Mount Morrison Roof Pendant Geology

Evidence for its original paleogeographic position.

Mount morrison roof pendant geology.

Biostratigraphy of upper paleozoic rocks in the mount morrison roof pendant sierra nevada california. In the mount morrison pendant structures produced during the morrison orogeny apparently were later refolded twice prior to sinistral displacement on the laurel convict fault which cross cuts. Granitoid plutons underlying the volcanic field have given 87 sr 86 sr values ranging from 0 70666 to 0 70987 and many other sierran plutons nearby range from 0 707 to 0 715 goff et al 1991. Type area is along john muir trail between mount morrison roof pendant and wheeler crest and pine creek septa on east and potter pass septum on west sierra nevada ca bateman 1992.

This roof pendant consists of a 15 000 m 50 000 ft thick sequence of complexly folded and faulted meta sedimentary strata and meta volcanic strata. The mount morrison roof pendant the only roof pendant in the central sierra nevada containing paleozoic fossils is complexly deformed and contains three generations of structures including folds reverse faults schistosities and lineations. The mount diablo ophiolite contra costa county california. Late cretaceous type section locality area and or origin of name.

Metasedimentary rocks of the mount morrison roof pendant just south of long valley caldera gave 87 sr 86 sr values that range from 0 7090 to 0 7250 goff et al 1991. Pelitic rocks in the mount morrison pendant some distance from any pluton contain biotite muscovite quartz k feldspar and andalusite or cordierite the mineral composition yielding maximum pressures of 2 0 2 2 kbar at temperatures of 600 615 c data of j. The metamorphic rock composing the mount morrison roof pendant block is the relict of a paleozoic sedimentary sequence overprinted by several deformation events which left the rocks isolated atop the sierra nevada batholith. This roof pendant is host to the pine creek mine deposits which have produced significant amounts of tungsten as well as accessory molybdenum copper silver and gold newberry 1982.

These rocks developed along the passive western continental margin of north america during the middle devonian. Sorensen 1988 personal commun.