四川盆地灯影组MVT型铅锌矿成矿金属元素的来源研究

四川盆地MVT型铅锌矿主要产于灯影组白云岩中,它们与古油(气)藏在空间上具有密切关系,显示出铅锌矿成矿与油气成藏紧密的成因联系.本次研究采用地质地球化学分析与扫描电镜观察相结合,对烃源岩和古油气藏中的沥青展开研究,揭示MVT型铅锌矿中成矿金属元素的物质来源.研究表明,与铅锌矿密切共生或伴生的油气藏的烃源岩主要为寒武系筇竹寺组(郭家坝组);部分烃源岩的Pb,Zn,Ba含量异常地高于地壳克拉克值,烃源岩中存在微米级的方铅矿、闪锌矿、黄铁矿和重晶石等,表明部分烃源岩具有为成矿提供金属元素的能力.MVT铅锌矿床中绝大部分沥青均具有异常高的Pb,Zn含量,沥青内也存在微米级的方铅矿、闪锌矿、黄铁矿、重晶石包裹物;沥青中的铅锌含量远高于MVT铅锌矿成矿流体所需要的铅锌含量,表明石油可能不仅起到了金属元素搬运载体的作用,油藏流体可能也是成矿流体.寒武系筇竹寺组(郭家坝组)泥质岩既是烃源岩层也是MVT矿源层,具有双源层特征.     

Water Soluble Gas in Deep Carbonate Reservoir,Sichuan Basin,Southwest China

Based on temperature and pressure of fluid inclusion,phase of organic inclusion in calcite and quartz filled in vug in the deep carbonate reservoir and the natural gas composition in Weiyuan (威远) gas field in Sichuan (四川) basin,research indicates that water soluble gas exists in deep carbonate reservoir,which reconstructs development and effusion process of water soluble gas.The overpressure formed during oil thermal cracking can reach 105-170 MPa in Sinian and Cambrian reservoir in Central Sichuan and 78-86 MPa in Cambrian reservoir in Southeast Sichuan.The high temperature caused by deep burial and overpressure caused by thermal cracking make thermal cracking gas dissolve in water so that it becomes water soluble gas.The ratios of gas to water can reach 50-90 m3/m3and 10-30 m3/m3,respectively,in deep carbonate reservoir in Central and Southeast Sichuan.Methane dissolving in water exists in form of liquid phase.Until now,the decreases in temperature and pressure due to the uplift during 74 Ma make water soluble gas separate from water,water soluble gas pool or mixed gas pool of thermal-cracking gas and water soluble gas are modified or even destroyed in varying degrees.This may be the case of Weiyuan gas field.     

滇西高原第四纪以来的隆升和剥蚀

由滇西高原内古夷平面的抬高、外流水系的河流阶地、高原外营歌海盆地和琼东南盆地的沉积响应,共同揭示滇西高原第四纪以来的快速隆升和剥蚀历史。第四纪以来滇西高原区域性抬升了610～700余米、被剥蚀了1095～1600m,其平均剥蚀速率为0．68～0．94mm／a。根据河流阶地计算出第四纪以来各时段的隆升速率;隆升在0．386～0．296Ma达到峰期,隆升速率为2．24～2．SOmm／a;1．6～0.647Ma隆升速率最缓慢为0．68～0．94mm／a。滇西高原第四纪以来的隆升量和隆升峰期与同期的青藏高原具有相似性,但隆升速率明显低于东喜马拉雅构造结的隆升速率。     

四川盆地威远气田和资阳含气区震旦系油气成藏差异性研究

本文通过对四川盆地元古宇-下古生界勘探最成功的两个地区--威远震旦系气田和资阳震旦系含气区天然气成藏要素和成藏过程的详细比较,得出 ①资阳含气区和威远气田的原始烃源相同,均是下寒武统生成的油裂解的天然气,不同的是资阳为残留的气顶气,威远是水溶气脱溶气.②资阳含气区和威远气田震旦系碳酸盐岩基质孔隙度相近,资阳地区溶蚀洞穴发育,但裂缝不发育,储层渗透性较差,非均质性强;威远地区储层洞穴不发育,但裂缝发育,形成统一的裂缝-孔洞系统.③威远地区具有统一的圈闭,闭合度高(800 m),闭合面积大(895 km2).资阳含气区不具有统一的圈闭,多为局部的小高点.④喜马拉雅期隆升作用使资阳统一含气区分散化和气藏变小,形成多压力系统的含气区;威远地区快速大幅度隆升, 溶于水中的天然气脱溶, 形成具同一压力系统的整装气田.⑤资阳含气区的成藏过程为 (资阳-威远)古油藏→原油裂解→气顶天然气→隆升调整→现今(残留)含气区,其天然气藏是隆升调整成藏,是在原古气藏的基础上改造残留而成;威远地区的成藏过程则是(资阳-威远)古油藏→原油裂解→天然气大量溶于水中→隆升使得带有大量天然气的水向威远运移和天然气脱溶→现今(新生)气藏,属天然气的脱溶成藏.资阳含气区受古构造的控制明显;威远气田则主要受今构造的制约.因此, 在四川盆地震旦系和下古生界的油气勘探中, 既要研究其古构造的特征和演化, 也要研究今构造的特征和分布规律, 才能发现不同类型的天然气藏.     

云南金顶超大型铅锌矿床的成矿地质背景

采用构造－沉积综合分析的方法，研究了金顶超大型铅锌矿床成矿的盆地、构造和深部地质背景。研究表明，控矿的古新世－中始新世盆地为走滑拉张盆地，研究区先后经历了古新世－中始新世早期的走滑和拉伸，中始新世－渐新世的挤压推覆和中新世的隆升和走滑，分析了盆地演化、沉积体系、同生断裂活动和逆冲推覆等对金顶超大型铅锌矿床的控制作用，探讨了可能的成矿过程。     

PALEOCENE—MIDDLE EOCENE DEXTRAL STRIKE-SLIP DEFORMATION AND ITS TECTONIC IMPLICATION IN THE WESTERN YUNNAN, CHINA

PALEOCENE—MIDDLE EOCENE DEXTRAL STRIKE-SLIP DEFORMATION AND ITS TECTONIC IMPLICATION IN THE WESTERN YUNNAN, CHINA     

Fluid flow and mineralization of Youjiang Basin in the Yunnan-Guizhou-Guangxi area,China

Comprehensive studies, based on isotope geochemistry of C, H, O, S and Sr, chronology, common element and trace element geochemistry of fluid inclusions for the epithermal Au, As, Sb and Hg deposits in the Youjiang Basin and its peripheral areas, suggested that the ore fluid was the basin fluid with abundant metallic elements and the large-scale fluid flow of the same source in the late Yenshan stage was responsible for huge epithermal mineralization and silicification. The ore fluid flowed from the basin to the platform between the basin and the platform and migrated from the inter-platform basin to the isolated platform in the Youjiang Basin. The synsedimentary faults and paleokast surface acted respectively as main conduits for vertical and lateral fluid flow.

     

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Geochemistry,U-Pb,Hf isotopic characteristics and geological significance of Zhalaxiageyong trachydacite in Tuotuohe area,Qinghai

The Zhalaxiageyong lead-zinc-copper polymetallic deposit is a typical porphyry deposit of the Tuotuohe area. Whole-rock geochemical analyses,Zircon U-Pb dating and Hf isotope analysis are undertaken for the ore host trachydacite with the aim of constraining its petrogenesis,magma source and regional tectonic setting.LA-ICP-MS zircon U-Pb dating indicates that the trachydacite was formed in 32. 68 ± 0. 50 Ma( MSWD =1. 6),i. e.,Oligocene. The trachydacite is rich in potassium and poor in Mg#( 5. 10-9. 70),belonging to the peraluminous shoshonite series. The rocks are enriched in LILE( large ion lithophile elements) Rb,Ba,K and LREE,depleted in HFSE( high field strength elements) Nb,Ta,P,Ti,with high Sr and low Y and Yb,having the characteristics of the C type adakite. It is calculated that the initial εHf( t) of the zircons range from-0. 92 to 2. 07 and their two-stage Hf model ages T_(DM2) range from 978 Ma to 1 169 Ma. The magma source should be mainly the partially melt mafic rocks of the thickened Middle Neoproterozoic lower crust of the Northern Qiangtang massif with the addition of ancient aluminosilica material in the melting process. The rocks formed in the tectonic setting of delamination of lithosphere and extension of the thickened crust. During the period of 40-32 Ma,large-scale potassium rich alkaline magmatism occurred in this area. The porphyry metallogenesis is related to the magmatic activities in this period.     

中国区域经济发展收敛的空间计量分析

通过空间计量经济学经济收敛标准分析方法的扩展,就中国240 个地级及以上城市的经济增长收敛性展开讨论。运用Moran's I 探讨中国区域经济空间相关模式与集聚,发现1990-2007 年间人均GDP水平显示出强烈的全局正自相关,且局部空间结构相对稳定,各城市要脱离原来的集群有一定困难。文章指出收敛标准分析存在错误方程设定,空间计量分析方法是合适的。空间计量分析结果表明中国城市间存在绝对β收敛,与非空间模型相比收敛速度显著提高且可信,空间因素在区域经济增长与收敛过程中起到重要作用。但敏感性分析显示,绝对收敛的同一稳态以及在空间上并不稳健。从机制看,中国城市间同时存在新古典增长理论和新增长理论所强调的趋同机制。最后,对促进绝对收敛的区域政策进行了讨论,并提出通过模拟经济收敛过程,是判断区域政策有效性的重要工具。