Elemental geochemical records of seafloor hydrothermal activities in the sediments from the Okinawa Trough     

ZHAI Shikui  YU Zenghui  DU Tongjun 《海洋学报(英文版)》2007,26(4):53-62

The major and minor element contents in the sediment core H9 from the hydrothermal fields of the Okinawa Trough show a sharp change at the depth of 80 cm. The elements enriched in the upper 80 cm core are those enriched in the hydrothermal deposits and in the surface sediments recovered from the hydrothermal fields in the trough, which indicates the input of hydrothermal materials. Comparing with other hydrothermal sediments from Mid-ocean Ridges or the Lau Basin, the degree of the enrichment of elements iron, copper,cobalt, and nickel is relatively low. However, the enrichment of elements manganese, lead, arsenic, antimony and mercury is remarkable. The average contents of these elements in the upper 80 cm core sediments are three to six times those in the lower section, and 3~12 times those in the surface sediments which are not influenced by hydrothermal activities. Hydrothermal activities have contributed significant manganese, lead, arsenic, antimony and mercury to the sediments, and these elements are distinct indicators for the hydrothermal activity in the Okinawa Trough. The significant enrichment of these elements in Core H9 upward from the depth 80 cm indicates the start or the significant enhancing of the hydrothermal activity in this area at about 5 740 aB.P. The average accumulation rate of manganese during this period is about 40 461 μg/(cm2·ka), which is similar to the hydrothermal sediments in the Lau Basin or the East Pacific Rise.  相似文献   

莱州湾东部滨海砂金成矿远景初步分析     

刘洪树  姜玉池 《海洋地质与第四纪地质》1991,11(2):17-24

本文阐述了莱州湾东部滨海砂金的物源、地貌、水动力、第四系、新构造运动和海平面变化等成矿条件以及砂金的富集特点,对该区砂金的成矿远景进行了区划和评价,初步认为该区具有良好的砂金成矿远景。  相似文献   

Native aluminium (spherules and particles) in the Central Indian Basin sediments: Implications on the occurrence of hydrothermal events     

Sridhar D. Iyer  M.B.L. Mascarenhas-Pereira  B. Nagender Nath 《Marine Geology》2007,240(1-4):177-184

We have sampled particles of native aluminium (Al°) in two sediment cores from the Central Indian Basin (CIB). The cores are geographically separated but are located at the base of two seamounts. The native Al° particles occurring as grains and spherules, have an average Al content of  95% and are associated with volcanogenic–hydrothermal material. Morphologically and compositionally, the specimens are similar to those reported from the East Pacific Rise. After ruling out several processes for the presence of the native Al°, we hypothesize that during progressive melting of magma, a basaltic magma is produced which has high contents of reductants such as methane and hydrogen, and a low oxygen fugacity. During the upward migration of such magma, reduction to metallic aluminium and the formation of native Al° particles takes place.  相似文献   

莱州湾东部滨海水域砂金分布特征   总被引：1，自引：0，他引：1  

谭启新  姜玉池 《海洋地质与第四纪地质》1996,16(4):79-86

通过对莱州湾东部滨海水域地球物理和地质钻综合调查，业已查明该海区地质的构造和古地理环境特征，并发现区内砂金分布较普遍，本文从砂金分布的地貌单元，沉积物类型，砂金成因类型，物质来源，古气候，构造作用，砂金成因等诸方面，研究了该海域内砂金特征。  相似文献   

太平洋三海区热液烟囱物的氧同位素特征及形成温度     

WU Shi ying  LIU Yan guang  ZHANG Dao jian  BAI Li ming  WU Jun rui 《海洋科学进展》2001,(3)

使用氧同位素方法 ,测试了西太平洋马里亚纳岛弧、马里亚纳海槽、冲绳海槽和东太平洋加拉帕戈斯裂谷的海底热液烟囱和硫化物全岩样品。结果表明 :马里亚纳岛弧上的埃斯梅拉尔达破火山口的热液硫化物的形成温度最高 (达 2 75℃ ) ,而成为高温产物的代表 ;冲绳海槽和加拉帕戈斯裂谷烟囱 ,表现为中高温类型 ,其氧同位素温度在 1 5 0℃左右 ;马里亚纳海槽以蛋白石为主要矿物的烟囱物 ,则显示出典型的低温热液类型 ,少量黄铁矿砂试样则表现出中温类型特征。但上述区域大都不同程度地存在有闪锌矿、黄铁矿、黄铜矿等中高温热液矿物 ,说明研究区除马里亚纳海槽明显有中低温热液活动类型外 ,其它区域皆具备中高温热液活动特征  相似文献   

南极长城湾沉积物中的自然金     

王先兰 《海洋学研究》1991,9(1):33-37

作者在南极长城湾沉积物中首次发现金矿化、自然金和含金的碲、铋、锑化合物。本文着重报导了自然金特征、成色、共生矿物和物质来源等问题。  相似文献   

大西洋中脊热液硫化物的矿物学研究     

初凤友  陈丽蓉 《海洋地质与第四纪地质》1995,15(2):73-83

利用１９８９年在大西洋热液活动区采集的块状硫化物样品，采用矿相显微镜、电子显微镜和电子探针等手段，进行了矿物共生组合、矿物形态与成分标型及其演化特征研究。结果表明，大西洋热液成矿作用可以划分为热液期与沉积期两个成矿期，和石英－黄铁矿阶段、黄铁矿阶段、多金属硫化物阶段、胶状黄铁矿阶段和非晶质ＳｉＯ２阶段等５个成矿阶段；不同成矿阶段黄铁矿的共生矿物和矿物特征不同，在晶体形态上具有从单形晶－聚形晶－胶状  相似文献   

自组织竞争人工神经网络在砂岩型铀矿测井数据解释中的应用     

徐建国  ;吴显礼  ;王卫国 《国外铀金地质》2008,(2):114-118

详细介绍了自组织竞争人工神经网络模型结构、原理和钻孔岩性自动识别过程,给出了神经网络模型在钻孔岩性自动识别过程中的有效性实例。自组织竞争人工神经网络具有自组织能力、自适应能力和较高的容错能力;与BP算法相比较,计算量小,收敛速度快,且不需要已知的先验信息而自动确定分类类别。钻孔岩性识别结果与岩心地质编录的对比试验表明,在砂岩型铀矿测井数据的解释中,应用自组织竞争人工方法可较好地完成钻孔岩性自动分类。  相似文献   

福建安溪铅山铅锌矿床地质特征及成因探讨     

黄铁民 《福建地质》2008,27(2):186-194

铅山铅锌矿位于清流—安溪北西向断裂带与平潭—漳平东西向断裂带的复合部,闽中多金属矿化集中区南端的洛阳—剑斗东西向多金属成矿带中段,矿体贮存于北东向断裂破碎带中,为岩浆期后中低温热液矿床,控矿的北东向断裂带是多期次构造活动的产物,主成矿期为燕山早期,铅山周围尚有较大的找矿远景。  相似文献   

Decrepitation Thermometry and Compositions of Fluid Inclusions of the Damoqujia Gold Deposit,Jiaodong Gold Province,China:Implications for Metallogeny and Exploration   总被引：20，自引：0，他引：20  

Yang Liqiang  Deng Jun  Zhang Jing  Guo Chunying  Gao Bangfei  Gong Qingjie  Wang Qingfei  Jiang Shaoqing  Yu Haijun 《中国地质大学学报(英文版)》2008,19(4):378-390

The recently discovered Damoqujia (大磨曲家) gold deposit is a large shear zone-hosted gold deposit of disseminated sulphides located in the north of the Zhaoping (招平) fault zone, Jiaodong (胶东) gold province, China. In order to distinguish the temperature range of cluster inclusions from different mineralization stages and measure their compositions, 16 fluid inclusions and 5 isotopic geochemistry samples were collected for this study. Corresponding to different mineralization stages, the multirange peaks of quartz decrepitation temperature (250-270, 310-360 and 380-430℃(2) indicate that the activity of ore-forming fluids is characterized by multistage. The ore-forming fluids were predominantly of high-temperature fluid system (HTFS) by CO2-rich, and SO2-4-K type magmatic fluid during the early stage of mineralization and were subsequently affected by low-temperature fluid system (LTFS) of CH4-rich, and Cl--Na /Ca2 type meteoric fluid during the late stage of mineralization. Gold is transferred by Au-HS- complex in the HTFS, and Au-Cl- complex can be more important in the LTFS. The transition of fluids from deeper to shallow environments results in mixing between the HTFS and LTFS, which might be one of the most key reasons for gold precipitation and large-scale mineralization. The ore-forming fluids are characterized by high-temperature, strong-activity, and superimposed mineralization, so that there is a great probability of forming large and rich ore deposit in the Damoqujia gold deposit. The main bodies are preserved and extend toward deeper parts, thereby suggesting a great potential in future.  相似文献