Download or read book A Paleomagnetic Rock Magnetic and Magnetic Mineralogic Investigation of the Northern Peninsular Ranges Batholith Southern California written by Bradley Gene Erskine and published by . This book was released on 1982 with total page 388 pages. Available in PDF, EPUB and Kindle. Book excerpt: Rock magnetic, paleomagnetic and magnetic mineralogic analysis of plutonic rocks and xenoliths from 29 K-Ar dated sites within the northern Peninsular Ranges batholith indicate that the magnetic stability of these rocks is mineralogically controlled. The relative stability of magnetic remanence during AF and thermal demagnetization is governed by the relative intensity contributed by stable magnetite and unstable hematite within a rock, rather than their coercivity or magnetic domain structure. Deuteric oxidation of magnetite into hematite below 550° c is a possible mechanism that produces the unstable remanence of the hematite. Compositions of magnetite, hematite and ilmentite in all rocks measured are close to the theoretical end-members of their respective solid solution series. The western samples contain magnetite, hematite and ilmenite while magnetite is absent in the east. The distribution of these phases define a western magnetite series belt and an eastern ilmenite-series belt. The presence of these paired belts and their association with geochemical, geochronological, lithological, structural and isotopic relationships across the batholith suggest two fundamentally different source regions for rocks on either side. The western magnetite-series rocks within the gabbroic belt represent rocks which originated by partial fusion of subducted oceanic lithosphere and the overlying mantle wedge, whereas the eastern ilmenite series rocks within the tonalite belt were produced through partial fusion of the lower continental crust. Paleomagnetic analysis of 12 western plutons ranging in age from about 115 to 90 mybp suggest an 11° northern translation and a 42° clockwise rotation relative to stable North America. This regional batholith direction is in agreement with previous studies. Reconstruction of the Baja Peninsula to its original site based on the paleomagnetic data presents certain problems, particularly with the overlapping of the Peninsula with Mexico and the rates of northward translation. The average northward component is calculated to be about 2.5 cm/yr, which is equal to the average northward component of the Farallon plate relative to the North American plate.
Download or read book Peninsular Ranges Batholith Baja and Southern California written by Douglas M. Morton and published by Geological Society of America. This book was released on 2014 with total page 774 pages. Available in PDF, EPUB and Kindle. Book excerpt: "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.
Download or read book The Prebatholithic Stratigraphy of Peninsular California written by R. Gordon Gastil and published by Geological Society of America. This book was released on 1993-01-01 with total page 183 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleomagnetic Study of Selected Holocene Miocene Mesozoic and Ordovician Rocks from Baja California Mexico written by Gerald Joseph McNaboe and published by . This book was released on 1986 with total page 184 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleomagnetic Investigation of the San Marcos Gabbro Southern California written by Ronald Franklin Teissere and published by . This book was released on 1968 with total page 140 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleontology and Geology of the Western Salton Trough Detachment Anza Borrego Desert State Park California written by Paul Remeika and published by San Diego Geological Soc. This book was released on 1995 with total page 244 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book The Nature and Origin of Cordilleran Magmatism written by J. Lawford Anderson and published by Geological Society of America. This book was released on 1990 with total page 428 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleomagnetic Analysis of Miocene Basalt Flows in the Tehachapi Mountains California written by Jeffrey B. Plescia and published by . This book was released on 1994 with total page 20 pages. Available in PDF, EPUB and Kindle. Book excerpt: New paleomagnetic directions and 40AR/39AR extrusion ages from Miocene basalt flows on the north flank of the Tehachapi Mountains, southern California.
Download or read book Special Publication written by California. Division of Mines and Geology and published by . This book was released on 1987 with total page 92 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleomagnetic Investigation of Mid Tertiary Volcanic Rocks in the Castle Dome and Southern Kofa Mountains Yuma County Southwestern Arizona written by Joseph E. Butterworth and published by . This book was released on 1984 with total page 390 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleomagnetic Investigation in the Vicinity of the Northern Tobacco Root Mountains Madison County Montana written by Alan Andrew Colville and published by . This book was released on 1962 with total page 336 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Special Publications written by California. Division of Mines and Geology and published by . This book was released on 1987 with total page 88 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book 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 written by Esper Signius Larsen and published by . This book was released on 1957 with total page 84 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Batholith and Associated Rocks of Corona Elsinore and San Luis Rey Quadrangles Southern California written by Esper Signius Larsen and published by Geological Society of America. This book was released on 1948 with total page 201 pages. Available in PDF, EPUB and Kindle. Book excerpt: 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.
Download or read book Mylonitic Deformation and Associated Low angle Faulting in the Santa Rosa Mylonite Zone Southern California written by Bradley Gene Erskine and published by . This book was released on 1986 with total page 514 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleomagnetic and Rock Magnetic Investigation of the Relationship Between Hydrocarbons and Authigenic Magnetic Minerals in the Permian Lyons Sandstone Northern Front Range and Denver Basin Colorado written by Robert Andrew McCollum and published by . This book was released on 1988 with total page 162 pages. Available in PDF, EPUB and Kindle. Book excerpt:
Download or read book Paleomagnetic Analysis of Eocene Rocks from the Peninsular Ranges Terrane San Diego California written by James Edward Powers and published by . This book was released on 1988 with total page 238 pages. Available in PDF, EPUB and Kindle. Book excerpt:
