The Cream Valley Shear Zone, in southeastern Pennsylvania, contains a proposed terrane boundary between Laurentia (north of the shear zone) and a displaced terrane (south of the shear zone). The Cream Valley shear zone is part of a Paleozoic dextral strike-slip shear zone system which extends from New Jersey through southeastern Pennsylvania and into Maryland. Within the field area, in southeastern Pennsylvania, the Cream Valley Shear Zone varies in width from 3 to 5 km and is characterized by a strong, penetrative, steeply dipping foliation with an overall strike of N70°E. The proposed terrane boundary lies between retrograde greenschist-facies phyllonite and prograde greenschist-facies phyllite near the southern edge of the shear zone. The terrane boundary divides Laurentian shelf sequence lithologies, including Cambrian Chickies quartzite and Cambro-Ordovician carbonates, from high-grade metamorphic rocks of the southern terrane. Rocks of the Laurentian cover sequence have experienced peak metamorphism of greenschist facies and a simple deformation history; at some localities primary structures are preserved. The southern terrane consists of schists and gneisses with some ultra-mafic pods. South of the boundary, Laurentian shelf-sequence rocks do not occur. Southern lithologies have experienced amphibolite to granulite facies metamorphism. Structures in these rocks indicate a complex deformation history not observed in the Laurentian rocks to the north. To the east the Cream Valley shear zone Is continuous with the Huntingdon Valley Shear Zone, which also separates distinct lithologies and metamorphic grades. A gravity anomaly, which is interpreted to result from major crustal offset coincides with the Cream Valley shear zone. Dissimilarities in lithology, metamorphic grade and deformation history north and south of this structure indicate that these rocks are not correlative. Paleozoic orogen-parallel displacement on a terrane boundary may explain the juxtaposition of these distinctly different metamorphic suites. / Earth and Environmental Science / Accompanied by one .pdf file: 1) Broh-Supplemental-1998.pdf
| Identifer | oai:union.ndltd.org:TEMPLE/oai:scholarshare.temple.edu:20.500.12613/8662 |
| Date | January 1998 |
| Creators | Broh, Laura Q. |
| Contributors | Hill, Mary Louise, Goodwin, Peter W., Myer, George H. |
| Publisher | Temple University. Libraries |
| Source Sets | Temple University |
| Language | English |
| Detected Language | English |
| Type | Thesis/Dissertation, Image |
| Format | 64 pages |
| Rights | IN COPYRIGHT- This Rights Statement can be used for an Item that is in copyright. Using this statement implies that the organization making this Item available has determined that the Item is in copyright and either is the rights-holder, has obtained permission from the rights-holder(s) to make their Work(s) available, or makes the Item available under an exception or limitation to copyright (including Fair Use) that entitles it to make the Item available., http://rightsstatements.org/vocab/InC/1.0/ |
| Relation | http://dx.doi.org/10.34944/dspace/8626, Digital copy of print original., Theses and Dissertations |
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