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You searched for subject:(Colorado Mineral Belt). Showing records 1 – 3 of 3 total matches.

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Colorado School of Mines

1. Lytle, Madison. Proterozoic history of the Idaho Springs-Ralston shear zone : evidence for a widespread ca. 1.4 Ga orogenic event in central Colorado, The.

Degree: MS(M.S.), Geology and Geological Engineering, 2016, Colorado School of Mines

The Idaho Springs-Ralston shear zone (IRSZ) is one of several Proterozoic NE-trending zones within the central-eastern Colorado Front Range. The zone is composed of multiple mylonitic strands of a few meters to several kilometers in width and is mapped from ~16 km NNW of Denver, CO to ~26 km to the SW (near Idaho Springs, CO). The IRSZ and other NE-trending 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 IRSZ, suggesting the presence of a subduction zone. New field data suggest that the IRSZ is not as extensive as previously interpreted. Additionally, a lack of pinch outs and offset of major units, as well as similar deformation histories and metamorphic conditions on either side suggest that the IRSZ did not form as a continental suture zone. Isoclinal F1 folds are overprinted by F2 folds. F2 folds NW of the IRSZ have subvertical NE-trending axial planes and shallowly NE-plunging fold hinge lines. SE of the IRSZ they also plunge shallowly NE, but axial planes dip shallowly ENE. We suggest that the isoclinal F1 folds are folded first by asymmetric NW-side-up meter-scale F2 folds, followed by a several km-scale NE-plunging, NW-dipping F3 folds, that are responsible for the current fold pattern. NW-side-down movement along the IRSZ may have been a result of flexural slip on the NW steeply dipping limb of the NE-plunging, NW-dipping F3 fold. U-Pb laser ablation inductively coupled mass spectrometry monazite dates revealed ~1.68 Ga and ~1.43 Ga events, both within and adjacent to the IRSZ. Relationships between microstructures and monazite grains suggest F1 folds formed at ~1.68 Ga and F2 and F3 folding and associated shearing along the IRSZ occurred at ~1.43 Ga. The relationship between shearing and widespread folding at ~1.43 Ga suggests that Mesoproterozoic deformation was much more extensive than movement along shear zones, as previously interpreted. Folding at ~1.43 Ga is interpreted to be associated with the Picuris orogeny recognized in New Mexico, and the IRSZ is interpreted as a result of folding, rather than as a major reactivated suture zone. Advisors/Committee Members: Kuiper, Yvette (advisor), Ridley, John (committee member), Pfaff, Katharina (committee member).

Subjects/Keywords: Colorado Mineral Belt; Picuris orogeny; U-Pb monazite dating; Mesoproterozoic; Automated mineralogy; Shear zone

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APA (6th Edition):

Lytle, M. (2016). Proterozoic history of the Idaho Springs-Ralston shear zone : evidence for a widespread ca. 1.4 Ga orogenic event in central Colorado, The. (Masters Thesis). Colorado School of Mines. Retrieved from http://hdl.handle.net/11124/170423

Chicago Manual of Style (16th Edition):

Lytle, Madison. “Proterozoic history of the Idaho Springs-Ralston shear zone : evidence for a widespread ca. 1.4 Ga orogenic event in central Colorado, The.” 2016. Masters Thesis, Colorado School of Mines. Accessed August 23, 2019. http://hdl.handle.net/11124/170423.

MLA Handbook (7th Edition):

Lytle, Madison. “Proterozoic history of the Idaho Springs-Ralston shear zone : evidence for a widespread ca. 1.4 Ga orogenic event in central Colorado, The.” 2016. Web. 23 Aug 2019.

Vancouver:

Lytle M. Proterozoic history of the Idaho Springs-Ralston shear zone : evidence for a widespread ca. 1.4 Ga orogenic event in central Colorado, The. [Internet] [Masters thesis]. Colorado School of Mines; 2016. [cited 2019 Aug 23]. Available from: http://hdl.handle.net/11124/170423.

Council of Science Editors:

Lytle M. Proterozoic history of the Idaho Springs-Ralston shear zone : evidence for a widespread ca. 1.4 Ga orogenic event in central Colorado, The. [Masters Thesis]. Colorado School of Mines; 2016. Available from: http://hdl.handle.net/11124/170423


University of New Mexico

2. McCoy, Annie Marie. The Proterozoic ancestry of the Colorado Mineral Belt : ca. 1.4 Ga shear zone system in central Colorado.

Degree: Department of Earth and Planetary Sciences, 2001, University of New Mexico

The Paleocene to Oligocene magmatism and mineralization that are the Phanerozoic expressions of the Colorado Mineral Belt developed along a NE-trending system of subvertical mylonites and ultramylonites that formed in the Mesoproterozoic and that, in turn, overprinted higher-temperature Paleoproterozoic high strain zones of similar orientation. In this thesis, I distinguish the Colorado Mineral Belt itself from a Proterozoic 'Colorado Mineral Belt shear zone system' that includes the Homestake, Gore Range, St. Louis Lake, and Idaho Springs-Ralston shear zone segments. In situ electron microprobe monazite dating of mylonites of the Colorado Mineral Belt shear zone system, coupled with field studies of relative timing of shearing and pluton emplacement, demonstrate a ca. 100 Ma history of recurrent 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, synchronous with emplacement of the Silver Plume pluton. At 1.38 Ga, movement took place along Homestake and Idaho Springs-Ralston shear zones, synchronous with emplacement of the St. Kevin pluton, and post-1.38 Ga movements reactivated Homestake, St. Louis Lake, and Idaho Springs-Ralston shear zones. In each shear zone segment, kilometer-wide Mesoproterozoic mylonite zones consist of multiple, parallel, one to ten meter-wide mylonite strands, which overprint higher-temperature Paleoproterozoic high-strain domains that are several kilometers wide. Monazite dating of the higher temperature high-strain domains indicates pulses of Paleoproterozoic deformation that occurred at 1.71-1.69 Ga, 1.67 Ga, 1.65, and 1.62 Ga. Thus, the tectonic fingerprint of the Colorado Mineral Belt shear zone system includes two ~100 Ma long orogenic periods in the Proterozoic, each with important pulses of deformation that occurred every fifteen to twenty million years. This shear zone system may be analogous to modern-day intracontinental zones of weakness like the Tien Shan, which record both original assembly of tectonic blocks and reactivation of intracontinental weaknesses during later plate convergence at a distant margin. Advisors/Committee Members: Karlstrom, Karl, Selverstone, Jane, Williams, John.

Subjects/Keywords: Proterozoic; Colorado Mineral Belt; Colorado; 1.4 Ga

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APA (6th Edition):

McCoy, A. M. (2001). The Proterozoic ancestry of the Colorado Mineral Belt : ca. 1.4 Ga shear zone system in central Colorado. (Masters Thesis). University of New Mexico. Retrieved from http://hdl.handle.net/1928/24721

Chicago Manual of Style (16th Edition):

McCoy, Annie Marie. “The Proterozoic ancestry of the Colorado Mineral Belt : ca. 1.4 Ga shear zone system in central Colorado.” 2001. Masters Thesis, University of New Mexico. Accessed August 23, 2019. http://hdl.handle.net/1928/24721.

MLA Handbook (7th Edition):

McCoy, Annie Marie. “The Proterozoic ancestry of the Colorado Mineral Belt : ca. 1.4 Ga shear zone system in central Colorado.” 2001. Web. 23 Aug 2019.

Vancouver:

McCoy AM. The Proterozoic ancestry of the Colorado Mineral Belt : ca. 1.4 Ga shear zone system in central Colorado. [Internet] [Masters thesis]. University of New Mexico; 2001. [cited 2019 Aug 23]. Available from: http://hdl.handle.net/1928/24721.

Council of Science Editors:

McCoy AM. The Proterozoic ancestry of the Colorado Mineral Belt : ca. 1.4 Ga shear zone system in central Colorado. [Masters Thesis]. University of New Mexico; 2001. Available from: http://hdl.handle.net/1928/24721


Baylor University

3. Wegert, Daniel James. Lithospheric magmatism in southern Colorado and northern New Mexico.

Degree: Geology., 2014, Baylor University

This dissertation looks at the formation of three different volcanic centers throughout southern Colorado and northern New Mexico to evaluate potential sources for their subduction-like trace element signatures. These subduction signatures are found in volcanic rocks formed well away from concurrent subduction and are, in many cases, rift related. The Laramide-age McDermott Formation is a lahar deposit deposited into the San Juan Basin formed through melting of Proterozoic subduction-modified lithospheric mantle. Near zero εNdt values (-1.94 and 0.47) rule out a crustal source for these magmas, while trace element ratios suggest a subduction-modified continental lithosphere source. Geochemical analyses suggest a possible relationship to the La Plata Mountains intrusive complex, though weathering and sericitization have made confirming this hypothesis impossible. The Nathrop domes are crustal melts formed due to partial melting associated with crustal extension along the Arkansas Valley Graben segment of the Rio Grande Rift. εNdt values (-10.1, Bald Mountain and -13.9, Precambrian granite) suggest that the magmas ancestral to those of the Nathrop Domes were largely the result of partial melting of Precambrian crustal rock. These crustal melts then evolved through protracted crystal fractionation of observed phenocrysts, yielding the large enrichment/depletion patterns observed in incompatible element diagrams. The Raton-Clayton volcanic field lies on the Jemez Lineament, on the eastern flank of the Rio Grande Rift. The Jemez Lineament coincides with the ancient Proterozoic boundary between the Matzatzal and Yavapai terranes, which have been interpreted as accreted arc complexes. The subduction signature present in the RCVF lavas is attributed to modification during this event. The RCVF magmas show evidence that both assimilation and fractional crystallization played significant roles in their evolution. εNd values for all samples indicate derivation from lithospheric mantle. Olivine back-calculation results were used to determine that magmas ancestral to Raton-Clayton basalts were formed between 50 and 217 km inside the Earth. Advisors/Committee Members: Parker, Donnie Franklin, 1948- (advisor).

Subjects/Keywords: Raton-Clayton volcanic field.; Nathrop Domes.; McDermott Formation.; Rio Grande Rift.; Colorado Mineral Belt.; La Plata Mountains.; San Juan Basin.; Petrogenesis.; Ruby Mountain.; Jemez Lineament.; Peraluminous rhyolite.

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APA (6th Edition):

Wegert, D. J. (2014). Lithospheric magmatism in southern Colorado and northern New Mexico. (Thesis). Baylor University. Retrieved from http://hdl.handle.net/2104/9196

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Chicago Manual of Style (16th Edition):

Wegert, Daniel James. “Lithospheric magmatism in southern Colorado and northern New Mexico. ” 2014. Thesis, Baylor University. Accessed August 23, 2019. http://hdl.handle.net/2104/9196.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

MLA Handbook (7th Edition):

Wegert, Daniel James. “Lithospheric magmatism in southern Colorado and northern New Mexico. ” 2014. Web. 23 Aug 2019.

Vancouver:

Wegert DJ. Lithospheric magmatism in southern Colorado and northern New Mexico. [Internet] [Thesis]. Baylor University; 2014. [cited 2019 Aug 23]. Available from: http://hdl.handle.net/2104/9196.

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

Council of Science Editors:

Wegert DJ. Lithospheric magmatism in southern Colorado and northern New Mexico. [Thesis]. Baylor University; 2014. Available from: http://hdl.handle.net/2104/9196

Note: this citation may be lacking information needed for this citation format:
Not specified: Masters Thesis or Doctoral Dissertation

.