Late Cenozoic Climate History of the Ross Embayment from the AND-1B Drill Hole: Culmination of Three Decades of Antarctic Margin Drilling

Because of the paucity of exposed rock, the direct physical record of Antarctic Cenozoic glacial history has become known only recently and then largely from offshore shelf basins through seismic surveys and drilling. The number of holes on the continental shelf has been small and largely confined to three areas (McMurdo Sound, Prydz Bay, and Antarctic Peninsula), but even in McMurdo Sound, where Oligocene and early Miocene strata are well cored, the late Cenozoic is poorly known and dated. The latest Antarctic geological drilling program, ANDRILL, successfully cored a 1285-m-long record of climate history spanning the last 13 m.y. from subsea-floor sediment beneath the McMurdo Ice Shelf (MIS), using drilling systems specially developed for operating through ice shelves. The cores provide the most complete Antarctic record to date of ice-sheet and climate fluctuations for this period of Earth’s history. The >60 cycles of advance and retreat of the grounded ice margin preserved in the AND-1B record the evolution of the Antarctic ice sheet since a profound global cooling step in deep-sea oxygen isotope records ~14 m.y.a. A feature of particular interest is a ~90-m-thick interval of diatomite deposited during the warm Pliocene and representing an extended period (~200,000 years) of locally open water, high phytoplankton productivity, and retreat of the glaciers on land

Operations Overview for the ANDRILL McMurdo Ice Shelf Project, Antarctica

During the austral summer of 2006, a record-setting 1 284.87 metre (m)-long rock and sediment core (ANDRILL [AND]-1B) was recovered from beneath the McMurdo Ice Shelf (MIS) in 917m of water. A custom built drilling system comprising a UDR-1200 rig, jack-up platform, hot water drill, sea riser, and diamond-bit wireline coring string was set up on the McMurdo Ice Shelf approximately 9 kilometres (km) from Scott Base (NZ). The drilling sytem employed technology developed to handle challenging environmental conditions including an 85 m-thick ice shelf ‘platform’ that moved both laterally and vertically, strong tidal currents, and high winds. Drill site set up commenced on 18 August 2006, and the first core for AND-1B was recovered on 31 October 2006. Drilling operations continued through 26 December 2006. Science operations were conducted at the drill site, in both the borehole and a purpose built laboratory (lab) complex, and at the Crary Science and Engineering Center (CSEC), McMurdo Station (USA). Drill site science operations involved downhole logging, which was carried out in the borehole casing and in parts of the open hole, fracture studies, and physical properties measurements. Core was transported from the drill site to McMurdo Station, where it was split, scanned, described, and sampled for initial characterisation. Once initial studies were completed, the core was packed into crates for shipment to the Antarctic Research Facility (ARF; core respository) at Florida State University in the United States

Operations Overview for the ANDRILL McMurdo Ice Shelf Project, Antarctica

During the austral summer of 2006, a record-setting 1 284.87 metre (m)-long rock and sediment core (ANDRILL [AND]-1B) was recovered from beneath the McMurdo Ice Shelf (MIS) in 917m of water. A custom built drilling system comprising a UDR-1200 rig, jack-up platform, hot water drill, sea riser, and diamond-bit wireline coring string was set up on the McMurdo Ice Shelf approximately 9 kilometres (km) from Scott Base (NZ). The drilling sytem employed technology developed to handle challenging environmental conditions including an 85 m-thick ice shelf ‘platform’ that moved both laterally and vertically, strong tidal currents, and high winds. Drill site set up commenced on 18 August 2006, and the first core for AND-1B was recovered on 31 October 2006. Drilling operations continued through 26 December 2006. Science operations were conducted at the drill site, in both the borehole and a purpose built laboratory (lab) complex, and at the Crary Science and Engineering Center (CSEC), McMurdo Station (USA). Drill site science operations involved downhole logging, which was carried out in the borehole casing and in parts of the open hole, fracture studies, and physical properties measurements. Core was transported from the drill site to McMurdo Station, where it was split, scanned, described, and sampled for initial characterisation. Once initial studies were completed, the core was packed into crates for shipment to the Antarctic Research Facility (ARF; core respository) at Florida State University in the United States

Petrology and Geochemistry of the AND-1B Core, ANDRILL McMurdo Ice Shelf Project, Antarctica

This section reports preliminary data and results on petrology and geochemistry of AND-1B core

Petrology and Geochemistry of the AND-1B Core, ANDRILL McMurdo Ice Shelf Project, Antarctica

This section reports preliminary data and results on petrology and geochemistry of AND-1B corePublishedin press2.3. TTC - Laboratori di chimica e fisica delle rocceN/A or not JCRreserve

Sedimentology and stratigraphy of the ANDRILL McMurdo Ice Shelf (AND-1B) core

During the 2006-2007 austral summer, the ANDRILL McMurdo Ice Shelf Project recovered a core 1285 m long (AND-1B) from Windless Bight in McMurdo Sound. This core contains a range of lithologies, including both siliciclastic and volcanic diamictites, sandstones and mudstones; diatomites; and volcanic ash/tuff and one phonolitic lava flow. This sequence has been subdivided into eight lithostratigraphic units and 25 subunits, based on lithological abundances. Eleven lithofacies have been identified, ranging from open marine diatomites and mudstones to turbidites to ice-proximal massive and stratified diamictites. More than 50 glacimarine sequences have been recognized, bounded by glacial surfaces of erosion. Three distinct stacking patterns are present, showing evidence of glacial advance/retreat/advance with varying degrees of preservation. Carbonate and pyrite are the dominant secondary phases in the core. The pyrite overprint is especially notable in volcanic sediments below ~400 mbsf, where it often obscures stratification and sediment texture

Petrology and Geochemistry of the AND-1B Core, ANDRILL McMurdo Ice Shelf Project, Antarctica

This section reports preliminary data and results on petrology and geochemistry of AND-1B core