Geology topics

T. Wilson

Publications and source records attributed to T. Wilson.

6 recordsLinked to original sources

USGS2009

Obliquity-paced Pliocene West Antarctic ice sheet oscillations

Thirty years after oxygen isotope records from microfossils deposited in ocean sediments confirmed the hypothesis that variations in the Earth's orbital geometry control the ice ages 1 , fundamental questions remain over the response of the Antarctic ice sheets to orbital cycles 2 . Furthermore, an understanding of the behaviour of the marine-based West Antarctic ice sheet (WAIS) during the 'warmer-than-present' early-Pliocene epoch ( 5–3 Myr ago) is needed to better constrain the possible range of ice-sheet behaviour in the context of future global warming 3 . Here we present a marine glacial record from the upper 600 m of the AND-1B sediment core recovered from beneath the northwest part of the Ross ice shelf by the ANDRILL programme and demonstrate well-dated, 40-kyr cyclic variations in ice-sheet extent linked to cycles in insolation influenced by changes in the Earth's axial tilt (obliquity) during the Pliocene. Our data provide direct evidence for orbitally induced oscillations in the WAIS, which periodically collapsed, resulting in a switch from grounded ice, or ice shelves, to open waters in the Ross embayment when planetary temperatures were up to 3 °C warmer than today 4 and atmospheric CO 2 concentration was as high as 400 p.p.m.v. (refs 5 , 6 ). The evidence is consistent with a new ice-sheet/ice-shelf model 7 that simulates fluctuations in Antarctic ice volume of up to +7 m in equivalent sea level associated with the loss of the WAIS and up to +3 m in equivalent sea level from the East Antarctic ice sheet, in response to ocean-induced melting paced by obliquity. During interglacial times, diatomaceous sediments indicate high surface-water productivity, minimal summer sea ice and air temperatures above freezing, suggesting an additional influence of surface melt 8 under conditions of elevated CO 2 .

Nature↗

USGS2007

Tectonic history of mid-Miocene to present southern Victoria Land Basin, inferred from seismic stratigraphy in McMurdo Sound, Antarctica

New and existing seismic reflection data in southern McMurdo Sound have been used to investigate Neogene tectonic history of the Terror Rift adjacent to the Transantarctic Mountains and along the western margin of the West Antarctic Rift System. Seismic data image a young rifting episode that is largely unsampled by CRP and CIROS drill holes. Data reveal up to 3.5 km of post middle Miocene strata deposited in this part of the NNW- SSE trending Terror Rift basin. Mapped fault trends in the southern Terror Rift parallel the axis of the basin and are prominent in a 40 km wide zone north of Ross Island. Displacement on individual faults in this zone can exceed 100 m and faults collectively accommodate approximately 10-15 km of middle Miocene to recent extension.

Open-File Report↗

USGS2007

Microstructural study of natural fractures in Cape Roberts Project 3 core, Western Ross Sea, Antarctica

Microstructures in natural fractures in core recovered offshore from Cape Roberts, Ross Sea, Antarctica, provide new constraints on the relative timing of faulting and sedimentation in the Victoria Land Basin along the Transantarctic Mountain rift flank. This study characterizes the textures, fabrics and grain-scale structures from thin section analysis of samples of microfaults, veins, and clastic dikes. Microfaults are abundant and display two different types of textures, interpreted to record two different deformation modes: pre-lithification shearing and brittle faulting of cohesive sediment. Both clastic dikes and calcite veins commonly follow fault planes, indicating that injections of liquefied sediment and circulating fluids used pre-existing faults as conduits. The close association of clastic injections, diagenetic mineralization, and faulting indicates that faulting was synchronous with deposition in the rift basin

Open-File Report↗

USGS2006

Panel: Eco-informatics and decision making managing our natural resources

This panel responds to the December 2004 workshop on Eco-Informatics and Decision Making [1], which addressed how informatics tools can help with better management of natural resources and policy making. The workshop was jointly sponsored by the NSF, NBII, NASA, and EPA. Workshop participants recommended that informatics research in four IT areas be funded: modeling and simulation, data quality, information integration and ontologies, and social and human aspects. Additionally, they recommend that funding agencies provide infrastructure and some changes in funding habits to assure cycles of innovation in the domain were addressed. This panel brings issues raised in that workshop to the attention of digital government researchers.

Conference Paper↗

USGS2006

Eco-informatics and natural resource management

This project highlight reports on the 2004 workshop [1], as well as follow-up activities in 2005 and 2006, regarding how informatics tools can help manage natural resources and decide policy. The workshop was sponsored jointly by sponsored by the NSF, NBII, NASA, and EPA, and attended by practitioners from government and non-government agencies, and university researchers from the computer, social, and ecological sciences. The workshop presented the significant information technology (IT) problems that resource managers face when integrating ecological or environmental information to make decisions. These IT problems fall into five categories: data presentation, data gaps, tools, indicators, and policy making and implementation. To alleviate such problems, we recommend informatics research in four IT areas, as defined in this abstract and our final report: modeling and simulation, data quality, information integration and ontologies, and social and human aspects. Additionally, we recommend that funding agencies provide infrastructure and some changes in funding habits to assure cycles of innovation in the domain were addressed. Follow-on activities to the workshop subsequent to dg.o 2005 included: an invited talk presenting workshop results at DILS 2005, publication of the workshop final report by the NBII [1], and a poster at the NBII All Hands Meeting (Oct. 2005). We also expect a special issue of the JIIS to appear in 2006 that addresses some of these questions. As we go to press, no solicitation by funding agencies has as yet been published, but various NASA and NBII, and NSF cyber-infrastructure and DG research efforts now underway address the above issues.

Conference Paper↗

USGS2005

Eco-informatics for decision makers advancing a research agenda

Resource managers often face significant information technology (IT) problems when integrating ecological or environmental information to make decisions. At a workshop sponsored by the NSF and USGS in December 2004, university researchers, natural resource managers, and information managers met to articulate IT problems facing ecology and environmental decision makers. Decision making IT problems were identified in five areas: 1) policy, 2) data presentation, 3) data gaps, 4) tools, and 5) indicators. To alleviate those problems, workshop participants recommended specific informatics research in modeling and simulation, data quality, information integration and ontologies, and social and human aspects. This paper reports the workshop findings, and briefly compares these with research that traditionally falls under the emerging eco-informatics rubric. ?? Springer-Verlag Berlin Heidelberg 2005.

Conference Paper↗