The Hamburg klippe: Record of the destruction of the proto-North American continental margin
- State Univ. Coll., Fredonia, NY (United States). Dept. of Geosciences
The Hamburg klippe, a Taconic allochthon in the central Appalachian orogen of southeastern Pennsylvania, has long been in the focus of debate. Although initially interpreted by some to be either autochthonous or simply a facies of the parautochthonous Martinsburg Formation, essentially all workers now agree that rocks of the Hamburg klippe comprise a far-travelled sequence of deep-marine deposits thrust onto the proto-North American platform in Ordovician time. The klippe is composed of two tectonic slices that contain rocks that formed in very different tectonic environments. The structurally lowest slice, the Greenwich slice, is interpreted to be an ancient subduction complex that formed in Cambrian-Ordovician time. This slice consists chiefly of turbidite sandstone and hemipelagic mudstone of Middle Ordovician age (85%) underlain by relatively thin sequences of red and light-green pelagic mudstone, deep-water limestone and chert of Early to Middle Ordovician age (14%). The vertical stratigraphy of the deposits of the Greenwich slice is interpreted to reflect migration of a site on oceanic lithosphere from an abyssal plain setting toward and ultimately into a trench southeast of the proto-North American continental margin by Middle Ordovician time. The tectonically highest slice, the Richmond slice, is composed predominantly of Middle Ordovician carbonate turbidites and black shale interpreted to have accumulated on the subsiding proto-North American continental margin as it approached the trench to the southeast. Eventually the Richmond slice was thrust to the northwest over the subduction complex which was, by this time, on the continental platform. Similar rock types in other allochthons in the Appalachian orogen may reflect an analogous mode of origin.
- OSTI ID:
- 5505803
- Report Number(s):
- CONF-9303211-; CODEN: GAAPBC
- Journal Information:
- Geological Society of America, Abstracts with Programs; (United States), Vol. 25:2; Conference: 28. annual Geological Society of America (GSA) Northeastern Section meeting, Burlington, VT (United States), 22-24 Mar 1993; ISSN 0016-7592
- Country of Publication:
- United States
- Language:
- English
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Related Subjects
GEOLOGIC FAULTS
GEOLOGIC MODELS
GEOLOGY
GEOLOGIC FORMATIONS
DEPOSITION
STRATIGRAPHY
PENNSYLVANIA
APPALACHIAN MOUNTAINS
CONTINENTAL MARGIN
GEOLOGIC HISTORY
ORDOVICIAN PERIOD
PLATE TECTONICS
SEDIMENTARY ROCKS
SUBDUCTION ZONES
DEVELOPED COUNTRIES
GEOLOGIC AGES
GEOLOGIC FRACTURES
GEOLOGIC STRUCTURES
MOUNTAINS
NORTH AMERICA
PALEOZOIC ERA
ROCKS
TECTONICS
USA
580000* - Geosciences