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Ehrmann, Werner; Polozek, Kerstin (1999): Relative abundance of heavy minerals in sediment core CIROS-2 from McMurdo Sound, Antarctica (App A). PANGAEA, https://doi.org/10.1594/PANGAEA.55366, Supplement to: Ehrmann, W; Polozek, K (1999): The heavy mineral record in the Pliocene to Quaternary sediments of the CIROS-2 drill core, McMurdo Sound, Antarctica. Sedimentary Geology, 128(3-4), 223-244, https://doi.org/10.1016/S0037-0738(99)00071-8

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Abstract:
The heavy mineral assemblages of the Lower Pliocene to Quaternary glacial sediments of the CIROS-2 drill site, situated near the mouth of Ferrar Glacier on the McMurdo Sound shelf, Antarctica, were analysed by optical means in order to reconstruct the source areas and dynamics of the late Cenozoic Antarctic ice masses. The assemblages are dominated by pyroxenes, amphiboles, altered minerals and opaque minerals. Within the pyroxene group, clinopyroxenes are most abundant; within the amphibole group, green and brown hornblendes are dominant. Other important heavy minerals present in minor amounts are zircon, titanite, epidote, garnet and apatite. The downcore distribution of the heavy minerals allows a subdivision of the sedimentary sequence into two major units, which can both be further subdivided into two subunits. The Pliocene interval between 166 and 110 mbsf is characterized by relatively high concentrations of apatite, zircon, titanite, garnet, epidote and green hornblende. This assemblage accounts for some 40-60% of the heavy minerals and points to a source to the west of the drill site, in the Transantarctic Mountains, where intrusive, metamorphic and sedimentary rocks cover large areas. The interval 166-137 mbsf (Lower Pliocene) contains additional brown hornblende and palagonite, indicative of a volcanic, probably hyaloclastitic source, which possibly has to be sought beneath the ice of the Ferrar Glacier. In contrast, the uppermost Pliocene and Quaternary interval between 110 mbsf and the top of the core is characterized by high concentrations of clinopyroxenes, altered minerals and opaque minerals. This record points to a main source area in the south or east, where large areas are occupied by basaltic rocks of the McMurdo Volcanic Group. A slight change in the composition of the pyroxene group occurs within this interval, at 48 mbsf. Thus, the heavy minerals in the sediments of core CIROS-2 document different source areas and therewith major changes in the ice dynamics. During the Pliocene the ice discharged through the Transantarctic Mountains into the McMurdo Sound. The source area shifted in the Quaternary to the south, to the region of the present-day Ross Ice Shelf.
Related to:
Polozek, Kerstin (2001): Die Schwermineralverteilung känozoischer Sedimente des McMurdo-Sunds, Ross-Meer, Antarktis: Rekonstruktion von Liefergebieten und Eisschildfluktuationen. PhD Thesis, Leipzig University, Leipzig, 120 pp, hdl:10013/epic.32120.d001
Coverage:
Latitude: -77.683333 * Longitude: 163.533333
Minimum DEPTH, sediment/rock: 0.01 m * Maximum DEPTH, sediment/rock: 165.64 m
Event(s):
CIROS-2 * Latitude: -77.683333 * Longitude: 163.533333 * Elevation: -211.0 m * Location: McMurdo Sound * Campaign: CIROS * Basis: Sampling/drilling ice * Device: Drilling/drill rig (DRILL)
Parameter(s):
#NameShort NameUnitPrincipal InvestigatorMethodComment
1DEPTH, sediment/rockDepthmGeocode
2ApatiteAp%Ehrmann, WernerHeavy mineral analysisrelative abundance in the fraction 63-125 µm
3ZirconZrn%Ehrmann, WernerHeavy mineral analysisrelative abundance in the fraction 63-125 µm
4TitaniteTtn%Ehrmann, WernerHeavy mineral analysisrelative abundance in the fraction 63-125 µm
5GarnetGrt%Ehrmann, WernerHeavy mineral analysisrelative abundance in the fraction 63-125 µm
6EpidoteEp%Ehrmann, WernerHeavy mineral analysisrelative abundance in the fraction 63-125 µm
7Clinopyroxene, greenCpx gr%Ehrmann, WernerHeavy mineral analysisrelative abundance in the fraction 63-125 µm
8PyroxenePyrox%Ehrmann, WernerHeavy mineral analysisrelative abundance in the fraction 63-125 µm
9Opaque mineralsOpaque%Ehrmann, WernerHeavy mineral analysisrelative abundance in the fraction 63-125 µm
10Minerals, alteredMin altered%Ehrmann, WernerHeavy mineral analysisrelative abundance in the fraction 63-125 µm
11PalagonitePalagonite%Ehrmann, WernerHeavy mineral analysisrelative abundance in the fraction 63-125 µm
12Clinopyroxene, brownCpx br%Ehrmann, WernerHeavy mineral analysisrelative abundance in the fraction 63-125 µm
13TitanaugiteTi-Aug%Ehrmann, WernerHeavy mineral analysisrelative abundance in the fraction 63-125 µm
14Volcanic glassVolc glass%Ehrmann, WernerHeavy mineral analysisrelative abundance in the fraction 125-250 µm
15Quartz/standard ratioQz/stdEhrmann, WernerHeavy mineral analysisrelative contents in the fraction 2-63 µm
Size:
562 data points

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