نتایج جستجو برای: crustal contamination
تعداد نتایج: 61183 فیلتر نتایج به سال:
voluminous quaternary extrusive rocks, associated with widespread volcanic activities, occur in the northwestern iran and across the turkish-iranian plateau. field and petrographic studies reveal that these volcanic rocks, consisting of basalt to trachyandesite, occur as lava flows, columnar basalts, and cinder cones in three distinct areas of northern (bazergan-maku-burlan), middle (chalderan)...
salafchegan-khorhe volcanic rocks are exposed within urumieh-dokhtar magmatic belt. different kinds of volcanic and subvolcanic rocks of calc-alkaline to alkaline character have been reported throughout this magmatic belt. since, isotopic investigations are very useful for detection of magma petrogenesis and because no isotopic studies have been done in this area, so a geochemical and isotopic ...
S U M M A R Y Accurate accounting for the effects of crustal structure on long-period seismic surface waves and overtones is difficult but indispensable for determining elastic structure in the mantle. While standard linear crustal corrections (SLC) have been shown to be inadequate on the global scale, newer non-linear correction (NLC) techniques are computationally expensive when applied to wa...
Eruptive sequences can be used as windows into the thermal and chemical evolution of magma chambers. We examined a continuous vertical section of the Baichahe basalt flow associated with the late Cenozoic Chifeng flood basalt in Inner Mongolia, North China. From oldest to youngest, MgO increases, K2O, light rare earths and other incompatible elements decrease, and Nb/La and radiogenic Pb isotop...
A wide range of plutonic rocks, ranging from mafic to felsic compositions, including various gabbros, diorites, tonalites, granodiorites, monzogranites, syenogranites and leucocratic granitoids, occur in the Alvand plutonic complex, Sanandaj-Sirjan zone, Iran. Age of this complex is middle Jurassic. In this complex, granitic and dioritic rocks occur as major constituents. Granites contain plagi...
Melt inclusions from Oligocene continental flood basalts (CFB) erupted in Yemen provide unique insight into the timing and nature of the processes that lead to crustal contamination and melt aggregation in CFB magmas. Large variations in trace element indices that are sensitive to the degree and composition of assimilated crustal material (e.g. K2O=0.20^1.94 wt%, Ba= 13^543 ppm, K/Nb=128^1603, ...
The Kahrizbeyg pluton is located northwest of Iran in Central Iran zone. It is emplaced into the Cretaceous limestones in which contact metamorphism has happened. Meanwhile, rock fragments of this pluton are found in conglomerate units of Early Oligocene Lower Red Formation. Therefore, the relative age of pluton is between Cretaceous and Oligocene. The Kahrizbeyg pluton consists of granite and ...
The Paleogene volcanic rocks of Damash have a considerable outcrops in Alborz structural zone in Guilan Province. These volcanic rocks show a compositional range from olivine basalt, basaltic andesite, pyroxene andesite to andesite. The petrographical and geochemical studies indicate that the fractional crystallization of clinopyroxene and olivine play an important role in lithological varietie...
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