نتایج جستجو برای: clastic rocks
تعداد نتایج: 22678 فیلتر نتایج به سال:
In the geological record one tends to think of formations composed of either limestones or sandstones, but rarely both. In fact, there are many cases of interbedded clastics and carbonates in repeated cyclic arrangements. Such units occur on the small-scale (metre-thick cycles or parasequences, 4/5 order), and on the larger-scale (10’s metre-thick, 4 order high-frequency sequences and 100’s met...
Rocks exposed west of the Coast Plutonic Complex in southern southeast Alaska form an imbricate thrust belt that overprints the tectonic boundary between two of the largest allochthonous crustal fragments in the North American Cordillera, the Insular and Intermontane composite terranes. In the Alexander terrane (Insular composite terrane), lower Paleozoic metavolcanic and metasedimentary rocks ...
The study area is located in the northeast of Iran. Miankuhi Formation is 500m thick and comprises homogeneous shales, brown granular sandstone and siltstone. In this study, 45 samples were taken from Miankuhi shales and sandstones in order to determine their tectonic origin by using a polarizing microscope. Samples were analysed by X-Ray Fluorescence (XRF) method to determine their chemical...
The Eocene rocks in Shabraweet area comprise the Lower, Middle and Upper Eocene stages. Each stage consists of only one rock unit; the Minia Formation, the Mokattam Formation and the Maadi Formation, respectively. The Minia Formation shows angular unconformity relationship with the underlying Cretaceous rocks and disconformity relationship with the overlying Mokattam Formation. The Maadi Format...
In previous work we have described and validated robust techniques for partitioning the pore space of a porous material into simple regions, thereby allowing it to be represented by a network of simple building blocks. The primary purpose of this analysis is the generation of a pore-throat network for modelling immiscible multi-phase fluid displacements. However, combining our partitioning algo...
One of the most prominent features on gravity and aeromagnetic maps of the United States is a series of major, generally linear anomalies that extend from central Kansas to Lake Superior and then turn southward into central Michigan (Figures 1, 2). This system of anomalies clearly reflects major geological features, and as such it must represent a very significant episode in the history of the ...
Home Plate is a layered plateau in Gusev crater on Mars. It is composed of clastic rocks of moderately altered alkali basalt composition, enriched in some highly volatile elements. A coarsegrained lower unit lies under a finer-grained upper unit. Textural observations indicate that the lower strata were emplaced in an explosive event, and geochemical considerations favor an explosive volcanic o...
[1] In the Inner Basin of the Columbia Hills, Gusev Crater is Home Plate, an 80 m platform of layered clastic rocks of the Barnhill class with microscopic and macroscopic textures, including a bomb sag, suggestive of a phreatomagmatic origin. We present data acquired by the Spirit Mars Exploration Rover by Alpha Particle X-Ray Spectrometer (APXS), Mössbauer Spectrometer, Miniature Thermal Emiss...
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