FRINK Linked Data Fragments server

Matches in SemOpenAlex for { <https://semopenalex.org/work/W2220170028> ?p ?o ?g. }

• W2220170028 abstract "LATE EOCENE IMPACT EJECTA: THE NORTH AMERICAN TEKTITE STREWN FIELD AND ITS SOURCEE, THE CHESAPEAKE BAY IMPACT STRUCTURE: UPDATE ON THE ICDP-US GS DEEP DRILLING PROJECTS Christian Koeberl1, W. Uwe Reimold2, Gregory S. Gohn3, Kenneth G. Miller. Center of Earth Sciences, University of Vienna, Althanstrasse 14, A-1090 Vienna, Austria (christian.koeberl@univie.ac.at); Museum of Natural History, Humboldt-University, Invalidenstrasse 43, D10115 Berlin, Germany (uwe.reimold@museum.hu-berlin.de); U.S. Geological Survey, Reston, VA 20192, USA (ggohn@usgs.gov); Rutgers University, Department of Geological Sciences, Piscataway, NJ 08854, USA (kgm@rci.rutgers.edu). Late Eocene Impacts and the North American Tektite Strewn Field. Upper Eocene marine sediments around the world contain evidence for at least two closely spaced impactoclastic layers – i.e., layers containing impact debris, such as tektites and microtektites and shocked minerals and rock fragments (for references see e.g., Montanari and Koeberl [1]). Initially, it was thought that there is only one layer known from the eastern U.S. coast, the Caribbean, and the Gulf of Mexico, which is correlated with the North American tektite strewn field. This layer contains microtektites (i.e., glassy, not recrystallized spherules), shocked minerals, and highpressure phases (e.g., coesite), but no marked siderophile element anomaly. The presence of crystalline spherules composed mostly of clinopyroxene (cpx) was detected in the same deep sea sediments and initially it was considered that these spherules also belong to the North American tektite strewn field. The cpx spherules were found not only in the Caribbean and the Gulf of Mexico but also in the Pacific Ocean. Fig. 1. The two large late Eocene impact craters (Chesapeake Bay and Popigai) and location of coeval impact ejecta deposits. The North American tektite strewn field is also outlined (from [2]). Impact-produced, crystallite-bearing spherules are called microkrystites. More detailed work showed that the microtektite layer and the microkrystite (cpx) layer (both in middle to lower magnetic chron C15) are in fact separated from each other by about 25 cm, with the cpx layer being the lower (i.e., older) one. The separation between the two layers amounts to about 10 to 20 k.y. Microtektites and tektite fragments at DSDP Site 612 show chemical and isotopic similarities with other North American tektites (e.g., [1, 2]). The microkrystite layer has now been found at numerous other locations, indicating that it has a more or less global distribution, Koeberl et al.: North American tektites and Chesapeake Bay Impact Structure and it seems to be associated at several locations with enhanced Ir abundances. Impact ejecta interpreted to be part of the cpx layer also have been found in rocks from the marine Umbria-Marche succession in Italy at the Global Stratotype Section and Point for the EoceneOligocene boundary at Massignano near Ancona. At this location two impactoclastic layers – the other possibly related to Chesapeake Bay – are present. As mentioned above, the source of the North American tektite strewn field has now been linked, with a certain degree of confidence, to the Chesapeake Bay impact structure [3]. An impact event that created a crater of this size would be capable of globally distributing its distal ejecta (e.g., [1]). There is a second large crater with an age indistinguishable from that of the Chesapeake Bay structure and the two ejecta layers, namely the 100-km-diameter Popigai impact structure in Siberia, which has been dated at 35.7±0.8 Ma. The Popigai structure is exposed in Archean crystalline rocks of the Anabar Shield, with overlying Proterozoic to Mesozoic sedimentary sequences (e.g., [1, 3]), and is the largest Cenozoic crater on Earth. It is now commonly assumed that the global upper Eocene microkrystite layer originated from the Popigai impact event, but this link has yet to be confirmed, probably by using isotope geochemical methods, because radiometric age determinations do not allow to resolve an age difference of 10 or 20 k.y. It is also interesting to note that much enhanced levels of He were found to coincide with the two upper Eocene impactoclastic layers. This isotope is a proxy for the influx of extraterrestrial dust and is interpreted as indicating that, during the late Eocene, there was a time of enhanced comet activity in the inner solar system, probably resulting in a higher impact rate than usual. There are numerous questions associated with the link between the Chesapeake Bay crater and the North American tektites. Chesapeake Bay impact structure: The late Eocene Chesapeake Bay impact structure is among the largest and best preserved of the known impact craters on Earth [3]. It has a diameter of 85 km (Fig. 2) with what has been called an “inverted sombrero”-.shape cross section. The crystalline basement beneath the impact structure, and beneath the Mid-Atlantic Coastal Plain in general, is one of the most poorly understood geologic provinces in the United States. Granite is the only basement rock type encountered by the five boreholes that reached pre-Cretaceous rocks below the impact structure [3]). Clasts of basement rock found as reworked ejecta within the impact structure consist primarily of cataclastic granites and porphyritic felsites. Atlantic Coastal Plain sediments overlie this basement and constitute a seaward-thickening wedge of dominantly unconsolidated to poorly consolidated siliciclastic sands, silts, and clays of marine and nonmarine origin. This succession was deposited between the Early Cretaceous and the Holocene Chesapeake Bay is distinctive among impact craters on Earth because it is a relatively young and well-preserved structure, which is the source of the North American tektites – one of only 4 known tektite strewn fields on Earth. The Chesapeake Bay structure is unique among subaerial and submarine impact craters on Earth because: (1) it is a relatively young structure and, in comparison to other known impact structures of such size, very wellpreserved; (2) its location on a passive continental margin has prevented tectonic or orogenic disruption or distortion that is typical of many large terrestrial craters; (3) its original location on a relatively deep continental shelf allowed marine deposition to resume immediately following the impact, which buried it rapidly and completely, thereby preventing subsequent erosion; (4) the upper part of the breccia section inside the crater was derived from resurge currents and impact-generated tsunami waves; (5) the breccia body contains a large volume of impactgenerated brine; (6) the crater underlies a densely populated urban corridor, whose two million citizens are still affected by crater-related phenomena, such as freshwater availability. Previous studies have raised many questions that can only be answered by a deep drilling project. The ICDP drilling project also included a deep biosphere research opportunity. Drilling: The International Continental Scientific Drilling Program (ICDP) and the U.S. Geological Survey (USGS) completed two deep coreholes to a composite depth of almost 1.8 km into the Chesapeake Bay impact structure during September-December 2005. Post-impact sediments were cored from land surface to a depth of 140 m in a third corehole during April and May 2006. Field operations began in July 2005 with site preparations at Eyreville Farm in Northampton County, Virginia; subsequently, Koeberl et al.: North American tektites and Chesapeake Bay Impact Structure three coreholes were drilled at the Eyreville site. Eyreville hole A was cored between depths of 125 m and 941 m from September through early October 2005. Problems with lost mud circulation and swelling clays in Eyreville A led to a lengthy period of reaming and ultimately to deviation of the bit from Eyreville A to a new hole, Eyreville B, at a depth of 738 m. Eyreville B was cored from that depth to a final depth of 1,766 m from October through early December 2005. Post-impact sediments were cored from land surface to a depth of 140 m in the Eyreville C hole during April and May 2006. Fig. 2. Schematic cross section through half of the Chesapeake Bay impact structure, showing the deep central part of the crater (including the central uplift), and the location of the ICDP-USGS deep corehole" @default.
• W2220170028 created "2016-06-24" @default.
• W2220170028 creator A5025511346 @default.
• W2220170028 creator A5044944163 @default.
• W2220170028 creator A5069489687 @default.
• W2220170028 creator A5076871437 @default.
• W2220170028 date "2007-01-01" @default.
• W2220170028 modified "2023-09-28" @default.
• W2220170028 title "ABSTRACT: LATE EOCENE IMPACT EJECTA: THE NORTH AMERICAN TEKTITE STREWN FIELD AND ITS SOURCEE, THE CHESAPEAKE BAY IMPACT STRUCTURE: UPDATE ON THE ICDP-US GS DEEP DRILLING PROJECTS" @default.
• W2220170028 hasPublicationYear "2007" @default.
• W2220170028 type Work @default.
• W2220170028 sameAs 2220170028 @default.
• W2220170028 citedByCount "0" @default.
• W2220170028 crossrefType "journal-article" @default.
• W2220170028 hasAuthorship W2220170028A5025511346 @default.
• W2220170028 hasAuthorship W2220170028A5044944163 @default.
• W2220170028 hasAuthorship W2220170028A5069489687 @default.
• W2220170028 hasAuthorship W2220170028A5076871437 @default.
• W2220170028 hasConcept C111368507 @default.
• W2220170028 hasConcept C115880899 @default.
• W2220170028 hasConcept C121332964 @default.
• W2220170028 hasConcept C127313418 @default.
• W2220170028 hasConcept C127413603 @default.
• W2220170028 hasConcept C127592171 @default.
• W2220170028 hasConcept C151730666 @default.
• W2220170028 hasConcept C166957645 @default.
• W2220170028 hasConcept C179537507 @default.
• W2220170028 hasConcept C205649164 @default.
• W2220170028 hasConcept C21790881 @default.
• W2220170028 hasConcept C25197100 @default.
• W2220170028 hasConcept C2776779945 @default.
• W2220170028 hasConcept C2985168408 @default.
• W2220170028 hasConcept C62520636 @default.
• W2220170028 hasConcept C78519656 @default.
• W2220170028 hasConcept C87355193 @default.
• W2220170028 hasConcept C88160329 @default.
• W2220170028 hasConcept C92150305 @default.
• W2220170028 hasConceptScore W2220170028C111368507 @default.
• W2220170028 hasConceptScore W2220170028C115880899 @default.
• W2220170028 hasConceptScore W2220170028C121332964 @default.
• W2220170028 hasConceptScore W2220170028C127313418 @default.
• W2220170028 hasConceptScore W2220170028C127413603 @default.
• W2220170028 hasConceptScore W2220170028C127592171 @default.
• W2220170028 hasConceptScore W2220170028C151730666 @default.
• W2220170028 hasConceptScore W2220170028C166957645 @default.
• W2220170028 hasConceptScore W2220170028C179537507 @default.
• W2220170028 hasConceptScore W2220170028C205649164 @default.
• W2220170028 hasConceptScore W2220170028C21790881 @default.
• W2220170028 hasConceptScore W2220170028C25197100 @default.
• W2220170028 hasConceptScore W2220170028C2776779945 @default.
• W2220170028 hasConceptScore W2220170028C2985168408 @default.
• W2220170028 hasConceptScore W2220170028C62520636 @default.
• W2220170028 hasConceptScore W2220170028C78519656 @default.
• W2220170028 hasConceptScore W2220170028C87355193 @default.
• W2220170028 hasConceptScore W2220170028C88160329 @default.
• W2220170028 hasConceptScore W2220170028C92150305 @default.
• W2220170028 hasLocation W22201700281 @default.
• W2220170028 hasOpenAccess W2220170028 @default.
• W2220170028 hasPrimaryLocation W22201700281 @default.
• W2220170028 hasRelatedWork W1557085334 @default.
• W2220170028 hasRelatedWork W1625450426 @default.
• W2220170028 hasRelatedWork W1649280413 @default.
• W2220170028 hasRelatedWork W1682157537 @default.
• W2220170028 hasRelatedWork W1683908564 @default.
• W2220170028 hasRelatedWork W1830163240 @default.
• W2220170028 hasRelatedWork W190898154 @default.
• W2220170028 hasRelatedWork W1994796300 @default.
• W2220170028 hasRelatedWork W2012427988 @default.
• W2220170028 hasRelatedWork W2023762873 @default.
• W2220170028 hasRelatedWork W2076731197 @default.
• W2220170028 hasRelatedWork W2084335426 @default.
• W2220170028 hasRelatedWork W2120547296 @default.
• W2220170028 hasRelatedWork W243688084 @default.
• W2220170028 hasRelatedWork W2913931125 @default.
• W2220170028 hasRelatedWork W3125776682 @default.
• W2220170028 hasRelatedWork W324454769 @default.
• W2220170028 hasRelatedWork W183482860 @default.
• W2220170028 hasRelatedWork W3121648957 @default.
• W2220170028 hasRelatedWork W3124064438 @default.
• W2220170028 isParatext "false" @default.
• W2220170028 isRetracted "false" @default.
• W2220170028 magId "2220170028" @default.
• W2220170028 workType "article" @default.