赣东北元古代蛇绿岩Sm—Nd同位素年龄及地质意义   总被引：9，自引：0，他引：9  

邢凤鸣  徐祥  陈江峰  周禧泰  K.Afoland 《岩石矿物学杂志》1992,11(2):120-124

江南古陆东南缘赣东北弋阳—德兴—婺源一线有一条蛇绿岩带,普遍认为它是二个一级大地构造单元的分界线,形成于元古代。推断蛇绿混杂岩是元古代古洋壳俯冲时被挤上来的碎片;也有人认为它是中生代二大古陆之间的缝合线。Sm-Nd矿物等时线给出1034±16Ma(MSWD=1.0)的同位素年龄,它符合元古代缝合带的观点,而不利于中生代缝合带。  相似文献   

铀-铅同位素测年新技术及其地质应用的最新发展     

李惠民 《华北地质》1992,(4)

本文着重介绍了国内外铀-铅同位素测年工作所取得的新进展,并指出灵活地将铀-铅同位素测年的各种新技术方法结合起来应用,往往可以获得“多、快、好、省”的效果。  相似文献   

Sm—Nd and Zircon U—Pb Isotopic Constraints on the Age of Formation of the Precambrian Crust in Southeast China   总被引：1，自引：0，他引：1  

李献华  赵振华等 《中国地球化学学报》1992,11(2):111-120

Nd model ages(TDM) of the Pre-Mesozoic crustal rock samples from Southeast China range from 1.2 to 3.5Ga.Two age peaks of 1.4Ga and 1.8 Ga are observed in the histogram of TDM model ages.Available U-Pb zircon inheritance ages are concentrated around 1.2-1.4Ga,1.8Ga and 2.5Ga,respectively.The combined use of Sm-Nd and U-Pb zircon inheritance ages suggests that the formation of the Precambrian curst is of episodic character.The oldest crustal nucleus may have been formed during the Late Archean(2.5Ga or older?).A rapid production of the crust took place 1.8 Ga ago,consistent with the global crust formation event at 1.7-1.9Ga.Another important episode of the addition of juvenile crustal material from the mantle in Southeast China took place 1.2-1.4Ga ago,during which the pre-existing crust was strongly reworked and/or remelted.  相似文献   

^3He／^4He Ratios and Heat Flow in the Continental Rift—valley,Eastern China     

Du Jianguo 《中国地球化学学报》1992,11(3):237-243

Heat flow and the origin of helium in natural gases from fault basins of the continental rift-valley in eastern China are discussed in terms of helium isotope geochemistry.³He/⁴He ratios in natural gases from the rift-valley range from 2.23 × 10⁻⁷ to 7.21 × 10⁻⁶, which are directly proportional to the concentration of helium and ΣNHC/ΣHC ratio in natural gases. Geological and isotope geochemical data suggest that helium in natural gases consists predominantly of crustal radio-genic and upper mantle-derived helium. In a simple mixing pattern between crustal He and mantle-derived He, mantle-derived helium in natural gases would account for 10–60%. Calculated values for heat flow (Q) range from 59.7 to 82.4mWm⁻², of which about 60 percent in the rift-valley is derived from the upper mantle. Natural helium reservoirs would be found in the areas where the upper mantle uplifted greatly and heat flow is large in the continental rift-valley. The project is financially supported by the National Natural Science Foundation of China.  相似文献   

内华达州莫哈韦沙漠东部土壤的稳定碳同位素化学与气候...     

Amun.  RG 刘俊峰 《地质地球化学》1992,(6):53-59

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苏北—胶南构造混杂岩带冷却历史的多重扩散...   总被引：12，自引：5，他引：12  

陈文寄  刘若新 《岩石学报》1992,8(1):1-17

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土壤和古土壤中的碳同位素可作为生态学和古生态学...     

Cerl.  TE 干国梁 《国外第四纪地质》1992,(2):43-47

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应用氢氧同位素方法研究兰州市傍河水源地地下水水体的形成和循环机理     

余振国  连炎清 《甘肃地质》1992,1(1):68-84

本文通过测定水中氢氧同位素的变化来对兰州市傍河水源地地下水体的形成和循环机理进行分析探讨。分析了兰州市马滩水源地水质恶化的程度,探讨了恶化的原因。对其工作原理及方法作了较详尽的论述。  相似文献   

内蒙黄岗梁—孟恩陶勒盖多金属矿床同位素地质特征     

冯建忠 《辽宁地质》1992,(2):117-126

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地球上最古老的矿物年龄和它们的地质意...     

高劢  刘敦一 《国外前寒武纪地质》1992,(4):6-13

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