全球现代海底块状硫化物战略性金属富集机理及资源前景初探

海底块状硫化物(SMS)蕴藏有丰富的Cu、Cd、Au、Fe、Ag、Co等战略性金属,是未来可供人类开发利用的战略资源.本文搜集了全球3 946组SMS化学成分数据,根据构造环境可将其分成4类(快速、中速、慢速、超慢速扩张)洋中脊型和2类(弧后扩张中心和弧火山)岛弧型SMS矿床.利用多元统计方法分析了SMS战略性金属的分布特征和主控因素,探讨了其资源前景.结果表明:洋中脊型SMS矿床富集Cu+Fe+Co±Mo,而岛弧型普遍富集Zn+Pb+Cd+Sb+Ag±Au等关键元素.分析表明,成矿温度、成矿物质来源、酸碱度和氧化还原条件是战略性金属富集的主要影响因素,其中流体温度主要受水深条件控制,成矿物质来源主要受控于构造地质环境,酸碱度和氧化还原性主要受控于围岩类型.Cu+Au+Fe+Co在水深超过约2 650 m的慢速—超慢速扩张脊非转换不连续带和拆离断层带等区域具较好的勘查前景;而Cu+Au+Cd+Ag在水深约1 080~2 160 m的弧后扩张中心区域具较好的勘查前景.      

Distribution of large-scale detachment faults on mid-ocean ridges in relation to spreading rates

Large-scale detachment faults on mid-ocean ridges （MORs） provide a window into the deeper earth. They have megamullion on their corrugated surfaces, with exposed lower crustal and upper mantle rocks, rela- tively high residual Bouguer gravity anomaly and P-wave velocity, and are commonly associated with ocean- ic core complex. According to 30 detachment faults identified on MORs, we found that their distances to the axis mostly range from 5 to 50 km, half-spreading rates range from 6.8 to 17 mm/a, and activity time ranges from recent to 3 Ma. Most of the detachment faults are developed on the slow spreading Mid-Atlantic Ridge （MAR） and ultra-slow spreading Southwest Indian Ridge （SWIRl, with the dominant half-spreading rates of 7-13 mm/a, especially 10-13 mm/a. Furthermore, they mostly occur at the inside corner of one segment end and result in an asymmetric seafloor spreading. The detachment faults on MORs are mainly controlled by the tectonism and influenced by the magmatism. Long-lived detachment faults tend to be formed where the ridge magma supply is at a moderate level, although the tectonism is a first-order controlling factor. At the slow spreading ridges, detachment faults tend to occur where local magma supply is relatively low, whilst at the ultra-slow spreading ridges, they normally occur where local magma supply is relatively high. These faults are accompanied by hydrothermal activities, with their relationships being useful in the study of hydrothermal polymetallic sulfides and their origin.     

“全新特提斯洋”概念与广义特提斯构造域

特提斯最初是指欧亚大陆南缘的古海洋,后逐渐引申出从元古宙、古生代到中生代的一系列位于劳亚大陆与冈瓦纳大陆之间的古大洋,如原特提斯洋、古特提斯洋和新特提斯洋,不同大洋在时间上前后交叠。如今横亘在冈瓦纳大陆(南极洲)和欧亚大陆之间的是印度洋,是新特提斯洋的继承者,可以另称为“全新特提斯洋”。这一概念的引申直接体现了印度洋与特提斯构造域一脉相承的关系,有助于将今论古、由此及彼,更直观地了解特提斯构造域的演化过程。本文按时间序列梳理了印度洋的大地构造演化和岩浆作用过程,识别了印度洋在155 Ma、120 Ma、90～84 Ma、76 Ma、65 Ma、52 Ma、45 Ma、38 Ma等关键时期的异常海底扩张记录,这些扩张事件将为标定新特提斯构造域的演化提供参照。其中155 Ma可能指示了新特提斯洋的鼎盛期,90 Ma指示了新特提斯洋的洋中脊俯冲,76～52 Ma是非洲-阿拉伯大陆与欧亚大陆初始碰撞-主碰撞(即新特提斯洋西部关闭)的时期,65～45 Ma是印度次大陆与欧亚大陆初始碰撞-主碰撞(即新特提斯洋中部关闭)的时期,38 Ma是澳大利亚北部大洋开始净俯冲(即新提斯洋东部开始消减)的时间。...     

Fractional crystallization processes of magma beneath the Carlsberg Ridge(57°–65°E)

Fractional crystallization of basaltic magma at variable depths in?uences strongly the geochemical compositions of mid-ocean ridge basalts(MORBs), especially at slow-spreading mid-ocean ridges. The Carlsberg Ridge is a typical slow-spreading ridge located in the northwestern Indian Ocean. In this study, we conducted petrological, geochemical and modelling studies of MORBs collected along the Carlsberg Ridge from 57°–65°E to understand the fractional crystallization processes of magma and the controls on variations in MORB geochemistry. Our results show that the mantle sources beneath the Carlsberg Ridge are heterogeneous even on the local scale of a segment; such heterogeneity may be ubiquitous beneath the Carlsberg Ridge. Mantle heterogeneity may be caused by the enriched components resulting in the "DUPAL" anomaly, whereas the ef fect of pyroxenite on mantle heterogeneity is negligible. The parental melts experienced crystallization of olivine, plagioclase and clinopyroxene prior to eruption, which played a signi?cant role in the major and trace element variations in MORBs from the Carlsberg Ridge. The liquid lines of descent(LLDs), deduced from the forward modelling of three parental magma compositions using the Petrolog3 program at pressures between 1 atm and 10 kbar, demonstrate that clinopyroxene joined the olivine and plagioclase cotectic. The over-enrichment in highly incompatible elements relative to LLDs may be caused by the processes of replenishment-tapping-crystallization in magma chambers. The calculated crystallization pressures suggest that parental magmas beneath the Carlsberg Ridge experienced moderateto high-pressure crystallization and that crystallization beneath the slow-spreading Carlsberg Ridge may start at upper mantle depths.     

Diagenetic reactions in reservoir strata and geochemical properties of pore fluid and its origin in Songliao Basin

The reservoirs of the SOngliao Basin are composed of typical unstable sandstones,with high percentages of volcanic fragments and feldspar,In the course of sedimentation and burying,a series of physical and chemical reactions took place between minerals and pore water and water-rock reactions and ion exchange caused changes in ion assemblage of pore water,Hydration-hydrolysis,dissolution and the albitization of feldspar made many ions free from their framework and inter into the pore water,and induced the precipitation of a large amount of authigenic minerals such as smectite and chlorite,During the diagenesis of sandstone.diagenetic reactions involved several stages with increasing depth,and so did the precipitation of authigenic minerals and the transformaiton of minerals.The migration of ions is related with the precipitation,transformation and dissolution of authigenic minerals.Thus,to deepen our study on sandstone diagenesis is an important link for the analysis of ion migration in the evolution of pore water ,the origin and evolution of pore water could be tracked in terms of the geochemistry of fluid inclusions in authigenic minerals.And the isotopic composition of the authigenic mineral calcite can provide its genetic information.     

答《关于深海锰结核中“纳米级超微生物化石”的思考和建议》一文

本文详细讨论了东太平洋深海锰矿结核中新发现的中华微放线菌和太平洋螺球孢菌究竟是不是超微结构，首先，它们是笔者根据形态，结构和元素成分作为超微生物化石进行鉴定的，其次，透射电子显微镜中可以清楚地区分出完整的微生物结构，包括菌丝，孢子，孢囊和菌落等，它们之间的尺寸比例也是适当的，此外，透射电子显微像还揭示，深海锰质叠层石的纹层就是这些超微生物韵律性生长的结果，与滨海叠层中的纹层十分相似，笔者认为，已知微生物的最小尺寸不能作为否定新发现的超微生物化石的依据。本文还讨论了超微生物化石的术语问题。     

东太平洋多金属结核的叠层石包壳及其沉积环境意义

对东太平洋C-C区深海多金属结核的叠层石包壳、多金属结核的表面类型及其分布规律进行了详细研究和合理解释,认为叠层石的形态学特征既是建造叠层石的微生物种类差异的表现,也是环境水动力条件和溶解氧含量不同的反映,这些因素共同决定了多金属结核的表面类型,而南极底流是造成海底水体能量环境、氧化还原电位和微生物种类变化的根本原因.为多金属结核的分布规律和成矿预测提供科学依据.     

MapGIS在菏泽市第二次土地调查中的应用

介绍了MapGIS在菏泽市第二次土地调查中的应用,通过使用MapGIS软件,查清了渮泽市各类用地的分布、面积、权属等基本情况,查清了各类不合理用地,掌握了土地利用动态变化趋势。同时对第二次土地调查数据库的应用方向及运用计算机纹理识别技术提高建库自动化提出合理化建议。     

Turbidite Events Recorded in Deep-sea Core IR-GC1 off Western Sumatra: Evidence from Grain-size Distribution

Sediment core IR-GC1, from the abyssal basin of the Indian Ocean off Sumatra, may provide important information on depositional events related to earthquakes and tsunamis. In this study, based on a combination of grain-size analysis with lithological studies and oxygen isotope stratigraphy, seven deep-sea turbidite layers were identified, corresponding to seven turbidity events that occurred at 128–130, 105–107, 98–100, 86–87, 50–53, 37–41 and 20–29 ka. The sediments of the turbidite deposits are characterized by coarse grain sizes, poor sorting, wide kurtosis, bimodal frequency distributions and clear depositional variations. Particle size grading is also an important signature of deep-sea turbidite deposits and can be used as an indicator to identify turbidite layers. Possible triggering mechanisms for the turbidite events include tsunamis, earthquakes, volcanic eruptions and sea-level changes.     

中印度洋脊Edmond热液区成矿流体属性与来源:来自流体包裹体和He-Ar同位素的证据

To understand the source and nature of the ore-forming fluids of the Edmond hydrothermal field on the Central Indian Ridge, we studied the He-Ar isotope composition and fluid inclusions of the hydrothermal precipitates.Our results show that the sulfide samples contain noble gases He, Ne, Kr, and Xe with their abundances in between those of air-saturated water(ASW) and mid-ocean ridge basalt(MORB). The ~3He/~4He ratio varies from1.3 to 8.7 R_a(n=10, average: 5.1 R_a), whereas the ~(40)Ar/~(36) Ar ratio is from 285.3 to 314.7(n=10, average: 294.8). These results suggest that the He was derived from a mixture of MORB with variable amounts of seawater, but the Ar in the ore-forming fluids trapped in the sulfides is predominantly derived from seawater. The fluid inclusions of barite have a wide range of homogenization temperatures and salinities varying from 163°C to 260°C and 2.6 wt%to 8.5 wt% Na Cl equiv., respectively. It is suggested that the ore-forming fluids were produced by phase separation, which agreed with the present-day vent fluid study.