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131.
云南兰坪白秧坪铜钴多金属矿集区矿石中石英的40Ar-39Ar快中子活化年龄谱呈马鞍形,坪年龄为56.53±0.43Ma,最小视年龄为55.52±1.78Ma,等时线年龄为55.90±0.29Ma,三者在误差范围内一致(1σ)。40Ar/36Ar初始值为294.7±1.14,与尼尔值(295.5±5)十分接近,坪年龄和等时线年龄均可作为石英的形成时代。因此,55.90~56.53Ma(喜马拉雅早期)代表了矿床的成矿年龄。 相似文献
132.
Sang Joon Pak Seon-Gyu Choi Chang-Whan Oh Chul-Ho Heo Sang-Hoon Choi Sung-Won Kim 《Resource Geology》2006,56(2):117-132
Abstract. The Yuryang gold deposit, comprising a Te‐bearing Au‐Ag vein mineralization, is located in the Cheonan area of the Republic of Korea. The deposit is hosted in Precambrian gneiss and closely related to pegmatite. The mineralized veins display massive quartz textures, with weak alteration adjacent to the veins. The ore mineralization is simple, with a low Ag/Au ratio of 1.5:1, due to the paucity of Ag‐phases. Ore mineralization took place in two different mineral assemblages with paragenetic time; early Fe‐sulfide mineralization and late Fe‐sulfide and Au‐Te mineralization. The early Fe‐sulfide mineralization (pyrite + sphalerite) occurred typically along the vein margins, and the subsequent Au‐Te mineralization is characterized by fracture fillings of galena, sphalerite, pyrrhotite, Te‐bearing minerals (petzite, altaite, hessite and Bi‐Te mineral) and electrum. Fluid inclusions characteristically contain CO2 and can be classified into four types (Ia, Ib, IIa and IIb) according to the phase behavior. The pressure corrected temperatures (≥500d?C) indicate that the deposit was formed at a distinctively high temperature from fluids with moderate to low salinity (<12 wt% equiv. NaCl) and CH4 (1?22 mole %). The sphalerite geo‐barometry yield an estimated pressure about 3.5 ?2.1 kbar. The dominant ore‐deposition mechanisms were CO2 effervescence and concomitant H2S volatilization, which triggered sulfidation and gold mineralization. The measured and calculated isotopic compositions of fluids (δ18OH2O = 10.3 to 12.4 %o; δDH2O = ‐52 to ‐77 %o) may indicate that the gold deposition originated from S‐type magmatic waters. The physicochemical conditions observed in the Yuryang gold deposit indicate that the Jurassic gold deposits in the Cheonan area, including the Yuryang gold deposit are compatible with deposition of the intrusion‐related Au‐Te veins from deeply sourced fluids generated by the late Jurassic Daebo magmatism. 相似文献
133.
Genetic types of diamond mineralization 总被引:1,自引:0,他引:1
A. A. Marakushev Sang Longkang You Zhendong I. A. Zotov N. N. Pertsev N. A. Paneyakh 《中国地球化学学报》1998,17(1):12-28
The paper describes the proposed models of diamond formation both in meteorites and in kimberlite and lamproite bodies, metamorphic
complexes and explosive-ring structures (“astroblemes”). The diamond distribution in meteorites (chondrites, iron meteorites
and ureilites) is restricted to taenite-kamasite phase. The diamond generation here is tied up with the first stage of evolution
of the planets. This stage is characterized by high pressure of hydrogen, leading to the formation of the planet envelope.
The second stage of planet evolution began with the progressive impoverishment of their atmospheres in hydrogen due to its
predominant emission into the space and to progressive development of oxidative conditions. The model appears to have proved
the relict nature of diamond mineralization in meteorites.
Diamond and other high-pressure minerals (its “satellites”) were crystallized without any exception in the early intratelluric
stages of peridotite and eclogite-pyroxenite magma evolution just before the magma intrusion into the higher levels of the
mantle and crust where diamond is not thermodynamically stable. The ultramafic intrusive bodies (bearing rich relict diamonds)
in the base of a platform appear to be the substrata for the formation of kimberlite-lamproite magma chambers as a result
of magmatic replacement. The model explains the polyfacial nature of diamondiferous eclogites, pyroxenites and peridotites
and discusses the process of inheritance of their diamond mineralization by kimberlites and lamproites.
Diamond productivity of metamorphic complexes is originated by the inheritance of their diamonds from the above-mentioned
primary diamondiferous rocks. Large diamondiferous explosive-ring structures were formed by high-energy endogenic explosions
of fluid which came from the Earth’s core. This high energy differs endogenic impactogenesis from explosive volcanism. It
proceeds at very high temperature to create diaplectic glasses (monomineral pseudomorphs) —the product of isochoric melting,
at the pressure high enough for the stable formation of very high-density minerals (coesite, stishovite, diamond, lonsdaleit,
and chaoite).
The research project was financially supported by the Russian Foundation of Fundamental Sciences (93-05-8566, 96-05-64307,
and 96-05-00026c0) and China National Natural Science Foundation (No.49794041, No.49611121831). 相似文献
134.
H_s型恩施球粒陨石K-Ar年龄为4503±91Ma,~(40)Ar-~(39)Ar坪年龄为4518±8Ma,总气体年龄为4515±23Ma,等时线年龄为4505±16Ma,年龄的一致性表明该陨石未经受过明显的热扰动,它是我国首次发现的Ar保存年龄高达45亿年以上的陨石。陨石形成早期有过短期的快速冷却。陨石母体在4.66±0.04Ma时破裂。恩施球粒陨石原始捕获(~(40)Ar/~(36)Ar)_t为0.89±0.44,推测4.5Ga前太阳风中~(40)Ar/~(36)Ar近于l。 相似文献
135.
地震活动性中心Gutenberg-Richter关系(logN=a-bM)在确定地震发生率时起着重要作用,实际分析中存在的对G-R关系的偏离主要是由于地震目录的不完全性引起:即在低震级端因地震的监测能力有限,在高震级端因大震的稀少导致的统计涨落。 相似文献
136.
本文采用准静力大气热力——动力学方程组和平流扩散方程的数值解方法,模拟了汾河河谷地区的流场、温度场和浓度场。所得结果和1984年春该地区进行的一次SF_6示踪试验资料做了对比。计算浓度场采用了三种方法:一般网格的数值模式、套网格数值模式和正态模式。和实测值的比较表明,套网格模式给出较好的计算结果,并且不需要增加过多的计算时间。 相似文献
137.
高凡Au异常受控于Nw向和NE向断裂构造交汇部位的特征,打破了前人局限于燕山期中酸性斑岩体内外接触带找Au—Ag矿的常规,为晋东北构造蚀变岩型Au—Ag矿的寻找提供了先例。另外,各种地球化学参数表明,高凡矿区Ag矿远景比Au矿更大。 相似文献
138.
139.
巴什托普构造带已经发现了石炭系的生物碎屑灰岩油藏,其烃源岩为寒武系—奥陶系海相碳酸盐岩层。推测油气运移必经之路上的志留系圈闭和奥陶系圈闭中可能存在油气藏。对巴什托普构造带石炭系以下志留系和奥陶系的分析表明,志留系下砂岩段与其上覆的红色泥岩段可以构成一个有利的储盖组合,下奥陶统石灰岩段有可能形成石灰岩岩溶并与其上覆志留系巨厚的暗色泥岩段组成一套储盖组合。在巴什托普构造带,在与油源沟通良好、构造圈闭有利的位置上,应该可以形成工业性油气藏。 相似文献
140.
The objective of this study is to investigate the effect of boundary element details of structural walls on their deformation capacities. Structural walls considered in this study have different sectional shapes and/or transverse reinforcement content at the boundaries of the walls (called boundary element details hereafter). Four full‐scale wall specimens (3000mm (hw)×1500mm (lw)×200mm (T)) were fabricated and tested. Three specimens are rectangular in section and the other specimen has a barbell‐shaped cross‐section (a wall with boundary columns). The rectangular wall specimens are reinforced according to the common practice used for reinforced concrete residence buildings in Korea and Chile. In this study, the primary variable for these rectangular specimens is the content of transverse reinforcement to confine the boundary elements of a wall. The barbell‐shaped specimen was designed in compliance with ACI 318‐95. The response of the barbell‐shaped specimen is compared with those of other rectangular specimens. The effective aspect ratio of the specimens is set to two in this study. Based on the experimental results, it is found that the deformation capacities of walls, which are represented by displacement ductility, drift ratio and energy dissipation capacities, are affected by the boundary element details. Copyright © 2002 John Wiley & Sons, Ltd. 相似文献