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Showing 1 to 12 of 12 for “"1.4 Ga"”.
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Proterozoic thermal and deformational history and geochemical evolution of the 1.4 Ga Priest pluton and its aureole
Paleoproterozoic (1.7-1.6 Ga) supracrustal rocks in the aureole of the 1.43 +/- 0.01 ga Priest pluton provide evidence for a polyphase Proterozoic metamorphic history in central New Mexico. This history involved pre-, syn-, and post-emplacement metamorphic mineral growth. The Priest pluton contact …
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The Proterozoic ancestry of the Colorado Mineral Belt : ca. 1.4 Ga shear zone system in central Colorado
… shearing. This history involves movement at 1.45 Ga along Idaho Springs-Ralston shear zones and possibly along Homestake shear zone, synchronous with emplacement of the Mt. Evans pluton. At 1.42 Ga, movement took place along St. Louis Lake and again along Idaho Springs-Ralston shear zones, …
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Proterozoic history of the Idaho Springs-Ralston shear zone: evidence for a widespread ca. 1.4 Ga orogenic event in central Colorado, The
… zones have previously been interpreted as ~1.45 Ga reactivated shear zones, following a pre-existing crustal-scale weakness, such as a suture zone that formed at ~1.7 Ga. The interpreted suture zone was based on the presence of tectonic mélange at the St. Louis Lake shear zone, ~40 km NNW of the …
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Polyphase Proterozoic tectonometamorphic history of the Taos Range, northern New Mexico
… a protracted tectonic history involving pre-1.7 Ga, 1.65 Ga, 1.4 Ga, and possible 1.1 Ga tectonism. The southern Taos Range is a 1.76 – 1.7 Ga volcano-plutonic complex with tectonically interlayered remnants of the Hondo Group. Similar rock types are exposed in the northern Taos Range where …
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Proterozoic evolution of the Zuni Mountains, New Mexico: Peridotites, granites, rhyolites, shear zones, and a reactivation history through the present
… represent shallow-level magmatism at ca. 1.65 Ga. The peridotite exists in an elongate lens and several discrete pods that were metamorphosed and hydrothermally altered to the assemblage serpentine – hornblende – chlorite – talc – dolomite – actinolite – spinel. The absence of associated mafic …
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Analysis of the Cabin Canyon shear zone in the Virgin Mountains : implications for an early accretionary province boundary and later transpressional zone.
… rocks involved in shearing are similar to ~1.7 Ga of the Grand Canyon, but mylonitization is inferred to be ~1.4 Ga based on relatively low temperature microstructures and similarity to other partitioned dextral/transpressive shear zones in northwestern Arizona. Mapping and microstructural …
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Microstructural, geochronologic and thermochronologic evidence for both Paleo- and Mesoproterozoic displacement across the Gneiss Canyon shear zone : lower Granite Gorge, Grand Canyon, Arizona
… northwest-striking D1 fabric. Previous investigations of D2 domains show west-side-up and dextral displacement forming at amphibolite grade. D2 field and microstructures suggest deformation temperatures of >500 oC. Zoned monazite displays 1696 Ma cores and 1649 Ma outermost rims, suggesting …
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Origin and geological significance of mylonitic shear zones, northern Lucy Gray Range, Clark County, Nevada
… Nevada, is part of a continent-scale belt of 1.4 Ga intrusive rocks that extend from California to Labrador. These granites are conventionally interpreted as anorogenic; however, recent work has documented that some of these plutons may have been deformed during or after emplacement. In the Lucy …
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Geologic and tectonic evolution of the Manzano Peak Quadrangle, central New Mexico
… plutonism occurred during accretion (ca. 1.65 Ga) and also in the Mesoproterozoic between 1.45 and 1.35 Ga; both sets of plutons intrude the older Proterozoic rocks. Within the Manzano Mountains, it is controversial whether the present fabrics and foliations record the older accretion-related …
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History and timing of polyphase Proterozoic deformation in the Manzano thrust belt, central New Mexico
… assembly of Laurentia, particular the 1.65-1.60 Ga Mazatzal orogeny and the later 1.4 Ga thermo-tectonic event. This study focuses on the Los Pinos Mountains, near the southern end of the Manzano thrust belt, an area that has been only weakly overprinted by a later phase of Mesoproterozoic …
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Structural Analysis of the Northwest Wind Mountain Quadrangle, New Mexico: Proterozoic Shearing to Cenozoic Brittle Faulting in the Burro Mountains
<p>Preliminary investigation of the Bullard Peak metamorphic series (BPMS) in the northwestern Wind Mountain quadrangle within the Burro Mountains of southwestern New Mexico suggests a possible previously unidentified shear zone, prompting detailed (1:12,000) geologic mapping and collection of …
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Evolution of continental crust in the Proterozoic : growth and reworking in orogenic systems
… models. To accurately address the question regarding continental crustal growth using combined zircon U–Pb-Lu–Hf(-O) isotope data, one needs to have contextual control and minimise the uncertainties of the applied models. In papers included in this thesis such an approach has been used on …