نتایج جستجو برای: rock alteration
تعداد نتایج: 83344 فیلتر نتایج به سال:
the area is located 20 km northwest of kashmar and about 4 km of kalateh taimour in khorasan razavi province. the study area is part of tertiary volcanic-plutonic belt north of daruneh fault and its situation in tectonic inliers between two important active faults, doruneh and taknar. volcanic rocks are mainly intermediate to acid pyroclastic type. they formed during early tertiary. the volcani...
As part of the European Hot Dry Rocks Project, a second exploration borehole, EPS-1, has been cored to a depth of 2227 m at Soultz-sous-For@ts (France). The target was a granite beginning at 1417 m depth, overlain by post-Paleozoic sedimentary cover. Structural analysis and petrographic examination of the 800-111 porphyritic granite core, have shown that this rock has undergone several periods ...
Introduction: Secondary carbonate minerals produced by low temperature aqueous processes [1] in the martian meteorite ALH 84001 are evidence of an early active hydrosphere on Mars when they were formed ~3.9 Ga ago [2]. Further evidence for an early hydrosphere includes orbital and surface observations of diverse alteration mineral assemblages [e.g. 3-5] and fluvial geomorphology [6]. While carb...
A combination of subsurface borehole imaging data and drilling logs were used to characterize the fractures and lithology in 40 bedrock wells at the fractured-rock research site in the Mirror Lake area in Grafton County, New Hampshire. The purpose of the research was to determine whether subsurface lithology and fractures have an effect on the hydraulic conductivity of the crystalline-rock aqui...
The critical Rayleigh number for convective flow of pore water through a permeable spherical body is derived. The result affords constraints on carbonaceous chondrite planetesimal sizes and rates of heat production. If the chemical compositions of carbonaceous chondrites are taken as evidence against flow of pore water, then the present calculations suggest that the parent bodies were less than...
New occurrences of free gold were identified during fieldwork at outcrops located in the western part of the Castro Basin, state of Paraná. These are associated with silicified and sulfide-rich zones in hydrothermally-altered volcanic rocks. The aerogeophysical data indicate that the areas of the new targets show high K and eU relative to eTh, suggesting intense hydrothermal alteration. The str...
The Mars Exploration Rover Opportunity has spent more than 2 years exploring Meridiani Planum, traveling approximately 8 kilometers and detecting features that reveal ancient environmental conditions. These include well-developed festoon (trough) cross-lamination formed in flowing liquid water, strata with smaller and more abundant hematite-rich concretions than those seen previously, possible ...
A fast and accurate technique has been developed for the determination of the total volatile content of rocks. The loss on fusion (LOF) results are comparable to the conventional time-consuming wet-chemical procedure but require no additional effort or cost when conducted as part of the usual sample preparation procedure for quantitative X-ray fluorescence spectrometric analysis (XRF). The tech...
Introduction: Spectroscopic observations offer the best means to evaluate chemical weathering on Mars at regional and global scales. Near-infrared (NIR) spectral data from OMEGA and CRISM have revealed hydrated minerals that indicate aqueous alteration, including different clay minerals [1-3], sulfates [1,4], silica [5], and carbonates [6], which are regionally localized across the Martian high...
introduction agates are presumed as a kind of precious stone that could be formed in magmatic, metamorphic and even sedimentary environment. mechanism for agate formation is not clear and is produced in laboratories. some hot springs and geothermal activity or white chimneys in the ocean floor, have some deposits like chalcedony but never produce agate. agate formation temperature varies betwee...
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