Recognizing the importance of methane hydrate research and the need for a coordinated effort, the United States Congress enacted the Methane Hydrate Research and Development Act of 2000. At the same time, the Ministry of International Trade and Industry in Japan launched a research program to develop plans for a methane hydrate exploratory drilling project in the Nankai Trough. India, China, the Republic of Korea, and other nations also have established large methane hydrate research and development programs. Government-funded scientific research drilling expeditions and production test studies have provided a wealth of information on the occurrence of methane hydrates in nature. Numerous studies have shown that the amount of gas stored as methane hydrates in the world may exceed the volume of known organic carbon sources. However, methane hydrates represent both a scientific and technical challenge, and much remains to be learned about their characteristics and occurrence in nature. Methane hydrate research in recent years has mostly focused on: (1) documenting the geologic parameters that control the occurrence and stability of methane hydrates in nature, (2) assessing the volume of natural gas stored within various methane hydrate accumulations, (3) analyzing the production response and characteristics of methane hydrates, (4) identifying and predicting natural and induced environmental and climate impacts of natural methane hydrates, (5) analyzing the methane hydrate role as a geohazard, (6) establishing the means to detect and characterize methane hydrate accumulations using geologic and geophysical data, and (7) establishing the thermodynamic phase equilibrium properties of methane hydrates as a function of temperature, pressure, and gas composition. The U.S. Department of Energy (DOE) and the Consortium for Ocean Leadership (COL) combined their efforts in 2012 to assess the contributions that scientific drilling has made and could continue to make to advance our understanding of methane hydrates in nature. COL assembled a Methane Hydrate Project Science Team with members from academia, industry, and government. This Science Team worked with COL and DOE to develop and host the Methane Hydrate Community Workshop, which surveyed a substantial cross section of the methane hydrate research community for input on the most important research developments in our understanding of methane hydrates in nature and their potential role as an energy resource, a geohazard, and/or as an agent of global climate change. Our understanding of how methane hydrates occur in nature is still growing and evolving, and it is known with certainty that field, laboratory, and modeling studies have contributed greatly to our understanding of hydrates in nature and will continue to be a critical source of the information needed to advance our understanding of methane hydrates.

Ocean Drilling Program Leg 166 drilled a total of 17 holes at seven sites (Sites 1003 through 1009) on the western flank of the Great Bahama Bank, recovering almost 3 km of core ranging in age from late Oligocene to Holocene. Leg 166 was designed to address two important geologic themes: (1) causes and effects of eustatic sea-level fluctuations and (2) fluid-flow processes in the margins of isolated platforms. To address fundamental questions regarding sea level fluctuations, five sites in the Straits of Florida were drilled (Sites 1003-1007), completing a transect through prograding carbonate sequences formed in response to sea-level fluctuations along the western margin of the Great Bahama Bank. Two boreholes (Clino and Unda) drilled previously on the western Great Bahama Bank as part of the Bahamas Drilling Project represent the shallow-water sites of the transect. The primary goal of the transect was to document the record of the Neogene-Holocene sea-level changes by determining the ages of the major unconformities in the sedimentary record and comparing the timing of these unconformities with ages predicted from the oxygen isotopic record of glacio-eustasy. Core borings from the complete transect document the facies variations associated with oscillations of sea level, and, therefore, the sedimentary response of the carbonate environment to sea-level changes. The correlation between the two independent records of sea-level changes, sequence stratigraphy and oxygen isotope proxy, has the potential to evaluate rate and amplitude of eustatic vs. relative sea-level changes and to establish a causal link between glacio-eustasy and the stratigraphic pattern. With the sedimentary sequence recovered in advanced hydraulic piston coring, extended core barrel, and rotary core barrel drilling and the abundance of biostratigraphic markers, it was possible to define the ages of the Neogene sequence boundaries and to test their consistency with ages determined in the boreholes previously drilled on the platform. This yielded an excellent correlation between sites, documenting the age consistency of the sequence boundaries and chronostratigraphic significance of the seismic reflections. By reaching the Oligocene at Site 1007, a complete record for the sequence stratigraphic architecture is available for the entire Neogene. At all five transect sites (Sites 1003, 1004, 1005, 1006, and 1007), alternating high (up to 15 to 20 cm/k.y.) and low sedimentation rates (<2 cm/k.y.) reflect a long-term pattern of (1) bank flooding (0.5-2 m.y.), (2) concomitant shedding to the slope and periods of exposed banks, (3) a shutdown of shallow-water carbonate production, and (4) largely pelagic sedimentation. The pulses of bank-derived material coincide with the prograding pulses seen in the seismic data as sequences, which with their geometries indicate base-level lowerings as a result of sea-level falls. Within these long-term changes, high-frequency sea-level changes are recorded in decimeterscale depositional cycles. The ages of 17 seism...

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During Ocean Drilling Program (ODP) Leg 189, five sites were drilled in bathyal depths on submerged continental blocks in the Tasmanian Gateway to help refine the hypothesis that its opening near the Eocene/ Oligocene boundary led to formation of the Antarctic Circumpolar Current (ACC), progressive thermal isolation of Antarctica, climatic cooling, and development of an Antarctic ice sheet. A total of 4539 m of largely continuous upper Maastrichtian-Holocene marine sediments were recovered with a recovery rate of 89%. The sedimentary sequence broadly consists of shallow-marine mudstones until the late Eocene, glauconitic siltstones during that time, and pelagic carbonates thereafter. The microfossils in the mudstones and siltstones are largely palynomorphs and diatoms, and those in the carbonates are largely nannofossils and foraminifers. During the Late Cretaceous, northward movement of Australia away from Antarctica commenced, forming the Australo-Antarctic Gulf (AAG). However, a Tasmanian land bridge at 70°-65°S almost completely blocked the eastern end of the widening AAG until the late Eocene; there is no evidence of extensive current circulation across the ridge until the earliest Oligocene. Prior to the Oligocene, muddy marine siliciclastic sediments were deposited in temperate seas. During the late Eocene, the northeastern AAG was warmer and less ventilated than the gradually widening southwest sector of the Pacific Ocean, which was affected by a cool northwesterly flowing boundary current-a difference that may have existed since the Maastrichtian. In the late Eocene (~37 Ma), the Tasmanian land bridge and its broad shelves began to subside,

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