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Lake Junin

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Lake Junin Scientific Drilling Project

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Lake Junín, located at ~4100 m asl in the inner tropics of the Southern Hemisphere, is a prime target for drilling because it contains a thick (>200 m) sediment package deposited at a high rate (0.2 to 1.0 mm yrF1). Moraine mapping coupled with cosmogenic radionuclide dating indicate that paleoglaciers reached the lake edge, but have not overridden the lake in one million years, or more. Lake Junín is thus one of the few lakes in the tropical Andes that predates the maximum extent of glaciation and is in a geomorphic position to record the waxing and waning of glaciers in nearby cordillera. The lake also contains ideal sediments for multiproxy analysis that can be reliably dated using both the radiocarbon and UFTh methods. The oxygen isotopic composition of marl and ostracod carapaces recovered in multiple preliminary cores covering the last 50 ka demonstrate that the d18O of authigenic calcite primarily records the isotopic composition of precipitation and secondarily the degree of evaporative enrichment of lake water. Lake Junín contains a continuous record of tropical hydroclimate over interglacial and interstadial intervals for much of the past several hundred thousand years that both complements and significantly extends stable isotope records from regional ice cores and speleothems.

Read more about this scientific drilling project at ICDP.

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Geothermal Play Fairway Analysis of the Snake River Plain, Idaho

Geothermal Play Fairway Analysis

 

GEOTHERMAL PLAY FAIRWAY ANALYSIS OF THE SNAKE RIVER PLAIN, IDAHO
Presented by Dennis L. Nielson, DOSECC President, at the Workshop on Geothermal Reservoir Engineering Stanford University, Stanford, California, January 26-28, 2015

ABSTRACT

Play Fairway Analysis is a systematic approach to exploration that integrates data at the regional or basin scale in order to define exploration targets (plays), and then interrogates these data to highlight plays that have the highest likelihood of success. Play Fairway Analysis provides greater technical rigor than traditional geothermal exploration approaches, and facilitates quantification of play risks even when data are sparse or incomplete. It is a mature practice in petroleum, but represents a new approach for geothermal that we believe will aid in the discovery of buried or blind systems. A key challenge will be adapting fairway analysis to geothermal exploration in a way that provides both meaningful results and measurable return on investment. In this project, we focus on the Snake River Plain where, during Project HOTSPOT, our team discovered a blind hydrothermal system at Mountain Home Air Force Base in Idaho. From that discovery we are able to define key parameters that characterize the elements necessary for a geothermal reservoir based on basaltic (plume-related) magmatism, fracturing that defines a reservoir volume, seals that are provided by lake beds, hyaloclastics, and highly altered clay-rich basalts, and fluid recharge that is controlled by faulting and the primary permeability of basalt flows. Project Hotspot identified three different play types in the SRP (a) high thermal gradients along the volcanic axis beneath the SRP aquifer, (b) extremely large low temperature systems, and (c) blind high-temperature systems like that discovered at Mountain Home. Phase 1 of this project will assess the distribution and viability of these plays throughout the SRP region; Phase 2 will focus on detailed analyses of specific plays as we move from a Regional/Basin focus to a Play/Prospect focus. Our approach is to analyze direct and indirect methodologies for identifying critical reservoir parameters: heat source, reservoir permeability, seal and recharge.

Read full publication here.

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Pagosa Springs

Pagosa Springs Geothermal Drilling

Pagosa Springs Geothermal Drilling Project

Pagosa Springs Geothermal Drilling

Pagosa Verde LLC received a grant from the Department of Energy (DOE) to investigate the potential development of geothermal resources near the town of Pagosa Springs, Colorado. As part of the geothermal investigation, Pagosa Verde worked with the DOSECC geothermal drilling to drill several thermal gradient monitoring (TG) wells to test the geothermal capabilities of the area. Should data from the TG wells indicate a usable resource, then additional investigations may take place in the area. These investigations may include the drilling of exploration and confirmation wells and development of the geothermal resource for an end use. However, further exploration of the resource is dependent on the data results from the TG wells. The end use may range from geothermal-supported community greenhouse operations to construction of a 4-megawatt geothermal power plant, dependent on the results of the TG well drilling.

PROJECT DETAILS

pagosa-springs

Six test holes were drilled in Pagosa Springs, Colorado, to help with development of future geothermal resources in the area. The Pagosa Verde project consists of one 2,000-foot-deep wells and five 1,000-foot-deep holes on private and schools lands near Pagosa Springs, about 60 miles east of Durango in southern Colorado. Developers believe temperatures of up to 180 degrees will be measured from the holes. Exploration hole drilling is scheduled to be completed by year’s end.

“Geothermal is a critical energy source to be explored and developed, especially as climate change and global warming become more of an issue,” said Dennis Nielson, DES chief executive officer. “We have the equipment and expertise to quickly, efficiently, and cost-effectively assist Pagosa Springs in this important project.”

Pagosa Springs is one of several projects DES is undertaking. In an ambitious and challenging move, DES is designing and building a drilling system that will map the bedrock beneath the Antarctic ice sheet and search for the oldest ice. Teams will drill through 1 1/2 miles of ice to reach bedrock. Subsequent optical logging is expected to reveal if the ice contains volcanic ash, gas bubbles, and other materials that will help the scientific community gauge what the Earth’s climate was like a million years ago – and how it’s changed since. Project details can be found at http://bit.ly/1lX6hKU.

The company is also overseeing and conducting projects in Indonesia, Africa, and other parts of the United States.

Commercial geothermal clients rely upon DOSECC for our ability to conduct full-service preliminary analysis, slim hole assessments, and data reporting in new prospective areas.  Contact us for more details.

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Olduvai Gorge

the-olduvai-gorge-scientific-drilling-project

Olduvai Gorge Scientific Drilling Projectthe-olduvai-gorge-scientific-drilling-project

The scientific goals of The Olduvai Project are to develop a better understanding of the evolution of the Olduvai basin throughout time, particularly in the impact of climate change to the evolution of hominins in the last two million years.  This approach extends archaeological investigation of hominin adaptation beyond the traditional method and beyond the Gorge.  Core samples from areas beyond the Gorge would greatly expand our knowledge about the basin-wide landscape contexts of hominin activities, and the basin’s structure, lacustrine history and how it relates to regional climate history.  The ultimate goal of this approach is to strengthen both research and conservation in the Gorge.

See more information on the goals and research relating to this project:

OlduvaiProject.org

StoneAgeInstitute.org

This project is related to:

Hominid Sites and Paleo Lakes Scientific Drilling Project HSPDP

Lake Olorgesallie Scientific Drilling Project

Smithsonian Human Origins Project

 

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Lake Ohrid

Lake Ohrid scientific core drilling project, located in Ohrid, Macedonia

Lake Ohrid project, located in Ohrid, Macedonia

Lake Ohrid project, located in Ohrid, Macedonia, a 2013 project was institutionally-funded.

Scientific Collaboration On Past Speciation Conditions in Lake Ohrid (SCOPSCO)

Lake Ohrid is a transboundary lake between the Republics of Macedonia and Albania. With more than 200 endemic species described, the lake is a unique aquatic ecosystem of worldwide importance. This importance was emphasized, when the lake was declared UNESCO World Heritage Site in 1979, and included as a target area of the International Continental Scientific Drilling Program (ICDP) already in 1993. The lake is considered to be the oldest, continuously existing lake in Europe. Concurrent genetic brakes in several invertebrate groups indicate that major geological and/or environmental events must have shaped the evolutionary history of endemic faunal elements in Lake Ohrid.

Read more about the scientific core drilling project on Lake Ohrid at ICDP.

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Critical Zone Observatory (CZO)

critical-zone-scientific-drilling

Critical Zone Observatory (CZO) Scientific Drilling Project

critical-zone-scientific-drillingThis is a NSF- funded scientific drilling project in California’s Sierra Nevada conducted by the DOSECC core drilling services team in 2013.  This overview is from their website, CriticalZone.org:

Spearheaded by colleagues at the University of Wyoming, researchers have been participating in a number of weathering studies investigating long-term versus short-term rates of erosion (sediment basins and solute fluxes versus cosmogenic nuclides and regolith geochemistry), landscape evolution, “stepped topography” and the role of bare rock in shaping landscapes, the role of dust in pedogenesis and nutrient supply to the forests in and around the CZO (from isotopic tracers), and the origins of coarse sediment in streams (also from isotopic tracers).

Geophysical imaging of weathered layers at the CZO has been studied over the past two summers to provide 2D and 3D knowledge of the subsurface. Methods of geophysical investigation include seismic refraction and resistivity. Tests on hypotheses include what controls the thickness of the subsurface (weathering and erosion), and how much water is stored in the subsurface (porosity versus depth).

Future studies focus on cosmogenic nuclide method development (10Be in magnetite), drilling and coring in partnership with DOSECC (Drilling, Observation and Sampling of the Earths Continental Crust).

 

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Hominid Sites and Paleo Lakes Drilling Project (HSPDP)

Kenya Human Origins Drilling1

Drilling for Human Origins

Andrew S. Cohen University of Arizona

We participated in this scientific core drilling services project to obtain sediment cores from several of the most important fossil hominin and early Paleolithic artifact sites in the world, located in Kenya and Ethiopia. Our objective was to drill in near-continuous lacustrine sedimentary sequences close to areas of critical importance for understanding hominin phylogeny, and covering key time intervals for addressing questions about the role of earth system (and especially climate)forcing in shaping human evolution. These sites are all currently on-land, but consist of thick lacustrine sedimentary sequences with rapid deposition rates. Therefore, the sites combined the attributes of relatively low cost targets (in comparison with open water, deep lake sites) and the potential for highly continuous and informative paleoenvironmental records obtainable from lake beds.

STUDY SITES

Tugen Hills – June 1, 2013

W. Turkana – June 21, 2013

Chew Bahir – November 6, 2014

Northern Awash – February 23, 2014

L. Magadi – June 15, 2014

BACKGROUND

Since the 1980s paleoanthropologists and geologists have made major strides in attempting to link our understanding of human origins with the tempo and mode of climate change and variability on the Earth (e.g. Vrba, 1988, Potts, 1996, deMenocal, 2004). Systematic efforts have addressed the key question of why hominin evolution displays a pulsed pattern, with well-defined periods of extensive speciation or extinction, cultural change and geographic expansion, interspersed with long periods when relatively little change seems to occur. Is this the result of broad forcing effects of either directional environmental change (climate, etc.), the result of changes in the variability of local or regional environments, or yet-unrecognized forcing mechanism(s). These efforts have proceeded along two fairly well established paths:

  • Correlating broad-scale patterns of hominin phylogeny with the global beat of climate variability, especially the rhythm of orbital forcing cycles, as recorded in the continuous archives of deep-sea sediment cores (e.g. DeMenocal, 1995 and 2004), or,
  • Correlating regional shifts in the hominin fossil and archaeological record with more local patterns of paleoenvironmental change, inferred from continental outcrop records of paleosols, lake beds and non-hominin fossils (e.g. Bobe and Behrensmeyer, 2004; Quade et al, 2004).

 

Kenya Human Origins Drilling

Figure 1. Outcrop of Middle Pliocene diatomaceous lake beds at Ledi Geraru, northern Afar region of Ethiopia, typical of the target lithologies for drilling in this area (photo: Roy Johnson.)

 

 

 

 

 

 

 

 

 

 

 

 

 

Our objective is to develop a new community-wide effort to address this central question about human origins, combining the strengths of both of the approaches above, and avoiding some of their inherent weaknesses. Our approach is to promote a concerted effort to obtain drill core records from near-continuous sedimentary sequences located close to areas of critical importance for understanding hominin evolution, focused around critical time intervals for our core question above.

Drill cores, with their continuity and potential preservation of organic matter, fossils and other archives that are frequently degraded or disjunct on the outcrop exposures, provide a record that will vastly improve understanding of environmental history in the places and times where various species of hominins lived. Obtaining such records from the continental interiors will provide a spatially resolved record at the landscape scale, much more localized (and with much higher temporal resolution) than the regional/global climate signals preserved in deep sea core records. Finally, because the largest number of critical events in hominin phylogeny occurred in Africa, such a drilling campaign should start in that continent. The rationale for such a research program was defined at a recent NSF/DOSECC-funded conceptual workshop “Paleoclimates and Human Evolution” (Cohen et al., 2006; Potts, REF).

Our approach to the use of scientific drilling to address questions of human origins has a precedent in the 2005 drilling campaign at Lake Malawi (e.g. Scholz et al., 2006; 2007; Cohen et al., 2007, Brown et al. 2007, 2008). This project yielded near-continuous core records spanning the last few hundred thousand years, an important time intervals in human prehistory. It also provided a “proof-of-concept” that high-quality core records can be retrieved from African lake deposits with profound implications for the connection between climate and human prehistory.

We now propose to conduct a scientific drilling campaign at four sites of outstanding importance for addressing questions of linkages between human origins and paleoenvironmental history:

  • The Awash River Valley-Ledi Geraru area, northern Afar area of Ethiopia (Middle Pliocene; Figure 1)
  • The West Turkana area, northern Kenya (Plio-Pleistocene)
  • The Olorgesailie area, southern Kenya (Pleistocene)
  • Lake Magadi, southern Kenya (Pleistocene)

As an outcome of this drilling project we will be able to:

  • Test the similarity between hominin site records within local depocenters and existing lake/deep sea core records using similar types of core data sets. By linking the site records to each other where they overlap (e.g. Olorgesailie and Magadi) we will be able to tease out which aspects of the paleoenvironmental records are a function of local hydrology and which are regional signals.
  • Identify climate “surprises” such as major, abrupt climate shifts or short duration events of wide spread impact, which may have played a role in shaping human evolutionary events or hominin species demography (e.g. Cohen et al., 2007).
  • Test hypotheses linking local environmental conditions/change/variability to adaptations (physical and cultural) (e.g. Potts, 1996 and in press). Our records will allow us to evaluate the records of terrestrial climate at key hominin sites through intervals of changing modes of variability in marine records. Marine records and solar insolation forcing suggest modal periods of high environmental variability, which Potts (1996 and in press) has argued should lead to pulses of evolutionary innovation. Whether orbitally modeled periods of high and low climate variability, which are well recorded in marine cores, are also the primary drivers of environmental variation in the African continental tropics remains to be tested, and would be an outcome of our drilling campaign.

As of late 2008 drilling funds for this project have not yet been secured. However, funding has been provided by NSF to conduct initial site and logistics surveys, including the acquisition of subsurface geophysical data (Figure 2) and from NSF and ICDP to hold a drilling workshop to discuss the target localities and other possible future drilling sites for collecting paleoclimate information relevant to human evolution.

 

Kenya Human Origins Drilling1

Figure 2. Reflection seismic survey of Plio-Pleistocene sediments at West Turkana (June 2008). Preparing to shoot using a Land Cruiser mounted accelerated weight drop system (photo: Craig Feibel)

 

 

 

 

 

 

 

 

 

 

 

 

 

References:

Bobe, R. and Behrensmeyer, A.K. 2004, The expansion of grassland ecosystems in Africa in relation to mammalian evolution and the origin of the genus Homo. Palaeogeography, Palaeoclimatology, Palaeoecology 207: 399-420.

Brown, E.T. Johnson, T.C., Scholz, C.A., Cohen, A.S. and King, J. 2007, Abrupt Change in Tropical African Climate Linked to the Bipolar Seesaw Over the Past 55,000 Years. In Press, Geophys. Res. Let. 34, L20702, doi:10.1029/2007/GL031240.

Brown, E.T., Johnson, T.C., Scholz, C.A., Cohen, A.S. and King, J.W., 2008, Reply to comment by Yannick Garcin on ‘‘Abrupt change in tropical African climate linked to the bipolar seesaw over the past 55,000 years’’ Geophysical Research Letters, Vol. 35, L04702, doi:10.1029/2007GL033004, 2008.

Cohen, A.S., Ashley, G.M., Potts, R., Behrensmeyer, A.K., Feibel, C., and Quade. J., 2006, Paleoclimate and Human Evolution Workshop. EOS 87:161.

Cohen, A.S., Stone, J.R., Beuning, K.R., Park, L.E., Reinthal, P.N., Dettman, D., Scholz, C.A., Johnson, T.C., King, J.W., Talbot, M.R., Brown, E.T., and Ivory, S.J., 2007 Ecological Consequences of Early Late-Pleistocene Megadroughts in Tropical Africa. Proc. Nat. Acad. Sci. 104:16422-16427.

deMenocal, P.B., 1995, Plio-Pleistocene African climate. Science 270:53-59.

deMenocal, P. 2004, African climate change and faunal evolution during the Plio-Pleistocene. EPSL 220:3-24.

Potts, R., 1996, Evolution and climate variability. Science 273:922-923.

Potts, R., in press Environmental context of Pliocene human evolution in Africa. In: Hominin Environments in the East African Pliocene: An Assessment of the Faunal Evidence (R. Bobe, Z. Alemseged, and A.K. Behrensmeyer, eds.), Kluwer, New York.

Potts, R., 2007, Paleoclimate and human evolution. Evolutionary Anthropology 16:1-3.

Quade, J., Levin, N., Semaw, S., Stout, D., Renne, P., Rogers, M., Simpson, M., 2004, Paleoenvironments of the earliest stone toolmakers, Gona, Ethiopia. GSA Bull. 116:1529-1544.

Scholz, C.A., Cohen, A.S., Johnson, T.C. and King, J. W., 2006 The 2005 Lake Malawi Scientific Drilling Project. Scientific Drilling Mar 2006:17-19, doi:10.2204/iodp.sd.1.04.2006.

Scholz, C.A., Johnson, T.C., Cohen, A.S., King, J.W., Peck, J., Overpeck, J.T., Talbot, M.R., Brown, E.T., Kalindekafe, L., Amoako, P., et al. 2007, East African megadroughts between 135-75 kyr ago and implications for early human history Proc. Nat. Acad. Sci. 104:16416-16421.

Vrba, E.,S 1988, Late Pliocene climate events and hominid evolution. In Grine, F.(ed) Evolutionary History of the “Robust” Australopithicines. Aldine Press, N.Y., pp. 405-426.

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Dead Sea

Dead Sea scientific core drilling company project, located in Ein Gedi, Israel

Dead Sea drilling project, located in Ein Gedi, Israel

Dead Sea project, located in Ein Gedi, Israel, a 2011-2012 scientific core drilling services project that was ICDP-funded.

The Dead Sea as a Global Paleo-environmental, Tectonic and Seismic Archive


(Photo ©:NASA)

A borehole in the deep basin of the Dead Sea (at water depth of ~200m) will recover a continuous sequence of the Pleistocene-Holocene sedimentary record. The core will provide a high-resolution record of the paleoenvironmental climatic, seismic and geomagnetic history (in scales ranging from sub-stage, through millennial, to sub decadal) of the East Mediterranean region.

Additionally this sequence will serve as a basic scale for basin development studies of this extraordinary sedimentary environment (e.g. salt formation) and the understanding of the geotectonic environment along the Dead Sea Transform fault.

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

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Lake Olorgesailie

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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