نتایج جستجو برای: sedimentary rock
تعداد نتایج: 48134 فیلتر نتایج به سال:
Beach rock has only rarely been observed in the coasts. It is a hard costal sedimentary formations consisting of various beach sediments, lithified through the precipitation of carbonate cements. One such formation is noted on the South East Coast of Tamilnadu, India. The objective of this contribution is to collect and review information on reported occurrences, characteristics and formation m...
We report a magnetostratigraphic and rock magnetic study of the Yaha section, located on the southern flank of the central Tian Shan mountains, Asia. Our results show a twofold increase in sedimentation rate as well as marked changes in rock magnetic characteristics ca. 11 Ma. After 11 Ma, sedimentation rate remained remarkably constant until at least 5.2 Ma. These findings are consistent with ...
[1] New slope measurements from the Mars Orbiter Laser Altimeter (MOLA), in conjunction with the Rock Mass Rating system (RMR), permit inversions of slope height and angle from wallrock and interior deposits within Valles Marineris troughs for strength and lithology. Wallrock (50 < RMR < 65) is stronger than interior deposits (30 < RMR < 55). These values are consistent with layered igneous roc...
Sedimentary rocks at Eagle crater in Meridiani Planum are composed of fine-grained siliciclastic materials derived from weathering of basaltic rocks, sulfate minerals (including magnesium sulfate and jarosite) that constitute several tens of percent of the rock by weight, and hematite. Cross-stratification observed in rock outcrops indicates eolian and aqueous transport. Diagenetic features inc...
Introduction: Recently published reports on chemical and physical properties of Mars sediments indicate that diagenetically altered volcanic rocks were reworked by sedimentary processes [1]. Furthermore, compositional and petrographic aspects of sediments show varying degrees of elemental enrichment as well as complex interaction between the minerals in partially saturated or saturated conditio...
The fossil record documents the history of life, but the reliability of that record has often been questioned. Spatiotemporal variability in sedimentary rock volume, sampling and research effort especially frustrates global-scale diversity reconstructions. Various proposals have been made to rectify palaeodiversity estimates using proxy measures for the availability and sampling of the rock rec...
Gadilam river basin has gained its importance due to the presence of Neyveli Lignite open cast mines and other industrial complexes. It is also due to extensive depressurization of Cuddalore aquifer, and bore wells for New Veeranam Scheme are constructed downstream of the basin. Geochemical indicators of groundwater were used to identify the chemical processes that control hydrogeochemistry. Ch...
Lineation is a general term to describe any repeated, commonly penetrative and parallel alignment of linear elements within a rock (to envision lineation, imagine packages of spaghetti). A lineation may be a primary igneous or sedimentary fabric element, such as an array of elongate K-feldspar porphyroblasts, inclusions or pebbles oriented with their long dimensions mutually parallel, or flute ...
In this study, we apply advanced numerical optimization techniques to extend the work of Imhof and Sharma (2005, 2006) to integrate geological and geophysical data and infer the sedimentary parameters that produce a match to seismic data. In particular, we seek to match not just event timing (phase) but also reflection strength (amplitude). This inverse problem of quantitatively matching presen...
Processes that operate at planetary surfaces have the potential to record a history of planetary evolution in the form of sedimentary rocks. This is important because our experience on Earth shows that sediments and sedimentary rocks are the dominant archive of high-resolution proxies of present and past tectonic, climatic, and biological processes. Our understanding of the evolution of Earth’s...
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