The Lake Baikal drilling project in the context of a global lake drilling initiative

Quaternary International 80–81 (2001) 3–18

The Lake Baikal drilling project in the context of a global lake drilling initiative Douglas F. Williamsa,*, Mikhail I. Kuzminb, Alexander A. Prokopenkoa,c, Eugene B. Karabanova,b, Galina K. Khursevichd, Elena V. Bezrukovae a

Department of Geological Sciences, University of South Carolina, Columbia, SC 29208, USA Institute of Geochemistry, Siberian Branch of Russian Academy of Science, Irkutsk, Russia c United Institute of Geology, Geophysics and Mineralogy, Siberian Branch of Russian Academy of Science, Novosibirsk, Russia d Institute of Geology, Belarus National Academy of Sciences, Minsk, Belarus e Limnological Institute, Siberian Branch of Russian Academy of Science, Irkutsk, Russia b

Abstract Records of the tectonic and climatic evolution of continental interiors are important for understanding the dynamics of the Earth’s climate system, evolutionary processes within the terrestrial biosphere, and human origins. Sediment drill cores recovered from Lake Baikal provide essential records not only for comparison with oceanic records of marine processes, but also benchmarks which can be used to help interpret other continental records including other lake archives scheduled to be drilled in the near future. Drilling of Lake Baikal made it possible for the first time to have a continental archive with the same scientific and chronostratigraphic integrity as marine records to address critical questions of the Quaternary and Pliocene. The Lake Baikal drilling project (BDP) rapidly progressed from piston coring and seismic reflection studies to conducting the first scientific drilling in 4 short years and to very deep drilling in over 8 years. BDP has taken advantage of the harsh Siberian winters by using the frozen surface of Lake Baikal as a drilling platform. The positioning of the drill sites was selected using seismic and piston coring surveys. By continuously improving the drilling operations and technology, BDP has achieved new core recovery and depth records over the last ten years and become the world’s leader in pioneering the recovery of high-quality, extremely long lacustrine sediment sequences from deep water. The success of BDP came at a time of growing interest in lake drilling among members of the paleoclimate community with few recent large-scale coordination efforts to draw upon. At the organizational, technological and financial levels, some recent changes are favorable for the development of a global lake drilling initiative, which could become as successful and efficient as the ocean drilling program. r 2001 Elsevier Science Ltd and INQUA. All rights reserved.

1. Scientific drilling in lacustrine basins One doesn’t have to look hard in the scientific literature to see abundant evidence of the fundamental contributions made from the long and continuous sedimentary sequences recovered through several decades of ocean drilling. Well-funded, superbly coordinated and well-publicized international programs such the ocean drilling program (ODP) have made it possible to collect and properly study sediment cores from every major ocean basin. The interconnected nature of the ocean basins, the nature of ocean circulation itself (the great ‘‘conveyor belt’’), and the resulting sea bottom *Corresponding author. E-mail address: [email protected] (D.F. Williams).

sediments, make it possible to resolve a powerful combination of paleoceanographically meaningful proxies and robust chronostratigraphies. The imaginative use of this combination has made it possible to correlate past climate signals from basin to basin with a high degree of resolution and reliability. As a result, the field of paleoceanography has flourished by documenting and furthering the understanding of how the oceans both influenced and responded to climate change through time and space. In addition to the scientific importance of these efforts, the ocean science community has set a standard of excellence by being well organized, highly visible (i.e., the Year of the Ocean) and politically astute. This degree of savvy plays a crucial role in establishing governmental funding levels and scientific priorities.

1040-6182/01/$ - see front matter r 2001 Elsevier Science Ltd and INQUA. All rights reserved. PII: S 1 0 4 0 - 6 1 8 2 ( 0 1 ) 0 0 0 1 5 - 5

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Given the above discussion of ocean sediments and climate change, the picture of continental processes from continental archives of earth history is much less developed and understood. This situation is partially due to the fragmentary and disconnected nature of most potential archives. Despite great strides made from studies of the distribution of past ice on land (moraines and other geomorphologic features), successive advances of Northern Hemisphere ice sheets in the Pleistocene have rearranged and/or obliterated many older deposits, making continuity of the record a difficult criterion to achieve. Tree rings, ice cores, loess deposits and lake sediments are among the few exceptions to this generality. Among these valuable continental archives, lake sediments have the highest potential for providing long records with a synoptic and holistic perspective of global change comparable with the ocean drilling perspective. Yet, until the PAGES pole-equator-pole (PEP) framework was envisioned in the 1990s (see PAGES, 1995), as the result of international efforts to understand the earth as a system of linked and interacting subsystems, no detailed conceptual plans existed for a systematic, global array of continental archives of any type. Lake systems have the latitudinal, longitudinal and altitudinal distribution needed to capture much of the intra- and intercontinental variability inherent in the climate system. Lake sediments also contain numerous proxies in the form of pollen, diatoms, ostracods and mollusks, authigenic carbonates, biogenic silica, and clay mineral fractions for resolving the paleoclimatic response of a lake system to changes in climate forcing, its watershed and its surrounding terrestrial biosphere. Lake sediments also accumulate at varying rates and degrees of continuity. These two factors accommodate the need for both high resolution and long duration, characteristics that make marine sediments so useful. In other words, lake sediments represent the best possible archives for reconstructing long-term conditions and responses of continental regions to global change processes on decadal to millennial scales. With or without the PAGES-PEP framework, however, there have been historical challenges to visualizing different lake systems as teleconnected and thereby using them as linked global change archives. Lakes have often been viewed as dependent upon but in some ways separate and distinct from the global system. Another part of the challenge to fully utilizing lake archives has revolved around issues of territoriality. Lacking a collective political will like the ocean science community, individual limnologists often laid informal, territorial-like claims to particular lakes or lake systems. Adding to or perhaps partially reflective of this lack of community esprit de corps, governmental funding agencies didn’t have readily identifiable programs for handling large limnological or paleolimnological-

oriented proposals. Thus, gaining the political and financial support to bring lacustrine archives on-line has had considerable difficulty. Sometimes geopolitical instability or logistical difficulties in various parts of the world discouraged the planning of large-scale lacustrine expeditions, especially in remote and inaccessible regions. It might be useful to recall the problems and frustrations with trying to start an initiative in the early 1980s for scientific drilling of lakes in the East African rift (EAR) valley. This noble effort appeared to have the requisite scientific rationale for a lake drilling program (resolution of tropical paleoclimate signals, sedimentary rift basin history and evolution, and even implications for understanding early human history and evolution) (Livingstone, 1981). Technology was not the main obstacle to drilling the deep-water EAR lakes because ODP engineering developments had made it possible to dynamically position a drilling platform in deep water to retrieve long sediment cores (hydraulic piston corers, riser technology, etc.). A seismic stratigraphic framework suitable for site selection was also a crucial element available for some of the EAR lakes from Project PROBE (Rosendahl et al., 1988; Scholz and Rosendahl, 1988; Scholz et al., 1989). Unfortunately, several other elements were frustratingly missing to make an EAR lake scientific drilling program possible in the early 80s. Not the least among the missing elements was the lack of necessary financial backing within the USA from the National Science Foundation. The lack of a sanctioning or sponsoring international organization did not help. The effort to organize an EAR drilling program was also not helped by the fact that many scientists in the looselyknit earth science community of the USA feared that ‘‘big science’’ projects, like drilling, would siphon off already scarce funding for the ‘‘small science’’ projects that most investigators were used to and dependent upon. Another factor was the fact that some nations surrounding the EAR lake systems had unstable scientific and logistical infrastructures. In some cases, outright civil unrest weakened the best and most earnest efforts to generate the momentum needed for a scientific EAR lake drilling effort.

2. The need for a global lake drilling initiative The clearest indication of a need or desire for a global lake drilling effort evolved from a PAGES-sponsored workshop in 1995 (Williams, 1995; Colman, 1996; Williams et al., 1996). At that workshop, reports were made concerning the PAGES-PEP framework for examining continental responses in pole-to-equatorialpole transects (i.e., the framework for conceptually linking lakes and other archives of continental processes together through the global climate and atmospheric systems). The emergence of the international continental

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Fig. 1. The distribution of lakes chosen as a basis for the first prospectus on global lake drilling (Williams et al., 1996).

scientific drilling program (ICDP) (Zoback and Emmermann, 1994; Zoback et al., 1994), efforts to form a European lake drilling program, and the first successful drilling in Lake Baikal were also made known and discussed at the meeting. The workshop participants in one of the working groups realized the opportunity at hand and formed, with PAGES sanction, the first Task Force for Global Lake Drilling. The Task Force went on to solicit brief proposals from the international community via advertisements in EOS (Transactions of the American Geophysical Union) (Williams, 1995) and the Internet. Based on an evaluation of over 60 proposals in the framework of the three PAGES PEP transects, the Task Force members then met at NSF headquarters, Washington, DC, to formulate a prospectus for a global lake drilling plan (Fig. 1; Williams et al., 1996). The prospectus sought to: (1) demonstrate the level of international interest in this scientific direction, regardless of nationality or fundability at that time; (2) prioritize the submitted sites in terms of PAGES objectives and chances of success; (3) provide a rough time table; and (4) roughly estimate the drilling costs. In one sense, the Task Force prospectus was meant as a wake-up call to science administrators and funding agencies that indeed a significant scientific need existed for a major new initiative, not just in the American scientific community but around the world. As important if not prescient as the prospectus was, however, the prospectus was flawed by appearing to be overly optimistic in scope and exorbitant in projected costs.

Implementation of the preliminary plan was not feasible for other reasons. The timetable in the prospectus was not realistic and did not allow adequate response time for national and international funding agencies to prepare for a program of such extent and cost. The emerging lake drilling community at that time lacked portable, adaptable and affordable drilling systems for drilling in the wide variety of lacustrine environments proposed. Although highly successful, the portable, adaptable and affordable drilling system deployed from a barge in Lake Baikal was not seriously given consideration largely because Russian membership in ICDP was complicated by the economic and political situation of the times. Another limitation of the prospectus was the lack of an international infrastructure to support mobilization and demobilization of drilling systems on various continents. ICDP’s ‘‘operational support group’’ was not yet established nor was DOSECC1 actively involved in the lacustrine basin arena. Recently the potential for a global lake drilling initiative has gained momentum. The PAGES organization has continued to play an important role in promoting high-resolution studies of lacustrine sedimentary archives. Last year, with limited input from the 1 DOSECC (Drilling, Observation and Sampling of the Earth’s Continental Crust, Inc.) is a nonprofit corporation owned by 47 research institutions, organized in 1984 to assist in the implementation of Continental Scientific Drilling by offering expertise to plan, budget and monitor drilling programs and thus by providing a bridge between earth science and drilling technology (www.dosecc.org).

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international scientific community, the Earth System History program at the US-NSF, in partnership with ICDP and DOSECC, funded the construction of a new drilling system called, with a hint of hope, the Global Lake Drilling 800 system (GLAD800). In the same NSF-ESH panel, two large-scale multi-million dollar proposals were approved for funding to deploy the GLAD800 system in Lake Titicaca and Lake Malawi. Under DOSECC technical supervision and operation, the initial GLAD800 deployment was a technological success in Great Salt Lake and Great Bear Lake, Utah (Kelts et al., 2000; Nielson et al., 2000), preparing the way for its deployment in Lake Titicaca (with drilling scheduled to commence in May 2001; D. Nielson, DOSECC, pers. comm.). One of the initial selling points of the GLAD800 system was that it could be deployed in a variety of water depths on an adaptable pontoon system that did not require the expense of a dynamic positioning system. This latter consideration is currently delaying final funding decisions on the Lake Malawi drilling effort (D. Nielson, DOSECC, and C. Scholz, Syracuse Univ., pers. comm.). Nonetheless, having the GLAD800 technology available, it is not difficult to envision the potential for large-scale drilling programs. One example of a potential program could involve expanding the results from the Lake Baikal drilling sites into an array of other lacustrine systems through the continental interior of Asia (Fig. 2). Such an integrated longitudinal program would also connect two of the prioritized latitudinal PAGES PEP transects, II and III.

Some significant and substantive issues remain to be tackled, however, before a bona fide global lake drilling program is to be realized on any sustainable scale. There is only one GLAD800 system currently available and the decision-making process on how to schedule the one GLAD800 system is still young and evolving. At the present time, it is fair to say that a somewhat complicated review process exists for continental drilling proposals that, despite the best efforts of the ICDP website, may or may not be well known to the international community. As the initial global lake drilling prospectus demonstrated in 1995, serious interest exists in the international scientific community outside of the ICDP member nations (Germany, China, Japan, Mexico, Poland, and USA) but as of 2001 a coherent plan or timetable does not exist, nor are there clearly defined and stable funding procedures to support this possibility. This statement is not meant as a criticism of ICDP or any other organization but instead is meant only as an observation of the current state of affairs. One conclusion from the above discussion is that the timing is right for a true global lake drilling program, openly announced, widely promoted by ICDP, PAGES, DOSECC and other organizations, and adequately funded by national and international funding agencies, perhaps on the model of the ODP. In hindsight, much of the above discussion seems logical today but such a perspective was not possible over a decade ago when organization of the Baikal Drilling Project (BDP) began in 1989. In many respects,

Fig. 2. The ‘‘golden ring’’ of Asian lakes which makes a prime target for large-scale continental drilling campaign connecting PEP II and PEP III transects prioritized by PAGES.

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BDP was and still is today a highly experimental project of international cooperation driven primarily by a high level of enthusiasm. When started, BDP lacked prior examples of such cooperation. The Lake Biwa drilling effort (Horie, 1972, 1984) was almost exclusively Japanese funded and therefore conducted. The Newark Basin project was extremely successful in drilling and studying ancient lacustrine sequences (Olsen and Kent, 1996) but the scientists involved did not have to deal with drilling in deep water, developing new technology, surviving harsh winters in remote regions of Siberia, nor negotiating international but often nationalistic considerations in shared funding, sampling and analytical work. BDP also lacked an engineering budget that would allow for pre-testing of drill rig design and coring tools. Each BDP drilling leg involved as much engineering as scientific effort. In addition, BDP was conceived prior to the PAGES-PEP program and thus had no officially sanctioned and global context within which to fit the BDP results other than the marine record (BDP did become a Core Project in PAGES but only later, in 1994–1995). Looking back, we can realize now that the success of BDP became an important example of how lake drilling can be manageable, feasible and worthwhile, even in risky and challenging environments. In this work we will next review the rationale for BDP, and some of the scientific, technological and logistical challenges that BDP had to face and overcome. Following this, we will briefly summarize some important BDP results, which are also highlighted in greater detail in the other BDP works in this volume.

3. Rationale for drilling the world’s deepest lake Due to its great depth, age and biodiversity, Lake Baikal is a natural laboratory for studying a wide variety of modern and ancient geological, biological– ecological and hydrological-atmospheric processes related to global change. (Fig. 3). The modern watershed of Lake Baikal includes over 300 rivers and streams that drain through the boreal forests of south-central Siberia and the steppe landscapes of Transbaikalia and northern Mongolia. The ecosystem of Lake Baikal includes the world’s highest faunal and floral biodiversity of any lacustrine system. From a geological perspective, Baikal’s thick sedimentary cover, undisturbed by the growth and decay of high latitude continental ice sheets during past ice ages, makes the sediments of Baikal ideal for obtaining continuous long sedimentary records. Baikal’s sediments are over 5 km thick in the central and southern depressions, currently the deepest basins of the Baikal rift zone (BRZ) contained in these sediments are records of the last 20–40 million years of lake history, an invaluable repository of geological information. These sediments can be used to address

Fig. 3. The Baikal lacustrine system, consisting of several elements with different response times, is located in the middle of continental interior Asia to provide new insights on tectonic and climatic evolution of the region. Cores retrieved by the Baikal Drilling Project make it possible to have a continental record of the same scientific and chronostratigraphic integrity as marine records to address critical questions of the Quaternary and Pliocene.

questions from tectonic and structural development of the BRZ, one of the world’s most active continental rift zones to past climate changes on different time scales (Fig. 4) and to the relationship between climate change and the biotic evolution of geographically isolated populations. These populations are expressively represented by well-preserved and rich assemblages of diatoms, the dominant primary producers in Lake Baikal’s ecosystem. In the above scientific context, the BDP was conceived as an international endeavor to drill, recover and sample Baikal’s extensive sedimentary record. The objectives summarized in Fig. 4 were set out as a prime target and justification of drilling in Lake Baikal. The overarching scientific goals were both comprehensive and integrated: (a) Understand the responses of Baikal’s

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Fig. 4. Schematic representation of the scientific objectives which initiated the Baikal Drilling Project. Recovery of long sedimentary records (scale to the right) makes it possible to study important climatic events of the past (scale to the left).

limno-ecosystem and watershed to forcing from both external and internal dynamics of the Earth’s climate system; (b) determine the evolution of the Baikal sedimentary basin in response to tectonic forcing; and (c) after separating the two processes, extract long continuous continental paleoclimate records.

4. Challenges to the Lake BDP Prior to drilling, however, extensive negotiations had to be carried out between the Soviet and American sides in order to produce an adequate organizational and scientific framework. Of top priority was the joint writing of proposals to secure adequate financing. Needless to day, these negotiations were not helped with the break-up of the Soviet Union, the ensuing economic collapse and the resulting turmoil in the institutes of the Russian Academy of Sciences and the Ministry of Geology. The delicacy of the negotiations cannot be overemphasized. First, we had to build trust after decades of generally prohibited contact and cultural-based differences in style and operation. Second, national security restrictions had to be overcome,

even extending to the long since antiquated 286 personal computers and hand-held GPS units that can now be easily purchased in most sporting good stores. As ridiculous as this sounds now, these considerations were major obstacles to the smooth planning of joint scientific surveys. On the Russian side, many maps were classified and many publications were not available to American investigators either because Russian scientists were not familiar with the importance of such information for writing credible proposals back in the USA and/or because most Americans could not read Russian. Nationalistic interests presented further challenges to decisions concerning sample and data distribution rights, the storage of archive cores for future studies, and publication rights. The entry of Japanese scientists in 1992 expanded the financial, scientific and analytical base of the project but did not simplify the other challenges, especially since no overall structure, like an ODP, ICDP, PAGES or DOSECC, was supporting or sponsoring BDP. The effort by the BDP Steering Committee to accommodate these competing challenges was further complicated by multiple funding sources and types, the American and Japanese sides with cash and the Russian side with limited money but substantial and crucial in-kind services. One lesson to be learned from this tremendously complicated but ultimately successful effort is that a properly sponsored, funded and equipped global lake drilling initiative will enable principal investigators to focus on the science and less on intergovernmental and nationalistic politics and policies. Besides the above political challenges, BDP faced some considerable scientific matters when seeking funding. Some concerns centered on the sensitivity of Lake Baikal to climate forcing. Some reviewers of initial proposals believed that Baikal was just too voluminous to respond to anything but the largest changes. Some reviewers questioned the presence of proxies for extracting climate-related signals and resolving a robust chronology from Baikal’s bottom sediments, starved of biogenic or authigenic carbonate. Others questioned the ability to recover sediments undisturbed by slumping and mass wasting from the steeply sided rift basin. Tremendous and some times clever efforts were needed to address these concerns and prove, not just state, that the sediments of Baikal were true archives of global climatic processes, not just responsive to local changes in the watershed and terrestrial biosphere (see results presented in this volume). In addition to these and other scientific considerations, significant technological decisions had to be made concerning how best to drill in great water depths in a land-locked ‘‘freshwater ocean’’ in which no drilling ships were available. Cost was an ever-present concern and restriction. Russian engineers of the world famous Nedra Deep Drilling Enterprise of Yaroslavl first

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D.F. Williams et al. / Quaternary International 80–81 (2001) 3–18 Table 1 Summary of Lake Baikal drilling project activities and scientific objectives Year

Activity

Site

Water depth

Drilled/recovered Scientific objectives

1989–1993

Recovery of numerous piston, gravity and box cores

All basins

up to 1600 m

up to 10 m

1993

Advance hydraulic piston coring, BDP-93, Leg I Hydraulic and rotary coring, BDP-96, Leg II Hydraulic and rotary coring, BDP-97, Leg III

Buguldeika Saddle Academician Ridge Southern Basin

1998

Hydraulic and rotary coring, BDP-98, Leg IV

Academician Ridge

333 m

600/670 m

1999

Hydraulic and rotary coring, BDP-96, Leg V

Posolskaya Bank

201 m

270/350 m

1996 1997

proposed the cheapest route: a sled-based system that could be positioned by tractor onto the frozen surface of Baikal. This plan seemed like a good first step because Baikal typically and historically freezes to a thickness of nearly 1 m. Starting first in northern Baikal, ice with sufficient strength to support this system usually lasts 3–4 months. To decrease the weight of the system, Nedra engineers chose threaded aluminum pipe for the drill stem. They designed several coring tools including a 2 m advanced hydraulic piston corer adapted from the successful ODP 9 m tool. Special precautions were taken to satisfy strict environmental considerations including using a slurry of Baikal clay as the drilling mud. With a very limited budget, Nedra did everything possible to make the drilling happen with maximum scientific returns at minimal cost. Naturally the drilling window is longer in the north and shorter in the southern basin so the initial plan in 1992 was to drill in the northern basin at a location in 900 m water depth. Everything cooperated but the weatherFan unusually warm and snowy winter kept the ice thickness to less than 60 cm. After two frustrating months waiting for the ice to thicken and numerous attempts to artificially thicken the ice by spraying water onto the surface, the Nedra drilling team disappointingly brought the drilling sled into a shallow satellite lake, a mere pond in comparison to mighty Baikal. The goal was to test the coring devices even though the water depth was only 10 m. The test core successfully demonstrated that the 2 m Baikal-APC was capable of retrieving undisturbed core with close to 100% recovery. However, the BDP drilling and scientific teams had to wait until 1993 for successful drilling. Moving the Nedra drilling system onto a barge, the Nedra Baikal team successfully proved

354 m

100/100 m

321 m

200/300 m

1428 m

120/225

Development of climatic proxies, geochronological framework, sediment deposition models Holocene and Late Quaternary paleoclimate change and evolution Pliocene-Quaternary paleoclimate change and ecosystem evolution Depositional history of Southern Basin, first-ever sampling of freshwater gas hydrates High-resolution Late MiocenePliocene climatic and biogeochemical evolution in response to uplift in Asia Quaternary paleoclimate, watershed response and tectonic history of Selenga accommodation zone

the capabilities of the system and drilling personnel in 354 m of water on the Buguldeika Saddle. Advancements and improvements also led to successful drilling during 1996–1999 (Table 1). Needless to say, nothing on the scale and complexity of the BDP project had ever happened before on Baikal. This necessitated major efforts by personnel of several institutes of the Russian Academy of Sciences (Siberian Branch) for transporting equipment and supplies long distances over treacherous winter roads and from the shore to the drilling sites. Open leads of water often form during the day and close at night making travel dangerous even in light vehicles. The early winter ice of Baikal moves and heaves in massive blocks. The massive blocks can crush; in 1996, the entire drilling operation on the Academician Ridge was in danger of failure when heaving ice tore a 30 cm crack in the side of the drilling barge, threatening to sink it with several tons of fuel oil aboard. After a heroic and harrowing rescue effort to save the 1996 drilling barge, efforts were made to strengthen the hulls of the ships and barges used in each successful drilling campaign.

5. BDP organization and first studies Political changes within the Soviet Union during 1987–1989 not only led to the wholesale restructuring of one of the world’s leading superpowers and the end of the Cold War, but also opened the potential for new international scientific initiatives as acknowledged in the US–USSR Basic Sciences Agreement of 1989. The idea of drilling Lake Baikal, the world’s deepest and arguably oldest extant lacustrine system, occurred in

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Fig. 5. Location of the Baikal drilling project sites where long drill cores were obtained. The inset at the bottom enlarges the area of Academician Ridge marked by dashed frame. The inset at the top represents the progression of drilling operations using two different drilling complexes. The water depth of drilling operations and the depths of penetration into sediment strata are shown for each BDP Leg.

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parallel with the internal decision of the Siberian Branch of the Russian Academy of Sciences to establish an international center for scientific cooperation called the Baikal international center for ecological research (BICER). Previous reconstructions of the sediments of Lake Baikal, while limited in resolution and extent, clearly showed that Baikal’s basins contained thick sediments (2.5–3 km) with potential age of Late to Middle Miocene, and BDP quickly became a centerpiece of BICER’s evolving scientific program. In 1995, BDP was adopted as a core project in the IGBP-PAGES PEPII transect. In August 1997, BDP was official endorsed by the Gore-Chernomyrdin Commission meeting in Moscow, as a cooperative scientific project in the Geosciences. In 1998, BDP became the first lake project to receive funding from the new ICDP headquartered in Potsdam, Germany. In order to address some of the initial scientific concerns mentioned earlier, the first studies on piston cores from Lake Baikal were essential to demonstrate that diatoms, biogenic silica content and pollen composition are highly responsive to glacial-interglacial climate change (Bezrukova et al., 1991; Karabanov et al., 1992; Granina et al., 1993; Bradbury et al., 1994). The early studies also showed that organic carbon productivity indices responded in accordance with diatom and biogenic silica signals (Ishiwatari et al., 1992; Prokopenko et al., 1993; Qiu et al., 1993; Williams and Jenkins, 1993). It was also found that lithology and rock-magnetic properties bear a paleoclimatic signal correlative with marine oxygen isotope records (King et al., 1993; Peck et al., 1994). The distinctive nature of the magnetic susceptibility and biogenic silica profiles led to the important construction of age models based on correlation with the marine oxygen isotope record (Peck et al., 1994; Colman et al., 1995). Comparison of the Baikal piston core records of the last climatic cycle revealed an early regional glaciation during substage 5d, which appears to be an important part of the mechanism of glacial inception in the northern hemisphere (Karabanov et al., 1998). All of these early studies were essential to justify funding of each subsequent drilling campaign. As a result, BDP progressed step-by-step from piston coring to conducting the first scientific drilling in 4 short years and to very deep drilling in over 8 years. In fact, the Lake BDP has become the world’s leader in pioneering the recovery of high-quality, extremely long lacustrine sediment sequences from deep water. BDP has taken advantage of the harsh Siberian winters by using the frozen surface of Lake Baikal as a drilling platform. The positioning of the drill sites was made using existing Russian-American seismic profiles. By continuously improving the drilling operations and technology, BDP has achieved new core recovery and depth records over the last ten years as shown in the Table 1.

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6. Overview of scientific results from Baikal Drilling cores The comprehensive efforts mentioned above made possible five drilling campaigns in 1993, 1996–1999 (Table 1, Fig. 5). Highlights are summarized below: 6.1. Leg I (BDP-93) Despite the first definite technological success in Baikal sediment core recovery, an immediate understanding of the value of the BDP-93 cores was compromised by the fact that the cores did not penetrate the Brunhes/Matuyama paleomagnetic reversal boundary (BDP-Members, 1995, 1997b). Also, not until a complete set of AMS radiocarbon dates became available (Colman et al., 1996) did it become clear that the BDP-93 drill cores recovered the most detailed 50–100 year resolution records of the last glacial/ interglacial transition (Prokopenko et al., 1999) and the Holocene (Karabanov et al., 2000c) in Lake Baikal. The d13C record of BDP-93 has revealed the sensitivity of the Baikal carbon cycle to past changes in the composition of the atmosphere (Prokopenko et al., 1999). The BDP-93 record also important for demonstrating the sensitivity of the Lake Baikal system to subMilankovitch forcing during the past 75,000 years (Prokopenko et al., 2001b; also this volume). Results from the BDP-93 cores provided the first strong evidence for climatic teleconnections between the Lake Baikal region of Siberia and the North Atlantic climatic trigger/amplifier (Broecker, 1994). 6.2. Leg II (BDP-96) This drilling program was truly historic in nature because it recovered a nearly complete sedimentary record for the last 5 million years. This record provided the first opportunity to establish a robust geochronology using paleomagnetic stratigraphy (Williams et al., 1997; BDP-Members, 1997a, 1998; Sakai et al., 2000). Detailed micropaleontological studies of BDP-96 cores (Khursevich et al., 1999a, b, 2000, 2001) have provided a new stratotype and biostratigraphic framework for continental paleoclimate studies (Fig. 6). The BDP-96 cores also showed that Plio-Pleistocene paleoclimate proxy records from Lake Baikal pollen and diatoms reliably reflect regional paleoenvironmental evolution (Bezrukova et al., 1999). The dramatic changes in terrestrial vegetation (Fig. 7) and lacustrine biota were apparently associated with episodes of early glaciation (Karabanov et al., 2000a, b) which became amplified by regional tectonic evolution (Prokopenko et al., this volume). The detailed biostratigraphic work on the Brunhes chron portion of the BDP-96-2 demonstrates a strong relation between diatom production in Lake

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the repetitive nature of the BioSi signal have made it possible to develop a detailed orbitally-tuned Baikal chronology (Prokopenko et al., 2001a). This result was very important for adopting marine oxygen isotope stratigraphy of stages and substages to the Baikal continental interior paleoclimate record, which is not marine but lacustrine and in which no oxygen isotopes have been measured. Linking Baikal with marine stratigraphy opens new opportunities for studying the extent and dynamics of past climate changes. 6.3. Leg III (BDP-97) This effort in the southern basin constitutes the world’s first lake drilling in water depths exceeding 1000 m in addition to the first ever sampling of the only known freshwater gas (methane) hydrates. A gas hydrate layer in Baikal sediments was revealed by the presence of a bottom simulating reflector in multichannel seismic profiles (Hutchinson et al., 1992, 1993), it was also predicted from thermodynamic calculations and measurements of geothermal gradients (Golubev, 1997, 1998). Baikal hydrates sampled in the BDP-97 drill core have a chemical composition of CH4
5H2O and carbon stable isotope compositions from 57m to 67m, typical of biogenic methane (Kuzmin et al., 2000a). 6.4. Leg IV (BDP-98)

Fig. 6. The new biostratigraphic framework from Lake Baikal planktonic diatoms for the last 5 million years in relation to the paleomagnetic event/reversal time scale. The onset of cooling at 2.8–2.5 Ma coincides with the extinction of the Stephanopsis genus, and the first appearance of the new genus Tertiarius, which in turn went extinct at the subsequent transition to warmer climatic conditions. Such sharp changes in the diatom assemblage at high taxonomic level indicate profound catastrophic environmental changes at Matuyama/ Gauss paleomagnetic reversal boundary. The high rate of extinctions and speciation during the Pleistocene (see Khursevich et al., this volume) reflects the dramatic impact of glacial/interglacial climatic changes on the Baikal ecosystem.

Baikal and insolation forcing (Khursevich et al., this volume). Lithologic studies combined with robust paleomagnetic models of BDP-96 allowed ground truthing the seismic interpretation and provided age constraints for the major Baikal tectonic and sedimentation events (Kuzmin et al., 2000b). A very important feature of the BDP-96 record, not observed previously in the BDP-93 record beyond the last climatic cycle of 130 ka, was the long-term stability on the biogenic silica (BioSi) signal during the past glacial/interglacial cycles extending as far back as 2.5 Ma (Williams et al., 1997). The high resolution and

This effort enabled BDP scientists to return to the area of the highly successful BDP-96 drilling site and to extend that 5 million year record back into the Miocene (to nearly the last 10 million years BP) by recovering a 601 m section. A total of three boreholes were drilled: (1) 0–201 m (BDP-98 Hole 1) drilled using advance piston coring without riser; (2) 191–670 m (BDP-98 Hole 2) drilled using APC, hydro-strike and rotary drilling with riser; (3) 0–50 m (BDP-98 Hole 3) drilled using APC technique to ensure complete recovery of the upper section of sediments. The core recovery is about 99% for the upper 200 m. The joint results of preliminary studies of BDP-98 (BDP-Members, this volume) demonstrate that this drill core recovered a 10 Ma record of regional climatic and tectonic evolution. 6.5. Leg V (BDP-99) Drilling in the 1998–1999 winter at Posolskaya Bank (southern termination of the Buguldeika saddle) in a water depth of 201 m recovered 250 m of sediments for the purpose of high-resolution scientific studies. The estimated core recovery is 96% for the upper part of the section (0–250 m). Below 250 m sediment depth, drilling continued to 350 m for technical purposes of testing new coring equipment designed by the NEDRA Drilling

D.F. Williams et al. / Quaternary International 80–81 (2001) 3–18

13

Fig. 7. Palynological analysis of BDP-96-1 drill core (Bezrukova et al., 1999) reveals dramatic changes in regional vegetation at Matuyama/Gauss paleomagnetic reversal boundary. The areas occupied by thermophilic light-coniferous and deciduous flora have greatly diminished at 2.5 Ma. The cold interval of 2.8–2.5 Ma is also characterized by expansion of non-arboreal steppe vegetation. The change in the entire structure of vegetation cover at this paleoclimate threshold indicates a dramatic irreversible change in climatic conditions and landscapes in continental interior Asia at the time of initiation of the northern hemisphere ice ages.

team, which resulted in lower recovery of about 70%. The upper part of sediment section at Posolskaya Bank consists of diatomaceous silty clay giving another highresolution Lake Baikal record similar to BDP-93 but from a different depositional system. The lower sedimentary section is primarily silty clay reflecting variations in terrestrial input from Baikal’s major tributary, the Selenga River. Preliminary studies on this core are currently being conducted.

7. Difficulties encountered in the course of BDP activities The largest organizational difficulties encountered by BDP were in fact due to its truly international character and the lack of a single or coordinated funding source. All of the BDP drilling campaigns were funded by three equal partner-countries, US, Russia and Japan. For BDP-93 and BDP-96 funding came primarily from US sources, BDP-98 drilling was jointly co-funded in approximately equal amounts. Disagreements on drill site selection and other matters resulted in the BDP-97 drilling campaign being funded primarily by the Japanese side. Three sides, representing their national interests and having somewhat different agendas, often had to resolve the disputes on drilling sites, sampling and analytical strategies in heated BDP Steering Committee negotiations. Part of this lack of a unified

approach contributed to our inability to adopt an ODPstyle sampling and analytical protocol despite our best attempts at forming analytical teams with coordinators. Instead, samples were split equally between participating sides with archive portions stored in Irkutsk. In addition, German scientists, while never becoming official partners in BDP, received sets of samples from the BDP-93 and BDP-96 cores. As a result, analytical works were performed by national teams with little true cooperation, often in competition, except in the paleomagnetic effort where Russian, Japanese and US scientists came the closest to achieving data sharing relationships. Nonetheless, joint Russian–Japanese– American teams proved very efficient in working on the BDP core descriptions, which involved up to 50 scientists and technicians for a consecutive period of 1–2.5 months for each drilling leg. In addition to the expected logistical complications of supplying a drilling operation with fuel and food while at ice-bound, remotely located sites, the BDP organization continuously encountered difficulties with making large-scale international shipments for the needs of the Project. These complications often involved customs clearance in Russia, which consumed significant funds, wasted valuable personnel time, and seriously delayed our scientific progress. Curiously enough, the standard ODP-type core shipping boxes, which we originally planned to use for core shipment overseas, arrived to

14

Isotope stratigraphy

BDP96 depth (m)

BDP96 age (ka)

MIS 1

0–0.17

0–11.3

MIS 2

0.17–0.25

MIS 3 MIS 4 MIS 5

1.00–1.76 1.76–2.56 2.56–5.47

MIS 6 MIS 7

5.47–8.13 8.13–10.99

11.3–24 24–58 58–71 71–130

130–179 179–244

Lake Baikal LDAZ

LDAZ depth (m)

1

1

0–0.17

0–11.3

2

2

11.3–13.7 13.7–36 36–58

4

0.17–0.25 0.25–1.00 1.00–1.76 1.76–2.56 2.56–4.12

5

4.12–4.58 4.58–5.47

104–113 113–120

6

4.97–5.47

120–130

7 8

5.47–8.13 8.13–9.74 9.74–10.42 10.42–10.68 10.68–10.99

130–179 179–225 225–234 234–239 239–244

10.99–13.15 13.15–14.53 14.53–14.72 14.72–14.84 14.84–15.57 15.57–15.99 15.99–17.00

244–279 279–315 315–319 319–322 332–338 338–347 347–369

3 4–6

7 8–10

9 10

MIS 8 MIS 9

MIS 10

10.99–13.15 13.15–15.57

15.57–17.00

244–279 279–338

334–369

LDAZ age (ka)

11 12–14

11 12

15

13 14 15

71–104

Planktonic diatom assemblages

Marine isotope events

Aulacoseira baicalensis–A. islandica–Cyclotella ornata–C. minuta–Cyclostephanus dubius Aulacoseira islandica–Stephanodiscus flabellatus Single fragments of diatoms Aulacoseira baicalensis–Cyclotella baicalensis Diatoms are absent Aulacoseira baicalensis–Stephanodiscus grandis–Cyclotella baicalensis–C. ornata–C. minuta Diatoms are absent Aulacoseira baicalensis–Cyclotella baicalensis Stephanodiscus grandis–S. formosus Aulascoseira islandica (cells and spores)–Stephanodiscus aff. flabellatus–S. grandis– S. formosus–Synedra acus var. radians Cyclotella minuta–C. ornata Stephanodiscus grandis–S. formosus–S. carconeiformis Diatoms are absent Stephanodiscus grandis Aulacoseira islandica (spores and cells)– Stephanodiscus formosus–S. baicalensis var. concinnis–S. grandis– S. carconeiformis Stephanodiscus grandis–S. formosus–S. carconeiformis Stephanodiscus grandis–S. formosus–S. carconeiformis Single fragments of S. grandis Stephanodiscus binderanus–S. exiguus Stephanodiscus exiguus–S. baicalensis var. concinnis Aulacoseira islandica Single fragments of diatoms

1 2/1 transition 3 5a–c 5d 5e 5e

7a–c 7d 7e 7e

9a–c 9d 9e 9e

D.F. Williams et al. / Quaternary International 80–81 (2001) 3–18

Table 2 Local diatom assemblage zones (LDAZ) in the Lake Baikal BDP-96-2 drill core record

MIS 11

17.00–19.93

369–427

16–18

16 17

17.00–18.13 18.13–19.27

369–393 393–413

18

19.27–19.93

413–427

19.93–20.84 20.84–21.88 21.88–24.09

427–445 445–474 474–529

19.93–21.88

427–474

19–20

MIS 13

21.88–24.09

474–529

21

19 20 21

MIS 14

24.09–25.08

529–553

22

22

24.09–25.08

529–553

MIS 15

25.08–28.14

553–624

23–24

23

25.08–26.58

553–584

24

26.58–27.65 27.65–28.14

584–612 612–624

25 26

28.14–29.30 29.30–30.24 30.24–30.88

624–644 644–664 664–687

27 28

30.88–31.18 31.18–31.96

687–698 698–720

MIS 16 MIS 17

28.14–30.24 30.24–31.96

624–664 664–720

25 26–28

MIS 18

31.96–33.87

720–766

29

29

31.96–32.54 32.54–33.11

720–736 736–751

MIS 19

33.87–35.16

766–798

30–31

30

33.11–33.87 33.87–34.41

751–766 766–779

31

34.41–35.16

779–798

11a 11b 11c

15a 15b–d 15e

D.F. Williams et al. / Quaternary International 80–81 (2001) 3–18

MIS 12

Cyclotella minuta Stephanodiscus distinctus var. distinctus–S. binderanus–C. minuta Stephanodiscus distinctus var. distinctus–S. exiguus–Synedra acus var. radians Stephanodiscus aff. binderanoides S. distinctus et var. excentricoides Stephanodiscus distinctus et var. excentricoides–Aulacoseira islandica Stephanodiscus distinctus et var. excentricoides–Cyclotella minuta Stephanodiscus distinctus et var. excentricoides–Synedra ulna var. danica Diatoms are absent Stephanodiscus bindera noides–S. princeps–Synedra ulna var. danica Single fragments of diatoms Cyclotella praeminuta Stephanodiscus baicalen sis var. concinnis–Cyclotella praeminuta Stephanodiscus veneris–C. praeminuta Stephanodiscus asteroides var. baicalensis Cyclotella praeminuta Single fragments of diatoms Cyclotella praeminuta–Stephanodiscus baicalensis var. concinnis–Aulacoseira islandica Single fragments of diatoms Stephanodiscus baicalensis var. concinnis–Stephanodiscus compactus Aulacoseira subarctica–Stephanodiscus notabilis– A. islandica

15

16

D.F. Williams et al. / Quaternary International 80–81 (2001) 3–18

Irkutsk already partly destroyed, so much tougher containers had to be built for this purpose. Most of these complications, however, simply caused some stress and delays, but did not compromise either the quality of the cores or the scientific results. Although the more efficient sampling/analytical ODP protocols were not adopted, the BDP cores were properly handled, described and sampled, and archived in a core storage facility specifically built for this purpose in Irkutsk. Most of the initial results were published jointly in the Russian Journal of Geology and Geophysics and in the IPPCCE Newsletter (International Project on Paleolimnology and Late Cenozoic Climate) selflessly edited and published by Shoji Horie. Despite the complications described above, we believe that overall the BDP operation represents a rather unique and valuable example of international collaboration. Future lake drilling projects, unless funded fully from a sole or coordinated source and involving a scientific team with no diverse national interests, are likely to face similar challenges, which are sometimes difficult but always rewarding to overcome. Successful acquisition of long continental paleoclimate and paleoenvironmental records requires large investments (on the order of 3–4 million USD to obtain 1000 m of core from drilling a deep lake (Colman, 1996) including planning, logistics, and drilling technology. Therefore, from a financial standpoint, BDP was also a success because less than $ 5 million was spent over a 10year period by USA, Russia and Japan in support of drilling and recovery of 1600 m of continuous sedimentary sections spanning the last 10 million years (Table 1).

further understanding and appreciation of Lake Baikal as a lacustrine system. In this volume we present some highlights of the on-going research on BDP cores. We believe that the BDP should be viewed as a long-term investment in studying the late Cenozoic history of continental Asia as well as an important demonstration of the need for a global lake drilling program.

Acknowledgements We thank all participants of the five BDP campaigns for the effort, passion and dedication that made BDP a reality and a success. The major funding for drilling operations was provided by US NSF grants EAR9119537, EAR-93-1720401 and EAR-9614770, the Siberian Branch of the Russian Academy of Sciences, the Russian Ministry of Geology, the Science and Technology Agency (STA) of Japan. The International Continental Scientific Drilling Program (ICDP) provided important technical support with BDP-98 core logging. Seismic reflection and coring cruises of 1990–1992 and the BDP-93 drilling campaign was in part supported by the US Geological Survey’s Climate History Program. We thank Dr. Norm Catto for his inspiration and patience in putting this special comprehensive volume together.

Appendix A See Table 2.

8. Conclusions References Joint efforts by a multi-national Russian–American– Japanese BDP team have made it possible to overcome many scientific, technological, logistical and organizational challenges. Having successfully completed five winter drilling campaigns in seven years with cumulative international funding for science and for drilling not exceeding $5 million, the BDP has retrieved a unique sedimentary archive from the continental interior of Asia. BDP cores total 1600 m of sediment with over 95% recovery. The Baikal archive contains a series of paleoclimate and paleoenvironmental proxies resolvable on different time scales with the potential for 250-year or less time resolution over the last 5–10 million years. This unique sedimentary archive is now available for in-depth scientific study of the paleoclimatic and paleoenvironmental evolution of the central Eurasian supercontinent that for the most part is still a terra-incognito for the scientific community. In many respects, scientific results from BDP are just emerging in the published literature as we begin to gain

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