Open Access. Powered by Scholars. Published by Universities.®
Physical Sciences and Mathematics Commons™
Open Access. Powered by Scholars. Published by Universities.®
Articles 1 - 4 of 4
Full-Text Articles in Physical Sciences and Mathematics
The Influence Of Oceanic Transform Boundaries On The Generation And Evolution Of Oceanic Lithosphere, David G. Gallo
The Influence Of Oceanic Transform Boundaries On The Generation And Evolution Of Oceanic Lithosphere, David G. Gallo
Geology Theses and Dissertations
The first-order geologic and morphologic relationships at, along and proximal to ridge-transform-ridge plate boundaries are used to construct an empirical and speculative tectonic model. The geometry of a ridge-transform intersection necessitates the juxtaposition of relatively cold, thick lithosphere against the truncated end of an accreting plate boundary. The cold face of lithosphere cools the adjacent wedge of asthenosphere rising beneath the axis of accretion and restricts the amount of partial melting thus attenuating the amount of basaltic melt segregated from the asthenosphere per unit time. The manifestation of this cold edge effect is a thinner oceanic crust. At depth, upper …
The Tectonic Evolution Of The Eastern Yukon Tanana Upland, Alaska, Grant W. Cushing
The Tectonic Evolution Of The Eastern Yukon Tanana Upland, Alaska, Grant W. Cushing
Geology Theses and Dissertations
Field, structural, and isotopic studies in the southeastern Eagle Quadrangle reveal a complex Mesozoic history involving major metamorphism, fold development, thrusting, and igneous intrusion. These events may be related to the accretion of a terrane, possibly Stikine, to the North American continental margin.
40Ar/39Ar incremental heating experiments on metamorphic minerals from amphibolite facies rocks reveal Late Triassic to Middle Jurassic plateau ages interpreted as the age of major metamorphism. Large scale northeast trending folds within these rocks formed after the major metamorphism and before the intrusion of an undeformed, unmetamorphosed cross-cutting dike in Middle Jurassic. These folds probably developed in …
The Geology Of Ophiolitic And Adjoining Rocks Of Chagnon Mountain, Southern Quebec, Janet M. Harris
The Geology Of Ophiolitic And Adjoining Rocks Of Chagnon Mountain, Southern Quebec, Janet M. Harris
Geology Theses and Dissertations
Chagnon Mountain is located near the southern end of the Baie Verte-Brompton Line in the Eastern Townships of southern Quebec. The lithologic units in the area of study, from west to east and going up structure, are: gabbro, quartz-diorite, diabase, volcanics, the St. Daniel Formation and the Peasley Pond Conglomerate of the Glenbrooke Group. All these rocks have been metamorphosed to the greenschist facies. Contacts between the plutonic rocks are irregular and gradational indicating only one parent magma. Diabase dikes are present in the diabase unit and in the volcanics indicating the dikes acted as feeders to the volcanics. Geochemical …
Chatham Fault Zone, Old Chatham-East Chatham, New York: Mesostructures And Microstructures: Their Spatial And Age Relationships, Jorge Mora M.
Chatham Fault Zone, Old Chatham-East Chatham, New York: Mesostructures And Microstructures: Their Spatial And Age Relationships, Jorge Mora M.
Geology Theses and Dissertations
Detailed studies in rocks of Mettawee (Late Precambrian? to Early Cambrian) and Walloomsac (Middle Ordovician) slates between Old Chatham and East Chatham, New York, have shown that these rocks were intensely deformed during the Taconic orogeny and a later deformation event(?). Two generations of structures are clearly recognized in the area. The first generation (G1) includes tight west-verging folds whose axial plane foliation is the regional foliation slaty cleavage (S1). These structures are considered synchronous with the regional metamorphism of the Taconic orogeny and correlative with those structures belonging to the D2 deformation event proposed by Ratcliffe (1979) and Rowley …