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101.
Calc-alkaline granites (excluding A-and M-type) could be divided into two petrogenic series,I,e,the syntexis series and the transformation series according to their genetic mechanisms.In the light of this classification we found that granites of these two series often aligne in paired zones parallel to contemporaneous B-type or intracontinental compression-subduction zones within ascended slabs,re-sulting in a regular zonal pattern together with subduction zones.Thus,they are defined as twin granite belts.According to the spatial relations between the granite belts and the subduction zones,the twin granite belts could be classified as A, AB and B-type .The zonation of granites of the two series in the northern part of the East Qinlin area could be cited as a typical example of A-type twin granite belts related to the Yenshanian intracontinenta compression-subduction movement in the area.In this paper the tectonic settings and petrogenic features of the twin granites belts in East Qinlin are systematically described,and a tectonic model for granitic magma genesis in intracontinental compression-subduction environments has been proposed.In this model the forma-tion of A-type twin granite belts is closely connected with tectonic movements in terms of the prince-ple,rule and dynamics of material differentiation in the lithosphere. 相似文献
102.
Hu Shouquan 《吉林大学学报(地球科学版)》1999,29(2):3
以泌阳断陷双河-赵凹地区下第三系核三上段陆相层序地层学研究为例,建立了断陷湖盆陡坡带陆相层序地层学模式①陆相层序及其体系域界面模式;②体系域模式;③陆相层序地层模式。其中,陆相层序地层模式包括岩相格架模式及年代框架模式两个内容。研究结果显示,断陷湖盆陡坡带可识别出Ⅰ型和Ⅱ型两类陆相层序;一个完整的Ⅰ型陆相层序从下往上发育LST、TST、HST及RST四个体系域,共五个界面,除顶、底界面归属层序界面之外,其它三个界面皆为体系域界面;而Ⅱ型陆相层序缺失LST。无论何种体系域,其沉积体的几何形状均为楔状体,且各体系域的沉积相横向配置呈现规律性变化。陆相层序地层等时框架模式清晰地显示了研究区下第三系核三上段的沉积充填史及其沉积层序时空展布特征。 相似文献
103.
Rare—Earth Element Geochemistry of Elogites from the Ultra—High Pressure Metamorphic Belt in Central China 总被引:1,自引:1,他引:1
Based on their REE contents and REE patterns,eclogites from the ultra-high pressure metamorphic belt in central China may be roughly divided into xis types including LREE-rich.LREE-rich positive Eu anomaly,LREE-rich negative Eu anomaly,REE pattern-smooth,MREE-rich and HREE-rich.The LREE_rich,LREE-rich positive Eu anomaly and LREE-rich negative Eu anomaly types of eclogites are dominant .REE types of eclogites in different areas can be compared and the REE feactures of the same REE type of eclogites in different areas are similar.The results of reconstruction of the primary rocks show that the primary rocks of eclogites possibly are dominated by continental tholeiites which are the product of partial melting of relatively fertile mantle and the rocks of tholeiite crystallization-differentiation.There is perfect evolution relationship among the primary rocks of the LREE-rich, LREE-rich positive Eu anomaly and LREE-rich negative Eu anomaly types of eclogites and among those of the REE pattern smooth and MREE-rich types of eclogites,the former three types were deried from continental settings and the latter two from nearly oceanic settings.Meanwhile,it is concluded that the mantle sources of primary rocks of the eclogites are inhomogeneous and the primary rocks of eclogites in this area appear to have undergone varying degree of crustal contamination. 相似文献
104.
Tin deposits are often closely associated with granitic intrusions. In this study, we analyzed tin partition coefficients between different fluids and melts (\({\text{D}}_{Sn}^{aq.fl./melt}\)) as well as various crystals and melts \({\text{D}}_{Sn}^{aq.fl./melt}\)(\({\text{D}}_{Sn}^{crystal/melt}\)) from the Furong tin deposit associated with the Qitianling A-type granite. Our experimental results indicate that tin partition behavior is affected by the chemical compositions of fluids, melts, and minerals. Tin is prone to partitioning into the residual magma in fractional crystallization or other differential magmatic processes if the magma originated from crustal sources with high alkali content, high volatile content, and low oxygen fugacity. Highly evolved residual peralkaline granitic magma enriched in tin can lead to tin mineralization in a later stage. Furthermore, the volatiles F and Cl in the magma play important roles in tin partitioning behavior. Low F contents in the melt phase and high Cl content in the aqueous fluid phase are favorable factors for tin partitioning in the aqueous fluid phase. High Cl content in the aqueous fluid catalyzes water–rock interaction and leads to the extraction of tin from tin-bearing minerals. All these findings support a hydrothermal origin for the tin deposits. In light of the geotectonic setting, petrochemical characteristics, and mineralizing physicochemical conditions of the Furong tin deposit, it is inferred that the ore-forming fluid of the Furong tin ore deposit could have derived from the Qitianling peralkaline intrusion. 相似文献
105.
吉林集安铅锌矿地球化学与分散元素 总被引:2,自引:0,他引:2
吉林集安铅锌矿床是我国最早报导的少数几个典型低温铅锌矿床之一。矿化具有多期次特点 ,富矿体都是多期次矿化叠加的产物。根据矿化先后和矿物生成顺序将矿化分为五个阶段 :①石英 黄铁矿矿化阶段 ;②重晶石 闪锌矿矿化阶段 ;③石英 方铅矿矿化阶段 ;④石英 黄铁矿矿化阶段 ;⑤碳酸盐 氧化矿物矿化阶段。用均一法和爆裂法测得石英、重晶石、闪锌矿包裹体成矿温度变化在 1 1 0℃~ 1 97℃之间。矿床中除含铅锌矿外 ,还有微量的Pt和Pd,并普遍含分散元素Cd、Ga、Tl、In、Se、Ge、Te,其中以Cd含量最高 ,闪锌矿中Cd含量最高可达 71 5 5× 1 0 6。分散元素主要呈类质同象形式赋存在各种矿物之中 ,未发现独立矿物。通过矿床地质和硫铅同位素研究表明该铅锌矿床属低温沉积 改造型层控矿床。 相似文献
106.
107.
High quality marine source rock (HQMSR) is the key prerequisite for medium to large hydrocarbon accumulations. However, the forming mechanism remains unclear. On the basis of the in-vestigation for the geodynamic setting of the Middle-Upper Yangtze during the Early Cambrian in dif-ferent spatial scales and the analysis of trace elements, the main controlling factors of the development of high quality marine source rock are discussed, with specific consideration of the burial rate of the organic matter. The ... 相似文献
108.
109.
银厂坡银矿床碳酸盐化蚀变作用与银的矿化富集在空间上紧密相伴,这种蚀变作用导致矿石与围岩中组分有明显差异。本文通过定量计算阐明组分之间的迁移方向;计算表明在银的原生富集过程中,常量组分的带入与带出最不明显;而微量组分Ag和Cu、Pb、Zn、As、Sb、Cd、Ge带入围岩明显。在银的次生富集过程表现为Ag和Cu、Pb、Cd、Ga、Ge、REE、AlO3、Fe2O3、MnO、K2O、P2O5的强烈带入,以Al2O3、Fe2O3、K2O、P2O5带入强度最大,这是由于CaO、MgO被淋滤,体积亏损造成强烈带入的假象,而As、Sb、Zn、V、Cr、Co、Ni、CaO、MgO为自围岩中带出组分,以CaO、MgO带出强度最大。REE除原生富集的弱蚀变白岩→矿化白云岩表现为带出外,其余原富集过程均表现为带入围岩。造成组分发生迁 相似文献
110.