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Showing 1 to 20 of 32 for “"Laurentia"”.
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Space-Time Analysis of Magmatism: Evidence for a Early Cryogenian Plume Track in Eastern Laurentia
In the Grenville age basement rocks of Virginia and North Carolina, nearly thirty Cryogenian volcanic/plutonic complexes have been recognized. A-type granites and rhyolites dominate the igneous complexes within the Cryogenian Magmatic Province (CMP), but compositional variations range from gabbro …
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DETRITAL-ZIRCON GEOCHRONOLOGIC PROVENANCE ANALYSES THAT TEST AND EXPAND THE EAST SIBERIA - WEST LAURENTIA RODINIA RECONSTRUCTION
Laurentia's position in the Neoproterozoic supercontinent Rodinia is a topic of continuing debate. Several reconstructions involving Laurentia and Siberia have been proposed, including the east Siberia-west Laurentia connection. The east Siberia-west Laurentia Rodinia reconstruction includes …
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DETRITAL-ZIRCON GEOCHRONOLOGIC PROVENANCE ANALYSES THAT TEST AND EXPAND THE EAST SIBERIA - WEST LAURENTIA RODINIA RECONSTRUCTION
Laurentia's position in the Neoproterozoic supercontinent Rodinia is a topic of continuing debate. Several reconstructions involving Laurentia and Siberia have been proposed, including the east Siberia-west Laurentia connection. The east Siberia-west Laurentia Rodinia reconstruction includes …
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High-Resolution Correlation Using Geophysical and Geochemical Methods on Three Cambrian Drumian Marine Sedimentary Successions in The House Range Embayment, Western Laurentia
… platform along the passive margin of western Laurentia, was tentative and uncertain. The complex lithological variations, the absence of lithostratigraphic and other reliable biostratigraphic markers, and the widely-spaced sampling and coarse correlation among HRE sections, have contributed to …
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A coming together: The juxtaposition of the Rae and Hearne cratons along the Virgin River shear zone (Snowbird tectonic zone), Saskatchewan, Canada, and the implications for proto-Laurentia
The Snowbird tectonic zone of western Laurentia remains an enigmatic feature; some researchers have suggested that it represents a Paleoproterozoic suture, whereas others have proposed that it represents a reactivated Archean intracratonic fault zone. The Virgin River shear zone is the most …
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The taxonomy, phylogeny and palaeobiogeography of the trilobite families pliomeridae and encrinuridae: reconstructing the Ordovician world using evolving lineages
… were observed: During the early Ordovician, Laurentia was juxtaposed to the eastern margin of Gondwana and close to areas of South America. Towards the end of the early Ordovician, Laurentia and Gondwana diverged, and did not subsequently re-approach each other during the Period although the …
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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
… of the tectonic history of southeastern Laurentia during the Mesoproterozoic (Chapter 1), to investigate the potential link between Laurentia and Amazonia during the formation of Rodinia (Chapter 2), and to elucidate the tectonic processes responsible for creating Zr-enriched magmas …
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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
… of the tectonic history of southeastern Laurentia during the Mesoproterozoic (Chapter 1), to investigate the potential link between Laurentia and Amazonia during the formation of Rodinia (Chapter 2), and to elucidate the tectonic processes responsible for creating Zr-enriched magmas …
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STRUCTURAL AND KINEMATIC INVESTIGATION OF THE DADEVILLE COMPLEX-BREVARD ZONE CONTACT (SOUTHERN APPALACHIANS): POLYPHASE EMPLACEMENT OF AN ALLOCHTHONOUS TERRANE ON THE LAURENTIAN MARGIN
… (Ordovician Period) and was accreted onto Laurentia during the Acadian orogeny (Devonian-Mississippian Periods); however, the mechanism and role of accretion during the Acadian orogeny is not well constrained. Three proposed emplacement mechanisms for the DC include: (1) …
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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
… provide new insight into tectonics of southern Laurentia: 1) Laramide-style (monoclines) deformation in the continental interior at 1250 Ma records Grenville-age shortening; 2) 1.1 Ga detrital muscovite (Ar/Ar) and zircon (U/Pb) indicate that an Unkar Group source in the Grenville highlands …
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Sedimentology, Stratigraphic Evolution and Provenance of the Cambrian – Lower Ordovician Potsdam Group in the Ottawa Embayment and Quebec Basin
… geologic and tectonic history of Early Paleozoic Laurentia. Nevertheless, in spite of 178 years of study the Potsdam in the Ottawa Embayment and Quebec Basin remains poorly understood. Also poorly understood is how the Potsdam relates with coeval strata regionally. In this work six siliciclastic …
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AN IMBRICATE MID CRUSTAL SUTURE ZONE: THE MOJAVE-YAVAPAI PROVINCE BOUNDARY IN GRAND CANYON, ARIZONA
The Mojave and Yavapai provinces in southwestern Laurentia contain evolved and juvenile crust respectively, but the nature of their boundary remains uncertain. This paper analyzes the U-Pb-Hf isotopic composition of zircons from both the oldest plutons and metasedimentary rocks in Grand Canyon. My …
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Basement and Cover Structural Analysis Along the Eagle River Gorge, Sawatch Range, Colorado
… volcanic island arcs and continental crust onto Laurentia, Ancestral Rocky Mountain Uplift and the Laramide orogeny. </p>
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Geochemical and petrologic study of the Fries-Rockfish Valley Fault near Roanoke, Virginia
… Precambrian basement emplaced on the margin of Laurentia during collisional events in the Paleozoic. This allochthonous basement is composed of Middle Proterozoic continental crust, Late Proterozoic intrusives, and Late Proterozoic-early Paleozoic metasediments and metavolcanics. Two distinct …
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The Durness Group of NW Scotland: a stratigraphical and sedimentological study of a Cambro-Ordovician passive margin succession
… passively-subsiding, continental margin of the Laurentian craton, and now forms part of the Hebridean terrane, lying to the west of the Moine Thrust zone. It represents c. 920 m of shallow marine, peritidal carbonates with minor siliciclastic and evaporitic strata. Facies analysis shows that the …
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Crystalline bedrock geology of the lower Susquehanna Gorge: Conowingo to Havre de Grace, Maryland
… possibly developed on a rift fragment of Laurentia (Canal Road Formation). The northern Conowingo Block represents a precursory mélange (Conowingo Dam Formation) intruded during the Ordovician by a layered mafic complex (State Line Mafic Complex) and associated plutons (Basin Run …
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The origin and tectonic significance of the mafic-ultramafic association in the central Virginia Blue Ridge post-Grenville cover sequence
… to be ophiolitic mélange that was obducted onto Laurentia, thus implying a suture or terrane boundary is associated with the rocks. Detailed field mapping and petrography of three typical mafic-ultramafic complexes in the central Virginia Blue Ridge (the Catfish, Flat Creek, and Schuyler …
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Geochemical investigations of the late early Cambrian extinctions
… carbonate deposition on the passive margin of Laurentia from early to middle Cambrian. While negative shifts in δ13Ccarb and δ13Corg resembling the two negative CIEs have been identified, incomplete drill core and pervasive alteration complicates this straightforward interpretation. In …
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PALEOCLIMATE DURING DEPOSITION OF THE GREATER TWILIGHT PARK CONGLOMERATE, UPPER DEVONIAN, SOUTHEAST NEW YORK
… of various exotic terranes with the continent of Laurentia, primarily during the Devonian Period. This created the southward propagating Acadian Orogeny. Formation of the basin and the cratonward-prograding Catskill clastic wedge promoted deposition of the Devonian siliciclastic rocks of the …
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Tectonic and geologic development of the Charlotte belt south central Virginia Piedmont
… the volcanic arc, Carolinia, that collided with Laurentia during the Late Cambrian to Late Ordovician Taconic orogeny. Both belts consist primarily of volcanic rocks, the major difference being that the Charlotte belt is amphibolite grade gneisses, whereas the slate belt is at greenschist grade. …
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