کد مقاله کد نشریه سال انتشار مقاله انگلیسی ترجمه فارسی نسخه تمام متن
4714866 1638458 2007 24 صفحه PDF سفارش دهید دانلود رایگان
عنوان انگلیسی مقاله ISI
Geology and geochronology of the Spirit Mountain batholith, southern Nevada: Implications for timescales and physical processes of batholith construction
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موضوعات مرتبط
مهندسی و علوم پایه علوم زمین و سیارات ژئوشیمی و پترولوژی
پیش نمایش صفحه اول مقاله
Geology and geochronology of the Spirit Mountain batholith, southern Nevada: Implications for timescales and physical processes of batholith construction
چکیده انگلیسی

The Spirit Mountain batholith (SMB) is a ∼ 250 km2 composite silicic intrusion located within the Colorado River Extensional Corridor in southernmost Nevada. Westward tilting of 40–50° has exposed a cross-section from the roof through deep levels of the batholith. Piecemeal construction is indicated by zircon geochronology, field relations, and elemental geochemistry. Zircon U/Pb data (SHRIMP) demonstrates a ∼ 2 million year (17.4–15.3 Ma) history for the SMB. Individual samples contain zircons with ages that span the lifetime of the batholith, suggesting recycling of extant zircon into new magma pulses. Field relations reveal several distinct intrusive episodes and suggest a common injection geometry of stacked horizontal sheets.The largest unit of the SMB is a gradational section (from roof downward) of high-silica leucogranite through coarse granite into foliated quartz monzonite. Solidification of this unit spans most of the history of the batholith. The 25 km × 2 km leucogranite was emplaced incrementally as subhorizontal sheets over most or all of the history of this section, suggesting repeated fractional crystallization and melt segregation events. The quartz monzonite and coarse granite are interpreted to be cumulate residuum of this fractionation. Age data from throughout this gradational unit show multiple zircon populations within individual samples. Subsequent distinct intrusions that cut this large unit, which include minor populations of zircons that record the ages of earlier events in construction of the batholith, preserve a sheeted, sill-on-sill geometry.We envision the SMB to have been a patchwork of melt-rich, melt-poor, and entirely solid zones throughout its active life. Preservation of intrusion geometries and contacts depended on the consistency of the host rock. Zircons recycled into new pulses of magma document remobilization of previously emplaced crystal mush, suggesting the mechanisms by which evidence for initial construction of the batholith became blurred.

ناشر
Database: Elsevier - ScienceDirect (ساینس دایرکت)
Journal: Journal of Volcanology and Geothermal Research - Volume 167, Issues 1–4, 1 November 2007, Pages 239–262
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