Mineralogy of sediments from AND-2A drill core (McMurdo Sound, Antarctica)

• Main Author: Iacoviello, Francesco
• Format: Doctoral or Postdoctoral Thesis
• Language: English
• Published: Università degli Studi di Siena (University of Siena) 2012
• Subjects: Antarctic; The Antarctic; East Antarctica; Ross Sea; McMurdo Sound; Transantarctic Mountains; Antarc*; Antarctica; Ice Sheet
• Online Access: https://discovery.ucl.ac.uk/id/eprint/10086421/8/Iacoviello_10086421_thesis_redacted.pdf; https://discovery.ucl.ac.uk/id/eprint/10086421/

The present study deals with a combined clay-heavy mineral analysis of marine sediments recovered in 2007 in the McMurdo Sound region (Ross Sea, Antarctica) during the ANtarctic DRILLing Program (ANDRILL) - Southern McMurdo Sound Project. The main objectives are to: 1) study how clay minerals reflect paleoclimatic conditions, in particular the Mid-Miocene Climatic Optimum, 2) investigate how heavy mineral assemblages reflect different source rocks and hence different provenance areas 3) study the ice sheet development in East-Antarctica in the last 20 Ma. The AND-2A drill core recovered several stratigraphic intervals that span from Early Miocene to Pleistocene and it collected a variety of terrigenous clastic lithologies. The clay mineral assemblages of the 1138,54 m thick sedimentary succession have been analyzed through X-Ray Diffraction (XRD) analyses on clay fraction, Field Emission scanning Electron Microscopy (FESEM), Scanning Electron Microscopy (SEM) observations and SEM-EDS microanalyses on smectite particles. SEM observations and SEM-EDS microanalyses were carried out on heavy mineral samples starting from 650 mbsf. In the upper sedimentary sections (36 - 440 mbsf, 0.7 - 16.5 Ma) smectites are interpreted to be predominantly detrital, whereas in the lower portion of the core (440 -1123.20 mbsf, 18.5 - 20.2 Ma) authigenic smectites are the most common feature. The predominance of illite, the abundance of chlorite and the nature of smectites in the upper part of the core indicate physical weathering under cold and dry climate and dominant provenance for the clay minerals from the Transantarctic Mountains. Smectites in the lower section are considered mostly authigenic and they are probably the result of early diagenetic processes being formed from the alteration of volcanic material and/or through precipitation from fluids of a possible hydrothermal origin. The heavy mineral analysis shows that the sediments are a mix of detritus dominated by McMurdo Volcanic Group (MVG) sources most likely located in ...