Author: Robert Edward MonizPublisher:
ISBN:
Category :
Languages : en
Pages : 126
Book Description
Geochemistry and U/Pb Geochronology of the Eastern-most Peninsular Ranges Batholith of Southern California and Northern Baja California
Author: Robert Edward MonizPeninsular Ranges Batholith, Baja and Southern California
Author: Douglas M. MortonPublisher: Geological Society of America
ISBN: 0813712114
Category : Science
Languages : en
Pages : 774
Book Description
"This book includes petrology, geochronology, and regional aspects of individual plutons, as well as evolution of the Peninsular Ranges batholith. Several chapters deal with geophysical, chemical, and isotopic based interpretations of the genesis and evolution of the batholith. An accompanying DVD contains detailed colored maps and chemical, isotopic, mineralogic, and physical properties data"--Provided by publisher.
Batholith and Associated Rocks of Corona, Elsinore, and San Luis Rey Quadrangles, Southern California
Author: Esper Signius LarsenPublisher: Geological Society of America
ISBN: 0813710294
Category : Science
Languages : en
Pages : 201
Book Description
The batholith of southern and Lower California is exposed continuously from near Riverside, California, southward for a distance of about 350 miles. In central Lower California it is covered in part by younger rocks, but discontinuous bodies extend to the southern end of Lower California. The batholith is probably over 1000 miles long. Its width is about 60 miles. A strip about 70 miles wide across the northern part of the batholith has been studied ; the western half was mapped in detail, and the eastern half was covered in rapid reconnaissance. In the area studied the batholith intrudes Triassic sediments and Jurassic (?) volcanic rocks along its western border, and Paleozoic sediments along its eastern border. Screens and roof pendants are common within the batholith. The Triassic rocks are mildly metamorphosed in the western part of the area but become progressively more coarsely crystalline toward the east. The Palezoic rocks are rather coarsely crystalline. The metamorphism in large part preceded the intrusion of the batholith, and only locally was there appreciable contact metamorphism. The batholith and older rocks are overlain by Upper Cretaceous and younger sediments. Small bodies of andesite and basalt of Quaternary age are present in the area. The batholith was intruded in early Upper Cretaceous time. The batholith in the area studied was emplaced by more than 20 separate injections. Most of the resulting rock types are found in only one or a few small bodies which are confined to a small area. In the area studied in detail (pi. 1) five types are present in many large, widely sepai-ated bodies, making up about 88 percent of the area underlain by the batholith. In the eastern half of the batholith three more widespread types are present. In the western half of the body the rocks range from gabbro to granite, but in the eastern half several tonalites constitute nearly the whole of the mass. The gabbro is composed of many related rocks. Some have hornblende, some pyroxene ; in some the plagioclase is anorthite, in others it is as sodic as andesine-labradorite. Some of the tonalites contain abundant inclusions that have been almost completely reworked by the magma and have been softened and stretched into thin discs. These inclusions are well oriented, and near the contacts with older rocks they parallel the contacts ; elsewhere they strike about N. 30° W. and dip steeply to the east. One tonalite, whose feldspar is andesine, has scattered crystals with cores of bytownite, and has well-crystallized hornblende with cores of pale uralitic hornblende and remnants of augite. Hornblende and biotite are the predominant mafic minerals of the tonalites and granodiorites. The general strike of the structures of the area have been about N. 30° "W. from Paleozoic to the present time. The Paleozoic and Triassic sediments, the orientation of the inclusions and other structures of the batholith, the elongation of the batholith and the mountain ranges, and the strike of the major faults are in about the same direction. In the batholith and the older sediments the dips are steep to the east. The batholith must have been emplaced by stoping and not by forceful injection. The different rocks of the batholith were formed from the intermediate gabbro by crystal differentiation and assimilation in depth. In early Upper Cretaceous time diastrophism folded the older rocks and formed, in depth, a strip of gabbroic magma about 1000 miles long. A small amount of this magma was intruded nearly to the surface. The deep magma differentiated quietly until its upper part attained the composition of a tonalite. Earth movements then occurred at least five times in rapid succession and caused the injection of the different tonalites. Some of these carry abundant inclusions, indicating a widespread shattering of the wall rock shortly before final emplacement. From time to time local movements caused the injections of the different granodiorites. When the deep-seated magma reached the composition of a light-colored granodiorite, widespread diastrophism moved the main granodiorite upward. Further local moremeut caused the emplacement of the many local granodiorites and granites.
Publications of the Geological Survey
Author: Geological Survey (U.S.)Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 828
Book Description
Geologic Evolution of the Mojave Desert and Southwestern Basin and Range
Author: Allen F. GlaznerPublisher: Geological Society of America
ISBN: 9780813711959
Category : Science
Languages : en
Pages : 380
Book Description
CD-ROM contains: Electronic version of text -- Maps.
Geochronological Constraints on the Thermal and Tilting History of the Peninsular Ranges Batholith of Alta and Baja California, Tectonic Implications for Southwestern North America, México
Author: Age Determinations of the Rocks of the Batholiths of Baja and Southern California, Sierra Nevada, Idaho, and the Coast Range of Washington, British Columbia, and Alaska
Author: Esper Signius LarsenPublisher:
ISBN:
Category : Batholiths
Languages : en
Pages : 84
Book Description
Isotopes and Ages in the Northern Peninsular Ranges Batholith, Southern California
Author: Ronald Wayne KistlerPublisher:
ISBN:
Category : Batholiths
Languages : en
Pages :
Book Description
Canadian Journal of Earth Sciences
Author: The Tectonic Setting and Origin of Cretaceous Batholiths within the North American Cordillera
Author: Robert S. HildebrandPublisher: Geological Society of America
ISBN: 0813725321
Category : Nature
Languages : en
Pages : 123
Book Description
In this Special Paper, Hildebrand and Whalen present a big-picture, paradigm-busting synthesis that examines the tectonic setting, temporal relations, and geochemistry of many plutons within Cretaceous batholithic terranes of the North American Cordillera. In addition to their compelling tectonic synthesis, they argue that most of the batholiths are not products of arc magmatism as commonly believed, but instead were formed by slab failure during and after collision. They show that slab window and Precambrian TTG suites share many geochemical similarities with Cretaceous slab failure rocks. Geochemical and isotopic data indicate that the slab failure magmas were derived dominantly from the mantle and thus have been one of the largest contributors to growth of continental crust. The authors also note that slab failure plutons emplaced into the epizone are commonly associated with Cu-Au porphyries, as well as Li-Cs-Ta pegmatites.