A comparison of detrital U-Pb zircon, Ar-40/Ar-39 hornblende, Ar-40/Ar-39 biotite ages in marine sediments off East Antarctica: Implications for the geology of subglacial terrains and provenance studies

作者：Pierce E L^*; Hemming S R; Williams T; van de Flierdt T; Thomson S N; Reiners P W; Gehrels G E; Brachfeld S A; Goldstein S L

来源：Earth-Science Reviews, 2014, 138: 156-178.

DOI：10.1016/j.earscirev.2014.08.010

• Thermochronology
• Geochronology
• Ice-rafted debris
• Glacial diamict
• Detrital zircon

U-Pb ages of detrital zircon grains have provided an extraordinary tool for sedimentary provenance work, given that they are ubiquitous, resistant to damage and weathering, and that the U-Pb age records the crystallization age of the mineral. Although not as widely used, Ar-40/Ar-39 dating of detrital homblende and biotite grains can also serve as powerful sedimentary provenance tools, particularly in situations where chemical weathering is minor (e.g., Antarctica). Certain natural biases exist among these mineral chronometers (e.g., abundance in different rock types, durability during abrasion, resistance to dissolution) that determine the extent to which they are found in sedimentary deposits. Additionally, the Ar-40/Ar-39 systems in hornblende and biotite have lower closure temperatures for thermally activated diffusion (similar to 500 degrees C and similar to 300 degrees C, respectively). Thus, for areas that have experienced a polymetamorphic history, such as East Antarctica, combining these approaches can provide added detail to provenance studies.
In this study we provide a comparison of the detrital U-Pb zircon, Ar-40/Ar-39 hornblende and Ar-40/Ar-39 biotite age populations from 28 glacial-diamict and glacial-marine sediment core samples located around East Antarctica (55 degrees W to 163 degrees E). We present 3370 new detrital age measurements of U-Pb zircon, 40Ar/39Ar hornblende, and Ar-40/Ar-39 biotite, in conjunction with previously published data from some of the same core sites, as well as 78 U-Pb zircon ages measured on dispersed zircons from five ice-rafted debris (IRD) layers recovered at ODP Site 1165. Our data indicate that detrital U-Pb zircon, Ar-40/Ar-39 hornblende and Ar-40/Ar-39 biotite ages faithfully document the onshore geology of source areas within East Antarctica, as expressed in their respective age populations. In addition, a number of previously unknown age populations are recorded by the combined thermochronometers. Assuming an East Antarctic provenance, this approach helps to identify otherwise hidden geologic provinces. Previously unrecognized age populations include Archean Ar-40/Ar-39 homblende and biotite ages in Dronning Maud Land; 1200-1300 Ma Ar-40/Ar-39 homblende ages in the Weddell Sea; similar to 1560 Ma population of U-Pb zircons from the Wilkes Land margin; and Grenvillian (1000-1200 Ma) U-Pb zircon ages from the Adelie/George V Land margin.

• 出版日期2014-11