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Paper No. 32
Presentation Time: 4:45 PM

AFFIRMATION OF ANTARCTIC-LAURENTIAN RODINIAN JUXTAPOSITION DURING THE MESOPROTEROZOIC


HODGSON, Justin1, LICHT, Kathy1 and SWOPE, R. Jeffrey2, (1)Department of Earth Sciences, Indiana University-Purdue University Indianapolis, 723 West Michigan Street, SL 118, Indianapolis, IN 46202, (2)Department of Geology, Indiana University - Purdue University Indianapolis, 723 West Michigan Street, SL118, Indianapolis, IN 46202-5132, jwhodgso@iupui.edu

AFFIRMATION OF ANTARCTIC-LAURENTIAN RODINIAN JUXTAPOSITION DURING THE MESOPROTEROZOIC

Granite (MA11 - Gr) and deformed granitoid (MA11 - Gn) samples collected from a moraine near Mt. Achernar, Antarctica have provided new evidence supporting an East Antarctic and Laurentian juxtaposition within Rodinia. Sample MA11 - Gr is a pink, porphyritic, very coarse-grained (>10 mm) muscovite-biotite granite. In hand sample, potassium feldspar, quartz, amphibole, and plagioclase feldspar are observed. Additionally in thin section, muscovite, biotite, and feldspar grains displaying rapakivi texture are evident. Sample MA11 - Gn is a deformed muscovite-biotite granitoid. The rock is foliated and feldspar grains have an augen texture. In thin section both muscovite and biotite are present.

Zircons from these samples were dated with U/Pb using LA-ICPMS. The granite is 1447 ± 37 Ma based on 23 analyses on 16 grains. The granitoid is 1446 ±25 Ma based on 50 analyses on 30 grains. In both cases the core and rim ages were indistinguishable.

These samples are interpreted to be related to sample TNQ, a 1441 ± 6.4 Ma granite, collected ~110 km north of Mt. Achernar within the Nimrod Glacier catchment. TNQ granite is a pink, very coarse-grained (>10mm), porphyritic, rapakivi-type muscovite-biotite granite as described by Goodge et al 2008. Within error the two Mt. Achernar samples share the same age as TNQ. SiO2, K2O, CaO, Na2O, Fe2O3, and MgO weight percentages and Sr, Nb, Ba, Hf, Y, and Zr ppm were examined using FUS-ICP and FUS-MS at Activation Laboratories Ltd. The geochemical data sets of these two samples are indistinguishable from TNQ and Laurentian granite geochemical data sets and support the SWEAT hypothesis.

Reference

Goodge, J. W., Vervoort, J. D., Fanning, C. M, Brecke, D. M, Farmer, G. L., Williams, I. S. Myrow, P. M, DePaolo, D. J., 2008, A positive test of East Antarctica-Laurentia juxtaposition within the Rodinia supercontinent: Science, v.231, p.235 – 240.

Session No. 247

T165. Sigma Gamma Epsilon Undergraduate Research (Posters)
Tuesday, 29 October 2013: 9:00 AM-6:30 PM
Hall D (Colorado Convention Center)
Geological Society of America Abstracts with Programs. Vol. 45, No. 7, p.585
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