Provenance and alteration of the Triassic Fremouw and Falla Formations, central Transantarctic Mountains, Antarctica [microform]
- Bib ID:
- 3287438
- Format:
- Book and Microform
- Author:
- Vavra, Charles Lee
- Description:
- 193 p.
- Summary:
-
The Fremouw and Falla formations are part of a thick sequence of alluvial sediments that accumulated in a foreland basin (foredeep) between the Antarctic craton and the Gondwanian orogen, an Andean-type mountain belt along the Pacific margin of Gondwana. Detrital constituents suggest that source terrains consisted of a silicic to intermediate volcanic rocks with subordinant sedimentary, metamorphic and plutonic rocks. The bulk of the sediment was derived from a volcanic source, probably an active calc-alkaline complex in the orogen.
Sediment dispersal and sandstone composition data suggest that streams flowed from the orogen and craton into and down the axis of the foreland basin. Post-depositional alterations in the Fremouw and Falla formations including grain dissolution, grain destruction and replacement and formation of clay, silica and zeolite cements resulted from Triassic-Jurassic diagenesis during sediment accumulation in the foreland basin and later zeolite-facies alteration associated with emplacement of Jurassic diabase during the initial phases of rifting of Gondwana. Early diagenesis consisted of reactions between sediment and pore fluid, probably ground water, at near-surface temperature and pressure. Zeolite-facies alterations resulted from simple rock-fluid reactions that occurred at elevated pressure and temperature.
Coal rank suggests that away from local effects of the diabase intrusions temperatures may have been as low as 130(DEGREES) to 160(DEGREES)C, whereas stratigraphic evidence suggests maximum pressures of about 750 bars. Chemical patterns in sandstone near intrusions indicate that, although diabase supplied heat to drive rock-fluid reactions in the sandstone, it did not contribute a significant amount of cations to the hydrothermal system. Mineral and chemical patterns, together with hypothesized mineral reactions, suggest that significant mass transfer of Na('+), Ca('+2) and Si('+4) occurred in the sandstone during alteration, whereas Al('+3) mobility was restricted to migration from the reaction site to nearby pore space where Al('+3) was incorporated into clay and/or zeolite cements. Mineral and chemical patterns also emphasize the importance of parent material composition, fluid chemistry, permeability and temperature in controlling authigenic mineral assemblages.
- Notes:
-
- (UnM)AAI8300370
- Source: Dissertation Abstracts International, Volume: 43-08, Section: B, page: 2480.
- Thesis (Ph.D.)--The Ohio State University, 1982.
- Reproduction:
- Microfiche. Ann Arbor, Mich.: University Microfilms International.
- Subject:
- Geology
- Other authors/contributors:
- Ohio State University
- Copyright:
-
In Copyright
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Copyright status was determined using the following information:
- Material type:
- Literary Dramatic Musical
- Published status:
- Unpublished
- Creation date:
- 1982
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