| Description |
ix, 103 pages : illustrations ; 29 cm |
| Summary |
"In the Wichita province of southwestern Oklahoma the Cold Springs Breccia Formation, exposed in a 15 km² area in Kiowa County, is characterized by blocks and pillows of microdiorite surrounded by pink granite. Intimately associated with this mixed zone are sill-like bodies of intermediate rocks, granodiorites and tonalites. The intermediate rocks have been interpreted as hybrids produced by assimilation of microdiorite by granitic magma, and the mixed zone has been interpreted as an intrusion breccia formed at the margins of the hybrid sills. Major, minor and trace element data have been obtained on a suite of granites, intermediates, and microdiorites. Q-mode factor analysis, along with linear programming and least-squares techniques, have been used to test the chemical feasibility of an assimilation model. The results indicate that the intermediate rocks do not fit a linear mixing model and are too enriched in Al, Na, Ti and P to be products of hybridization between granite and microdiorite. Petrographic and field data indicate the microdiorite was still plastic at the time of intrusion of the granite, and that in some places microdiorite may have been injected into granitic melt. Based on the chemical, petrographic, and field data, the sequence of events is interpreted as follows: (1) near-simultaneous intrusion of microdiorite and granite along zones of weakness in the Glen Mountains Layered Complex, closely followed by (2) intrusion of the intermediate rocks, with compositional variation attributed to fractional crystallization of a primary intermediate magma modified by minor assimilative reaction with microdiorite and granite"--Abstract, pages ii-iii. |
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