehole strainmeters were included because they are designed to record nanostrain-level signals over periods of hours to weeks. They therefore provide an improved ability to record the evolution of strain transients such as those associated with Episodic Tremor and Slip (ETS) events and slow fault slip. DOSECC drilled the first six PBO boreholes, B001, B003, B004, B005, B006, and B007, on the Pacific Northwest Olympic Peninsula. Strainmeters installed in those holes have successfully recorded ETS related strain transients in 2005, 2007 and 2008.

To get the best performance strainmeters must be isolated from thermal and human induced tectonic strains and to record tectonic strain, it is essential they be well coupled to the surrounding rock. Hence, PBO strainmeters were installed in steel-cased boreholes at depths of up to 800 feet. The instruments are installed below the cased section ideally in an unfractured 8-12 foot section of rock. Samples and cutting were collected every 20 feet during drilling to identify the change in lithology and hydrology with depth. When the target depth was reached the boreholes were logged with a full wave sonic tool, an acoustic televiewer, a natural gamma tool and calipers. The DOSECC holes were then cored to determine whether or not the installation zone consisted of competent enough rock to host a strainmeter. Once a strainmeter was installed additional instruments such as a seismometer and in some cases pore pressure sensors were installed it. The holes were then backfilled with cement. In the Pacific Northwest it took about 3 days to complete the coring of a hole, extracting about 30 feet of core each day at a rate of about 1.5 inches per minute. Information on how to access the core from each site is available from UNAVCO. Links to logging information, photos of drilling and the installations plus strain data recorded in each of the DOSECC drilled holes can be found at http://pboweb.unavco.org/strain_data.

Plate Boundary Observatory1

Schematic drawing of PBO borehole B004 at Hoko Falls, WA. The strainmeter is installed at the bottom of the borehole in a bath of grout. When the grout cures the strainmeter is bonded to the surrounding rock. Most PBO boreholes include a seismometer installed above the strainmeter and several include pore pressure sensors. After the equipment is installed the hole is backfilled with cement.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

List of 2007/2008 publications using data from DOSECC drilled holes:

Seismological Society of America 2007 Annual Meeting, Hawaii, April 11-13 2007:

Hodgkinson, K.M., Anderson, G., Jackson, M., Mencin, D., and Johnson, W. Plate boundary Observatory Borehole Strainmeters: Results from the Pacific Northwest, Parkfield, and ANZA.

Roeloffs, E. Monitoring Aseismic Deformation in Northern Cascadia with Plate Boundary Observatory Borehole Strainmeters.

Schmidt, D.A., Observations of the Recent Slow Slip Events in Cascadia Captured by the PBO Strainmeters.

Hasting, M.A., Johnson, W.C., Venator, S.C., Dittman, S.T., Stair, J.M., Tiedeman, A.P., Gottlieb, M.H., Stroeve, A.R., Mencin, D.J., and Jackson, M. The Deployment of a PBO Strainmeter Site: Four Steps to a Better Understanding of the Earth.

Fall AGU 2007, San Francisco, 10–14 December 2007:

Roeloffs, E., McCausland, W. Areal and Shear Strain Coupling of PBO Borehole Strainmeters From Teleseismic Surface Waves.

Hodgkinson, K., Anderson, G., Dittmann, T., Henderson, B., Jackson, M., Johnson, W., Matykiewicz, J., Mencin, D., Wright, J. PBO Borehole Strainmeters: Bridging the Gap Between Seismology and GPS.

McCausland, W., Roeloffs, E.,Detection of Slow Slip Events Along the Cascadia Subduction Zone Using Plate Boundary Observatory Borehole Strainmeters.

Dragert, H., Wang, K. Observing Episodic Slow Slip with PBO Borehole Strainmeters along the Northern Cascadia Margin.

UNAVCO Science Meeting, March 11-13, 2008, Boulder Colorado:

Roeloffs, E, McCausland, W. Calibration of PBO Borehole Strainmeters: Time and Frequency Dependence.

Seismological Society of America 2008 Annual Meeting, 16 – 18 April 2008, Santa Fe, New Mexico:

McCausland, W. Scanning for strain transients along the Cascadia subduction zone using Plate Boundary Observatory borehole strainmeters.

 

Plate Boundary Observatory2

PBO strainmeter borehole drilling, Washington.