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Lake Bosumtwi

Lake Bosumtwi Scientific Core Drilling Services Project

The 2004 ICDP Bosumtwi Impact Crater Drilling Project, Ghana

Christian Koeberl University of Vienna

Bernd Milkereit University of Toronto

Jonathan T. Overpeck University of Arizona

Christopher A. Scholz Syracuse University

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

Introduction and Geological Setting

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

Lake Bosumtwi Drilling

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

Paleoclimatic Studies at Bosumtwi

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

 

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

Geophysics and Impact Results

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

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

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

Lake Bosumtwi Drilling1

Figure 2 – Seismic section with deep boreholes.

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

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

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

Lake Bosumtwi Drilling2

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

 

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

Acknowledgments

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

References:

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

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

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

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

Secondary References:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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Hawaii Scientific Drilling Project

Hawaii Scientific Core Drilling Services

Hawaii Scientific Drilling Project (1991 – 2008)

D.J. DePaolo Lawrence Berkeley National Laboratory

E.M. Stolper California Institute of Technology

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

 

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

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

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

Representative References:

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

HSDP2 Papers (G-Cubed):

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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

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Iceland Lakes

Iceland Lakes Scientific Core Drilling Services Project

Iceland Lakes Drilling Project

Gifford Miller University of Colorado

Aslaug Geirsdottir University of Iceland

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

Major Findings

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

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

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

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

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

 

Iceland Lakes Drilling

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

Iceland Lakes Drilling1

 

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Geoclutter

ONR Geoclutter Program

 

ONR Geoclutter Program: Final Analysis of Geophysical and Geological Data

James A. Austin, Jr. and John A. Goff University of Texas Institute for Geophysics

Long-Term Goals

The primary goal of the Geoclutter program is to assess geologic clutter/reverberation issues in a seismically and geologically well-characterized shallow-water environment. The mid-outer continental shelf off New Jersey provides such an opportunity, because both bathymetry (a known and prominent cause of backscatter) and portions of the shallow subsurface have been mapped in detail as a result of STRATAFORM. The Geoclutter program consists of three field program phases: (I) an acoustic reconnaissance survey utilizing Navy gray ships and assets to identify potential geoclutter hot spots; (II) a full bistatic acoustic experiment focusing on the chosen areas, and (III), the focus of the work described here, detailed geologic and geophysical surveys of the hot spots identified in Phases I and II.

Objectives

Our primary objective for this grant were to finalize analysis of geological and geophysical data collected as part of the ONR Geoclutter program. In particular, we intend to complete the interpretation of the 2001 and 2002 chirp seismic data in conjunction with the analysis of cores collected in the region. These products will provide critical constraints on geoacoustic modeling of the New Jersey shelf region, which continues to be a focus of ONR-sponsored acoustic field work.

Approach

We employed a variety of approaches in our work. Stratal horizons are interpreted from chirp seismic data using commercial seismic interpretation software. Seafloor measurements, including grain size, porosity, in situ velocity and attenuation, backscatter strength, and acoustic impedance, are compared with each other using correlation analyses. Cores have been both logged for geoacoustic properties, providing ground truth, and sampled, to corroborate geologic interpretation and provide age dating of the sedimentary strata evident in the chirp data.

Work Completed

Interpretation of the chirp data has continued with significant progress. The analysis of seafloor properties based on in situ acoustic data, grab samples, short cores and remote sensing data (chirp and backscatter) is complete. Three long cores, ranging in length from 4 to 13 m, were collected in 2002 aboard the R/V Knorr using the Active Heave Compensated AHC-800 system supplied and operated by DOSECC (Figs. 1 and 4). These cores are the longest high-quality cores collected from this part of the margin and represent a unique sample set to provide temporal, stratigraphic and environmental context both for seismic stratigraphic interpretation and future sampling efforts. Geotechnical measurements from these cores were logged at sea, and samples have recently been collected which have undergone detailed analyses for time stratigraphy, sediment texture and paleoenvironmental conditions.

ONR Geoclutter Program

Figure 1. Location of deep-towed chirp-sonar tracklines collected aboard R/V Endeavor (EN359 and EN370), superimposed on NOAA’s bathymetry of the New Jersey middle and outer continental shelf. The small inset locates our study area regionally. Drill sites 1-3 cored with DOSECC’s AHC-800 system aboard R/V Knorr in fall 2002 are marked as yellow stars.

Results

Previous progress reports have detailed our extensive results to date (Fulthorpe and Austin, 2004; Goff and Nordfjord, 2004; Goff et al., 2004; Nordfjord et al., 2005; Goff et al., 2005; Gulick et al., 2005). Here we focus on the latest results from an extensive analysis of the internal stratigraphy of fill units within the channel networks that are shallowly buried across most of the middle and outer shelf. These results are presented in a newly submitted manuscript (Nordfjord et al., in press).

The fill strata of incised valleys on the New Jersey outer shelf demonstrate an upward and landward progression of four sedimentary facies (Figure 2), as observed in 1-4 kHz deep-towed chirp seismic data. From oldest to youngest, these are interpreted as fluvial lags (SF1), estuarine mixed sand and muds (SF2), estuary central bay muds (SF3) and redistributed estuary mouth sands (SF4). These fill units are covered by a transgressive oceanic ravinement surface, “T”, and Holocene marine sand deposits. Seismic facies of the transgressive systems tract (SF2-SF4) are interpreted to represent fluvial, estuarine and shelf depositional systems that are bounded by seismic reflectors marking source diastems or unconformities.

ONR Geoclutter Program1

Figure 2. Representative collocated chirp images at crossing the edge of a buried fluvial channel. The 1-15 kHz data were used as a guide for interpreting significant seismic boundaries, while the 1-4 kHz data provided more detail of the seismic facies.

 

Transgressive paleovalley-fill Successions identified in the New Jersey outer shelf Quaternary section contain three transgressive surfaces identified best in the 1-15 kHz chirp data (Figure 2), B1-3, interpreted as bay ravinement, intermediate flooding surface and tidal ravinement, respectively, which are wholly or partly preserved in vertical succession. These incised-valley-confined diastems significantly modify the antecedent, regionally developed, fluvial erosion surfaces. This modification is affected by erosion accompanying submergence and hypsometric change as the paleo-river valley evolves into a paleo-estuary. The original fluvially-incised surface, “Channels”, is generally only preserved as a distinct surface within valley axes, beneath a partly preserved fluvial depositional system. The fluvial erosion surfaces have typically been modified by bay (B1) and tidal (B3) ravinements within incised valleys, which then becomes a composite erosional surfaces cut by fluvial, estuarine and shoreface-shelf processes. The regionally developed “T” horizon caps subjacent incised-valley fill successions and marks landward passage of an oceanic shoreface over the underlying infilled paleo-estuaries. Dipward changes in the thickness of the SF3 and SF4 units suggest either a stillstand in the passage of the shoreline, which allowed for variations in unit thicknesses, or that the valley shape controlled the hydrodynamic conditions for sediment transport and deposition. In particular, we suggest that narrower valleys will promote tidally-dominated, fine-grained deposition while broader valleys will attenuate tidal flow velocities, allow the estuary to be dominated by wave energy and promote coarse-grained deposition. Our study demonstrates wave- and tide- dominated facies can coexist within the fill strata. A model for the development of valley fill strata is presented in Figure 3.

Impact / Applications

The primary application of our geological and geophysical characterization is in the establishment of critical paleoenvironmental characteristics for the understanding of acoustic interactions with the seabed. For example, the model presented in Figure 3 can be used as a basis for predicting the geoacoustic properties of sediments within the buried channels, as well as predict physical property contrasts between those sediments and the host strata that could give rise to a significant acoustic response.

Related Projects

The ONR STRATAFORM program provided initial site characterization for the Geoclutter natural laboratory. The SWAT acoustic experiment was also carried out in this area, and the 2006 Shallow Water Acoustics experiment is now planned for this area.

ONR Geoclutter Program2

Figure 3. Schematic representations of the evolution of New Jersey outer shelf incised valley systems, including their stratigraphic boundaries and sedimentary facies, as they went from (A) fluvial systems with preserved fluvial lags to (B) more aggradational stage as the system started to get backfilled and finally to (C) a typically passive infilling stage with the central basin mud and estuary mouth complexes. Not shown is the formation of the transgressive oceanic ravinement, following infilling, which likely reworked and removed significant portions of the incised valley fill deposited.

ONR Geoclutter Program3

Figure 4. DOSECC’s Active Heave Compensated drilling rig aboard the R/V Knorr.

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

 

Publications

Fulthorpe, C.S., and J.A. Austin, Jr., 2004. Shallowly buried, enigmatic seismic stratigraphy on the New Jersey outer shelf: Evidence for latest Pleistocene catastrophic erosion? Geology 32, 1013–1016. [published, refereed]

Goff, J. A., and S. Nordfjord, 2004. Interpolation of fluvial morphology using channel-oriented coordinate transformation: A case study from the New Jersey Shelf. Math. Geol. 36, 643-658. [published, refereed]

Goff, J. A., B. J. Kraft, L. A. Mayer, S. G. Schock, C. K. Sommerfield, H. C. Olson, S. P. S. Gulick, and S. Nordfjord, 2004. Seabed characterization on the New Jersey middle and outer shelf: Correlability and spatial variability of seafloor sediment properties. Mar. Geol. 209, 147-172. [published, refereed]

Goff, J. A., J A. Austin, Jr., S. Gulick, S. Nordfjord, B. Christensen, C. Sommerfield, and H. Olson, C. Alexander, 2005. Recent and modern marine erosion on the New Jersey outer shelf, Mar. Geol. 216, 275-296. [published, refereed]

Gulick, S. P. S., J. A. Goff, J. A. Austin, Jr., C. R. Alexander, Jr., S. Nordfjord, and Craig S. Fulthorpe, 2005. Basal inflection-controlled shelf-edge wedges off New Jersey track sea-level fall. Geology 33, 429-432. [published, refereed]

Nordfjord, S., J. A. Goff, J. A. Austin, Jr., and C. K. Sommerfield, 2005. Seismic geomorphology of buried channel systems on the New Jersey outer shelf: Assessing past environmental conditions. Mar. Geol. 214, 339-364. [published, refereed]

Nordfjord, S., J. A. Goff, J. A. Austin, Jr., and S. P. S. Gulick, Seismic facies analysis of shallowly buried incised valleys, New Jersey continental shelf: understanding late Quaternary paleoenvironments during the last transgression, submitted to J. Sed. Res.

The Geoclutter Program was funded by the Office of Naval Research

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Koolau

Koolau Volcano Drilling scientific core drilling company

Rock Coring Koolau Volcano, Hawai’i: Implications for Deep Mantle Recycling of the Crust

Michael O. Garcia University of Hawai’i

 

Mantle plumes produce basalts which provide fundamental information on the composition and history of the mantle.Ê The Hawaiian plume is the classic example of a mantle plume and its basalts are unquestionably the best studied suite from any plume. The subaerially exposed lavas of Koolau Volcano belong to the Enriched Mantle1 endmember of ocean island basalts and they define a geochemical endmember among Hawaiian shield lavas in major and trace elements and in isotopes. Koolau lavas are important to an understanding of the origin and evolution of the Hawaiian plume and the mantle. In particular, Koolau lavas appear to provide the strongest evidence for deep mantle recycling of crust (sediments and basalt), although this interpretation remain controversial and is based on sampling only the uppermost veneer of the volcano. It is important to establish the longevity of the distinctive Koolau geochemical signature by sampling deeper and older lavas from the volcano. If there were basaltic and sedimentary components in the Hawaiian plume, were they restricted to the final stages of Koolau volcano’s growth? Scientific drilling will allow us to answer this question by obtaining lavas from subsurface of this enigmatic volcano.

Koolau Volcano Drilling

Figure 1 – Schematic drawing and photos of Kalihi Shaft Well drilling.

Funding in support of this project has been obtained from the U.S. National Science Foundation and from several U.S., German and Japanese research groups that will support collecting about 300 m of rock cores from the base of the Kalihi, a 345 m deep, water observation hole, which has just been drilled by the City of Honolulu. This coring will extend below any surface exposures of the volcano’s lavas and it is expected that the rocks obtained will have experienced less topical weathering than surface rocks. As part of this project, we will systematically log the chips obtained from the upper part of the well. The cores from the lower 300 m of the well will be logged following procedures we have developed for the Hawaii Scientific Drilling Program. We have assembled an international team of experts to make a thorough petrographic and geochemical characterization of the core and chips from the Kalihi hole as part of this one year project. This will include petrography, mineral and glass chemistry by microprobe, and whole-rock major and trace element (Rb, Sr, Y, Zr, Nb, V, Ni, Cr, Zn, by XRF , and all REE, Ta, Ba, Nb, Th, Hf, U, Pb, Rb, Cs by ICP-MS) compositions for approximately 50 lavas flows and O, Pb, Sr, Nd and Hf isotope ratios for select samples. Several of the flows will also be dated by Ar-Ar.

 

DOSECC has provided core drilling services for the Koolau Drillling Project that is under the direction of Dr. Michael Garcia of the University of Hawaii. Their CS1500 rig was used for deepen an existing well on the Kalihi Board of Water Supply Site (Figure 3.) The drilling project began on April 14 and drilling ended on May 24, 2000.

The Kalihi Shaft Well had previously been drilled to a depth of 1150 feet. 8-5/8″ casing extends from the surface to a depth to 150 feet; beneath that, the well has no casing. In order to core the bottom part of the well, a temporary liner is installed from the surface to 1150 feet. The core drilling is being done through this temporary liner.

The coring uses rod with an outer diameter of 3.65 inches and collects core of 2.4 inches. The coring assemblies are shown on the right. The rock is cut using a diamond core bit, and the core sample is fed into a 10 foot core barrel. When this barrel is full, it is retrieved to the surface using a wireline while the core bit and rods remain in the hole.

The major funding for the drilling project is from the University of Hawaii, NSF and ICDP, with additional funding from the following institutions: California Institute of Technology, Massachusetts Institute of Technology, University of California at Berkeley. Woods Hole Oceanographic Institute, Tokyo Institute of Technology, Carnegie Institute of Washington, Max-Plank-Institute fur Chemie.

Koolau Volcano Drilling1

Figure 2 – University of Hawaii geology and geophysics professor Mike Garcia, examines a core sample taken from the Koolau mountains. Graduate research assistant Eric Haskins works in the background. (George F. Lee, Star-Bulletin)

 

 

 

 

 

 

 

 

 

 

 

 

Related Publications:

Chen, C.-Y., et al., The tholeiite to alkalic basalt transition at Haleakala Volcano, Maui, Hawaii, Contrib. Mineral. Petrol. 106, 183-200, 1991.

Clague, D. A., Dalrymple, G. B., The Hawaiian Emperor Volcanic Chain, USGS Prof. Paper 1350, 5-54, 1987.

Eiler, J.M., Farley, K.A., Valley, J.W., Hofmann, A.W. and Stolper, E.M., Oxygen isotope constraints on the sources of Hawaiian volcanism, Earth Planet. Sci. Lett., 144, 453-468, 1996a.

Eiler, J. M., Valley, J. W. and Stolper, E. M., Oxygen isotope ratios in olivine from the Hawaii Scientific Drilling Project, J. Geophys. Res., 101, 11,807-11,814, 1996b.

Frey, F. A., Garcia, M. O. and Roden, M. F., Geochemical characteristics of Koolau Volcano: Implications of intershield geochemical differences among Hawaiian volcanoes, Geochim. Cosmochim. Acta, 58, 1441-1462, 1994.

Frey, F. A. and Rhodes, J. M., Intershield geochemical differences among Hawaiian volcanoes: implications for source compositions, melting process and magma ascent paths, Phil. Trans. R. Soc. Lond. A, 342, 121-136, 1993.

Garcia, M. O., Foss, D.J.P., West, H.B. and Mahoney, J.J., Geochemical and isotopic evolution of Loihi Volcano, Hawaii, Jour. Petrol., 36, 1647-1674, 1995.

Garcia, M., Muenow, D., Aggrey, K. and O’Neil, J., Major element, volatile and stable isotope geochemistry of Hawaiian submarine tholeiitic glasses. J. Geophys. Res., 94, 10,525-10,538, 1989

Garcia, M., Rubin, K.H., Norman, M.D., Rhodes, J.M., Graham, D.W., Muenow, D.,

Spencer, K., Petrology and geochronology of basalt breccia from the 1996 earthquake swarm of Loihi Seamount, Hawaii: Magmatic history of its 1996 eruption. Bull. Volcanol. 59, 577-592, 1998

Hauri, E. H., Major-element variablity in the Hawaiian mantle plume. Nature 382, 415-419, 1996.

Hauri, E. H., Lassiter, J. C. and DePaolo, D. J., Osmium isotope systematics of drilled lavas from Mauna Loa, Hawaii, J. Geophys. Res., 101, 11,793-11,806, 1996.

Jackson, M. C., Frey, F.A., Garcia, M.O. and Wilmoth, R.A., Geology and petrology of basaltic lavas and dikes of the Koolau Volcano in the Trans-Koolau exploratory tunnels, Bull. Volcan., 60, 381-401, 1999.

Kyser, T. K. O=Neil, J.R., and Carmichael I. S. E., Genetic relations among basic lavas and ultramafic nodules: Evidence from oxygen isotope compositions: Contrib. Mineral. Petrol., v. 81, p. 88-102, 1982.

Lassiter, J. C., DePaolo, D. J. and Tatsumoto, M., Isotopic evolution of Mauna Kea volcano: Results from the initial phase of the Hawaiian Scientific Drilling Project, J. Geophys. Res., 101, 11,769-11,780, 1996.

Koolau Volcano Drilling2

Figure 3 – DOSECC’s CS1500 drilling rig at the Koolau drillsite.

 

 

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Hawaii Volcano Observatory

Hawaii Volcano1 scientific drilling core drilling services core drilling companies

A Geochemical Investigation of the Role of Recycled Oceanic Crust in Hawaiian Magmatism

Amy M. Gaffney Lawrence Livermore National Laboratory

Investigations of the role of oceanic lithosphere in the geochemistry of Hawaiian magmas have generated two main families of hypotheses. One invokes ancient oceanic lithosphere that has been subducted, stored in the mantle for some length of time and recycled into the plume source where it contributes to compositional variation in the plume-generated lavas (e.g., White & Hofmann, 1982; Lassiter & Hauri, 1998; Blichert-Toft et al., 1999). Alternatively, plume-generated magmas may acquire geochemical characteristics of oceanic lithosphere by interacting with or assimilating it as they rise to the surface (e.g., Chen & Frey, 1985; Eiler et al., 1996). Singly or together, these processes may contribute to the range of compositional variability expressed through the two primary compositional endmembers of Hawaiian shield-stage magmatism: the relatively enriched Ko’olau component and the relatively depleted Kea component.

Hawaii Volcano1

Kea-type lavas have the most depleted Sr and Nd isotopic compositions of all Hawaiian shield-stage lavas, and thus the Kea source material has been interpreted as having an association with or derivation from ambient depleted mantle or oceanic lithosphere. Identification and characterization of oceanic lithosphere associations and the resulting compositional variations within Kea-type lavas require high-density sampling as well as stratigraphic (i.e., time) control. This approach was successfully implemented for the young Kea-type Mauna Kea volcano with the multi-disciplinary work on the Hawaii Scientific Drilling Project (HSDP) cores (e.g., Stolper et al., 1996, and included papers; Blichert-Toft & Albarede, 1999; Abouchami et al., 2000; DePaolo et al., 2001; Blichert-Toft et al., 2003; Eisele et al, 2003; Huang & Frey, 2003).

From this project, broad conclusions were drawn about the compositional structure of the Hawaiian plume and the origin of the compositional variations within Mauna Kea lavas. However, in order to evaluate the role of oceanic lithosphere in the origin of geochemical heterogeneity in Kea-type volcanoes on an inter- and intra-volcano scale, analogous studies on older volcanoes are important. Thus, a study was undertaken to geochemically characterize stratigraphically-controlled sequences of shield-stage lavas from West Maui volcano, an older (~1.8 Ma) Kea-type volcano.

Questions Addressed With this Research

  • What is the range of chemical variability that characterizes the Kea component?
  • What is the role of oceanic lithosphere in generating the chemical variability among Kea-type lavas?
  • How, if at all, does the contribution of oceanic lithosphere to geochemical heterogeneity in Kea-type lavas vary on an intra- and inter-volcano scale?

The samples used for this study were collected from a monitoring well at the Mahinahina Water Treatment Facility near Honokawai, Maui. This study site was an exceptional location for this investigation, as the samples collected provided a stratigraphic sequence representing the late shield-stage of magmatism at West Maui volcano. This sequence of lavas is comparable to those obtained in the early stages of drilling on the HSDP core on Mauna Kea, thus enabling comparison between the two sets of data and testing of the broad applicability of models of magmatism derived from individual volcanoes. Comprehensive geochemical data set was obtained for these samples, including major and trace element and Sr-Nd-Hf-Pb-O-Os isotopic data.  A variety of geochemical modeling techniques were used to assess contributions of oceanic lithosphere to these magmas, and evaluate the origin of the Kea component. This work led to several conference presentations as well as three publications (Gaffney et al., 2004; Gaffney et al., 2005a; Gaffney et al., 2005b).

This study resulted in several important conclusions that have contributed to current understanding of the origin of geochemical heterogeneity in Hawaiian magmatism. First, it was showed that although Kea-type magmatism at West Maui and other Kea-type volcanoes derives its primary geochemical characteristics from ancient recycled oceanic crust in the plume source, some lavas from these volcanoes also carry geochemical fingerprints of Pacific oceanic crust that was assimilated by the plume-derived magmas. This shallow source is identifiable only within relatively short stratigraphic sequences of lavas, indicating that oceanic crust contamination is an episodic, rather than continuous, process.

Second, it was showed that recycled oceanic crust in the Hawaiian plume controls geochemical variability in erupted magmas on an inter- and intra-volcano scale. Whereas the different parts of recycled oceanic crust (upper vs. lower crust) control the large compositional differences observed between Kea-type and Ko’olau-type Hawaiian volcanoes, the physical mechanisms of melting recycled oceanic crust in the plume control the chemical variability observed within any individual volcano. Thus, the relatively narrow range of chemical variability that characterizes the Kea component reflects the processes involved with melting of recycled lower oceanic crust (peridotite and eclogite), whereas the relatively large range of chemical variability that characterizes Ko’olau-type Hawaiian volcanoes reflects the processes involved in melting the lithologically distinct recycled upper oceanic crust (eclogite and metamorphosed sediment).

Lastly, through comparing the time-compositional relationships on an intra- and inter-volcano scale for Hawaiian magmatism over the last ~3 million years, it was concluded that the scale of oceanic crust heterogeneities in the Hawaiian plume is large enough that they are sampled over the lifespans of several volcanoes. In contrast, the chemical variability introduced by assimilation of Pacific oceanic crust reflects a process that only operates in the latest stages of the volcano’s life, once magma flux from the plume has decreased considerably from its peak flux during the main stages of volcanic shield-building.

References:

Abouchami, W., Galer, S. J. G. & Hofmann, A. W. (2000). High precision lead isotope systematics of lavas from the Hawaiian Scientific Drilling Project. Chemical Geology 169, 187-209.

Blichert-Toft, J. & Albarède, F. (1999). Hf isotopic compositions of the Hawaii Scientific Drilling Project core and the source mineralogy of Hawaiian basalts. Geophysical Research Letters 27(7), 935-938.

Blichert-Toft, J., Weis, D., Maerschalk, C., Agranier, A. & Albarède, F. (2003). Hawaiian hot spot dynamics as inferred from the Hf and Pb isotope evolution of Mauna Kea volcano. Geochemistry Geophysics Geosystems 4, 2002GC000340.

Chen, C.-Y. & Frey, F. A. (1985). Trace element and isotopic geochemistry of lavas from Haleakala Volcano, East Maui, Hawaii: implications for the origin of Hawaiian basalts. Journal of Geophysical Research 90, 8743-8768.

DePaolo, D. J., Bryce, J. G., Dodson, A., Schuster, D. L. & Kennedy, B. M. (2001). Isotopic evolution of Mauna Loa and the chemical structure of the Hawaiian plume. Geochemistry, Geophysics, Geosystems 2, 2000GC000139.

Eiler, J. M., Farley, K. A., Valley, J. W., Hofmann, A. W. & Stolper, E. M. (1996). Oxygen isotope constraints in the sources of Hawaiian volcanism. Earth and Planetary Science Letters 144, 453-468.

Eisele, J., Abouchami, W., Galer, S. J. G. & Hofmann, A. W. (2003). The 320 kyr Pb isotope record of Mauna Kea lavas recorded in the HSDP-2 drill core. Geochemistry, Geophysics, Geosystems 4, 2002GC000339.

Gaffney, A.M., Nelson, B.K., and Blichert-Toft, J., 2005 Melting in the Hawaiian plume at 1-2 Ma as recorded at Maui Nui: the role of eclogite, peridotite and source melting. Geochemistry, ‘Geophysics, Geosystems 6, 10.1029/2005GC000927.

Gaffney, A.M, Nelson, B.K., Reisberg, L. and Eiler, J., 2005, Oxygen-osmium isotopic compositions of West Maui lavas: a record of shallow-level magmatic processes. Earth and Planetary Science Letters 239, 122-139.

Gaffney, A.M., Nelson, B.K., and Blichert-Toft, J, 2004, Geochemical constraints on the role of oceanic lithosphere in intra-volcano heterogeneity at West Maui, Hawaii, Journal of Petrology 45, 1663-1687.

Hauri, E. H. (1996). Major-element variability in the Hawaiian mantle plume. Nature 382, 415-419.

Huang, S. & Frey, F. A. (2003). Trace element abundances of Mauna Kea basalt from phase 2 of the Hawaii Scientific Drilling Project: petrogenetic implications of correlations with major element content and isotopic ratios. Geochemistry Geophysics Geosystems 4, 2002GC000322.

Lassiter, J. C. & Hauri, E. H. (1998). Osmium-isotope variations in Hawaiian lavas: evidence for recycled oceanic lithosphere in the Hawaiian plume. Earth and Planetary Science Letters 164, 483-496.

Stolper, E. M., DePaolo, D. J. & Thomas, D. M. (1996). Introduction to special section; Hawaii Scientific Drilling Project. Journal of Geophysical Research 101, 11,593-11,598.

White, W. M. & Hofmann A. W. (1982) Sr and Nd isotope geochemistry of oceanic basalts and mantle evolution. Nature 296, 821-825.