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Scientific drilling beneath the oceans Australian Journal of Maritime and Ocean Affairs (2010) Vol 2(2) Scientific drilling beneath the oceans solves earthly problems Neville Exon* Abstract Australia and New Zealand are partners in the world’s largest international geoscience program, the Integrated Ocean Drilling Program (IODP), which involves both geoscientists and microbiologists. IODP takes sediment and rock cores from as deep as several kilometres below the sea bed, in order to explore how the Earth has worked in the past and how it is working now. Many ocean drilling expeditions have been carried out in our region since the early 1970s and a great amount of fascinating scientific knowledge of global significance has been gained. ______________________________________________ The importance of ocean drilling to a marine We have one of the world’s largest marine audience jurisdictions (larger than onshore Australia) to study and manage, and marine geoscience plays a key role The Integrated Ocean Drilling Program (IODP) is a in both environmental and resource assessment. program of exciting science but some parts of that Australia has present claims to about 14 million km² science are of more immediate interest to a general of offshore territory,1 consisting of 11.65 million audience than others; of especial interest are the km² off Australia that is accepted by the studies of past changes in climate, ocean currents Commission of the Limits of the Continental Shelf, and sea level, which can help us better predict the and our Extended Economic Zone off Antarctica of future. Ocean drilling is complementary to the study 2.21 million km²; the maximum potential claimable of ice cores, which provides information about past area is about 15 million km². Under the United atmospheric changes but not oceanic changes, and Nations Convention on the Law of the Sea 1982 which is limited to very high latitudes (Antarctica arrangements, we need to understand and manage and Greenland), whereas ocean drilling has and is our offshore jurisdiction; the understanding must be being carried out from the Equator to Antarctica and based largely on marine science. For this purpose the Arctic Ocean. The other area of high general we actually need more scientists than we have, interest is the study of natural hazards; the history of specialised equipment that we do not have, and volcanic outbursts can inform our understanding of vessels with capabilities that Australian research future hazards and the planning for them. The agencies do and will not possess. The planned drilling study of the mechanisms of earthquakes Australia research vessel, The Investigator, will associated with oceanic trenches, including improve our situation considerably but will still not instrumenting the fault zones, can help us to better be capable of some important research activities.2 understand how the earthquakes occur and hopefully There is a new government emphasis on marine to help predict them in the long term. matters as exemplified by recent initiatives such as Australia and Marine Science the recently released A Marine Nation: National Framework for Marine Research and Innovation Australia is a small but influential player in report.3 international marine science, including its role within IODP. 1 Philip Symonds, Mark Alcock and Colin French, ‘Setting Australia’s limits: understanding Australia’s marine * Professor Neville Exon is the Program Scientist in charge of jurisdiction’, AUSGEO News 93, March 2009, p. 7, the Australian and New Zealand IODP Office at the Research <www.ga.gov.au/image_cache/GA13583.pdf> (26 July School of Earth Sciences at the Australian National 2010). 2 University in Canberra. He has wide experience in land CSIRO media release 09/82, $120 million for new Marine geology and marine geology and geophysics, and has written Research Vessel, 12 May 2009, <www.csiro.au/news/New- successful proposals for and participated in past marine-research-vessel> (26 July 2010). 3 ocean drilling expeditions. He is also part of the Technical See Australian Government Oceans Policy Science Advisory Group for the new deepwater Australian research Advisory Group, A Marine Nation: National Framework for vessel The Investigator. He can be contacted at Marine Research, Bureau of Meteorology, Melbourne, Neville.Exon@anu.edu.au or by phone on 02 6125 5131. 2009, <www.opsag.org/pdf/opsag-marine-nation-01.pdf> (26 37 Scientific drilling beneath the oceans Australian Journal of Maritime and Ocean Affairs (2010) Vol 2(2) We have natural advantages in marine geoscience holes across fault zones that generate earthquakes because, along with New Zealand, we are probably and tsunamis, with the aim of better understanding the major players in the southern hemisphere and are earthquakes, and ideally predicting them and thus the only IODP members in this hemisphere. saving untold numbers of human lives. This Fortunately, international research institutes are technology could perhaps be used later west of already heavily involved in cooperation with Sumatra – we all know of the devastating Australian groups (government agencies and earthquakes and tsunamis generated there.4 universities) in the field. It should be noted that there is strong cooperation between geoscience and What is IODP? other disciplines such as physical oceanography and The sediments and rocks beneath the world’s oceans marine biology. contain a remarkable story of how the Earth works now and has worked in the past, and suggestions The Nature of Marine Geoscience about how it may work in the future. Australian Marine geoscience involves examining the nature of geoscientists and microbiologists are involved in the sea bed and the processes shaping it, and the studies of cores taken through these sediments and nature and mineral resources of all that lies beneath rocks, using the latest technology from the IODP, the sea bed. The nature of the sea bed is of vital which is the world’s largest multinational importance to the food chain that is based on it and geoscience program.5 The rationale for these studies hence to our wild fisheries and aquaculture. The includes the realisation that the past is often a key to sediments below the sea bed tell us about past the future of the Earth. environments, and host resources such as petroleum, IODP controls drill ships worth roughly US$1 metallic ore deposits of various types, and sand and billion, and has an annual working budget of about gravel that are vital to our future. Offshore US$210 million for the United States fiscal year.6 petroleum is one of Australia’s largest export The primary exploration tools are dynamically- earners, and its discovery depends on geoscience. positioned Japanese and American coring vessels Much geoscience work involves remote sensing, but, where the primary vessels are not suitable, the such as acoustic swath mapping to map the sea bed, European Union through the European Consortium reflection seismic profiling to reveal the structures for Ocean Drilling Research (ECORD) charters (and by inference, resources) below the sea bed, and other coring platforms. The available equipment can the taking of sediment cores to study climate take continuous sediment or rock cores in all oceans, history. It also includes taking sea bed samples on in most water depths and up to 5000m below the sea steep slopes where the ancient strata of sedimentary bed. Deepwater drilling has been likened to drilling basins are exposed, thus giving us a better into the pavement with a string of spaghetti from the understanding of those basins and their petroleum top of the Empire State Building. potential. Onboard ship, an average of 30 scientists and 30 A completely different field is the study of active technicians from around the world works around the and extinct volcanoes in island arcs and adjacent to clock on the cores. They have an array of laboratory oceanic trenches, both to better understand them and and other research equipment aboard the primary the hazards they present, and also to study modern vessels that few Australian university departments gold and copper deposits, not only for their own can match. A single two-month expedition can worth but also to better understand and predict recover thousands of metres of cores, which keep 30 ancient deposits that formed in the ocean but that are or more scientists busy for several years. A host of now on land. publications appear in the open scientific literature 2-3 years after each expedition, and the IODP’s own IODP coring is the ultimate tool to study many of scientific reports on expeditions are publicly these matters deep below the sea floor. For example, off Japan the hazards from earthquakes are well known and devastating. There, IODP will place 4 geophysical, pressure and chemical sensors in bore Phil Cummins and Mark Leonard, ‘The Boxing Day 2004 Tsunami – a repeat of 1833?’, AUSGEO News 77, March 2005, pp. 3-5, <www.ga.gov.au/image_cache/GA6137.pdf> (26 July 2010). 5 July 2010); and Kate Wilson, Providing a framework for See the Integrated Ocean Drilling Program website our Marine Nation, Australian Government Oceans Policy <www.iodp.org> (2 July 2010). 6 Science Advisory Group, <www.opsag.org/powerpoint/ IODP, Annual Program Plan FY2009, pp 7-8, 090617-AmericanChamberOfCommerce-OPSAG-KWilson. <www.iodp.org/index.php?option=com_docman&task=doc_ ppt> (26 July 2010). download&gid=2416> (26 July 2010). 38 Scientific drilling beneath the oceans Australian Journal of Maritime and Ocean Affairs (2010) Vol 2(2) Figure 1: Map showing the locations of IODP scientific drilling until mid 2010. Courtesy H.C. Larsen, IODP-MI available,7 and an example of a mature publication of Australia; drilling to the earth’s mantle; and covers the results of scientific drilling off Tasmania understanding earthquakes and tsunamis. in 2000.8 • The deep biosphere and ocean floor. IODP’s main research fields are: ‘Extremophile’ microbes have been shown to live deep beneath the sea floor. In total they • Environmental change processes and effects. have an enormous biomass, and they could be of This covers past rapid climate change and industrial importance. Accumulations of frozen extreme climates, climatic cycles, and the gas hydrates (largely methane) beneath the sea evolution of oceanic currents and boundaries. floor are a huge potential energy resource and Ocean drilling has been and will be a key to their release has been shown to trigger bursts of understanding past climate change on all time global warming in the past.9 scales and at many locations, and hence in helping to predict future climate changes. Studies of past changes in climate and global sea level, and of past volcanic eruptions, are obviously • Solid earth cycles and geodynamics. This of great immediate societal relevance. In this area deals with continental breakup and sedimentary the past can illuminate the future. Climate change basin formation, which is especially important and sea level rise are pressing issues, and some of in petroleum exploration; large igneous the best evidence about past variations and what provinces like the Kerguelen Plateau southwest appears to have driven them comes from ocean drilling cores. Evidence of the size, damage caused 7 See IODP Scientific Publications <www.iodp.org/scientific- by, and frequency of past volcanic eruptions can publications> (26 July 2010). 8 NF Exon, JP Kennett, MJ Malone (eds), The Cenozoic 9 Southern Ocean: Tectonics, Sedimentation and Climate Integrated Ocean Drilling Program Initial Science Plan, 2003- Change between Australia and Antarctica. American 2013, Earth, Oceans and Life: Scientific Investigation of the Geophysical Union, Geophysical Monograph Series 151, Earth System using Multiple Drilling Platforms and New 2004. Technologies, <www.iodp.org/isp> (2 July 2010). 39 Scientific drilling beneath the oceans Australian Journal of Maritime and Ocean Affairs (2010) Vol 2(2) Table 1. ANZIC participants on IODP expeditions Expedition Date Participant NanTroSeize 1: 316 December 2007 - Chris Fergusson (University of Wollongong), Nankai Trough Faulting February 2008 sedimentology PEAT 1: 320 5 March - Christian Ohneiser (Otago University), Eastern Pacific environments 5 May 2009 palaeomagnetism Bering Sea: 323 5 July - Kelsie Dadd (Macquarie University), Connections from Pacific to Arctic 4 September 2009 sedimentology of volcanic ash Shatsky Rise: 324 4 September - David Murphy (QUT), petrology of volcanics Volcanic buildup: NW Pacific 4 November 2009 NanTroSeize 2: 319 10 May - Gary Huftile (QUT), structural geology Nankai Trough deep observatory 31 August 2009 NanTroSeize 2: 322 5 September - John Moreau (Melbourne University), microbiology Nankai Trough Subduction 10 October 2009 Great Barrier Reef: 325 11 January - Jody Webster (Sydney University), Co-Chief environmental change caused by post-glacial sea 5 March 2010 Scientist, reef formation level rise Canterbury Basin: 317 4 November 2009 - Bob Carter (JCU), Simon George (Macquarie), Greg sea level fluctuations in last 20 million years 4 January 2010 Browne, Martin Crundwell (GNS), Kirsty Tinto (Otago) Wilkes Land: 318 4 January - Kevin Welsh (Queensland) and climate and oceanographic changes in last 53 9 March 2010 Robert McKay (Victoria University, Wellington), million years both sedimentology South Pacific oceanic gyre microbiology. East of 8 October - Jill Lynch (Melbourne University), microbiology New Zealand 12 December 2010 Louisville Seamount geodynamics. Southeast of 12 December 2010 - Ben Cohen (Queensland University), volcanic Tonga 11 February 2011 petrology, David Buchs (ANU), volcanic sedimentology also be found in such cores and used to help predict only those that address global problems in the future. Although IODP is designed as a program particularly suitable areas have any chance of of pure science, a better understanding of the success. The membership of IODP is led by the sedimentary sequences of poorly known continental United States, Japan and Europe, and the other margins is important to the petroleum exploration countries involved are Australia, Canada, China, industry. Previous ocean drilling in the Exmouth India, New Zealand and the Republic of Korea. Plateau off the Australian northwest shelf, and off A map showing the location of IODP drilling since Tasmania, has helped companies better understand 2004 indicates just how geographically widespread some aspects of the petroleum potential of these were the various expeditions. Before the present regions, thus better focusing their efforts on phase of ocean drilling ends in 2013, more work will petroleum search. Successful petroleum search is in be done in the Pacific, Atlantic and Indian oceans. the nation’s interest, because it increases our self sufficiency and decreases our import costs. The Australian and New Zealand IODP IODP coring tests global geoscientific theories that Consortium are often developed largely on the basis of remote Australia and New Zealand form the Australian and sensing. New technologies and concepts in New Zealand IODP Consortium (ANZIC), and the geoscience are continuously being developed two countries have access to all IODP activities through IODP. Proposals for drilling are rigorously including shipboard and post-cruise research, assessed under intense international competition and 40 Scientific drilling beneath the oceans Australian Journal of Maritime and Ocean Affairs (2010) Vol 2(2) participation in planning committees and groups, later covered in sediment, thus contributing and visits from outstanding scientific speakers. The greatly to the concept of plate tectonics. Australian involvement is supported by the • Proving that the oceanic rocks existing at Australian Research Council (ARC), 14 universities present have all formed in the last 200 million (Adelaide, ANU, Curtin, James Cook, Macquarie, years, and showing that such rocks are Melbourne, Monash, Newcastle, Queensland, QUT, continuously poured out at mid-oceanic ridges Sydney, Tasmania, Western Australia, and and destroyed at oceanic trenches. Continental Wollongong), CSIRO, ANSTO and AIMS, and rocks, by contrast can be billions of years old. MARGO (a marine geoscience peak body). The Many of these ‘continental rocks’ are, in fact, Australian annual budget is almost $2.2 million, of ancient sedimentary and volcanic rocks that which the ARC provides $1.55 million.10 formed in the ocean but have been accreted to Membership of IODP helps Australia and New the continents. Zealand maintain our leadership in southern hemisphere marine research. For geographic, • Providing a detailed history of the climate and climatic, oceanographic and plate tectonic reasons, oceanographic changes that have affected the our region is vital to addressing various global world’s oceans in the last 200 million years. science problems, and some of them cannot be This was the exploration phase of ocean drilling, addressed elsewhere. Accordingly, the Australasian with holes being drilled in most parts of the world’s region has seen a great deal of ocean drilling since oceans to test existing ideas and also to see what 1968, when the first program was established.11 actually was there. A great deal was learned about Although drilling in the Australian region has ended the volcanic ridges and the intervening sedimentary for the time being, our scientists have and will be basins that characterise the sea floor in our region, involved in a variety of expeditions elsewhere in the and about the plate tectonic history of Australia. It world, addressing global scientific problems. was shown that other Gondwanan continents broke Australian scientists gain in various ways: through away from Australia, starting about 160 million shipboard and post-cruise participation in cutting years ago, with Australia moving north from edge science, by building partnerships with overseas Antarctica in the last 90 million years. scientists, by being research proponents and co-chief scientists who can steer programs and scientific Early Maturity: The Ocean Drilling Program emphasis, and by early access to key samples and In 1985, a larger and more capable new drilling data. Post-doctoral and doctoral students have an vessel, the JOIDES Resolution, replaced the Glomar opportunity of training in areas of geoscience and Challenger in the new Ocean Drilling Program microbiology that could not be obtained in any other (ODP). This phase of ocean drilling was still largely way. funded by the United States, but considerable funds were provided by European countries and Japan, and Early Days: The Deep Sea Drilling Project Australia joined as an associate member in a Between 1968 and 1983, the Deep Sea Drilling regional consortium in 1988.12 Although scientists Project (DSDP) began the study of the deep ocean from member countries took up most positions on sediments and rocks using the Glomar Challenger. vessels, scientists from countries that were not DSDP was funded by the US National Science members, but where drilling was taking place, also Foundation but welcomed foreign scientists, participated. Australian scientists were heavily including Australians and New Zealanders, to its involved both before Australia joined and afterward, drilling campaigns. This ship started to build a story and New Zealand scientists were commonly about what was happening and had happened in the involved near New Zealand although New Zealand 70 per cent of the Earth’s crust that lies beneath the was not a member. By the time ODP ended in 2003, oceans. Its major achievements included: there had been 17 two-month expeditions in our region (13 in Australian waters), 71 Australian • Drilling and dating the oceanic basalts that form scientists had participated in expeditions, and 7 on the sea floor as continents drift apart and are 10 See the Australian Integrated Ocean Drilling Program website <www.iodp.org.au> (2 July 2010). 11 Integrated Ocean Drilling Program Initial Science Plan, 2003- 12 2013, Earth, Oceans and Life: Scientific Investigation of the Elaine Baker and Jock Keene, Full Fathom Five – 15 years of Earth System using Multiple Drilling Platforms and New Australian involvement in the Ocean Drilling Program, Technologies, <www.iodp.org/isp> (2 July 2010). WYSIWIG DESIGN, Sydney, 2004. 41 Scientific drilling beneath the oceans Australian Journal of Maritime and Ocean Affairs (2010) Vol 2(2) Figure 2: Chikyu at sea. This huge drillship can drill in water 2500m deep, and is designed to take cores up to 6000m below the sea bed. Australian scientists had acted in the key position of purposes) Chikyu.14 The Europeans charter co-chief scientist.13 specialised drilling vessels for occasional expeditions where neither of the other two vessels This was a phase of ocean drilling which aimed to has the right capability.15 This means that drilling in solve global scientific problems, rather than one of the Arctic Ocean and in shallow reefal areas, for curiosity-driven exploration like DSDP. Numerous example, is now possible. Australians were proponents of successful proposals and the Australian geoscience research vessel, Rig Recent IODP expeditions: western Pacific Ocean Seismic, was instrumental in carrying out the and Southern Ocean detailed site surveys that were essential for successful proposals. When Rig Seismic was Australians and New Zealanders have recently been disposed of by the Australian Geological Survey involved in various expeditions using three vessels. Organisation (AGSO) in 1998, Australia no longer In 2009, six Australian scientists and one New had the world-class seismic profiling capability Zealander sailed on expeditions in the northern needed for most site survey work. Pacific. An Australian led the microbiological program on an expedition off Japan – the first Maturity: The Integrated Ocean Drilling Australian to sail in this role in the history of ocean Program drilling. The giant Japanese drillship, Chikyu, has IODP has access to more drilling platforms than the and will be drilling south of Japan to investigate the one that ODP had, but the JOIDES Resolution is still geology of the oceanic trench where the Pacific a very important part of the drilling capability, along Ocean crust is plunging beneath the Japanese with the larger and more capable (for some islands, causing devastating earthquakes and 14 See American vessel JOIDES Resolution <http://joidesresolution.org/> (2 July 2010); Japanese 13 Integrated Ocean Drilling Program Initial Science Plan, 2003- information on the drill vessel Chikyu and its program 2013, Earth, Oceans and Life: Scientific Investigation of the <www.jamstec.go.jp/chikyu/eng/Expedition/NantroSEIZE/in Earth System using Multiple Drilling Platforms and New dex.html> (2 July 2010). 15 Technologies, <www.iodp.org/isp> (2 July 2010). See the ECORD website <www.ecord.org> (2 July 2010). 42 Scientific drilling beneath the oceans Australian Journal of Maritime and Ocean Affairs (2010) Vol 2(2) resultant tsunamis. A better grasp of the geology, Figure 3: JOIDES Resolution in Hobart. This drillship can and the installation of seismometers and other drill in water 6000m deep, and take cores up to 2000m below the sea bed. analytical instruments deep beneath the seabed, will help scientists understand and perhaps even predict earthquakes. The large American drillship, JOIDES Resolution, has recently drilled on two expeditions in our region. The first is studying past climates and global sea level fluctuations over the last 15 million years in the especially suitable Canterbury Basin east of New Zealand. This expedition is described in some detail later. The second, in the Australian-claimed Wilkes Land region south of Australia off Antarctica, is studying the onset of Antarctic glaciation about 33 million years ago, and the fluctuations in glacial history since then. Senator Kim Carr, Minister for Science and Innovation, visited the JOIDES Resolution in Hobart in March. He made the point that the government strongly supports marine science through its funding for building the new deepwater research vessel, The Investigator, through its support for IODP, and in other ways.16 This expedition is also described in some detail later. Another drilling expedition has recently used the smaller GreatShip Maya to investigate the history of the 120m sea level rise in the Great Barrier Reef since the last glaciation about 18,000 years ago, and the associated changes in water properties and in the composition of the reef as it migrated landward. It is clear from seabed mapping that from time to time the reef suddenly stepped back westward to a new of Shinshu University in Japan. Among the position, and it is probable that this was caused by a scientific party were Bob Carter of James Cook sudden rise in sea level followed by slow rise. University, Simon George of Macquarie University, Understanding what has happened to the reef as the George Brown and Martin Crundwell of GNS ocean warmed and sea level rose can surely help us Science in Wellington, and Kirsti Tinto of better understand what might happen to the reef in a Canterbury University. The following text is drawn future warming world. largely from the Preliminary Report.17 Canterbury Basin expedition: initial results This expedition was devoted to understanding the relative importance of changes in global sea level The Canterbury Basin Expedition (317), carried out versus local tectonic (uplift and erosion) and in late 2009 in a sedimentary basin east of New sedimentary processes in controlling continental Zealand’s South Island, was designed as one of margin sedimentary cycles. The expedition several ocean drilling expeditions carried out recovered sediments deposited offshore in the last worldwide, to look at the details of how the world’s 35 million years, with a particular focus on the sea level has varied over many millions of years. sedimentary cycles of the last 10 million years, The vessel used was the JOIDES Resolution. The when global sea level change was dominated by the co-chief scientists were Craig Fulthorpe from the waxing and waning of huge ice sheets on Antarctica University of Texas in Austin, and Koichi Hoyanagi and, in the last 5 million years, in the northern 16 17 Senator the Hon. Kim Carr, Research Ship Arrives with 54- Integrated Ocean Drilling Program Expedition 317 million-year old climate samples, Media Release, Department Preliminary Report: Canterbury Basin sea level, February of Innovation, Industry, Science and Research, Canberra, 12 2010 <www.iodp.org/preliminary_report/317/317PR.PDF> March 2010. (2 July 2010). 43 Scientific drilling beneath the oceans Australian Journal of Maritime and Ocean Affairs (2010) Vol 2(2) hemisphere. Drilling in the Canterbury Basin takes thermohaline circulation. This new mode of ocean advantage of high rates of sediment supply, which circulation, caused by a much greater temperature preserve a high-frequency (0.1-0.5 million years) gradient from the equator to the poles, followed the record of depositional cycles. The applied value of separation of Australia and Antarctica and the this research is that such sedimentary cycles are freezing of Antarctica. It and the changes in land related to global sea level changes. The global configuration, largely caused by plate tectonics, cycles are used in petroleum exploration to help drive a very different pattern of ocean currents, the interpret local cycles seen in seismic reflection ones with which we are familiar today. profiles (cross-sections through the strata). If the Expedition 317 set a number of technological ocean cycles are better understood and better dated, drilling records: petroleum exploration becomes more efficient. • The deepest hole drilled in a single expedition The expedition results allow the study of the complex and second deepest hole in the history of interactions of the processes responsible for scientific ocean drilling (Hole U1352C, 1927m). preserving the sedimentary sequences, in a region where an uplifting and eroding mountain chain (the • The deepest hole drilled by the JOIDES Southern Alps) provides large volumes of derived Resolution on a continental shelf (Hole U1351B, sediment, and strong ocean currents erode and 1030m). deposit those sediments. Currents have locally built large, elongate sediment drifts or wedges. Expedition • The shallowest water depth for a site drilled by 317 did not drill into one of these elongate drifts, but the JOIDES Resolution for scientific purposes currents are inferred to have strongly influenced (Site U1353, 84.7m water depth). deposition across the basin, including in locations • The deepest sample taken by scientific ocean lacking prominent mounded drifts. drilling for microbiological studies (Site U1352, Sedimentary sequences covering the last 10 million 1925m). years were cored in a transect of three sites on the Expedition 317 supplements previous drilling of continental shelf (landward to basinward), and one sedimentary sequences for sequence stratigraphic site on the continental slope. The transect provides a and sea level objectives, particularly drilling on the record of depositional cycles across the shallow- New Jersey margin of America, and in the Bahamas, water environments that were most directly affected but includes an expanded Pliocene (2-5 million by sea level change. The boundaries of different years old) section. Completion of at least one sedimentary sequences, provisionally correlated transect across a geographically and tectonically with seismic reflectors, have been identified in cores distinct siliciclastic-dominated (quartz, feldspar and from each site. These help in understanding the other rock grains) continental margin was the origins of sequences identified by seismic profiling, necessary next step in deciphering the strata on this which provide cross-sections through the earth. This continental margin. Expedition 317 also record will be used to estimate the timing and complements ODP Leg 181, which focused on drift amplitude of global sea level change and to development in deeper water areas of the Eastern document the sedimentary processes that operate New Zealand Oceanic Sedimentary System. Plans during sequence formation. Superb sections through are underway for another complementary drilling the last 3 million years of sediments will yield high- expedition on the northwest shelf off Australia.18 resolution records of recent glacial cycles in a continental shelf setting. Wilkes Land expedition: initial results Continental slope Site U1352 has a complete The full scientific results of the Wilkes Land sedimentary section from modern land-derived expedition (318) will not be known for several years, sediment to hard marine Eocene limestone, with all but the following is drawn largely from the the associated sedimentary, biological (fossil), Preliminary Report.19 physical, geochemical, and microbiological information. The site also provides a record of ocean circulation and fronts during the last 35 million 18 years. A break in sedimentation about 30 million See Proposal 667 on the Integrated Ocean Drilling Program years ago (the Marshall Paraconformity), was the website <www.iodp.org/index.php?option=com_docman& task=doc_download&gid=487> (26 July 2010). deepest drilling target of the expedition and is 19 Integrated Ocean Drilling Program Expedition 318 believed to represent intensified current erosion (or Preliminary Report: Wilkes Land Glacial History level, April non-deposition) associated with the initiation of 2010 <www.iodp.org/preliminary_report/318/318PR.PDF> (2 July 2010). 44 Scientific drilling beneath the oceans Australian Journal of Maritime and Ocean Affairs (2010) Vol 2(2) The international team of scientists worked for two preserved within the cores will document the onset months aboard the JOIDES Resolution in early of cooling and the development of the first Antarctic 2010, and took cores of sediments and sedimentary glaciers and the growth and recession of rocks from the seafloor near the coast of Antarctica, Antarctica’s ice sheets. Cores from one shallow site at four drill sites. Despite negotiating icebergs, near contain sediment alternations that can be used like gale-force winds, and snow and fog, they managed tree rings to sort out environmental changes – to recover approximately 2000m of sediment core. alternating bands of light and dark sediment record Wilkes Land lies due south of Australia, and is seasonal variability during the last de-glaciation, believed to be one of the more climate-sensitive which began some 10,000 years ago.20 regions of the polar continent. The new core Understanding the behaviour of Antarctica’s ice samples collected during the expedition are unique sheets plays a fundamental role in our ability to build because they provide a direct record of the waxing robust, effective global climate models, which are and waning of the ice sheet in this region of used to predict future climate. ‘These models rely on Antarctica. These sediments preserve the history of constraints imposed by data from the field’, the co- how the ice sheets formed and interacted with chiefs pointed out. ‘Measurements of parameters such changes in the climate and the ocean. as age, temperature, and carbon dioxide concentration In response to growing concerns about our planet’s provide invaluable inputs that help increase the changing climate, rising global temperatures and sea accuracy of these models. The more we can constrain levels, and increasing concentrations of atmospheric the models, the better they’ll perform – and the better carbon dioxide (CO2), many scientists are looking to we can predict ice sheet behaviour.’ Earth’s past to help predict its future. This research What's next? The science team now embarks on a expedition will provide critical clues to multi-year process of onshore analyses to further understanding one of the most dramatic periods of investigate the Wilkes Land cores. Age-dating and climatic change in Earth’s history – and a glimpse chemistry studies among other analyses are expected into what might lie far ahead in our climate’s future. to resolve changes in Antarctica’s climate over The poles control much of our global climate. Giant unprecedentedly short timescales (50-20,000 years). ice sheets in Antarctica behave like mirrors, Data collected from the expedition will complement reflecting the sun’s energy and moderating the previous research from ocean drilling operations world’s temperatures. The waxing and waning of conducted elsewhere in the Antarctic over the last these ice sheets contribute to changes in sea level 40 years. Together, this research will provide and affect ocean circulation, which regulates our important age constraints for models of Antarctic ice climate by transporting heat around the planet. sheet development and evolution, thereby forming Despite their present cold temperatures, the poles the basis for models of future ice sheet behaviour were not always covered with ice. Like a history and polar climatic change. book, the sediment cores tell the story of how, approximately 53 million years ago, Antarctica had Great Barrier Reef Environmental Change a warm, sub-tropical environment covered in forest. During this same period, known as the ‘greenhouse’ The Great Barrier Reef Environmental Change or ‘hothouse’ world, atmospheric CO2 levels were (GBREC) Expedition (325) was carried out in early ten times as high as those of today. 2010. It used the dynamically positioned drilling vessel, GeatShip Maya, and the program was Then quite quickly, about 33.5 million years ago, approved and closely monitored by the Great Barrier Antarctica’s lush environment changed into an icy Reef Marine Park Authority. The following realm not much different from the present one. In description is drawn largely from the Scientific only 400,000 years – a mere blink of an eye in Prospectus and a post-cruise scientific press geologic time – concentrations of atmospheric release.21 The expedition was designed to study the carbon dioxide decreased greatly. Global temperatures dropped. Ice sheets developed. 20 Antarctica became ice-bound. How did this change Integrated Ocean Drilling Program Expedition 318 happen so abruptly and how stable can we expect Preliminary Report: Wilkes Land Glacial History level, April ice sheets to be in the future? 2010 <www.iodp.org/preliminary_report/318/318PR.PDF> (2 July 2010). 21 Combined, the cores will tell the story of Integrated Ocean Drilling Program Expedition 325 Scientific Prospectus: covering the Great Barrier Reef Environmental Antarctica’s transition from an ice-free, warm, Change expedition, August 2009, ‘greenhouse’ world to an ice-covered, cold, dry <www.publications.iodp.org/scientific_prospectus/325/325S ‘icehouse’ world. Sediments and microfossils P.pdf> (2 July 2010); and ECORD media release, Great Barrier Reef corals unveil sea-level changes and climate 45 Scientific drilling beneath the oceans Australian Journal of Maritime and Ocean Affairs (2010) Vol 2(2) Figure 4: GreatShip Maya in the Great Barrier Reef. This smaller drillship is designed to work in relatively shallow water, and took cores in carbonates in water as shallow as 30m on this expedition. (Photograph courtesy of ECORD). sea level rise and sea-surface temperature warming • The first objective was to reconstruct the de- since the peak of the last glaciation about 20,000 glaciation curve of sea level rise for the period years ago. This will help our understanding the 20,000 to 10,000 ago in order to establish the dynamics of the melting of large ice sheets and what minimum sea level during the Last Glacial happened as they turned to water. Before this Maximum and to assess the validity, timing, and expedition, the only sea level records covering the amplitude of a number of known glacial whole de-glaciation came from offshore drilling of meltwater pulses. These are thought to have Barbados and Tahitian coral reefs. IODP Expedition disturbed the general oceanic circulation, which 310 (Tahiti Sea Level), which was successfully was driven by temperature and salinity, and completed in 2005 and 2006, recovered a near- hence changed global climate. The meltwater complete record of sea level change since the last pulses, when ice dams confining great northern glaciation.22 hemisphere glacial lakes burst, are also believed GBREC was designed to establish the course and to have caused at least three periods of effects of the last de-glaciation in a reef setting in a accelerated sea level rise, about 19,000, 13,800 tectonically inactive area. Offshore sites were cored and 11,300 years ago. A series of drowned reef along transects on the Great Barrier Reef. terraces had been identified before the expedition, and those between 120m deep (about 20,000 years ago), and 30m deep (about history, 19 July 2010 <www.ecord.org/p/gbrec- 10,000 years ago) were cored away from living osp_press_release.pdf> (26 July 2010). coral. The terraces presumably correspond to 22 Integrated Ocean Drilling Program, Tahiti Sea Level: periods of relatively slow sea level rise, with the Expedition 310 of the mission-specific drilling platform sudden jumps upslope related to meltwater from and to Papeete, Tahiti, French Polynesia, Sites pulses. M0005–M0026, 6 October-16 November 2005, <http://publications.iodp.org/proceedings/310/310title.htm> (26 July 2010). 46 Scientific drilling beneath the oceans Australian Journal of Maritime and Ocean Affairs (2010) Vol 2(2) • The second objective was to establish the sea- design the next ten-year phase of IODP from 2013. surface temperature variation accompanying the Several Australians played key roles at INVEST, sea’s transgression at each transect. These data and Australia and New Zealand produced a white will allow the researchers to examine the impact paper before it. Richard Arculus of ANU is a of sea level changes on reef growth, geometry, member of the post-INVEST New Science Plan and biological makeup, especially during reef Writing Committee, as is New Zealander Peter drowning events, and will help improve the Barrett, showing the scientific regard in which we modelling of reef development. are held. Chris Yeats of CSIRO is the only representative on a key structural planning group • The third major objective was to identify and from outside the United States, Japan, and the establish patterns of short-term paleoclimatic European IODP consortium. Geoff Garrett, former changes that are thought to have punctuated the CSIRO Chief Executive and now Chairman of the transitional period between present-day climatic ANZIC Governing Council, was on another conditions following the Last Glacial important committee investigating how well the Maximum. It is proposed to quantify the scientific arrangements in IODP have worked in the variations of sea-surface temperatures using last three years, and making suggestions for the high-resolution isotopic and trace element future. analyses on massive coral colonies. When possible, the researchers will try to identify At a recent meeting in Cambridge, California, the specific climatic phenomena such as El Niño- Science Plan Writing Committee decided on the Southern Oscillation in the time frame prior to tentative titles for four overarching themes for the 10,000 years ago.23 next phase of ocean drilling: The cores from the expedition were sampled in July • Earth's Climate Systems: Extremes, Linkages 2010 in Bremen, Germany, and detailed scientific and Sensitivity. work is to start now. Enough is already known of • The Crust below the Ocean: Window to the the cores to suggest that much of the planned Inner Earth. science will be achieved. The post-cruise scientific press release, produced after the sampling program, • Limits of Life: Deep Life, Extreme stated that cores had come from 34 holes in three Environments and External Forcing. key locations on the outer edge of the Great Barrier Reef.24 Altogether 225m of material were recovered, • Earth in Motion: Sub-seafloor Observatories. including 191m of fossil coral reef whose age varies Ocean drilling has proved hugely successful in from 30,000 to 9000 years. revealing past and present Earth processes, and there is a strong drive to continue this work in existing Future Plans for Ocean Drilling and new directions. The aim is to have a new ten- Ocean drilling will continue in the South Pacific year plan in existence when IODP terminates in Ocean east of New Zealand late this year and early 2013. Australian and New Zealand science has next year. Then the JOIDES Resolution will move profited greatly from ocean drilling, and the away eastward from our region, but return to the geoscientists and microbiologists who have been Indian Ocean until the present phase of ocean involved in the work thus far are dedicated and drilling ends in 2013. The Chikyu will continue to enthusiastic supporters of our continuation in the drill in the Japanese region, and an alternative future program. platform may be used to drill ancient and deeply drowned Hawaiian reefs next year. In September 2009, there was a very large scientific meeting (INVEST) in Germany, which started to 23 Integrated Ocean Drilling Program Expedition 325 Scientific Prospectus: covering the Great Barrier Reef Environmental Change expedition, August 2009, <www.publications.iodp.org/scientific_prospectus/325/325S P.pdf> (2 July 2010). 24 ECORD media release, Great Barrier Reef corals unveil sea- level changes and climate history, 19 July 2010 <www.ecord.org/p/gbrec-osp_press_release.pdf> (26 July 2010). 47
"Scientific drilling beneath the oceans solves earthly problems"