75 research outputs found
Reconstructions of the continents around the North Atlantic at about the 60th parallel
Abstract Late Carboniferous^Early Tertiary apparent polar wander (APW) paths (300^40 Ma) for North America and Europe have been tested in various reconstructions. These paths demonstrate that the 500 fathom Bullard et al. fit is excellent from Late Carboniferous to Late Triassic times, but the continental configuration in northern Pangea changed systematically between the Late Triassic (ca. 214 Ma) and the Mid-Jurassic (ca. 170 Ma) due to pre-drift extension. Best fit North Atlantic reconstructions minimize differences in the Late Carboniferous^Early Jurassic and Late CretaceousT ertiary segments of the APW paths, but an enigmatic difference exists in the paths for most of the Jurassic, whereas for the Early Cretaceous the data from Europe are nearly non-existent. Greenland's position is problematic in a Bullard et al. fit, because of a Late Triassic^Early Jurassic regime of compression ( s 300 km) that would be inherently required for the Norwegian Shelf and the Barents Sea, but which is geologically not defensible. We suggest a radically new fit for Greenland in between Europe and North America in the Early Mesozoic. This fit keeps Greenland`locked' to Europe for the Late Paleozoic^Early Mesozoic and maintains a reconstruction that better complies with the offshore geological history of the Norwegian Shelf and the Barents Sea. Pre-drift (A24) extension amounted to approximately 450 km on the Mid-Norwegian Shelf but with peak extension in the Late Cretaceous. ß 2001 Published by Elsevier Science B.V
Linking Taiwan's subcritical Hsuehshan Range topography and foreland basin architecture
Peer Reviewedhttp://deepblue.lib.umich.edu/bitstream/2027.42/95204/1/tect2249.pd
Western Préalpes Médianes Romandes: Timing and structure. A review.
Between the original position and their present day location as klippen,
the Prealpes Medianes underwent a complex history of paleotectonics and
alpine tectonics. Due to the opening of the Piemont ocean the
Brianconnais sedimentation realm of the Prealpes Medianes evolved as a
rim basin of the northern passive margin during Jurassic to Eocene
times. Different paleotectonic features (normal faults, synsedimentary
growth structures, inversion structures) developed and were active above
a basal detachment in evaporitic layers. The tectonic movements were a
consequence of thermal events in the crust. Isolated from the Iberic
continent at the end of the Late Cretaceous, the Brianconnais exotic
terrain was incorporated into the accretionary prism of the closing
Piemont ocean and the incipient alpine orogeny during the
Lutetian-Bartonian. The Prealpes Medianes were detached from their
homeland during the Bartonian-Priabonian and were transported onto the
foreland. The tectonic style is one of a thin-skinned foreland fold and
thrust belt. Fault associated fold development above a main decollement,
together with internal deformation, represent the Prealpes Medianes main
structural features. The very low-grade metamorphic conditions have
their origin in the heat flux induced by tectonic burial by overriding
nappes in the accretionary prism. After having been transported on top
of the developing Helvetic nappes the Prealpes were emplaced in their
present day position in front of the Alpine mountain belt during
Oligocene times. Post-emplacement and out of sequence thrusting,
possibly younger than Oligocene, is observed and can be related to
thrusting in the sedimentary substratum and the basement
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