Valence dipolarization is an important factor and one of the basic rules govering the formation of the earth's crust, the evolution of ultrabasic-basic→intermediateacidic→ultraacidic rock series, magmatie differ...Valence dipolarization is an important factor and one of the basic rules govering the formation of the earth's crust, the evolution of ultrabasic-basic→intermediateacidic→ultraacidic rock series, magmatie differentiation of igneous intrusions and the distribution and concentration of rare and radioactive elements in igneous rocks, and orthomagmatic metallogenesis. Ichor, transmagmatic fluids or ascending thermal fluids from the upper mantle, produced by dewatering, degassing, dealkalization, desilification and the loss of heat are all exclusive valence dipolarizing agents within the earth.Ca- and Mg-skarns are products of anti-valence dipolarization. Alkaline metasomatism is regarded as valence dipolarization in the hydrothermal stage.展开更多
晶质铀矿是花岗岩中广泛产出的副矿物,其铀离子价态的变化及比例关系,对于岩浆氧逸度具有一定的指示意义。笔者利用硅酸盐熔浆中U^(6+)-U^(4+)的平衡关系,推导出花岗岩副矿物——晶质铀矿的氧逸度计热力学计算方程,以及氧逸度(f O2)、温...晶质铀矿是花岗岩中广泛产出的副矿物,其铀离子价态的变化及比例关系,对于岩浆氧逸度具有一定的指示意义。笔者利用硅酸盐熔浆中U^(6+)-U^(4+)的平衡关系,推导出花岗岩副矿物——晶质铀矿的氧逸度计热力学计算方程,以及氧逸度(f O2)、温度(T)和不同价态铀离子比值(U^(6+)/U^(4+))的对数关系。以赣南五里亭花岗岩体为例,借助X射线光电子能谱分析,获得U^(6+)与U^(4+)的比例关系(U^(6+)/U^(4+)=0.30～0.46);利用晶质铀矿氧逸度计热力学方程,计算出该岩体形成时的平均氧逸度(为FMQ+0.58)。在温度(T)与氧逸度(lg f O2)协变图中,该结果靠近矿物反应缓冲线(FMQ),显示岩浆为弱还原性。因此,晶质铀矿U^(6+)/U^(4+)氧逸度计算结果能够代表岩浆源区的氧逸度特征,可作为常规氧逸度计算方法的一种有效补充。展开更多
文摘Valence dipolarization is an important factor and one of the basic rules govering the formation of the earth's crust, the evolution of ultrabasic-basic→intermediateacidic→ultraacidic rock series, magmatie differentiation of igneous intrusions and the distribution and concentration of rare and radioactive elements in igneous rocks, and orthomagmatic metallogenesis. Ichor, transmagmatic fluids or ascending thermal fluids from the upper mantle, produced by dewatering, degassing, dealkalization, desilification and the loss of heat are all exclusive valence dipolarizing agents within the earth.Ca- and Mg-skarns are products of anti-valence dipolarization. Alkaline metasomatism is regarded as valence dipolarization in the hydrothermal stage.
文摘晶质铀矿是花岗岩中广泛产出的副矿物,其铀离子价态的变化及比例关系,对于岩浆氧逸度具有一定的指示意义。笔者利用硅酸盐熔浆中U^(6+)-U^(4+)的平衡关系,推导出花岗岩副矿物——晶质铀矿的氧逸度计热力学计算方程,以及氧逸度(f O2)、温度(T)和不同价态铀离子比值(U^(6+)/U^(4+))的对数关系。以赣南五里亭花岗岩体为例,借助X射线光电子能谱分析,获得U^(6+)与U^(4+)的比例关系(U^(6+)/U^(4+)=0.30～0.46);利用晶质铀矿氧逸度计热力学方程,计算出该岩体形成时的平均氧逸度(为FMQ+0.58)。在温度(T)与氧逸度(lg f O2)协变图中,该结果靠近矿物反应缓冲线(FMQ),显示岩浆为弱还原性。因此,晶质铀矿U^(6+)/U^(4+)氧逸度计算结果能够代表岩浆源区的氧逸度特征,可作为常规氧逸度计算方法的一种有效补充。
