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Showing 1 to 20 of 44 for “"Mesoproterozoic"”.
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The Mesoproterozoic Hallandian event - a region-scale orogenic event in the Fennoscandian Shield
The Sveconorwegian Province occupies the southwestern part of the Fennoscandian Shield. The easternmost tectonic unit of the Province is the 1710-1660 Ma parautochthonous Eastern Segment, which bears the imprint of at least two metamorphic events; the 1460-1380 Ma Hallandian and the 1150-970 Ma …
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Mesoproterozoic tectonic evolution of southwestern North America : protracted intracratonic deformation, sedimentation, and differential exhumation in Grand Canyon and the Rocky Mountain Region
… is one of the best preserved remnants of Mesoproterozoic sedimentary rocks in the southwestern United States. It provides an exceptional record of intracratonic basin formation and associated tectonics kinematically compatible with protracted "Grenville-age" NW-directed shortening. New …
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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
The Gneiss Canyon shear zone (GCSZ) in north-western Arizona sits between high grade migmatites on the west and lower amphibolite grade schists on the east. This 13 km-wide zone, contains domains of intense D2 strain up to 100m wide that separate blocks of preserved northwest-striking D1 fabric. …
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Mesoproterozoic Basement From The Central And Southern Appalachians Reveal High-temperature Magmatic Conditions And Non-laurentian Origin Of Earth’s Most Zircon Fertile Magmas
<p>The Mesoproterozoic (1.4-0.9 Ga) Grenville Orogeny led to the formation of the supercontinent Rodinia. One unique characteristic of the Grenville Orogeny is that it produced a volumetrically significant amount of zirconium- (Zr) enriched granitoids, evidently more than any period both prior to …
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Mesoproterozoic Basement From the Central and Southern Appalachians Reveal High-temperature Magmatic Conditions and Non-laurentian origin of Earth's Most Zircon Fertile Magmas
<p>The Mesoproterozoic (1.4-0.9 Ga) Grenville Orogeny led to the formation of the supercontinent Rodinia. One unique characteristic of the Grenville Orogeny is that it produced a volumetrically significant amount of zirconium- (Zr) enriched granitoids, evidently more than any period both prior to …
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Petrogenesis of the Mesoproterozoic anorthosite, syenite and carbonatite suites of NW Namibia and their contribution to the metasomatic formation of the Swartbooisdrif sodalite deposits
During the Mesoproterozoic large volumes of magma were repeatedly emplaced within the basement of NW Namibia. Magmatic activity started with the intrusion of the anorthositic rocks of the Kunene Intrusive Complex (KIC) at 1,385-1,347 Ma. At its south-eastern margin the KIC was invaded by syenite …
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Tectono-thermal evolution of Gjelsvikfjella, Western Dronning Maud Land, Antarctica
… belt has traditionally been interpreted as a Mesoproterozoic-age (1.3-0.9 Ga) mobile belt that was later affected by thermal overprint associated with little or no deformation during the Neoproterozoic (0.6-0.5 Ga). Therefore the Maud Belt has been used as a piercing point in Mesoproterozoic …
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Thermochronology of ‘The Gap’, Western Australia
… U−Pb systems record metamorphism during the late Mesoproterozoic tectonomagmatic Maralinga event in both the Coompana and Madura Provinces. Apatite Lu−Hf and U−Pb reset ages of c. 1.20−1.14 Ga were obtained for the eastern Coompana, while for the western Coompana and Madura Provinces, only the …
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Bedrock and surficial geology of the southern half of the Montezuma 7.5' quadrangle, central Colorado Front Range, Colorado, USA
… Front Range, and to investigate the Paleo- and Mesoproterozoic history of the area. The Paleoproterozoic geologic history in the southwestern United States is characterized by the Yavapai (~1.71-1.68 Ga) and Mazatzal (~1.65-1.60 Ga) orogenies, which both involved terrane accretion along the …
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Metamorphic and crustal evolution of Australian-Antarctic Proterozoic margins
… and thermally extreme conditions during the Mesoproterozoic (D1/M1: 1345–1260 Ma; D2/M2: 1220–1130 Ma). Occurring along the margins of the Australian and East Antarctic Archean–Paleoproterozoic cratons, this system is geographically and geodynamically central to models for the Proterozoic …
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Geologic and tectonic evolution of the Manzano Peak Quadrangle, central New Mexico
… 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 event, or the …
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Petrology of the Gradational Intrusive Contact Between the Packsaddle Schist and the Town Mountain Granite, Enchanted Rock State Natural Area, Llano Uplift, Central Texas
<p>The Mesoproterozoic intrusive contact between the ~1.1 Ga anorogenic Town Mountain Granite and the ~1.3 Ga Packsaddle Schist is a gradational contact exhumed within the Llano uplift. This contact is exposed along the southeastern margin of the Enchanted Rock batholith in central Texas. Field …
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The Proterozoic ancestry of the Colorado Mineral Belt : ca. 1.4 Ga shear zone system in central Colorado
… 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' …
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Contributions to the Proterozoic and Cambrian Evolution of Eukaryotes
… macroalgae was low but increased in the Mesoproterozoic and Ediacaran, with a plateau in between. There was also a significant increase in thallus surface/volume ratio and maximum canopy height of the Ediacaran macroalgal communities. The prolonged plateau between the Mesoproterozoic and …
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Tectonometamorphic evolution of Medium-P granulites of the Namaqua Metamorphic Province at the Gordonia Subprovince marginal zone, southern Namibia
… western Namaqua Metamorphic Complex (NMC) is a Mesoproterozoic mediumto low-pressure, high temperature metamorphic belt that is characterised by a complex, polyphase Mesoproterozoic metamorphic history. Using an integrated approach, the P-T-t evolution of a portion of the marginal zone between …
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Metamorphic evolution of ultrahigh-temperature granulite facies and upper amphibolite facies rocks of the Epupa Complex, NW Namibia
… the Epembe Unit were affected by two distinct Mesoproterozoic metamorphic events, as is evident from differences in their metamorphic grade, in the P-T paths and in the age of peak-metamorphism: (1) The Orue Unit consists of a Palaeoproterozoic volcano-sedimentary sequence, which was intruded …
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N-S shortening during orogenesis in the Mt Isa Inlier: the preservation of W-E structures and their tectonic and metamorphic significance
Mesoproterozoic Mt Isa inlier of NW Queensland exhibits complex tectonometamorphic history that is generally considered to result from low-pressure/high-temperature (LP/HT) metamorphism with an anticlockwise pressure-temperature-deformation path. Yet studies regarding the nature of the P-T history …
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Early neoproterozoic marine redox conditions recorded in black shale from the little Dal Group, Northwest Territories, Canada
… which is in very good agreement with data from Mesoproterozoic black shales, but is much lower than Mo enrichments in Paleozoic black shales (typically >100 ppm). Several black muddy siltstones yielded similar results, but authigenic iron was greatly overwhelmed by siliciclastic sedimentation. …
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A metamorphic and geochemical study of mafic rocks across the Pencksökket-Jutulstraumen Discontinuity, western Dronning Maud Land, East Antarctica
A petrological and metamorphic comparison of Mesoproterozoic metabasic rocks on the easern margin of the Archaean Grunehogna Craton and the adjacent Maud Belt in western Dronning Maud Land, East Antarctica, revealed a difference in peak metamorphic conditions from T = ~275° to 730°C and P=2 to 10.7 …
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Tertiary Sediments of the Big Hole Valley and Pioneer Mountains, Southwestern Montana: Age, Provenance, and Tectonic Implications
… the early Tertiary. Late Cretaceous, Eocene, and Mesoproterozoic detrital zircon populations, along with consistently immature lithic sands, all indicate sediments were derived from local bedrock sources found around the rim of the modern Big Hole Valley. While these results indicate the Tertiary …
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