Abstract
Variations in grain size, clay mineral composition, and stable isotopes (δ13C and δ15N) are closely linked to the sedimentary facies that reflect mineralogical and geochemical modification during the retreat and advance of the Larsen ice shelf. A whole round core of marine sediment (EAP13-GC17, 236 cm below the sea floor) was collected on the northwestern Larsen B embayment of the Antarctic Peninsula during a marine geological expedition (the ARA13 Cruise Expedition by the Korea Polar Research Institute, 2013). Four sedimentary facies (U1–U4) were clearly distinguishable: bioturbated sandy mud (open marine, U1), laminated sandy mud (sub–floating ice shelf, U2), sandy clay aggregates (deglacial, U3), and muddy diamictons (sub-glacial, U4), as well as interbedded silty. Clay minerals, including smectite, chlorite, illite, and kaolinite, were detected throughout the core. An increase in the clay mineral ratio of smectite/(illite + chlorite) was clearly observed in the open marine condition, which was strongly indicated by both a heavier isotopic composition of δ13C and δ15N (−24.4‰ and 4.3‰, respectively), and an abrupt increase in 10Be concentration (~30 times). An increase in the average values of the crystal packet thickness of illite (~1.5 times) in U1 also indicated sediments transported in open marine conditions. Based on the clay mineral composition in U1, the sediments are likely to have been transported from the Weddell Sea. The clay mineralogical assessments conducted in this region have significant implications for our understanding of paleodepositional environments.
Highlights
Mineralogical and geochemical investigations of marine sediments from the continental shelf around Antarctica provide significant clues about the stability and proximity of ice shelves, and the influx of terrigenous sediments and meltwater during deglaciation [1,2]
Based on clay mineral composition, sediment sources can be subdivided into an illite province, a chlorite province, and a kaolinite province (Amundsen Sea) [14]
This study provides new mineralogical and geochemical data for the worldwide database on Holocene paleoclimatic observations, which will allow for comparisons of the Holocene environmental changes of different continental shelves
Summary
Mineralogical and geochemical investigations of marine sediments from the continental shelf around Antarctica provide significant clues about the stability and proximity of ice shelves, and the influx of terrigenous sediments and meltwater during deglaciation [1,2]. Typical of the chemical alteration of mafic igneous rocks in warm and humid climates [10], and structurally defect-rich hydrous minerals [11] are good indicators of sediments provenance from a warm and humid location; in contrast, illite and chlorite result from the physical weathering of metamorphic and sedimentary rocks under cold climate conditions [12]. Variations in clay mineral composition are useful for investigating the provenance and source rock of sediments, in Antarctic environments where secondary mineral alteration is minimal [9,13]. The clay mineralogical heterogeneity of the diamictons indicates that the ice streams were derived from different source areas on the southern
Sign-in/Register to view highlights & summary Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
