有机质萃取东川铜矿紫色泥砂质白云岩中铜的实验研究     

赵劲松  赵斌 《大地构造与成矿学》1996,20(3):238-245

对云南东川铜矿的紫色泥砂质白云岩进行了有机质萃取铜的实验。研究结果表明，有机质溶液从白云岩中萃取出的铜浓度大大低于矿区主要矿石沉淀所要求的最低浓度。白云岩中大量Ｃａ、Ｍｇ、Ｋ、Ｆｅ、Ｍｎ离子的存在，制约了成矿流体中有机和无机络合剂对岩石中铜的萃取能力。实验结果在一定程度上削弱了对白云岩是矿源岩说法的支持。  相似文献   

金属矿床中的有机物质：特征,分类方案与研究方法   总被引：5，自引：0，他引：5  

庄汉平  卢家烂 《地球科学进展》1996,11(4):372-377

金属矿床中的有机质具有重要的成因指示意义。从有机质赋存地层时代、岩性，有机质类型、丰度、来源和成熟度等方面总结了金属矿床中有机质的基本特征；提出了以干酪根、沥青和固体碳为端员组分的有机质三级分类方案；对目前所广泛采用的分子有机地球化学、有机岩石学、物理学和化学、稳定同位素、热力学平衡计算，以及有机质参与下的模拟实验等六种方法进行了评述  相似文献   

黔中沉积磷灰石的硫碳同位素及其地质意义   总被引：5，自引：0，他引：5  

陈其英  封兰英 《岩石学报》1996,12(4):594-597

本文研究了黔中磷块岩中磷灰石的结构硫同位素组成。磷灰石的δ３４Ｓ值为３４．２‰～４２．４‰，它高于同期海水的δ３４Ｓ（约３４．２‰），也高于共生的成岩黄铁矿的δ３４Ｓ（１５．４‰～１９．８‰），表明磷灰石形成于富有机质沉积物早期成岩作用硫酸盐还原带的最上部，其间同时伴有大量硫酸盐细菌的还原过程。磷灰石的碳同位素组成（δ１３Ｃ＝－３．６３‰～１．０‰），表明它含有微生物有机质分解演化而来的ＣＯ２－３，而磷灰石比胶结白云石更富集轻同位素则反映出沉积阶段生物作用的影响比成岩阶段更为明显  相似文献   

广东长坑金银矿床石英和方解石的地球化学特征     

张生  李统锦 《矿产与地质》1997,(6):397-402

石英和方解石是长坑金银矿床的主要脉石矿物，石英的自然热发光曲线为单峰型，方解石包括单峰型、双峰型和多峰型；石英、方解石的热发光强度和峰型与深度和矿化类型有关，可作为找矿标志。二者的稀土总量均很低，其中方解石的ＲＥＥ显著低于与岩浆热液有关方解石，而具有围岩侧分泌或加热大气水成因特点。碳、氧同位素特征也支持二者来源于沉积地层的观点。  相似文献   

同位素古温度与海平面变化的关系初探   总被引：5，自引：0，他引：5  

王兆荣  胡秀章 《地层学杂志》1997,21(4):289-292

用稳定同位素地球化学古温度的测定方法对北京周口店石笋进行氧、碳同位素测定，获得的古温度与年龄值与同期的海平面变化进行比较，表明古温度的变化与海平面变化密切相关。  相似文献   

Organic–mineral interactions in marine sediments studied using density fractionation and X-ray photoelectron spectroscopy     

Thorarinn S. Arnarson  Richard G. Keil 《Organic Geochemistry》2001,32(12):434

Interactions between organic matter (OM) and minerals are important for the preservation of organic material in marine sediments. Recent evidence suggests that these interactions may not be due to protection of the organic matter via simple sorption to minerals, but rather that the organic matter is acting as a glue between mineral particles resulting in aggregate formation. Density fractionation into multiple density intervals is a powerful approach for looking at the patchy nature of organic matter distribution (Bock, M.J., Mayer, L.M., 2000. Mesodensity organo-clay associations in a near-shore sediment. Marine Geology 163, 65–75), because isolates with varying organic matter loadings can be obtained. The aggregate surfaces can be examined using X-ray photoelectron spectroscopy (XPS), because this technique is restricted to the top 10 nm of the sample surface. XPS gives quantitative information on all the elements on the surface (except H and He) and, in addition, gives information on the chemical bonding of carbon and nitrogen. We used these techniques, along with more standard geochemical tools (CHN, surface area and amino acid analyses), to study a sediment sample of high organic matter content from the oxygen deficient zone off the western coast of Mexico. We found that amino acid composition indicates that the fractions get progressively more degraded as density increases, while the fraction of carbon bonded to oxygen suggests that the oxidation state of the organic matter is similar for all fractions. In addition, the comparison of surface carbon concentrations from XPS and OC:SA suggests that the OM is located in discrete spots on the surface and that as density increases (OC:SA decreases) the organic matter decreases in thickness while retaining the same proportional areal extent.  相似文献   

Palaeoproterozoic magnesite: lithological and isotopic evidence for playa/sabkha environments   总被引：2，自引：0，他引：2  

Victor A. Melezhik  Anthony E. Fallick  Pavel V. Medvedev  & Vladimir V. Makarikhin 《Sedimentology》2001,48(2):379-397

Magnesite forms a series of 1‐ to 15‐m‐thick beds within the ≈2·0 Ga (Palaeoproterozoic) Tulomozerskaya Formation, NW Fennoscandian Shield, Russia. Drillcore material together with natural exposures reveal that the 680‐m‐thick formation is composed of a stromatolite–dolomite–‘red bed’ sequence formed in a complex combination of shallow‐marine and non‐marine, evaporitic environments. Dolomite‐collapse breccia, stromatolitic and micritic dolostones and sparry allochemical dolostones are the principal rocks hosting the magnesite beds. All dolomite lithologies are marked by δ¹³C values from +7·1‰ to +11·6‰ (V‐PDB) and δ¹⁸O ranging from 17·4‰ to 26·3‰ (V‐SMOW). Magnesite occurs in different forms: finely laminated micritic; stromatolitic magnesite; and structureless micritic, crystalline and coarsely crystalline magnesite. All varieties exhibit anomalously high δ¹³C values ranging from +9·0‰ to +11·6‰ and δ¹⁸O values of 20·0–25·7‰. Laminated and structureless micritic magnesite forms as a secondary phase replacing dolomite during early diagenesis, and replaced dolomite before the major phase of burial. Crystalline and coarsely crystalline magnesite replacing micritic magnesite formed late in the diagenetic/metamorphic history. Magnesite apparently precipitated from sea water‐derived brine, diluted by meteoric fluids. Magnesitization was accomplished under evaporitic conditions (sabkha to playa lake environment) proposed to be similar to the Coorong or Lake Walyungup coastal playa magnesite. Magnesite and host dolostones formed in evaporative and partly restricted environments; consequently, extremely high δ¹³C values reflect a combined contribution from both global and local carbon reservoirs. A ¹³C‐rich global carbon reservoir (δ¹³C at around +5‰) is related to the perturbation of the carbon cycle at 2·0 Ga, whereas the local enhancement in ¹³C (up to +12‰) is associated with evaporative and restricted environments with high bioproductivity.  相似文献   

人类活动地全球碳循环的影响   总被引：11，自引：0，他引：11  

郑淑颖  管东生 《热带地理》2001,21(4):369-373

工业革命前，碳循环是碳在大气、海洋和陆地生态系统间的流动。工业革命以来，化石燃料的使用使贮存于地质碳库中的碳参与短期碳循环，因森林和草原开垦等土地利用增加的CO2排放量加重了大气的负担；另一方面造林和再造林形成CO2汇。大气CO2增加导致的气候变化反馈过程影响碳循环。文中提出从控制人类活动入手平衡全球碳循环的收支。  相似文献   

若尔盖RM孔有机碳、总氮和碳氮比值的垂直分布     

钱君龙  吉磊  王苏民 《山地学报》1996,(4)

分析了ＲＭ孔岩心样５９５个．孔内总有机碳含量ＴＯＣ变动范围较大，低者１—２％，高者１０—２０％；总氮含量ＴＮ多０．１—０．２％，少数０．４—０．８％；碳氮比值Ｃ／Ｎ较低（≤８）段属浅湖沉积，Ｃ／Ｎ较高（＞８）段属湖滨沼泽沉积；ＴＯＣ，ＴＮ和Ｃ／Ｎ明显有四个波动段．  相似文献   

安徽铜陵早二叠世茅口期Tubiphytes—叶状藻丘储集条件研究     

沈安江  鞠天吟 《海相油气地质》1996,1(2):47-51,T001

茅口期 Tubiphytes—叶状藻丘及其碳酸盐岩组合的储集空间类型包括孔隙、洞穴、缝隙和喉道,形成了孔隙—喉道型、裂隙—喉道型、孔洞—裂隙型等三种类型的储集空间结构。据孔隙度、渗透率、压汞等分析测试认为,叶状藻障积岩可以成为差的储集岩,而亮晶藻屑灰岩、生屑灰泥岩、Tubiphytes 粘结岩等均为非储集岩。研究区藻丘中含有大量的碳沥青(尤其是深埋溶孔中)也说明了在潜伏礁(丘)体中寻找良好油气储层的潜力是很大的。  相似文献