Environmental Indicators and Impact Assessment Commons^™

Sequence Stratigraphy Of The Andrill And-2a Drillcore, Antarctica: A Long-Term, Ice-Proximal Record Of Early To Mid-Miocene Climate, Sea-Level And Glacial Dynamism, Christopher R. Fielding, Greg H. Browne, Brad Field, F. Florindo, D. M. Harwood, L. A. Krissek, Richard Levy, K. Panter, Sandra Passchier, Stephen F. Pekar

ANDRILL Research and Publications

Present understanding of Antarctic climate change during the Early to Mid-Miocene, including major cycles of glacial expansion and contraction, relies in large part on stable isotope proxies from deep sea core drilling. Here, we summarize the lithostratigraphy of the ANDRILL Southern McMurdo Sound Project drillcore AND-2A. This core offers a hitherto unavailable ice-proximal stratigraphic archive from a high-accommodation continental margin setting, and provides clear evidence of repeated fluctuations in climate, ice expansion/contraction and attendant sea-level change over the period c. 20.2–14.2 Ma, with a more fragmentary record of Late Miocene and Pliocene time. The core is divided into seventy-four high-frequency …

Late Cenozoic Oscillations Of Antarctic Ice Sheets Revealed By Provenance Of Basement Clasts And Grain Detrital Modes In Andrill Core And-1b, Franco M. Talarico, Robert M. Mckay, Ross D. Powell, Sonia Sandroni, Tim Naish

ANDRILL Research and Publications

Petrological investigations of the sand fraction and of granule- to cobble-sized clasts in the Plio-Pleistocene sedimentary cycles of the AND-1B drill core at the NW edge of the Ross Ice Shelf (McMurdo Sound) highlight significant down-core modal and compositional variations. These variations provide: (i) direct information about potential source regions during both glacial maxima and minima; and (ii) evidence of an evolving provenance, documented by long-term shifts in compositional patterns that can be interpreted as reflecting variations in ice volume and ice sheet thermal regimes and changes in paleogeography related to the emergence of several volcanic centers during the deposition …

Selection Of Andrill Papers

ANDRILL Research and Publications

No abstract provided.

Heat Flow And Hydrologic Characteristics At The And-1b Borehole, Andrill Mcmurdo Ice Shelf Project, Antarctica, Roger H. Morin, Trevor Williams, Stuart A. Henrys, Diana Magens, Frank Niessen, Dhiresh Hansaraj

ANDRILL Research and Publications

The Antarctic Drilling Program (ANDRILL) successfully drilled and cored
a borehole, AND-1B, beneath the McMurdo Ice Shelf and into a flexural moat basin that surrounds Ross Island. Total drilling depth reached 1285 m below seafloor (mbsf) with 98 percent core recovery for the detailed study of glacier dynamics. With the goal of obtaining complementary information regarding heat flow and permeability, which is vital to understanding the nature of marine hydrogeologic systems, a succession of three temperature logs was recorded over a five-day span to monitor the gradual thermal recovery toward equilibrium conditions. These data were extrapolated to true, undisturbed temperatures, …

40Ar–39Ar Dating Of Volcanogenic Products From The And-2a Core (Andrill Southern Mcmurdo Sound Project, Antarctica): Correlations With The Erebus Volcanic Province And Implications For The Age Model Of The Core, Gianfranco Di Vincenzo, Laura Bracciali, Paola Del Carlo, Kurt Panter, Sergio Rocchi

ANDRILL Research and Publications

The AND-2A drillcore (Antarctic Drilling Program—ANDRILL) was successfully completed in late 2007 on the Antarctic continental margin (Southern McMurdo Sound, Ross Sea) with the aim of tracking ice proximal to shallow marine environmental fluctuations and to document the 20-Ma evolution of the Erebus Volcanic Province. Lava clasts and tephra layers from the AND-2A drillcore were investigated from a petrographic and stratigraphic point of view and analyzed by the ⁴⁰Ar–³⁹Ar laser technique in order to constrain the age model of the core and to gain information on the style and nature of sediment deposition in the Victoria Land …

Provenance Signatures Of The Antarctic Ice Sheets In The Ross Embayment During The Late Miocene To Early Pliocene: The Andrill And-1b Core Record, Franco M. Talarico, Sonia Sandroni

ANDRILL Research and Publications

Significant down-core modal and compositional variations are described for granule- to cobble-sized clasts in the Early Pliocene to Middle/Late Miocene sedimentary cycles of the AND-1B drill core at the NW edge of the Ross Ice Shelf (McMurdo Sound).

Long-term shifts in compositional patterns outline an evolving provenance which is interpreted as reflecting the combined effects and complex interactions among variations in ice volume, ice flow patterns and paleogeographic changes linked to the local tectonic and volcanic activity. High-frequency variations and the petrological features of the basement clast fraction provide direct information about the potential source regions during both glacial maxima …

Modeling West Antarctic Ice Sheet Growth And Collapse Through The Past Five Million Years, David Pollard, Robert M. Deconto

ANDRILL Research and Publications

The West Antarctic ice sheet (WAIS), with ice volume equivalent to ~5 m of sea level, has long been considered capable of past and future catastrophic collapse. Today, the ice sheet is fringed by vulnerable floating ice shelves that buttress the fast flow of inland ice streams. Grounding lines are several hundred meters below sea level and the bed deepens upstream, raising the prospect of runaway retreat. Projections of future WAIS behavior have been hampered by limited understanding of past variations and their underlying forcing mechanisms. Its variation since the Last Glacial Maximum is best known, with grounding lines advancing …

New Seismic Methods To Support Sea-Ice Platform Drilling, M. A. Speece, Richard Levy, D. M. Harwood, Stephen F. Pekar, R. D. Powell

ANDRILL Research and Publications

The ANtarctic geological DRILLing Program (ANDRILL) is currently a consortium of five nations (Germany, Italy, New Zealand, the United Kingdom, and the United States of America).  By drilling, coring and analyzing stratigraphic archives along the Antarctic continental margin, ANDRILL pursues its primary goal of better understanding the role the Antarctic cryosphere plays in the global climate system (Harwood et al., 2006).  The ANDRILL drilling system was developed to operate on both ice shelf and sea-ice platforms (Harwood et al., 2006; Falconer et al., 2007; Naish et al., 2007; Florindo et al., 2008).  While thick multiyear sea ice provides stable and …

Provenance Of Pleistocene Sediments In The Andrill And-1b Drillcore: Clay And Heavy Mineral Data, Giovanna Giorgetti, Franco M. Talarico, Sonia Sandroni, Antonio Zeoli

ANDRILL Research and Publications

The cryosphere in the McMurdo Sound region has undergone significant modifications during the last 1 Ma. Consequently, the sedimentary sequences underlying the modern McMurdo Ice-Shelf provide geological data to reconstruct variations in transport and depositional mechanisms of terrigenous material due to variations in ice sheet extension, grounding line position and main icestream flow directions during glacial and interglacial periods. The present study aims to investigate the clay and heavy mineral assemblages of the late Pleistocene subglacial and glaciomarine sediments recovered during the ANDRILL-McMurdo Ice Shelf Project in Windless Bight (South of Ross Island). The analyses show that the sediments are …

Sediment Cores Reveal Antarctica’S Warmer Past, Quirin Schiermeier

ANDRILL Research and Publications

A unique drilling project in the western Ross Sea has revealed that Antarctica had a much more eventful climate history than previously assumed. A new sediment core hints that the western part of the now-frozen continent went through prolonged ice-free phases — presumably offering a glimpse of where our warming world might be heading. Researchers reported initial results from ANDRILL, a US$30-million international drilling project, on April 16 at the assembly of the European Geosciences Union in Vienna. During the past two years, the team has extracted two cores, each containing some 1,200 meters of sediment, from the seabed below …

Fracture Logging Of The And-2a Core, Andrill Southern Mcmurdo Sound Project, Antarctica, T. Paulsen, C. Millan, S. Pierdominici, T. J. Wilson, S. Drew, Andrill-Sms Science Team

ANDRILL Research and Publications

Fractures in AND-2A drillcore were documented in this study. Over 4100 fractures of all types were logged. A population of 510 steeply-dipping, petal, petal-centreline and core-edge induced fractures is present, reaching a maximum density of c. 10 fractures/metre. Subhorizontal induced extension fractures are also abundant. There are 1008 natural fractures in the core, including faults, brecciated zones, veins and sedimentary intrusions. Kinematic indicators document dominant normal faulting, although reverse faults are also present. The natural fractures occur in strata ranging in age from the Miocene to the Plio-Pleistocene.

Palaeomagnetism Of The And-2a Core, Andrill Southern Mcmurdo Sound Project, Antarctica, G. Acton, F. Florindo, L. Jovane, B. Lum, C. Ohneiser, L. Sagnotti, E. Strada, K. L. Verosub, G. S. Wilson, Andrill-Sms Science Team

ANDRILL Research and Publications

We conducted initial palaeomagnetic studies on cores from site AND-2A (77°45.488’S, 165°16.605’E, ~383.57 metres water depth). A total of 813 samples were collected that span from the top of the section down to the base at 1138.54 metres below sea floor (mbsf). Samples were collected every one or two metres down the core, with paired (pilot) samples being collected about every ten to twenty metres to allow us to assess the demagnetisation behaviour of the samples using either alternating field (AF) or thermal demagnetisation. With the exception of only a few intervals, AF demagnetisation was observed to resolve a characteristic …

Preliminary Integrated Chronostratigraphy Of The And-2a Core, Andrill Southern Mcmurdo Sound Project, Antarctica, G. Acton, J. Crampton, G. Di Vincenzo, Christopher R. Fielding, F. Florindo, M. Hannah, D. M. Harwood, S. Ishman, K. Johnson, L. Jovane, Richard Levy, B. Lum, M. C. Marcano, S. Mukasa, C. Ohneiser, M. P. Olney, C. Riesselman, L. Sagnotti, C. Stefano, E. Strada, M. Taviani, E. Tuzzi, K. L. Verosub, G. S. Wilson, M. Zattin, Andrill-Sms Science Team

ANDRILL Research and Publications

We use all available chronostratigraphic constraints – biostratigraphy, magnetostratigraphy, radioisotopic dates, strontium-isotope stratigraphy, and correlation of compositional and physical properties to well-dated global or regional records – to construct a preliminary age model for ANDRILL SMS Project’s AND-2A drillcore (77°45.488’S, 165°16.605’E, 383.57 m water depth). These diverse chronostratigraphic constraints are consistent with each other and are distributed throughout the 1138.54 m-thick section, resulting in a well-constrained age model. The sedimentary succession comprises a thick early and middle Miocene section below 224.82 mbsf and a condensed middle/late Miocene to Recent section above this. The youngest sediments are Brunhes age (<0.781 Ma), as confirmed by a radioisotopic age of 0.691±0.049 Ma at 10.23 mbsf and the occurrence of sediments that have normal magnetic polarity down to ~31.1 mbsf, which is interpreted to be the Brunhes/Matuyama reversal (0.781 Ma). The upper section is punctuated by disconformities resulting from both discontinuous deposition and periods of extensive erosion typical of sedimentary environments at the margin of a dynamic ice sheet. Additional breaks in the section may be due to the influence of tectonic processes. The age model incorporates several major hiatuses but their precise depths are still somewhat uncertain, as there are a large number of erosional surfaces identified within the stratigraphic section. One or more hiatuses, which represent a total 7 to 8 million years of time missing from the sedimentary record, occur between about 50 mbsf and the base of Lithostratigraphic Unit (LSU) 3 at 122.86 mbsf. Similarly, between about 145 mbsf and the base of LSU 4 at 224.82 mbsf, one or more hiatuses occur on which another 2 to 3 million years of the sedimentary record is missing. Support for the presence of these hiatuses comes from a diatom assemblage that constrains the age of the core from 44 to 50 mbsf to 2.06-2.84 Ma, two radioisotopic dates (11.4 Ma) and a Sr‑isotope date (11.7 Ma) that indicate the interval from 127 to 145 mbsf was deposited between 11.4 and 11.7 Ma, and three diatom occurrence datums from between 225.38 and 278.55 mbsf that constrain the age of this upper part of Lithostratigraphic Unit (LSU) 5 to 14.29 - 15.89 Ma. Below the boundary between LSU 5 and 6 sedimentation was relatively continuous and rapid and the age model is well-constrained by 9 diatom datums, seven ^{40 …}

Physical Properties Of The And-2a Core, Andrill Southern Mcmurdo Sound Project, Antarctica, Gavin B. Dunbar, C. Atkins, D. Magens, F. Niessen, Andrill-Sms Science Team

ANDRILL Research and Publications

Whole-core measurements of Wet Bulk Density (WBD), compressional (P)-wave velocity (Vp), and Magnetic Susceptibility were measured at a sampling interval of 1 or 2 centimetres (cm) throughout the AND-2A drill core for initial core characterisation and on-site correlation with seismic modeling to predict target-reflector depth. Measurements were made using a GEOTEK (Multi-Sensor-Core-Logger MSCL). Density and velocity standards were measured together with core runs of 3-6 metres (m) (and occasionally up to 18 m) throughout the entire depth range to monitor data quality. Drift of the magnetic susceptibility sensor was also monitored and corrected where necessary. These physical properties show a …

Operations Overview For The Andrill Southern Mcmurdo Sound Project, Antarctica, T. Falconer, A. Pyne, D. Wilson, Richard Levy, S. Nielsen, S. Petrushak, Andrill-Sms Science Team

ANDRILL Research and Publications

During the austral spring of 2007-08, a 1138 metre (m)-long rock and sediment core (ANDRILL [AND]-2A) was recovered from beneath the land-fast sea-ice in southern McMurdo Sound (SMS) in 384 m of water. A custom-built drilling system comprising an UDR-1200 rig, jack-up platform, hot water drill, sea riser, and diamond-bit wireline coring string was set up on the sea-ice approximately 32 kilometres (km) from Scott Base (NZ) and McMurdo Station (USA). The drilling system employed technology developed to handle challenging environmental conditions, including drilling from an 8 metre-thick sea-ice ‘platform’ that moved both laterally and vertically, tidal currents, and high …

Sedimentology And Stratigraphy Of The And-2a Core, Andrill Southern Mcmurdo Sound Project, Antarctica, Christopher R. Fielding, C. B. Atkins, K. N. Bassett, G. H. Browne, G. B. Dunbar, B. D. Field, Tracy D. Frank, L. A. Krissek, K. S. Panter, S. Passchier, S. F. Pekar, S. Sandroni, F. Talarico, Andrill-Sms Science Team

ANDRILL Research and Publications

During the 2007 – 2008 austral spring season, the ANDRILL Southern McMurdo Sound Project recovered a core 1138 metres long (AND-2A) from a location in the southern McMurdo Sound near the Dailey Islands. This core contains a range of lithologies, including various types of terrigenous clastic diamictite, conglomerate and breccia, sandstone and mudrocks, volcanic lava, pyroclastic and reworked volcanic sedimentary rocks, and diatomite. The succession is divided into fourteen lithostratigraphic units (LSUs), two of which (LSUs 1 and 8) are further subdivided into three and four sub-units, respectively, based on changes in abundance of lithologies. Thirteen lithofacies are recognized, ranging …

Background To The Andrill Southern Mcmurdo Sound Project, Antarctica, F. Florindo, D. M. Harwood, F. Talarico, Richard Levy

ANDRILL Research and Publications

During the austral spring of 2007, the Southern McMurdo (SMS) Project recovered a 1138.54 meter long drill core (AND-2A) from a 8.5 m thick floating seaice platform (~8.5 meters thick) over approximately 380 meters of water (77°45.488S; 165°16.613E) (Fig. 1). This demonstrated the ANDRILL Program’s continuing success in recovering high quality marine and glacimarine sedimentary drill core (> 98% core recovery) from high latitude ice-covered areas. A primary goal of the SMS Project, the second drillhole
of the McMurdo Sound Portfolio (Harwood et al., 2006), was to recover an Antarctic marine sediment record depositied during the middle Miocene, which has …

Explanatory Notes For The Andrill Southern Mcmurdo Sound Project, Antarctica, F. Florindo, D. M. Harwood, Richard Levy, G. Acton, Christopher R. Fielding, K. Panter, T. Paulsen, F. Sangiorgi, F. Talarico, M. Taviani, V. Willmott, Andrill-Sms Science Team

ANDRILL Research and Publications

This Explanatory Notes section complements and supports four other documents, which collectively describe the process and procedures of scientific investigations employed during the ANDRILL SMS Project: (1) ANDRILL Southern McMurdo Sound Project - Scientific Prospectus (ANDRILL contribution 5 - Harwood et al., 2005); (2) a Science Plan summary of SMS Project research compiled from research proposals of Science Team menbers (available on the SMS Project ‘Science Drive’ – Harwood et al., 2007); (3) SMS Project Science Logistics Implementation Plan (SLIP) - draft documents developed and distributed to SMS team members prior to deployment; (4) Operations overview – Falconer et al., …

Late Cenozoic Climate History Of The Ross Embayment From The And-1b Drill Hole: Culmination Of Three Decades Of Antarctic Margin Drilling, T. R. Naish, R. D. Powell, Peter J. Barrett, R. H. Levy, S. Henrys, G. S. Wilson, L. A. Krissek, F. Niessen, M. Pompilio, J. Ross, R. Scherer, F. Talarico, A. R. Pyne, Andrill-Mis Science Team

ANDRILL Research and Publications

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 …

Petrologic And Geochemical Composition Of The And-2a Core, Andrill Southern Mcmurdo Sound Project, Antarctica, K. Panter, F. Talarico, K. Bassett, P. Del Carlo, B. Field, T. Frank, S. Hoffmann, G. Kuhn, L. Reichelt, S. Sandroni, M. Taviani, L. Bracciali, G. Cornamusini, H. Von Eynatten, S. Rocchi, Andrill-Sms Science Team

ANDRILL Research and Publications

The compositional record of the AND-2A drillcore is examined using petrological, sedimentological, volcanological and geochemical analysis of clasts, sediments and pore waters. Preliminary investigations of basement clasts (granitoids and metasediments) indicate both local and distal sources corresponding to variable ice-volume and ice-flow directions. Low abundance of sedimentary clasts (e.g., arkose, litharenite) suggests reduced contributions from sedimentary covers while intraclasts (e.g., diamictite, conglomerate) attest to intrabasinal reworking. Volcanic material includes pyroclasts (e.g., pumice, scoria), sediments and lava. Primary and reworked tephra layers occur within the Early Miocene interval (1093 to 640 metres below sea floor). …

Palaeontological Characterisation And Analysis Of The And-2a Core, Andrill Southern Mcmurdo Sound Project, Antarctica, M. Taviani, M. Hannah, D. M. Harwood, S. E. Ishman, K. Johnson, M. Olney, C. Riesselman, E. Tuzzi, A. G. Beu, S. Blair, V. Cantarelli, A. Ceregato, S. Corrado, B. Mohr, S. H.H. Nielson, D. Persico, S. Petrushak, J. I. Raine, S. Warny, Andrill-Sms Science Team

ANDRILL Research and Publications

The palaeontological yield of the 1138.54 metre-long AND-2A sedimentary rock core provides unique documentation of Neogene environments in the Ross Sea region of Antarctica. Especially important is the biological legacy of the climatically crucial ‘mild’ middle Miocene phase. Diatom-bearing units provide key information for stratigraphic intervals never previously recovered from locations proximal to the Antarctic continent and constrain the age model for the AND-2A core. Benthic calcareous (and agglutinated) foraminifera were present at many levels; remarkable is the occurrence of planktonic taxa only seldom found in the Neogene nearshore record of the Ross Sea region. The sporadic occurrence of calcareous …

Downhole Measurements In The And-2a Borehole, Andrill Southern Mcmurdo Sound Project, Antarctica, T. Wonik, T. Grelle, D. Handwerger, R. D. Jarrard, A. Mckee, T. Patterson, T. Paulsen, S. Pierdominici, D. R. Schmitt, H. Schröder, M. Speece, T. J. Wilson, Andrill-Sms Science Team

ANDRILL Research and Publications

Under the framework of the ANDRILL Southern McMurdo Sound (SMS) Project successful downhole experiments were conducted in the 1138.54 metre (m)-deep AND-2A borehole. Wireline logs successfully recorded were: magnetic susceptibility, spectral gamma ray, sonic velocity, borehole televiewer, neutron porosity, density, calliper, geochemistry, temperature and dipmeter. A resistivity tool and its backup both failed to operate, thus resistivity data were not collected. Due to hole conditions, logs were collected in several passes from the total depth at ~1138 metres below sea floor (mbsf) to ~230 mbsf, except for some intervals that were either inaccessible due to bridging or were shielded by …

Andrill’S Education And Outreach Programme 2005‑2008: Mis And Sms Project Activities During The 4th Ipy, L. T. Huffman, Richard Levy, Laura Lacy, D. M. Harwood, M. Berg, M. Cattadori, J. Diamond, J. Dooley, L. Dahlman, R. Frisch-Gleason, J. Hubbard, R. Lehmann, K. Mankoff, V. Miller, K. Pound, F. R. Rack, G. Scotto Di Clemente, A. Seigmund, J. Thomson, E. Trummel, R. Williams, Andrill-Mis Science Team, Andrill-Sms Science Team

ANDRILL Research and Publications

A key goal of the ANDRILL programme’s education and outreach (E&O) activities was to engage the public in, and inform it about, our scientific endeavour to uncover the behavior of Antarctica’s ice sheets over the past 20 million years. We recognized that a critical component of ANDRILL’s research effort was to ensure that our motivation, methods, and results were conveyed to non-experts in a clear and understandable manner. This effort benefited from several factors: a synergy between scientists and educators generated by the 4^th International Polar Year (IPY); the allure of the Antarctic region as one of Earth’s few …

Antarctica, The Southern Ocean, And Climate Evolution: Insights From Drilling, Coring, And Geophysical Surveys, Timothy R. Naish, Ross Powell

ANDRILL Research and Publications

1.P2.A-1: The diatom record of the ANDRILL – McMurdo Ice Shelf project drillcore
Reed Scherer, Diane Winter, Charlotte Sjunneskog, and Paola Maffioli4

1.P2.A-2: Preliminary ⁴⁰Ar/³⁹Ar results from the AND-1B core
Jake I. Ross, William C. McIntosh, and Nelia W. Dunbar

1.P2.A-3: Preliminary chronostratigraphy for the upper 700 m (upper Miocene–Pleistocene) of the AND-1B drillcore recovered from beneath the McMurdo Ice Shelf, Antarctica
Gary S. Wilson, Richard H. Levy, Greg Browne, Fabio Florindo, Stuart A. Henrys, Ian Graham, William C. McIntosh, R. M. McKay, T. R. Naish, Christian Ohneiser, Ross D. Powell, Jake I. Ross, Leonardo Sagnotti, Reed …

Polar Research: School Of Rock, Alexandra Witze

ANDRILL Research and Publications

As Antarctica’s ice teams continue to hunt for the oldest ice their drills will reach, a smaller band of rockhounds is on a similar quest to plug the gaps in the geological record. The team now has a core that promises fresh insight into how Antarctica’s ice waxed and waned over the past few million years. On December 26, 2006, a US$30-million international project called ANDRILL pulled up the final piece of a core from beneath the Ross ice shelf. Previous coring efforts have offered peeks into Antarctica’s deep history — back as far as 34 million years when the …

Mcmurdo Ice Shelf Seismic Reflection Data And Correlation To The And-1b Drill Hole, D. Hansaraj, S. A. Henrys, T. R. Naish, Andrill Mis-Science Team

ANDRILL Research and Publications

Surface seismic reflection data from the ANDRILL-MIS Project site surveys are integrated with a regionally extensive McMurdo Sound seismic stratigraphic framework. In addition, these seismic data are correlated to the AND-1B drill hole using vertical seismic profiles acquired during drilling operations (December/January 2006/7). Six regionally interpreted reflectors are identified in core as distinct lithostratigraphic boundaries.

Late Pleistocene To Holocene Strata From Soft-Sediment Coring At The And-1b Site, Andrill Mcmurdo Ice Shelf Project, Antarctica, Gavin B. Dunbar, F. Niessen, S. Vogel, S. Tulaczyk, K. Mandernack, L. Krissek, L. Carter, E. A. Cowan, T. Wilch, C. Peng, C. P. Strong, R. Scherer, C. Sjunneskog, D. Winter, R. Mckay, F. Talarico, M. Pompilio, Andrill-Mis Science Team

ANDRILL Research and Publications

Prior to rotary coring, a range of soft-sediment coring tools were deployed to recover the sediment-water interface and the upper few metres of strata, whose integrity was threatened by embedment of the sea riser for drilling of the ANDRILL (AND)-1A/1B holes. These coring options included (1) a sediment gravity corer deployed through the ice-shelf hole, and (2) a push corer deployed through the sea riser suspended a few metres above the seabed. Within the AND-1A hole (during an attempt at sea-riser embedment) an extended-nose corer was advanced in front of the sea riser with limited success. The hydraulic piston corer …

Comprehensive Downhole And Core Physical-Property Measurements At The And-1b Drillsite, Andrill Mcmurdo Ice Shelf Project, F. Niessen, Roger H. Morin, Trevor Williams, Stuart A. Henrys, T. Crosby, Dhiresh Hansaraj, D. Magens, A. C. Gebhardt, Andrill-Mis Science Team

ANDRILL Research and Publications

As part of the ANDRILL McMurdo Ice Shelf (MIS) Project two comprehensive sets of geophysical data were collected on ice at the AND-1B drillsite. Whole-core physical properties were determined with high vertical resolution to a depth of 1285 mbsf. A multi-sensor-core-logger was used to determine bulk density, sonic velocity, magnetic susceptibility and electrical resistivity. After drilling, a set of downhole measurements was collected, which consisted of caliper, temperature, fluid conductivity, induction resistivity, magnetic susceptibility, natural gamma activity, acoustic televiewer, borehole deviation, and dipmeter. In addition, three vertical seismic profiles (VSP) were obtained. Physical properties were used for initial core characterization …

Using New Tools To Explore Undiscovered Country: Understanding The Stratigraphic And Tectonic History Of Greenhouse To Icehouse Worlds Of Offshore New Harbor, Ross Sea, Antarctica, Stephan Pekar, M. A. Speece, D. M. Harwood, F. Florindo, G. S. Wilson

ANDRILL Research and Publications

The Offshore New Harbor Project will investigate the stratigraphic and tectonic history of westernmost Southern McMurdo Sound. This will be used to address two widely recognized but unresolved issues regarding Antarctica’s history: 1) the mid-Paleogene cryospheric development on Antarctica; and 2) the abrupt climate shift across the Eocene/Oligocene transition. The first step for this project is to collect the requisite seismic and gravity data for identifying future drilling targets for the ANDRILL Program. ANDRILL is a multinational program, with the aim to recover stratigraphic intervals for interpreting Antarctica’s climate and glacial history over the past 50 million years. Offshore New …

Fracture Logging Of The And-1b Core, Mcmurdo Ice Shelf Project, Antarctica, Terry J. Wilson, T. Paulsen, A. L. Läufer, C. Millan

ANDRILL Research and Publications

Over 4300 natural and induced fractures were logged in AND-1B drill core. Induced fractures include steeply dipping, petal, petal-centreline, and core-edge induced fractures (n=421) which reach a maximum density of 5 fractures/metre. Subhorizontal induced extension fractures are also abundant. Natural fractures (n=1485) occur in Miocene to Pleistocene age strata and include faults, brecciated zones, veins and sedimentary intrusions. Kinematic indicators document dominant normal faulting, although reverse faults are also present. Vein types include slickenfiber veins along faults, opening-mode fibrous veins, pressure shadows on clast margins, and complex microvein webs within fault zones.