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Showing 1 to 20 of 24 for “"Late Ordovician"”.
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Sedimentation during the Taconic orogeny: a study of late Ordovician and early Silurian rocks of the Siegas area, New Brunswick.
Thesis (M.S.)--Massachusetts Institute of Technology, Dept. of Earth and Planetary Sciences, 1969.
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Sequence Stratigraphy and Petrophysics of the late Ordovician Utica-Point Pleasant Interval in the Middle Appalachian Basin, Eastern Ohio and Western Pennsylvania
… model of the Utica Shale and associated Upper Ordovician strata. Previous studies of outcrop data from the Cincinnati arch and Jessamine dome recognized a number of Late Mohawkian to Early Cincinnatian third-order sequences deposited in an active foreland basin during onset of the Taconic …
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Paleozoic Stratigraphy and Structure at Iron Point, Humboldt County, North-Central Nevada
… study using the most current understanding of Ordovician graptolite biostratigraphy. Previous studies at Iron Point had determined that the graptolites found in the siltstone units in the Comus Formation were middle Ordovician. This study determined that the species of graptolites found at Iron …
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The taxonomy, phylogeny and palaeobiogeography of the trilobite families pliomeridae and encrinuridae: reconstructing the Ordovician world using evolving lineages
The phylogeny of the Family Pliomeridae and the Ordovician representatives of the Encrinuridae was investigated using cladistics. This resulted in the diagnosis of seven subfamilies; five of pliomerids (including one erected herein) and two subfamilies of encrinurid: the Cybelinae and Encrinurinae. …
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Crystalline bedrock geology of the lower Susquehanna Gorge: Conowingo to Havre de Grace, Maryland
… (Conowingo Dam Formation) intruded during the Ordovician by a layered mafic complex (State Line Mafic Complex) and associated plutons (Basin Run Tonalite). Many olistoliths within the Conowingo Dam Formation could have originated in the Havre de Grace Block. The Havre de Grace Block was …
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Architecture of the Silurian sedimentary cover sequence in the Cadia porphyry Au-Cu district, NSW, Australia : implications for post-mineral deformation
… of the Cadia district are associated with Late-Ordovician monzonite intrusions, which were emplaced during the final phase of Macquarie Arc magmatism at the end of the Benambran Orogeny. N-striking faults, including the curviplanar, northerly striking, moderately west-dipping basement …
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Stratigraphic Architecture and Paleogeography of the Juniata Formation, Central Appalachians
Late Ordovician (Cincinnatian) strata of the central Appalachians provide an opportunity to study the effects of both tectonics and eustasy within a foreland-basin setting. The Juniata Formation consists of red sandstones, siltstones, and shales that were deposited as part of an extensive …
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Tectonic and geologic development of the Charlotte belt south central Virginia Piedmont
… but includes a portion of the adjacent Carolina slate belt. Both the Charlotte belt and the Carolina slate belt are major components of the volcanic arc, Carolinia, that collided with Laurentia during the Late Cambrian to Late Ordovician Taconic orogeny. Both belts consist primarily of volcanic …
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High Resolution Stratigraphy of Ordovician Carbonates, Kentucky: Evidence for a Greenhouse to Glacial Transition
Early Ordovician Knox Group carbonates consist of meter-scale dolomite cycles deposited on a passive margin. The meter-scale cycles were deposited under warm, semi-arid conditions, under low amplitude sea level fluctuations on a relatively ice-free earth. The overlying Knox unconformity (~10 m.y. …
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Paleoenvironmental Reconstruction of an Upper Ordovician Rocky Shoreline: The Lindsay Formation of Heywood and Partridge Islands, Ontario
… and Lorrain Formation quartz arenite and Upper Ordovician Lindsay Formation carbonate and mudrock. The Lindsay Formation strata record two transgressive pulses of an epeiric sea that flooded the North American continent during the Late Ordovician. During this time, mountain building processes …
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Fracture reactivation and gold mineralization in the epithermal environment : structural evolution of the Endeavour 42 gold deposit, New South Wales, Australia
… in the Junee-Narromine Volcanic Belt of the Ordovician Macquarie Arc, central New South Wales, has provided a 3D view of the structurally controlled deposit which was hitherto not available due to the paucity of outcrop in the region. Outcropping geological relationships present a complicated …
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Stratigraphy and Tectonics: Multi-Disciplinary Evaluation of Tectonic Models For the Eastern and Southern Continental Margins of North America
… detrital-zircon ages collected from the Upper Ordovician through upper Mississippian sandstones records the sedimentary response to Taconic, Acadian and Alleghanian phases of orogenesis. This analysis suggests the Late Ordovician accretion of Dahlonega terrane, the Devonian accretion of …
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Sm-Nd and C-isotope chemostratigraphy of Ordovician epeiric sea carbonates, midcontinent of North America
… water. Instead, eNd, d13C and Sm/Nd profiles of Ordovician Midcontinent carbonates of North America demonstrate that fluctuations in sea level and depth are driving local changes in the eNd, d13C and Sm/Nd composition of epeiric seawater. Dissolved Nd derived from the Transcontinental Arch, …
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Mineralogical, chemical and isotopic diversity in plutonic rock suites from the Coastal Maine Magmatic Province:the role of source region heterogeneity, tectonic setting and magmatic processes
… Province. A tectonic model is developed in which late Ordovician-Silurian bimodal magmatism is interpreted to reflect crustal melting as a result of intraplating of mantle melts at high crustal levels during a period of tension. Large scale melting of lower crustal source regions, represented by …
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Petrologic and Fluid Inclusion Constraints on the Tectonic Evolution of the Manhattan Prong, Southeastern New York
… Lake mafic complexes, intrusions thought to be related to the Late Ordovician Cortlandt Complex, record P-T estimates of 4 kbar and 700 oC and 4.2 kbar and 550-600 oC respectively. The lack of fluid inclusions in garnet porphyroblasts indicates that the regional metamorphic assemblage has been …
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Ultramafic Alteration and the Cooling of Earth and Mars
… 1-4 bar atmosphere as adsorbed methane. I postulate that this methane was formed abiotically during hydrothermal alteration of ultramafic rocks, a process which is observed in ultramafic systems on Earth. I show that this framework reconciles the histories of \dc{} and atmospheric loss-to-space …
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Depositional environments and paleogeography of the Winnipeg Group (Ordovician), Williston Basin, North Dakota
<p> The Winnipeg Group (Upper Ordovician) unconformably overlies the Deadwood Formation (Cambrian - Lower Ordovician) over most of North Dakota, except in the extreme eastern part, where it lies directly on Precambrian basement rocks. The Winnipeg is conformably overlain by the Red River Formation …
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Integrated numerical modelling of a polyhistory basin, Southern Cantabrian Basin (Palaeozoic, NW-Spain)
… information about minimal basin shortening and Late Devonian basin geometry. Three different structural domains can be distinguished along the synthetic, 18km long Bernesga Transect. The style of structural deformation defines the amount of shortening calculated for each domain. The Pedrosa …
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