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Investigating Large Igneous Province Formation and Associated Paleoenvironmental Events: a White Paper for Scientific Drilling by Clive R Workshop Reports Investigating Large Igneous Province Formation and Associated Paleoenvironmental Events: A White Paper for Scientific Drilling by Clive R. Neal, Millard F. Coffin, Nicholas T. Arndt, Robert A. Duncan, Olav Eldholm, Elisabetta Erba, Cinzia Farnetani, J. Godfrey Fitton, Stephanie P. Ingle, Nao Ohkouchi, Michael R. Rampino, Marc K. Reichow, Stephen Self, and Yoshiyuki Tatsumi doi:10.04/iodp.sd.6.01.008 Introduction 2006). To this end, a workshop on LIPs, sponsored by IODP Management International (IODP-MI) and the Consortium Earth’s history has been punctuated over at least the last for Ocean Leadership, was held at the University of Ulster in 3.5 billion years by massive volcanism on a scale unknown in Coleraine, Northern Ireland, U������������������������������.�����������������������������K.������������������������������������������������������� ��������������������������on������������������������ 22–25 July 2007 (Coffin the recent geological past. Largely unknown mechanical and et al., 2007). dynamic processes, with unclear relationships to seafloor spreading and subduction, generated voluminous,��������� predomi- A multi-disciplinary group of eighty scientists represent- nately mafic magmas that were emplaced into the �������E������arth’s ing academia, government, and industry from sixteen coun- lithosphere. The resultant large������������������������ igneous provinces (LIPs tries discussed strategies for advancing understanding of Coffin and Eldholm, 1994 Ernst and Buchan, 2001 Bryan LIPs and associated environmental events using the three and Ernst, 2008) were at times accompanied by catastrophic different IODP platforms and related technologies. During environmental changes. The interaction of the LIP-associ- the workshop, which began with an examination of the ated mantle processes with the Earth’s crust have produced United Nations Educational, Scientific, and Cultural a variety of surface expressions (Fig. 1a and 1b) the most Organization (UNESCO) World Heritage “Giant’s Causeway” common present-day examples are oceanic plateaus (e.g., exposure of the North Atlantic LIP (Fig. 2), scientists inves- Kerguelen/Broken Ridge, Ontong Java, Manihiki, Hikurangi, tigating LIPs through field, laboratory, and modeling Shatsky), ocean basin flood basalts (e.g., Caribbean, Nauru), approaches shared their expertise. Specifically, outstanding magma-dominated divergent continental margins (e.g., the problems related to LIP origin, emplacement, and environ- North Atlantic), and continental flood basalts (e.g., Columbia mental impacts were discussed in plenary and breakout ses- River, Deccan Traps, Siberian Traps). Environmental effects sions. The workshop������������������������ achieved the following: associated with LIP formation include climate changes, mass and other extinctions, variations in ocean and atmospheric • Identified multidisciplinary, synergistic approaches to chemistry, and Oceanic Anoxic Events (OAEs). Therefore, addressing outstanding Earth system problems associ- the geodynamic processes in the mantle that produce LIPs ated with LIP science. have potentially profoundly affected the Earth’s environ- • Brought together scientists from widely different areas ment, particularly the biosphere and climate. The Integrated of expertise (e.g., petrology, paleontology, geodynam- Ocean Drilling Program (IODP) affords unique opportuni- ics, oceanography, geophysics, logging, volcanology, ties to investigate LIPs and associated environmental effects, geochemistry, stratigraphy, tectonics, paleoceanogra- building upon results from the Ocean Drilling Program phy, paleomagnetics) to focus on how ocean drilling can (ODP) and Deep Sea Drilling Project (DSDP) (Coffin et al., address unresolved issues associated with the origin, B AA B Consequences of LIP Emplacement on the Earth System ICELAND Solar Radiation Hydrologic Cycle 60° Ocean Chemistry NORTH SIBERIA ATLANTIC Change Climate Change Deep EMPEROR Sea-Level Change CO + SO Biosphere Greenhouse Gas Release COLUMBIA 2 2 SHATSKY Impact CH + CO HESS RIVER Crustal Ocean Circulation 4 2 CENTRAL EMEISHAN Accretion Disruption ATLANTIC 30° DECCAN Lithosphere PIGAFETTA HAWAII YEMEN 200 km EAST CARIBBEAN MARIANA ETHIOPIA MAGELLAN CHAGOS- Superplume NAURU LACCADIVE- Hotspot-Ridge GALAPAGOS MALDIVE Interaction ONTONG 0° JAVA MASCARENE Lithosphere 2900 km Recycling NINETYEAST MANIHIKI PARANA ETENDEKA WALVIS MADAGASCAR KAROO SOUTH -30° LOUISVILLE ATLANTIC BROKEN SOUTH Heat ATLANTIC KERGUELEN Mantle Dynamics HIKURANGI Transportation 180° 270° 0° 90° ° -60 Core-Mantle Interaction ? Vigorously Convecting FERRAR Outer Core Figure 1. [A] Phanerozoic global LIP distribution. Red = LIPs (or portions thereof) generated by a transient “plume head”; Blue = LIPs (or portions thereof) generated by a persistent “plume tail”. Taken from Coffin (2006). [B] A holistic representation of the process of LIP emplacement and associated environmental effects. 4 Scientific Drilling, No. 6, July 2008 Workshop Reports emplacement, and evolution of LIPs, as well as their impact on the environment. • Exposed new scientists to the IODP and nurtured early career scientists, specifically with respect to how scien- tific drilling can advance understanding of LIPs. • Enhanced cooperation between the IODP and the International Continental Scientific Drilling Program (ICDP). • Explored partnerships among IODP, government, and industry. One of the major outcomes of the workshop was ���������to ������define multiple pathways to enhance our knowledge of LIPs through scientific drilling. These ranged from ancillary project let- ters, through individual expedition proposals, to a mission proposal. Figure 2. Giant’s Causeway (Ireland), part of the North Atlantic LIP. Note the stepped topography in the background, characteristic of flood basalt provinces. This white paper highlights the major problems associ- ated with LIPs that can be addressed through scientific drill- emplacement and relatively minor subsidence since emplace- ing and related studies. It also highlights multidisciplinary ment. Primarily on the basis of drilling results, multiple mod- approaches required to address such problems, as stud������ies��� of els—plume (e.g., Fitton et al., 2004a), bolide impact (Ingle LIPs encompass mantle geodynamics, emplacement pro- and Coffin, 2004), and upwelling eclogite (Korenaga, cesses, and environmental events affecting the lithosphere, 2005)—have been proposed for the origin of the Ontong Java hydrosphere, atmosphere, and biosphere. Plateau. Past ������������A�����������chievements Uppermost igneous basement of the Kerguelen Plateau/ Broken Ridge is dominantly tholeiitic basalt erupted above Scientific drilling has played a vital role in the exploration sea level (Barron et al., 1989, 1991 Schlich et al., 1989 Wise of LIPs, most importantly by providing the first, and in many et al., 1992 Coffin et al., 2000 Frey et al., 2003), and ��������it shows����� cases the only, ground truth from the igneous basement of two apparent peaks in magmatism at 119–110����������� Ma����������� and 105–95 submarine LIPs. While major advances ���������������in ������������LIP research Ma (Coffin et al., 2002). Geochemical differences among tho- involve holistic observational, experimental, and modeling leiitic basalts erupted at each site are attributable to varying studies involving a broad array of ������������������������E�����������������������arth science expertise, proportions of components from the primary mantle source results from scientific drilling have been and will continue to (plume?), depleted �������������������������������������mid-ocean ridge basalt (�������������MORB���������)��������-related be key components of interdisciplinary work. The first dedi- asthenosphere, and continental lithosphere. Proterozoic-age cated igneous basement sampling investigations of subma- zircon and monazite in clasts of garnet-biotite gneiss in a con- rine LIPs, conducted during the ODP, concentrated on three glomerate intercalated with basalt at one drill site demon- provinces����������������������������������������������:��������������������������������������������� the Ontong Java Plateau (Pacific Ocean), the strate the presence of fragments of continental crust in the Kerguelen Plateau/Broken Ridge (Indian Ocean), and the Kerguelen Plateau, as inferred previously from geophysical North Atlantic magma-dominated divergent continental (e.g., Operto and Charvis, 1995) and geochemical (e.g., margins (Fig. 1). Below,���������������������������������������� w��������������������������������e highlight the major results of Alibert, 1991) data. For the first time from an intra-oceanic these investigations, which have laid the groundwork for the LIP, alkalic lavas, rhyolite, and pyroclastic deposits were next major phase of discovery during the IODP. sampled. Flora and fauna preserved in sediment overlying igneous basement provide a long-term record of the plateau’s Drilling results from ~120�����������������������������-����������������������������Ma Ontong Java Plateau base- subsidence, beginning with terrestrial and shallow marine ment rocks are complemented by studies of obducted plateau deposition and continuing to deep water deposition. rocks exposed in the Solomon Islands (Andrews et al., 1975 Kroenke et al., 1991 Berger et al., 1993 Neal et al., 1997 Seaward-dipping reflector (SDR) wedges of the latest Mahoney et al., 2001 Fitton et al., 2004a, b). All Ontong Java Paleocene-earliest Eocene North Atlantic LIP drilled off the
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