In structural geology, a roof pendant, also known as a pendant, is a mass of country rock that projects downward into and is entirely surrounded by an igneous intrusion such as a batholith or other pluton. In lay terminology sometimes "rock hat" is used. A roof pendant is an erosional remnant that was created by the removal of the overlying country rock that formed the roof of the igneous intrusion that encloses it. If this downward protruding mass of roof rock still has a connection to the main, surrounding mass of country rock, they are known by structural geologists as either septa or screens.[1][2][3] Roof pendants typically have been strongly metamorphosed through the processes of contact metamorphism.[4]
View of Mount Kailash, Tibet (in the right distance), showing both the metasedimentary roof pendant and the underlying granite rock which caused the metamorphosis of the sediments above.
A classic, well-documented example of a roof pendant is the strata that comprise Mount Morrison within the Sierra Nevada in Mono and Fresno counties, California. It lies midway between Mono Lake on the north and Bishop, California, on the south. Mount Morrison consists of a roof pendant that underlies an area of 62 km2 (24 sq mi). This roof pendant consists of a 15,000 m- (50,000 ft-) thick sequence of complexly folded and faulted metasedimentarystrata and metavolcanic strata. The eastern two-thirds of this roof pendant consists of Cambrian to Silurian and Pennsylvanian to Permian metasedimentary strata. Metavolcanic rocks of Mesozoic age comprise the western third of the roof pendant. Mesozoic granitic rocks enclose and intrude the pendant rocks. These granitic rocks consist predominantly of quartz monzonite and granodiorite with local, minor, scattered bodies of granite, aplite, diorite and gabbro. These pendants are part of a discontinuous, 140 kilometres (87 mi)-long, northwest-trending belt of roof pendants that are preserved within the granitic plutons of Sierra Nevada.[5][6][7][8]
Referencesedit
^U.S. Bureau of Mines Staff (1996) Dictionary of Mining, Mineral, & Related Terms. Report SP-96-1, U.S. Department of Interior, U.S. Bureau of Mines, Washington, D.C.
^Neuendorf, KKE, JP Mehl, Jr., and JA Jackson, eds. (2005) Glossary of Geology (5th ed.). Alexandria, Virginia, American Geological Institute. 779 pp. ISBN0-922152-76-4
^Best, MG (2003) Igneous and metamorphic petrology, 2nd ed. Blackwell Science Ltd., New York, New York. 729 pp. ISBN1-40510-588-7
^Bucher, K, and R Grapes (2011) Petrogenesis of Metamorphic Rocks. Springer, New York, New York. 428 pp. ISBN978-3-540-74168-8
^Greene, DC, and CH Stevens (1999) Stratigraphy, depositional history, and tectonic evolution of Paleozoic continental-margin rocks in roof pendants of the eastern Sierra Nevada, California. Geological Society of America Bulletin. 111(6):919-933.
^Greene, DC, and CH Stevens (2002) Geologic Map of Paleozoic Rocks in the Mount Morrison Pendant, Eastern Sierra Nevada. California Map Sheet no 53. California Division of Mines and Geology, Sacramento, California.
^Rinehart, CD, and DC Ross (1964) Geology and mineral deposits of the Mount Morrison quadrangle, Sierra Nevada, California. Professional Paper no. 385. United States Geological Survey, Reston, Virginia. 106 pp.
^Russell, S, and W Nokleberg (1977) Superimposition and timing of deformations in the Mount Morrison roof pendant and in the central sierra Nevada, California. Geological Society of America Bulletin. 88(3):335-345.
roof, pendant, structural, geology, roof, pendant, also, known, pendant, mass, country, rock, that, projects, downward, into, entirely, surrounded, igneous, intrusion, such, batholith, other, pluton, terminology, sometimes, rock, used, roof, pendant, erosional. In structural geology a roof pendant also known as a pendant is a mass of country rock that projects downward into and is entirely surrounded by an igneous intrusion such as a batholith or other pluton In lay terminology sometimes rock hat is used A roof pendant is an erosional remnant that was created by the removal of the overlying country rock that formed the roof of the igneous intrusion that encloses it If this downward protruding mass of roof rock still has a connection to the main surrounding mass of country rock they are known by structural geologists as either septa or screens 1 2 3 Roof pendants typically have been strongly metamorphosed through the processes of contact metamorphism 4 View of Mount Kailash Tibet in the right distance showing both the metasedimentary roof pendant and the underlying granite rock which caused the metamorphosis of the sediments above A classic well documented example of a roof pendant is the strata that comprise Mount Morrison within the Sierra Nevada in Mono and Fresno counties California It lies midway between Mono Lake on the north and Bishop California on the south Mount Morrison consists of a roof pendant that underlies an area of 62 km2 24 sq mi This roof pendant consists of a 15 000 m 50 000 ft thick sequence of complexly folded and faulted metasedimentary strata and metavolcanic strata The eastern two thirds of this roof pendant consists of Cambrian to Silurian and Pennsylvanian to Permian metasedimentary strata Metavolcanic rocks of Mesozoic age comprise the western third of the roof pendant Mesozoic granitic rocks enclose and intrude the pendant rocks These granitic rocks consist predominantly of quartz monzonite and granodiorite with local minor scattered bodies of granite aplite diorite and gabbro These pendants are part of a discontinuous 140 kilometres 87 mi long northwest trending belt of roof pendants that are preserved within the granitic plutons of Sierra Nevada 5 6 7 8 References edit U S Bureau of Mines Staff 1996 Dictionary of Mining Mineral amp Related Terms Report SP 96 1 U S Department of Interior U S Bureau of Mines Washington D C Neuendorf KKE JP Mehl Jr and JA Jackson eds 2005 Glossary of Geology 5th ed Alexandria Virginia American Geological Institute 779 pp ISBN 0 922152 76 4 Best MG 2003 Igneous and metamorphic petrology 2nd ed Blackwell Science Ltd New York New York 729 pp ISBN 1 40510 588 7 Bucher K and R Grapes 2011 Petrogenesis of Metamorphic Rocks Springer New York New York 428 pp ISBN 978 3 540 74168 8 Greene DC and CH Stevens 1999 Stratigraphy depositional history and tectonic evolution of Paleozoic continental margin rocks in roof pendants of the eastern Sierra Nevada California Geological Society of America Bulletin 111 6 919 933 Greene DC and CH Stevens 2002 Geologic Map of Paleozoic Rocks in the Mount Morrison Pendant Eastern Sierra Nevada California Map Sheet no 53 California Division of Mines and Geology Sacramento California Rinehart CD and DC Ross 1964 Geology and mineral deposits of the Mount Morrison quadrangle Sierra Nevada California Professional Paper no 385 United States Geological Survey Reston Virginia 106 pp Russell S and W Nokleberg 1977 Superimposition and timing of deformations in the Mount Morrison roof pendant and in the central sierra Nevada California Geological Society of America Bulletin 88 3 335 345 See also editXenolith Retrieved from https en wikipedia org w index php title Roof pendant amp oldid 1071599306, wikipedia, wiki, book, books, library,
