遥感岩性识别研究的发展趋势--遥感与航空放射性信息集成

岩石的吸收光谱主要是由杂质、包体、蚀变及替代成分产生的,每种岩石都难以形成象它的组成成分那样具有可分辨的很清晰的光谱特征;不同类型的岩石放射性元素的含量和分布特征是不同的,岩石放射性信息是岩性识别研究的重要判据。遥感与航空放射性信息的集成．既能提取光谱图像中的光语信息和空间纹理信息。又可利用航空放射性信息常常具有的甚至是诊断性的岩性识别能谱标志。能明显提高识别岩性的精度,更重要的是能谱不受值被的影响,有利于识别植被覆盖区的岩性。因此,这可能是遥感岩性识别研究的发展趋势之一。     

新疆玛因鄂博断裂带中花岗质糜棱岩锆石U-Pb SHRIMP和黑云母40Ar-39Ar年龄及意义

玛因鄂博断裂带具有左型剪切活动特征,分布其中的花岗质糜棱岩呈脉状、条带状产出,展布方向与剪切拉伸方向一致,为同构造花岗岩。其岩石化学为高钾钙碱性系列,属后碰撞“I”型花岗岩;稀土元素含量较高,ΣREE为(239.14~266.31)×10-6;具有中等程度的铕负异常,δEu为0.45~0.66,轻稀土明显富集。其锆石U-PbSHRIMP年龄为281±4Ma,黑云母40Ar-39Ar等时线年龄为236.1±1.2Ma。二者分别代表岩石的侵入年龄和后期的剪切变形年龄。其形成与早二叠世区域性大规模剪切活动有关,而黑云母40Ar-39Ar等时线年龄代表中三叠世早期的剪切变形活动。结合前人资料分析,玛因鄂博断裂的剪切活动持续时间较长,高峰期可能为290~270Ma,而其最后结束时间为230Ma左右。     

加快南方油气勘探的几点认识

南方石油地质条件“先天国内第一，后天国内最差”。南方未变质的沉积岩自晚元古代的震旦纪至新生代的第三纪沉积齐全，厚度很大，油源丰富，油气苗遍布，含油气远景乐观。但由于印度、欧亚和太平洋三大板块的活动，受力交点在南方，且构造运动强烈、断层密集、强度又大，勘探条件极为困难，风险大，南方具有勘探价值的地区有十七块。即阜阳黄口、合肥、苏经－同、皖南、萍乡－乐平、弋阳－吉安、浙闽东部火山岩覆盖区、江汉、秭归、     

新疆阿合奇县布隆石英重晶石脉型金矿地质特征和硫、氦、氩同位素研究

位于新疆西南天山阿合奇县的布隆金矿赋存于上泥盆统细碎屑岩中,金矿体受层间缓倾斜破碎带控制,矿区内发育重晶石脉、石英大脉、石英重晶石脉,但金矿体只产于石英重晶石脉中,为一种比较少见的石英重晶石脉型金矿床。矿石中黄铁矿的 δ~(34)S 值变化于14.6‰～19.2‰,重晶石的 δ~(34)S 值介于35.0‰～39.6‰,反映硫来自于地层。黄铁矿流体包裹体的~3He/~4He 比值为0.24～0.82 R/Ra,趋近于地壳特征值。~(40)Ar/~(36)Ar=338～471,略高于大气氩的同位素组成。~(40)Ar/~4He 比值0.015～0.412,平均为0.153,与地壳~(40)Ar/~4He 比值(0.156)一致。成矿流体的He、Ar 同位素组成特征反映了成矿流体主要来源于地壳。     

赛坝沟金矿成矿特征及控矿条件

通过对青海赛坝沟岩金矿床的地质特征及其成矿地质条件的研究,笔者认为该矿床的成因类型为“与岩浆侵入及火山岩有关的中温热液矿床”。     

滩间山金矿矿床成因初步探讨

本文通过对滩间山矿区地层、构造及岩浆岩与成矿关系的研究,认为中元古界万洞沟群是金的矿源层;成矿构造具有多期次、多阶段活动的特点,矿体受单一及复合型式的构造控制;华力西期侵入体对成矿作用仅体现于为矿床的形成与再造提供热源。矿质在弱酸—中偏碱性溶液中,主要呈硫络合物的形式搬运、并在还原条件下成矿。特别指出,含磷质物地层是区内重要的岩金找矿标志之一。     

Cooling rates of type I chondrules from Renazzo: Implications for chondrule formation

Cooling rates are one of the few fundamental constraints on models of chondrule formation. In this study, we used Cu and Ga diffusion profiles in metal grains to determine the cooling rates of type I chondrules in the Renazzo CR2 chondrite. To improve previous estimations of cooling rates obtained using this method, we used CT scanning and serial polishing of our sections to analyze equatorial sections of large metal grains. Through the cores of these metal grains situated at the surface of chondrules, the cooling rates calculated range from 21 to 86 K h⁻¹ for a peak temperature T_p ~ 1623–1673 K. A metal grain embedded in the core of a chondrule exhibits a cooling rate of 1.2 K h⁻¹ at a T_p ~ 1573 K. We also measured Cu-Ga diffusion profiles from nonequatorial sections of metal grains and calculated a lower range of cooling rates of 15–69 K h⁻¹ for T_p ~ 1473–1603 K compared to our results from equatorial sections. The high cooling rates inferred from the lightning model (several thousand K h⁻¹) are clearly at odds with the values obtained in this work. The X-wind model predicts cooling rates (~6–10 K h⁻¹) lower than most of our results. The cooling rates calculated here are in close agreement with those inferred from shock wave models, in particular for temperatures at which olivine crystallizes (from ~10 to several hundreds K h⁻¹ between 1900 and 1500 K). However, the chemical compositions of metal grains in Renazzo are consistent with the splashing model, in which a spray of metal droplets originated from a partially molten planetesimal. Volatile siderophile element depletion is explained by evaporation before metal was engulfed within silicate droplets. Liquid metal isolated from the liquid silicate crystallized during cooling, reacted with the ambient gas, and then re-accreted within partially molten chondrules.     

西藏冈底斯成矿带达布矿区色日普金矿流体包裹体研究

色日普金矿位于西藏冈底斯成矿带中段达布斑岩铜钼矿床外围。本文对该矿床矿体中赋存于含矿石英脉中的流体包裹体进行了岩相学、显微测温、激光拉曼探针以及氢氧同位素分析。研究表明:与成矿有关的流体包裹体可以分为3个大类和5个亚类;流体包裹体均一温度变化范围为117~377℃,流体盐度范围为2.57%~45.59%NaCleqv,成矿流体早期为高温、高盐度的H2O-NaCl-CO2体系,成矿期为中高温、中盐度H2O-NaCl-CO2体系,成矿晚期为中低温H2O-NaCl体系;成矿期流体包裹体气相成分除CO2外,还含少量CH4、N2等。据测温结果估算的成矿压力为120~130 MPa。通过对该矿区石英和硅化脉石英流体包裹体研究得出成矿流体主要来源于大气降水和具有显著岩浆贡献的携带金属成矿物质的热液混合的产物。     

Tectonics and Petroleum Potential of the East China SeaShelf Rift Basin

There are two Cenozoic sedimentary basins in the East China Sea. They are the East China Sea shelf basin and the Okinawa Trough basin. The former can be divided into a western and an eastern rift region. The development of the shelf basin underwent continental-margin fault depression, post-rift and then tectonic inversion stages. Available exploration results show that the distribution of source rocks is controlled by the basin architecture and its tectonic evolution. In the Xihu depression, mudstones and coals are the main source rocks. The eastern rift region has good geological conditions for the formation of large oil and gas fields.