{"dp_type": "Project", "free_text": "Hugo Island"}
[{"awards": "0003060 Domack, Eugene", "bounds_geometry": null, "dataset_titles": "Expedition data of NBP0107", "datasets": [{"dataset_uid": "002656", "doi": null, "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition data of NBP0107", "url": "https://www.rvdata.us/search/cruise/NBP0107"}], "date_created": "Tue, 04 May 2010 00:00:00 GMT", "description": "This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports project to test and develop approaches for using thermoluminescence techniques to determine the age of Antarctic marine sediments. \u003cbr/\u003e\u003cbr/\u003eQuaternary (last 2 million yrs) marine sediments surrounding Antarctica record the waxing and waning of ice shelves and ice sheets, and also other paleoclimatic information, yet accurate chronologies of these sediments are difficult to obtain. Such chronologies provide the essential foundation for study of geological processes in the past. Within the range of radiocarbon (14C) dating (less than 30-40 thousand yrs, note - \"ka\" below means 1000 yrs) 14C dates can be inaccurate because of a variable 14C reservoir effect, and beyond 30-40 ka few methods are applicable. Photon-stimulated-luminescence sediment dating (photonic dating) of eolian and waterlain deposits in temperate latitudes spans the range from decades to hundreds of ka, but marine sediments in and around Antarctica pose special difficulty because of the potentially restricted exposure to daylight (the clock-zeroing process) of most detrital grains before deposition. This proposal will test the clock-zeroing assumption in representative Antarctic glaciomarine depositional settings, and thereby determine the potential reliability of photonic dating of Antarctic marine sediments.\u003cbr/\u003e\u003cbr/\u003eLimited luminescence dating and signal-zeroing tests using glaciomarine and marine deposits have been conducted in the northern temperate and polar latitudes, but the effects on luminescence of the different glaciomarine depositional processes have never been studied in detail. Furthermore, the depositional settings around Antarctica are almost entirely polar, with consequent specific processes operating there. For example, transport of terrigenous suspensions by neutrally buoyant \"cold-tongue\" (mid-water) plumes may be common around Antarctica, yet the effect of such transport on luminescence zeroing is unknown. Typical marine cores near Antarctica may contain an unknown fraction of detrital grains from cold-tongue and near-bottom suspensions. Thus the extent to which the polar glaciomarine depositional processes around Antarctica may limit the potential accuracy of photonic dating of marine cores is unknown (age overestimates would result if grains are not exposed to daylight before deposition).\u003cbr/\u003e\u003cbr/\u003eThis project will collect detrital grains from a variety of \"zero-age\" (modern) marine depositional settings within the Antarctic Peninsula, where representative Antarctic depositional processes have been documented and where logistics permit access. Suspensions will be collected from four fjords representing a transect from polar through subpolar conditions. Suspensions will be collected from two stations and from up to 3 depths (surface and 2 deep plumes) at each station. Sediment traps will be deployed at two of these fjord settings. As well, core-top sediments will be collected from several sites. All samples will be shielded from light and transported to Reno, Nevada, for luminescence analyses.\u003cbr/\u003e\u003cbr/\u003eSystematic study of the effectiveness of luminescence-clock-zeroing in Antarctic glaciomarine settings will determine if photonic dating can be reliable for future applications to Antarctic marine sediments. Refined sedimentological criteria for the selection of future samples for photonic dating are expected from this project. A photonic-dating capability would provide a numeric geochronometer extending well beyond the age range of 14C dating. Such a capability would permit answering a number of broader questions about the timing and extent of past glaciations near and on the Antarctic shelves.", "east": null, "geometry": null, "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e CTD; IN SITU/LABORATORY INSTRUMENTS \u003e MAGNETIC/MOTION SENSORS \u003e GRAVIMETERS \u003e GRAVIMETERS; IN SITU/LABORATORY INSTRUMENTS \u003e PHOTON/OPTICAL DETECTORS \u003e TURBIDITY METERS; EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e POSITIONING/NAVIGATION \u003e GPS \u003e GPS; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e ADCP; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e MSBS", "is_usap_dc": false, "keywords": "Palmer Deep; Hugo Island; R/V NBP", "locations": "Hugo Island", "north": null, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Domack, Eugene Walter", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V NBP", "repo": "R2R", "repositories": "R2R", "science_programs": null, "south": null, "title": "Collaborative Research: Development of a Luminescence Dating Capability for Antarctic Glaciomarine Sediments: Tests of Signal Zeroing at the Antarctic Peninsula", "uid": "p0000845", "west": null}, {"awards": "9908828 Aronson, Richard", "bounds_geometry": "POLYGON((-70.906 -52.350166,-69.4494 -52.350166,-67.9928 -52.350166,-66.5362 -52.350166,-65.0796 -52.350166,-63.623 -52.350166,-62.1664 -52.350166,-60.7098 -52.350166,-59.2532 -52.350166,-57.7966 -52.350166,-56.34 -52.350166,-56.34 -53.6028324,-56.34 -54.8554988,-56.34 -56.1081652,-56.34 -57.3608316,-56.34 -58.613498,-56.34 -59.8661644,-56.34 -61.1188308,-56.34 -62.3714972,-56.34 -63.6241636,-56.34 -64.87683,-57.7966 -64.87683,-59.2532 -64.87683,-60.7098 -64.87683,-62.1664 -64.87683,-63.623 -64.87683,-65.0796 -64.87683,-66.5362 -64.87683,-67.9928 -64.87683,-69.4494 -64.87683,-70.906 -64.87683,-70.906 -63.6241636,-70.906 -62.3714972,-70.906 -61.1188308,-70.906 -59.8661644,-70.906 -58.613498,-70.906 -57.3608316,-70.906 -56.1081652,-70.906 -54.8554988,-70.906 -53.6028324,-70.906 -52.350166))", "dataset_titles": "Expedition Data; Expedition data of NBP0107", "datasets": [{"dataset_uid": "001962", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/LMG0011"}, {"dataset_uid": "002656", "doi": null, "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition data of NBP0107", "url": "https://www.rvdata.us/search/cruise/NBP0107"}], "date_created": "Tue, 04 May 2010 00:00:00 GMT", "description": "9908828\u003cbr/\u003eAronson\u003cbr/\u003e\u003cbr/\u003eThis award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a paleoecological and paleoenvironmental study of Seymour Island. Global climate change late in the Eocene epoch had an important influence in Antarctica. This was the beginning of the transition from a cool-temperate climate in Antarctica to the polar climate that exists there today. The cooling trend strongly influenced the structure of shallow-water, Antarctic marine communities, and these effects are still evident in the peculiar ecological relationships among species living in modern Antarctic communities. Cooling late in the Eocene reduced the abundance of fish and crabs, which in turn reduced skeleton-crushing predation on invertebrates. Reduced predation allowed dense populations of ophiuroids (brittlestars) and crinoids (sea lilies) to appear in shallow-water settings at the end of the Eocene. These low-predation communities appear as dense fossil echinoderm assemblages in the upper portion of the late Eocene La Meseta Formation on Seymour Island, off the Antarctic Peninsula. Today, dense ophiuroid and crinoid populations are common in shallow-water habitats in Antarctica but generally have been eliminated by predators from similar habitats at temperate and tropical latitudes; their persistence in Antarctica to this day is an important ecological legacy of climatic cooling in the Eocene. Although the influence of declining predation on Antarctic ophiuroids and crinoids is now well documented, the effects of cooling on the more abundant mollusks have not been investigated. This study will examine the evolutionary ecology of gastropods (snails) and bivalves (clams) in the late Eocene.\u003cbr/\u003e\u003cbr/\u003eA series of hypotheses will be tested in the La Meseta Formation, based on the predicted responses of mollusks to declining temperature and changing levels of predation. The shapes of gastropod shells, the activities of gastropods that prey on other mollusks by drilling holes in their shells, and the effects of predation on the thickness of mollusk shells should have changed significantly through late Eocene time. First, defensive features of gastropod shells, such as spines and ribbing, should decline as temperature and, therefore, the activity of skeleton-crushing predators declined. Second, drilling of bivalve prey by predatory gastropods should increase with time since the drillers should themselves have been subject to lower predation pressure as temperature declined. Drilled shells, therefore, should become more common through time. Third, patterns in the thickness of shells through time will make it possible to separate the direct, physiological effects of declining temperature (shells are more difficult to produce at cooler temperatures, and so should be thinner) from the indirect effects of temperature on evolving biological interactions (increased drilling predation should result in thicker shells). \u003cbr/\u003e\u003cbr/\u003eSeymour Island contains the only fossil outcrops readily accessible in Antarctica from this crucial period in Earth history. The La Meseta Formation on Seymour Island thus provides a unique opportunity to learn how climate change affected Antarctic marine communities. In practical terms, global climate change will probably increase upwelling over the next few decades to centuries in some temperate coastal regions. Recent ecological evidence suggests that the resultant lowering of sea temperatures could lower predation in those areas. Understanding the response of the La Meseta faunas to global cooling in the late Eocene will provide direct insight into the rapidly changing structure of modern benthic communities.", "east": -56.34, "geometry": "POINT(-63.623 -58.613498)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e CTD; IN SITU/LABORATORY INSTRUMENTS \u003e MAGNETIC/MOTION SENSORS \u003e GRAVIMETERS \u003e GRAVIMETERS; IN SITU/LABORATORY INSTRUMENTS \u003e PHOTON/OPTICAL DETECTORS \u003e TURBIDITY METERS; EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e POSITIONING/NAVIGATION \u003e GPS \u003e GPS; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e ADCP; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e MSBS", "is_usap_dc": false, "keywords": "R/V NBP; Hugo Island; R/V LMG; Palmer Deep", "locations": "Hugo Island", "north": -52.350166, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": null, "persons": "Aronson, Richard; Domack, Eugene Walter", "platforms": "WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V LMG; WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V NBP", "repo": "R2R", "repositories": "R2R", "science_programs": null, "south": -64.87683, "title": "Global Climate Change and the Evolutionary Ecology of Antarctic Mollusks in the Late Eocene", "uid": "p0000617", "west": -70.906}, {"awards": "9909665 Berger, Glenn", "bounds_geometry": "POLYGON((-67.25 -62,-66.025 -62,-64.8 -62,-63.575 -62,-62.35 -62,-61.125 -62,-59.9 -62,-58.675 -62,-57.45 -62,-56.225 -62,-55 -62,-55 -62.525,-55 -63.05,-55 -63.575,-55 -64.1,-55 -64.625,-55 -65.15,-55 -65.675,-55 -66.2,-55 -66.725,-55 -67.25,-56.225 -67.25,-57.45 -67.25,-58.675 -67.25,-59.9 -67.25,-61.125 -67.25,-62.35 -67.25,-63.575 -67.25,-64.8 -67.25,-66.025 -67.25,-67.25 -67.25,-67.25 -66.725,-67.25 -66.2,-67.25 -65.675,-67.25 -65.15,-67.25 -64.625,-67.25 -64.1,-67.25 -63.575,-67.25 -63.05,-67.25 -62.525,-67.25 -62))", "dataset_titles": "Expedition Data", "datasets": [{"dataset_uid": "001707", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/LMG0303"}, {"dataset_uid": "001818", "doi": "", "keywords": null, "people": null, "repository": "R2R", "science_program": null, "title": "Expedition Data", "url": "https://www.rvdata.us/search/cruise/NBP0107"}], "date_created": "Wed, 10 Oct 2007 00:00:00 GMT", "description": "9909665\u003cbr/\u003eBerger\u003cbr/\u003e\u003cbr/\u003eThis award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports project to test and develop approaches for using thermoluminescence techniques to determine the age of Antarctic marine sediments. \u003cbr/\u003e\u003cbr/\u003eQuaternary (last 2 million yrs) marine sediments surrounding Antarctica record the waxing and waning of ice shelves and ice sheets, and also other paleoclimatic information, yet accurate chronologies of these sediments are difficult to obtain. Such chronologies provide the essential foundation for study of geological processes in the past. Within the range of radiocarbon (14C) dating (less than 30-40 thousand yrs, note - \"ka\" below means 1000 yrs) 14C dates can be inaccurate because of a variable 14C reservoir effect, and beyond 30-40 ka few methods are applicable. Photon-stimulated-luminescence sediment dating (photonic dating) of eolian and waterlain deposits in temperate latitudes spans the range from decades to hundreds of ka, but marine sediments in and around Antarctica pose special difficulty because of the potentially restricted exposure to daylight (the clock-zeroing process) of most detrital grains before deposition. This proposal will test the clock-zeroing assumption in representative Antarctic glaciomarine depositional settings, and thereby determine the potential reliability of photonic dating of Antarctic marine sediments.\u003cbr/\u003e\u003cbr/\u003eLimited luminescence dating and signal-zeroing tests using glaciomarine and marine deposits have been conducted in the northern temperate and polar latitudes, but the effects on luminescence of the different glaciomarine depositional processes have never been studied in detail. Furthermore, the depositional settings around Antarctica are almost entirely polar, with consequent specific processes operating there. For example, transport of terrigenous suspensions by neutrally buoyant \"cold-tongue\" (mid-water) plumes may be common around Antarctica, yet the effect of such transport on luminescence zeroing is unknown. Typical marine cores near Antarctica may contain an unknown fraction of detrital grains from cold-tongue and near-bottom suspensions. Thus the extent to which the polar glaciomarine depositional processes around Antarctica may limit the potential accuracy of photonic dating of marine cores is unknown (age overestimates would result if grains are not exposed to daylight before deposition).\u003cbr/\u003e\u003cbr/\u003eThis project will collect detrital grains from a variety of \"zero-age\" (modern) marine depositional settings within the Antarctic Peninsula, where representative Antarctic depositional processes have been documented and where logistics permit access. Suspensions will be collected from four fjords representing a transect from polar through subpolar conditions. Suspensions will be collected from two stations and from up to 3 depths (surface and 2 deep plumes) at each station. Sediment traps will be deployed at two of these fjord settings. As well, core-top sediments will be collected from several sites. All samples will be shielded from light and transported to Reno, Nevada, for luminescence analyses.\u003cbr/\u003e\u003cbr/\u003eSystematic study of the effectiveness of luminescence-clock-zeroing in Antarctic glaciomarine settings will determine if photonic dating can be reliable for future applications to Antarctic marine sediments. Refined sedimentological criteria for the selection of future samples for photonic dating are expected from this project. A photonic-dating capability would provide a numeric geochronometer extending well beyond the age range of 14C dating. Such a capability would permit answering a number of broader questions about the timing and extent of past glaciations near and on the Antarctic shelves.", "east": -55.0, "geometry": "POINT(-61.125 -64.625)", "instruments": "IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e CTD; IN SITU/LABORATORY INSTRUMENTS \u003e PRESSURE/HEIGHT METERS \u003e PRESSURE SENSORS; EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e POSITIONING/NAVIGATION \u003e GPS \u003e GPS; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e ADCP; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e CTD; IN SITU/LABORATORY INSTRUMENTS \u003e MAGNETIC/MOTION SENSORS \u003e GRAVIMETERS \u003e GRAVIMETERS; IN SITU/LABORATORY INSTRUMENTS \u003e PHOTON/OPTICAL DETECTORS \u003e TURBIDITY METERS; EARTH REMOTE SENSING INSTRUMENTS \u003e PASSIVE REMOTE SENSING \u003e POSITIONING/NAVIGATION \u003e GPS \u003e GPS; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e ADCP; IN SITU/LABORATORY INSTRUMENTS \u003e PROFILERS/SOUNDERS \u003e ACOUSTIC SOUNDERS \u003e MSBS; IN SITU/LABORATORY INSTRUMENTS \u003e CORERS \u003e SEDIMENT CORERS", "is_usap_dc": false, "keywords": "R/V LMG; Not provided; Luminescence; Hugo Island; Geochronology; R/V NBP; Palmer Deep", "locations": "Hugo Island", "north": -62.0, "nsf_funding_programs": "Antarctic Earth Sciences", "paleo_time": "PHANEROZOIC \u003e CENOZOIC \u003e QUATERNARY \u003e HOLOCENE", "persons": "Berger, Glenn; Domack, Eugene Walter", "platforms": "Not provided; WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V LMG; WATER-BASED PLATFORMS \u003e VESSELS \u003e SURFACE \u003e R/V NBP", "repo": "R2R", "repositories": "R2R", "science_programs": null, "south": -67.25, "title": "Collaborative Research: Development of a Luminescence Dating Capability for Antarctic Glaciomarine Sediments: Tests of Signal Zeroing at the Antarctic Pennisula", "uid": "p0000592", "west": -67.25}]
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Project Title/Abstract/Map | NSF Award(s) | Date Created | PIs / Scientists | Dataset Links and Repositories | Abstract | Bounds Geometry | Geometry | Selected | Visible | |||||
---|---|---|---|---|---|---|---|---|---|---|---|---|---|---|
Collaborative Research: Development of a Luminescence Dating Capability for Antarctic Glaciomarine Sediments: Tests of Signal Zeroing at the Antarctic Peninsula
|
0003060 |
2010-05-04 | Domack, Eugene Walter |
|
This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports project to test and develop approaches for using thermoluminescence techniques to determine the age of Antarctic marine sediments. <br/><br/>Quaternary (last 2 million yrs) marine sediments surrounding Antarctica record the waxing and waning of ice shelves and ice sheets, and also other paleoclimatic information, yet accurate chronologies of these sediments are difficult to obtain. Such chronologies provide the essential foundation for study of geological processes in the past. Within the range of radiocarbon (14C) dating (less than 30-40 thousand yrs, note - "ka" below means 1000 yrs) 14C dates can be inaccurate because of a variable 14C reservoir effect, and beyond 30-40 ka few methods are applicable. Photon-stimulated-luminescence sediment dating (photonic dating) of eolian and waterlain deposits in temperate latitudes spans the range from decades to hundreds of ka, but marine sediments in and around Antarctica pose special difficulty because of the potentially restricted exposure to daylight (the clock-zeroing process) of most detrital grains before deposition. This proposal will test the clock-zeroing assumption in representative Antarctic glaciomarine depositional settings, and thereby determine the potential reliability of photonic dating of Antarctic marine sediments.<br/><br/>Limited luminescence dating and signal-zeroing tests using glaciomarine and marine deposits have been conducted in the northern temperate and polar latitudes, but the effects on luminescence of the different glaciomarine depositional processes have never been studied in detail. Furthermore, the depositional settings around Antarctica are almost entirely polar, with consequent specific processes operating there. For example, transport of terrigenous suspensions by neutrally buoyant "cold-tongue" (mid-water) plumes may be common around Antarctica, yet the effect of such transport on luminescence zeroing is unknown. Typical marine cores near Antarctica may contain an unknown fraction of detrital grains from cold-tongue and near-bottom suspensions. Thus the extent to which the polar glaciomarine depositional processes around Antarctica may limit the potential accuracy of photonic dating of marine cores is unknown (age overestimates would result if grains are not exposed to daylight before deposition).<br/><br/>This project will collect detrital grains from a variety of "zero-age" (modern) marine depositional settings within the Antarctic Peninsula, where representative Antarctic depositional processes have been documented and where logistics permit access. Suspensions will be collected from four fjords representing a transect from polar through subpolar conditions. Suspensions will be collected from two stations and from up to 3 depths (surface and 2 deep plumes) at each station. Sediment traps will be deployed at two of these fjord settings. As well, core-top sediments will be collected from several sites. All samples will be shielded from light and transported to Reno, Nevada, for luminescence analyses.<br/><br/>Systematic study of the effectiveness of luminescence-clock-zeroing in Antarctic glaciomarine settings will determine if photonic dating can be reliable for future applications to Antarctic marine sediments. Refined sedimentological criteria for the selection of future samples for photonic dating are expected from this project. A photonic-dating capability would provide a numeric geochronometer extending well beyond the age range of 14C dating. Such a capability would permit answering a number of broader questions about the timing and extent of past glaciations near and on the Antarctic shelves. | None | None | false | false | |||||
Global Climate Change and the Evolutionary Ecology of Antarctic Mollusks in the Late Eocene
|
9908828 |
2010-05-04 | Aronson, Richard; Domack, Eugene Walter |
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9908828<br/>Aronson<br/><br/>This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports a paleoecological and paleoenvironmental study of Seymour Island. Global climate change late in the Eocene epoch had an important influence in Antarctica. This was the beginning of the transition from a cool-temperate climate in Antarctica to the polar climate that exists there today. The cooling trend strongly influenced the structure of shallow-water, Antarctic marine communities, and these effects are still evident in the peculiar ecological relationships among species living in modern Antarctic communities. Cooling late in the Eocene reduced the abundance of fish and crabs, which in turn reduced skeleton-crushing predation on invertebrates. Reduced predation allowed dense populations of ophiuroids (brittlestars) and crinoids (sea lilies) to appear in shallow-water settings at the end of the Eocene. These low-predation communities appear as dense fossil echinoderm assemblages in the upper portion of the late Eocene La Meseta Formation on Seymour Island, off the Antarctic Peninsula. Today, dense ophiuroid and crinoid populations are common in shallow-water habitats in Antarctica but generally have been eliminated by predators from similar habitats at temperate and tropical latitudes; their persistence in Antarctica to this day is an important ecological legacy of climatic cooling in the Eocene. Although the influence of declining predation on Antarctic ophiuroids and crinoids is now well documented, the effects of cooling on the more abundant mollusks have not been investigated. This study will examine the evolutionary ecology of gastropods (snails) and bivalves (clams) in the late Eocene.<br/><br/>A series of hypotheses will be tested in the La Meseta Formation, based on the predicted responses of mollusks to declining temperature and changing levels of predation. The shapes of gastropod shells, the activities of gastropods that prey on other mollusks by drilling holes in their shells, and the effects of predation on the thickness of mollusk shells should have changed significantly through late Eocene time. First, defensive features of gastropod shells, such as spines and ribbing, should decline as temperature and, therefore, the activity of skeleton-crushing predators declined. Second, drilling of bivalve prey by predatory gastropods should increase with time since the drillers should themselves have been subject to lower predation pressure as temperature declined. Drilled shells, therefore, should become more common through time. Third, patterns in the thickness of shells through time will make it possible to separate the direct, physiological effects of declining temperature (shells are more difficult to produce at cooler temperatures, and so should be thinner) from the indirect effects of temperature on evolving biological interactions (increased drilling predation should result in thicker shells). <br/><br/>Seymour Island contains the only fossil outcrops readily accessible in Antarctica from this crucial period in Earth history. The La Meseta Formation on Seymour Island thus provides a unique opportunity to learn how climate change affected Antarctic marine communities. In practical terms, global climate change will probably increase upwelling over the next few decades to centuries in some temperate coastal regions. Recent ecological evidence suggests that the resultant lowering of sea temperatures could lower predation in those areas. Understanding the response of the La Meseta faunas to global cooling in the late Eocene will provide direct insight into the rapidly changing structure of modern benthic communities. | POLYGON((-70.906 -52.350166,-69.4494 -52.350166,-67.9928 -52.350166,-66.5362 -52.350166,-65.0796 -52.350166,-63.623 -52.350166,-62.1664 -52.350166,-60.7098 -52.350166,-59.2532 -52.350166,-57.7966 -52.350166,-56.34 -52.350166,-56.34 -53.6028324,-56.34 -54.8554988,-56.34 -56.1081652,-56.34 -57.3608316,-56.34 -58.613498,-56.34 -59.8661644,-56.34 -61.1188308,-56.34 -62.3714972,-56.34 -63.6241636,-56.34 -64.87683,-57.7966 -64.87683,-59.2532 -64.87683,-60.7098 -64.87683,-62.1664 -64.87683,-63.623 -64.87683,-65.0796 -64.87683,-66.5362 -64.87683,-67.9928 -64.87683,-69.4494 -64.87683,-70.906 -64.87683,-70.906 -63.6241636,-70.906 -62.3714972,-70.906 -61.1188308,-70.906 -59.8661644,-70.906 -58.613498,-70.906 -57.3608316,-70.906 -56.1081652,-70.906 -54.8554988,-70.906 -53.6028324,-70.906 -52.350166)) | POINT(-63.623 -58.613498) | false | false | |||||
Collaborative Research: Development of a Luminescence Dating Capability for Antarctic Glaciomarine Sediments: Tests of Signal Zeroing at the Antarctic Pennisula
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9909665 |
2007-10-10 | Berger, Glenn; Domack, Eugene Walter |
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9909665<br/>Berger<br/><br/>This award, provided by the Antarctic Geology and Geophysics Program of the Office of Polar Programs, supports project to test and develop approaches for using thermoluminescence techniques to determine the age of Antarctic marine sediments. <br/><br/>Quaternary (last 2 million yrs) marine sediments surrounding Antarctica record the waxing and waning of ice shelves and ice sheets, and also other paleoclimatic information, yet accurate chronologies of these sediments are difficult to obtain. Such chronologies provide the essential foundation for study of geological processes in the past. Within the range of radiocarbon (14C) dating (less than 30-40 thousand yrs, note - "ka" below means 1000 yrs) 14C dates can be inaccurate because of a variable 14C reservoir effect, and beyond 30-40 ka few methods are applicable. Photon-stimulated-luminescence sediment dating (photonic dating) of eolian and waterlain deposits in temperate latitudes spans the range from decades to hundreds of ka, but marine sediments in and around Antarctica pose special difficulty because of the potentially restricted exposure to daylight (the clock-zeroing process) of most detrital grains before deposition. This proposal will test the clock-zeroing assumption in representative Antarctic glaciomarine depositional settings, and thereby determine the potential reliability of photonic dating of Antarctic marine sediments.<br/><br/>Limited luminescence dating and signal-zeroing tests using glaciomarine and marine deposits have been conducted in the northern temperate and polar latitudes, but the effects on luminescence of the different glaciomarine depositional processes have never been studied in detail. Furthermore, the depositional settings around Antarctica are almost entirely polar, with consequent specific processes operating there. For example, transport of terrigenous suspensions by neutrally buoyant "cold-tongue" (mid-water) plumes may be common around Antarctica, yet the effect of such transport on luminescence zeroing is unknown. Typical marine cores near Antarctica may contain an unknown fraction of detrital grains from cold-tongue and near-bottom suspensions. Thus the extent to which the polar glaciomarine depositional processes around Antarctica may limit the potential accuracy of photonic dating of marine cores is unknown (age overestimates would result if grains are not exposed to daylight before deposition).<br/><br/>This project will collect detrital grains from a variety of "zero-age" (modern) marine depositional settings within the Antarctic Peninsula, where representative Antarctic depositional processes have been documented and where logistics permit access. Suspensions will be collected from four fjords representing a transect from polar through subpolar conditions. Suspensions will be collected from two stations and from up to 3 depths (surface and 2 deep plumes) at each station. Sediment traps will be deployed at two of these fjord settings. As well, core-top sediments will be collected from several sites. All samples will be shielded from light and transported to Reno, Nevada, for luminescence analyses.<br/><br/>Systematic study of the effectiveness of luminescence-clock-zeroing in Antarctic glaciomarine settings will determine if photonic dating can be reliable for future applications to Antarctic marine sediments. Refined sedimentological criteria for the selection of future samples for photonic dating are expected from this project. A photonic-dating capability would provide a numeric geochronometer extending well beyond the age range of 14C dating. Such a capability would permit answering a number of broader questions about the timing and extent of past glaciations near and on the Antarctic shelves. | POLYGON((-67.25 -62,-66.025 -62,-64.8 -62,-63.575 -62,-62.35 -62,-61.125 -62,-59.9 -62,-58.675 -62,-57.45 -62,-56.225 -62,-55 -62,-55 -62.525,-55 -63.05,-55 -63.575,-55 -64.1,-55 -64.625,-55 -65.15,-55 -65.675,-55 -66.2,-55 -66.725,-55 -67.25,-56.225 -67.25,-57.45 -67.25,-58.675 -67.25,-59.9 -67.25,-61.125 -67.25,-62.35 -67.25,-63.575 -67.25,-64.8 -67.25,-66.025 -67.25,-67.25 -67.25,-67.25 -66.725,-67.25 -66.2,-67.25 -65.675,-67.25 -65.15,-67.25 -64.625,-67.25 -64.1,-67.25 -63.575,-67.25 -63.05,-67.25 -62.525,-67.25 -62)) | POINT(-61.125 -64.625) | false | false |