نتایج جستجو برای: cretaceous rocks
تعداد نتایج: 30195 فیلتر نتایج به سال:
Since water is only composed of oxygen and hydrogen, δ18O and δ2H values are thus utilized to trace the origin of water(s) and quantify the water-rock interactions. While Triassic high pressure (HP) and ultrahigh pressure (UHP) metamorphic rocks across the Dabie-Sulu orogen in central-eastern China have been well documented, postcollisional magmatism driven hydrothermal systems are little known...
the kasian volcanic body is located in the eastern margin of the zagros thrust belt, close to the sanandaj-sirjan metamorphic zone. these volcanic rocks are mainly composed of andesite and andesite-basalt rocks with porphyritic, hypocrystalline porphyritic, hyalo-porphyritic and hyalo-microlitic porphyritic textures. analyses of the distributions of major, rare earth and trace elements reveal a...
Along the Isthmus of Panama 23 paleomagnetic sites were sampled in order to determine preliminary block rotations and paleolatitudinal movements. The lithology selected for this research corresponds to volcanic and sedimentary rocks with ages ranging from Upper Cretaceous to Pleistocene. Counterclockwise vertical axis rotations were uncovered in Paleocene and Oligocene units separated by a sini...
Intrusion of the Kalaybar nepheline syenite into the Cretaceous pelitic and calcareous sediments has produced a thermal aureole up to 1km thick. Six mineralogical zones are developed in the pelitic rocks with minerals such as cordierite, K feldspar, sillimanite and corundum. Chemically suitable rocks are partially melted in response to the heat from the pluton. Five mineralogical zones are deve...
Chromite is widely distributed in the east and southeast of Afghanistan, especially in Logar Province. Chromite mineralization is podiform-type and is hosted in the stratigraphically lowest ultramafic rocks of the Logar Ophiolite Complex. This ophiolite complex represents a remnant of an early Cretaceous oceanic crust that was thrusted over a late Permian to Mid-Jurassic platform-type sequence ...
Andarian area is located north of Tabriz city, north west Iran, and tectonically is a part of Ahar-Arasbaran magmatic belt. Geology of the area includes Miocene shallow pluton, Cretaceous flysch-type sediments, metamorphic rocks )hornfels and skarn( and volcanic rocks. Mineralization occurred in two stages: primary and secondary. The primary ore minerals include Au, pyrite and stibnite. Malachi...
Western Turkey has been dominated by N–S extension since the Early Miocene. The timing and cause of this N–S extension and related basin formation have been the subject of much debate, but new data from the Bigadiç borate basin provide insights that may solve this controversy. The basin is located in the Bornova Flysch Zone, which is thought to have formed as a major NEtrending transform zone d...
Australia produces over 90% of the world’s precious opal from highly weathered Cretaceous sedimentary rocks within the Great Artesian Basin. Since opal was first discovered around 1870 until the present day, opal mining has been carried out by private operators working a claim no larger than 50 50 m, usually in the direct vicinity of areas that have yielded precious opal in the past. Currently ...
r a 200 .015 : +1 570 qu.edu Summary Stable isotopes, radiogenic isotopes, and major ion chemistry are used to constrain flow paths in a fracture-controlled regional groundwater flow system in far west Texas. The flow system occurs in Permian and Cretaceous sedimentary rocks and Cenozoic alluvial basin fill. Samples from springs and wells in the study area were analyzed for major ions and hydro...
Sakhalin has been affected by several phases of Cretaceous and Tertiary deformation due to the complex interaction of plates in the northwest Pacific region. A detailed understanding of the strain is important because it will provide constraints on platescale processes that control the formation and deformation of marginal sedimentary basins. Anisotropy of magnetic susceptibility (AMS) data wer...
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