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Showing 1 to 20 of 50 for “"volcaniclastic"”.
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The sedimentology of coarse grained hyperconcentrated flow deposits within modern and ancient volcaniclastic and alluvial fan sequences
… grained hyperconcentrated flow deposits in the volcaniclastic environment of Mount Saint Helens. Hyperconcentrated flow deposits are generally homogeneous, matrix-supported, unstratified (except where defined by sub units), have sorting characteristics intermediate between debris flow and stream …
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Potential Petroleum Reservoir Rocks of North-Central Oregon
… based on the presence of volcanic and/or volcaniclastic rock, that regions such as northcentral Oregon do not hold potential as petroleum basins. The typical argument has been that volcanic flows have no effective porosity or permeability and poorly sorted volcaniclastic sediments contain …
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North Gale Landform and the Volcanic Sources of Sediment in Gale Crater Mars
… a hummocky terrain deposit to the south. Volcaniclastic sediments have been detected in the sedimentary rocks of Gale Crater by APXS. They can be grouped into distinct classes: Jake_M and Bathurst_Inlet. Jake_M are float rocks and cobbles made of igneous sediments with evolved, alkaline …
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The age, stratigraphy, and tectonic provenance of clastic deposits in the western Bikou terrane, southwestern Qinling Mountains, China
… a metamorphosed volcanic arc with minor marine volcaniclastic sediments, known as the Bikou Group, previously dated by SHRIMP U-Pb zircon and conventional U-Pb as Late Proterozoic in age (approximately 845 to 760 Ma). Separated by a NE/SW striking fault, the northwestern Bikou terrane consists …
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Gold-silver mineralization at the London-Virginia Mine, Buckingham County, Virginia
… of submarine volcanism (units 1 and 5) and volcaniclastic sedimentation (unit 3) with intervening episodes of hydrothermal exhalative activity (units 2 and 4). The mineralogic assemblages characteristic of the exhalative units suggest that the premetamorphic sediments were rich in …
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Detrital Zircon Analysis of Permian Victoria Group Sandstones, Transantarctic Mountains, Antarctica
… major detrital sources, a cratonic source and a volcaniclastic source that characterizes the upper Buckley Formation and younger Triassic beds. In order to investigate the sedimentary provenance further, detrital zircons have been examined from both flanks of the basin. At Clarkson Peak, samples …
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Eocene to Miocene geology of southwest Viti Levu, Fiji
… to Middle Miocene Wainimala Group which includes volcaniclastic turbidites, hemipelagic carbonates and vitric tuffs deposited in the Sigatoka sedimentary basin, and further south volcaniclastic rudites, intrusive/extrusive dacites and andesites, and minor reef/platform limestones representing the …
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Characterization of a volcanically impacted, overfilled continental rift basin within the southeastern Jemez Mountains, New Mexico
… rift basin models. Additionally, the reworked volcaniclastic sediments, which are mostly observed in the lower stratigraphy, were generally longitudinally transported through the basin, even at the basin margins, as opposed to transverse deposition on the footwall-derived alluvial fans. The …
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Igneous life cycles: geochemistry of magma from mantle to surface and back again
… settings, and diagenetic histories of volcaniclastic units to highlight the heterogeneity of volcanic systems on the Hikurangi Plateau. The presence of voluminous hydrous clays within thick, altered volcaniclastic units provides a ready source for excess pore fluids that may enable …
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Detection and Characterisation of Airborne Carcinogenic Erionite Fibres in New Zealand Roadside Environments Using a Novel Integrated Methodology
… are exposed and disturbed. In regions with volcaniclastic geology, such dust may contain naturally occurring carcinogenic minerals, including fibrous asbestos and erionite. Erionite, a fibrous zeolite, is of particular concern as it has been classified as a Group 1 carcinogen and exposure to …
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Stratigraphy, sedimentology, and paleotectonic setting of the Gazelle Formation, eastern Klamath Mountains, northern California
… of shale, siltstone, siliceous mudstone, volcaniclastic sandstone, and chert-rich flysch, in decreasing order of abundance. Sediment gravity flows were the dominant sedimentary process during deposition of the Gazelle Formation. Petrographic analysis of sandstones from the Gazelle reveal …
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An unconformity in the Carolina slate belt of central North Carolina: new evidence for the areal extent of the ca. 600 Ma Virgilina deformation
… of intermediate(?) lava flows, pyroclastic and volcaniclastic rocks. Deposition of these units was in a subaqueous environment although some units are indicative of transient subaerial conditions. The Aaron Formation is a volcanic epiclastic sequence composed of conglomerate, pebbly and …
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Deep explosive volcanism on the Gakkel Ridge and seismological constraints on shallow recharge at TAG active mound
… at the site. The morphology and distribution of volcaniclastic deposits observed on the seafloor at depths of ~3800 m, greater than the critical point for steam generation, are consistent with having formed by explosive discharge of magma and CO2 from source vents. Microearthquakes recorded on a …
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Deep explosive volcanism on the Gakkel Ridge and seismological constraints on Shallow Recharge at TAG Active Mound
… at the site. The morphology and distribution of volcaniclastic deposits observed on the seafloor at depths of ~3800 m, greater than the critical point for steam generation, are consistent with having formed by explosive discharge of magma and CO² from source vents. Microearthquakes recorded on a …
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Volcanology and geochemistry of selected kimberlites from the Lulo kimberlite field, Angola
… study aims to conduct a reconnaissance survey of volcaniclastic kimberlites within these pipes to classify eruptive styles, providing insights into the internal geology of pipes with implications for diamond grade bulk sampling. A total of 52 kimberlite targets were sampled, yielding 83 thin …
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The Utility of Foraminifera in Documenting Sediment Provenance for Overwash Deposits: A Case Study Using Sediments Deposited by Tropical Cyclone Pam In Vanuatu
… a mixed-carbonate embayment (Manuro), and a volcaniclastic beach (Port Resolution Bay; PRB). At Manuro, the TC Pam sediments were up to 10 cm thick and contained abundant foraminifera (955 to 2015 individuals per 5 cm<sup>3</sup>). At PRB, TC Pam sediments were up to 44 cm thick with lower …
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Iron inputs from sediments to the oceans
… of Fe cycling was investigated in deep-sea volcaniclastic surface-sediments<br/>(0-20 cmbsf). Pore-fluid and sediment samples were collected from tephra-rich sites near<br/>the active volcanic island of Montserrat, Caribbean Sea, and mixed biosiliceous sites<br/>around the dormant Crozet …
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Petrogenesis of the Willis Mountain and East Ridge kyanite quartzite, Buckingham County, Virginia
… formation, metamorphosed volcanic and volcaniclastic rocks. The entire package of rocks has been metamorphosed to amphibolite grade peak conditions of 6.5 kb and 600°C. The kyanite quartzite is very similar in bulk composition and accessory mineralogy to high-alumina rocks of probable …
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EPISODIC UPLIFT OF THE ROCKY MOUNTAINS: EVIDENCE FROM U-PB DETRITAL ZIRCON GEOCHRONOLOGY AND LOW-TEMPERATURE THERMOCHRONOLOGY WITH A CHAPTER ON USING MOBILE TECHNOLOGY FOR GEOSCIENCE EDUCATION
… unconformities, deposition of voluminous volcaniclastic aprons. This study suggests that relief has increased through time as the Rocky Mountain headwater regions of the fluvial systems that deposited progressively younger units of this study have gained in absolute elevation, while the …
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Depositional Environments of the Miocene Esmeralda Formation, Stewart Basin, Stewart Valley, Nevada
… The stratigraphic relationship of diatomaceous, volcaniclastic, stromatolitic, and dolomitic sediments provide new insights into ancient lake environments.</p>
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