Aspects of the evolution of the west Antarctic margin of Gondwanaland [microform]
- Bib ID:
- 3287714
- Format:
- Book and Microform
- Author:
- Grunow, Anne Marie
- Description:
- 143 p.
- Summary:
-
The West Antarctic margin of Gondwanaland has experienced a long, complex history. A combination of paleomagnetism, structural field mapping, microprobe analysis, microfabric analysis and $\sp{40}$Ar/$\sp{39}$Ar geochronology was used to elucidate the history of the West Antarctic crustal block and the evolution of subduction complexes along the Scotia Ridge. West Antarctica is composed of four crustal blocks whose relationship to East Antarctica and to each other throughout the Phanerozoic is not well known. These blocks are: the Ellsworth-Whitmore Mountains (EWM); the Antarctic Peninsula (AP); Thurston Island (TI); Marie Byrd Land (MBL). Paleomagnetic sampling and analysis were conducted on rocks from the EWM and TI blocks in the hope of constraining the motion of these blocks and the opening history of the Weddell Sea.
The paleomagnetic results suggest that the AP, EWM and TI blocks have moved relative to East Antarctica prior to the mid-Cretaceous and that the main opening of the Weddell Sea was between the Early and mid-Cretaceous. Detailed field mapping was conducted on the subduction complexes of the Scotia Metamorphic Complex (SMC) on Smith Island and Elephant Island (Antarctica). Smith Island consists entirely of blueschist tectonites. Elephant Island rocks consist of greenschist, blueschist and albite-epidote amphibolite facies schists. Polyphase ductile deformation characterizes the Smith Island and Elephant Island tectonites. Microprobe analyses indicate that the blue amphiboles from both areas are primarily crossite. Pressure-temperature estimates for Smith Island blueschist metamorphism are $\sim
The north to south increase in intensity of deformation and metamorphism on Elephant Island corresponds to decrease in $\sp{40}$Ar/$\sp{39}$Ar age. Uplift of the Smith Island blueschists occurred since 47 Ma while most of the uplift on Elephant Island occurred since $\sim
- Notes:
-
- (UnM)AAI8919151
- Source: Dissertation Abstracts International, Volume: 50-05, Section: B, page: 1813.
- Thesis (Ph.D.)--Columbia University, 1989.
- Reproduction:
- Microfiche. Ann Arbor, Mich.: University Microfilms International.
- Subject:
- Geology
- Other authors/contributors:
- Columbia 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:
- 1989
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