The Petrology and Geochemistry of the Lower Zone of the Mulcahy Gabbro, Northwestern Ontario PDF Download
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Author: Alan Robert Smith
Publisher:
ISBN:
Category : Gabbro
Languages : en
Pages : 350
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Author: Alan Robert Smith
Publisher:
ISBN:
Category : Gabbro
Languages : en
Pages : 350
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Book Description
Author: Wade H. Shafer
Publisher: Springer Science & Business Media
ISBN: 1461573947
Category : Science
Languages : en
Pages : 430
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Book Description
Masters Theses in the Pure and Applied Sciences was first conceived, published, and disseminated by the Center for Information and Numerical Oata Analysis and Synthesis (CINOAS) * at Purdue. University in 1957, starting its coverage of theses with the academic year 1955. Beginning with Volume 13, the printing and dissemination phases of the activity were transferred to University Microfilms/Xerox of Ann Arbor, Michigan, with the thought that such an arrangement would be more beneficial to the academic and general scientific and technical community. After five years of this joint undertaking we had concluded that it was in the interest of all con cerned if the printing and distribution of the volumes were handled by an interna tional publishing house to assure improved service and broader dissemination. Hence, starting with Volume 18, Masters Theses in the Pure and Applied Sciences has been disseminated on a worldwide basis by Plenum Publishing Cor poration of New York, and in the same year the coverage was broadened to include Canadian universities. All back issues can also be ordered from Plenum. We have reported in Volume 33 (thesis year 1988) a total of 13,273 theses titles from 23 Canadian and 1 85 United States universities. We are sure that this broader base for these titles reported will greatly enhance the value of this important annual reference work. While Volume 33 reports theses submitted in 1988, on occasion, certain univer sities do report theses submitted in previous years but not reported at the time.
Author: Sean O'Brien
Publisher:
ISBN:
Category :
Languages : en
Pages :
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The Crystal Lake Gabbro (CLG) is a Y-shaped, up to 750 m wide, layered mafic intrusion with a 5 km long northern limb and a 2.75 km long southern limb, with localized Cu-Ni and Cr mineralization. The Mount Mollie Dyke (MMD) is an arcuate, 60 to 350 m wide, macrodyke that lies on trend east of the CLG and extends for 35 km toward Lake Superior. Both intrusions are part of the 1.1 Ga Midcontinent Rift (MCR) and were emplaced into the Paleoproterozoic Rove Formation of the Logan Basin, approximately 50 km south of Thunder Bay. Current U-Pb age determination implies a ~10 m.y. age difference with CLG being formed at ~1100 Ma and the MMD being formed at ~1109 Ma. However, this age difference is at odds with both intrusions being normally polarized (an attribute of MCR rocks younger than 1102 Ma) and their being on trend with each other. This study seeks to determine whether the two intrusions may be petrogenetically linked by evaluating the petrography, geochemistry, mineral composition, and sulphur isotopes of samples collected from drill core. The CLG profiled in a drill core from its southern limb can be broadly divided into Upper, Main, and Lower Zones with further subdivisions of the Main and Lower Zones based largely on geochemistry. The Lower Zone occurs between two xenoliths of an early MCR (~1115 Ma) plagioclase porphyritic Logan Sill diabase. The Lower Zone consists of subophitic to ophitic troctolite, augite troctolite, and olivine gabbro and can be subdivided into an upper and basal marginal subzone as well as an interior subzone. Both marginal subzones host disseminated sulphides with the basal margin also containing Cr-spinel seams. An overall bottom-up-directed fractional crystallization of the Lower Zone is suggested by the progressive decrease in Fo content of olivine, Mg# of clinopyroxene, and whole-rock MgO upsection. Above the upper Logan Sill xenolith, the Main Zone similarly consists of subophitic to ophitic troctolite, augite troctolite, olivine gabbro, and gabbro. Petrography, lithogeochemistry, and mineral composition was used to subdivide the Main Zone into five subzones: a basal marginal subzone, upper margin subzone, and three interior cycles that display cryptic variations indicative of fractional crystallization and magma recharge events. Like the margins of the Lower Zone, the Upper Zone as well and the basal marginal subzone of the Main Zone contain disseminated sulphides and Cr-spinel, and are characterized by relatively high Fo content olivine and low incompatible trace element concentrations. These mineralized zones are interpreted to have crystallized from the same initial pulse of magma into the CLG, which was sulfide- and Cr-spinel-saturated. Cyclical cryptic variations in the internal subzone of the Main Zone are interpreted to indicate upward directed fractional crystallization, interrupted by emplacement of additional magma pulses into the core of the intrusion. All rocks of the Main Zone are olivine and plagioclase orthocumulates indicating that fractional crystallization was not particularly efficient (i.e., did not experience a strong segregation of cumulus minerals from the parental magma). The lack of Cr-spinel in the interior and upper marginal subzones of the Main Zone further indicates that subsequent magma pulses either were more evolved than the original parental magma or were volumetrically subordinate to the evolved magmas that resided in the chamber.
Author:
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 1504
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Author:
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 396
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Book Description
Author: Ontario. Ministry of Natural Resources
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 402
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Author: Ontario. Resident Geologists
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 396
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Book Description
Author: S.B. Lucas
Publisher: Geological Society of America
ISBN: 0813754461
Category : Science
Languages : en
Pages : 395
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Book Description
This volume contains a description of the geology and mineral deposits of the Superior Province of the Canadian Shield, an overview of Grenville Province geology, and a synopsis of Precambrian fossil occurrences in North America. Six large plates include a geological map of Canada, geological map of the Grenville Province, lithotectonic map of the Superior Province, Archean mineral deposit map of the Superior Province, and more.
Author:
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 644
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Book Description
Author: Geological Association of Canada. Meeting
Publisher:
ISBN:
Category : Geology
Languages : en
Pages : 452
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Book Description
