On the metal content and metal ion uptake of botanically specific peats and the derived humic acids     

Raymond Bonnett  Richard P.C. Cousins 《Organic Geochemistry》1987,11(6)

With respect to ten metals (Al, V, Cr, Mn, Fe, Co, Ni, Cu, Zn, Ga) which are continguous in the Periodic Table the natural metal content and the ability to take up metal ions has been determined for three peats of defined botanical origin, each peat being sampled at three different levels. A correlation is found between the natural metal content and botanical origin. Apart from aluminium, the concentration of individual metals increased in the series Sphagnum < fen sedge < reed, the increase being statistically significant (P = 0.001) for V, Mn, Co, Ni, and Ga and for the sum of the metal ions measured.No clear correlation emerged between botanical origin and metal uptake. The metal uptake by the humic acid derived from each peat sample was also determined, and correlated with the metal uptake of the source peat itself.In all the humic acid and peat metal-uptake experiments the selectivities were very similar. V, Cr, Cu, Ga were readily taken up while Mn, Co and Zn were consistently less preferred.  相似文献   

西藏纳木错过去200年来的环境变化^*   总被引：6，自引：6，他引：6       下载免费PDF全文

王荣  羊向东  朱立平 《第四纪研究》2006,26(5):791-798

文章通过纳木错浅钻沉积硅藻研究,结合青藏高原湖泊现代硅藻-电导率转换函数,对过去200年来的湖水盐度(电导率)变化进行了定量重建。纳木错在小冰期冷期为淡水环境;小冰期结束后,湖水盐度开始增加;至20世纪60年代中期以来,盐度增加幅度更加明显。过去100年来湖水盐度的增加与钻孔粒度变化所揭示的入湖径流量的增多,反映了增温背景下湖泊水文的响应特点。温度的上升,一方面引起了流域冰雪融水补给量的增加,但另一方面,湖泊水量平衡明显偏负,说明小冰期结束以来,尤其是最近40年,冰融水的增加并不足以弥补湖泊水量的负平衡。由此提出蒸发量在湖泊水量平衡中起重要作用,温度是影响湖泊水文变化的关键因子。区域湖泊综合对比结果进一步表明,不同湖泊盐度和水文变化趋势一致,反映了封闭湖泊对区域气候变化的共同响应特点。  相似文献   

The Neoproterozoic Mwashya–Kansuki sedimentary rock succession in the central African Copperbelt, its Cu–Co mineralisation, and regional correlations   总被引：1，自引：0，他引：1  

J.L.H. Cailteux  A.B. Kampunzu  C. Lerouge 《Gondwana Research》2007,11(3):414-431

Rocks of the Neoproterozoic Mwashya Subgroup (former Upper Mwashya) form the uppermost sedimentary unit of the Roan Group. Based on new field and drill hole observations, the Mwashya is subdivided into three formations: (1) Kamoya, characterized by dolomitic silty shales/siltstones/sandstones and containing a regional marker (the “Conglomerate de Mwashya” bed or complex); (2) Kafubu, formed by finely bedded black carbonaceous shales; and (3) Kanzadi, marked by feldspathic sandstones. Rocks of the Mwashya Subgroup are overlain by the Sturtian age Grand Conglomérat diamictite (equivalent to the Varianto/Brazil and Chuos/Namibia diamictites), and conformably overlie rocks of the Kansuki Formation (former Lower Mwashya), a carbonate unit containing volcaniclastic beds. New geochemical data confirm the continental rift context of this magmatism, which is contemporaneous with rift-related volcanism of the Askevold Formation (Nosib Group, Namibia). A gradational lithological transition between rocks of the Kansuki and the underlying Kanwangungu Formations, and similar petrological composition of these two formations, support the hypothesis that the Kansuki is the uppermost unit of the carbonate-dominated Dipeta/Kanwangungu sequence, and does not form part of the Mwashya Subgroup. Base metal deposits, mostly hosted in rocks of the Kansuki Formation, include weakly disseminated early-stage low-grade Cu–Co mineralisation, which was reworked and enriched, or initially deposited, by metamorphic fluids associated with the Lufilian orogenic event.  相似文献   

Metallogenic mechanism of cobalt in the Zhuchong cobalt -rich skarn iron deposit in the Middle -Lower Yangtze River Valley Metallogenic Belt: Constrained by in -situ sulfur isotopes and zircon U-Pb datingSCIEI北大核心CSCD     

Liang Xian  Wang FangYue  Zhou TaoFa  Wei ChangShuai  Zhang Long  Guo XianZheng  Zhang Kun 《岩石学报》2023,(10):3015-3030

Cobalt, being a vital strategic rare and precious metal, is primarily produced within diverse deposit types through co association. The cobalt -rich skarn iron deposit is a key deposit type with considerable development potential. However, the source and enrichment mechanism of cobalt in skarn iron deposit remain unclear. The Zhuchong cobalt -rich skarn iron deposit is located in the Anqing-Guichi district of the Middle -Lower Yangtze River Valley Metallogenic Belt ( MLYB). It is the first large-scale skarn iron -rich deposit discovered in the metallogenic belt in recent years. Its associated cobalt resources have reached a medium scale. Meanwhile, the cobalt grade in the Zhuchong cobalt -rich skarn iron deposit is the highest among similar deposits in the MLYB, reaching 190g/t. In this study, the zircon U-Pb dating of the ore -forming intrusions and the spatial variation of pyrite in -situ sulfur isotopes in the vertical direction ( drilling section) of the Zhuchong cobalt -rich skarn iron deposit were carried out. The results indicate that the U-Pb ages of the two deep concealed magmatic rock samples are 139. 6 +/- 1. 0Ma and 138. 9 +/- 0. 6Ma, respectively, which occurred during the Early Cretaceous. Vertically, the overall range of pyrite sulfur isotope is +5. 3%similar to + 13. 9%o, and delta S-34 varies greatly from top to bottom, and shows strong heterogeneity, which is obviously different from the sulfur isotope compositions of Anqing skarn Cu -Fe deposit. The pyrite delta S-34 in the cobalt -rich magnetite ore body in the bottom -up mineralization -alteration zone of the Zhuchong deposit ranges from 5. 3%o to 10. 0%o. In the diopside skarn belt near the ore, the delta S-34 range of the vein pyrite spans from 12. 1%o to 13. 9%o. Within the altered diorite, the delta S-34 values of vein pyrite vary from 7. 1%o to 10. 8%o. In the outer skarn, the delta S-34 range of vein pyrite ranges fall between 6. 8%o and 7. 6%o. Within the siltstone of the Yueshan Formation, located in the gypsum -bearing salt layer, the delta S-34 values of pyrite range from 12. 0%o to 12. 7%o. Similarly, the uppermost siltstone vein pyrite of the Tongtoujian Formation exhibits a delta S-34 range of 6. 1%o to 7. 8%o. The sulfur isotope composition of pyrite within the Zhuchong cobalt -rich magnetite ore exhibits an intermediate range between that of the Yueshan pluton and the gypsum -salt layer of the Yueshan Formation. This suggests that the sulfur isotope signature within the ore reflects a mixture of two distinct end members. Statistical analysis of scale and grade within the MLYB cobalt -rich skarn deposits ( Fe -Cu -Co) indicates no apparent correlation between cobalt mineralization and the type of Fe -Cu skarn deposits. Furthermore, the involvement of sulfur through the gypsum -salt layer in the ore -forming hydrothermal fluid does not exhibit a discernible  相似文献   

Impacts of Indian summer monsoon and stratospheric intrusion on air pollutants in the inland Tibetan Plateau     

Xiufeng Yin  Shichang Kang  Benjamin de Foy  Dipesh Rupakheti  Maheswar Rupakheti  Zhiyuan Cong  Xin Wan  Guoshuai Zhang  Qianggong Zhang 《地学前缘(英文版)》2021,12(6):294-298

Air pollutants can be transported to the pristine regions such as the Tibetan Plateau,by monsoon and stratospheric intrusion.The Tibetan Plateau region has limited local anthropogenic emissions,while this region is influenced strongly by transport of heavy emissions mainly from South Asia.We conducted a comprehensive study on various air pollutants(PM2.5,total gaseous mercury,and surface ozone)at Nam Co Station in the inland Tibetan Plateau.Monthly mean PM2.5 concentration at Nam Co peaked in April before monsoon season,and decreased during the whole monsoon season(June-September).Monthly mean total gaseous mercury concentrations at Nam Co peaked in July and were in high levels during monsoon season.The Indian summer monsoon acted as a facilitator for transporting gaseous pol-lutants(total gaseous mercury)but a suppressor for particulate pollutants(PM2.5)during the monsoon season.Different from both PM2.5 and total gaseous mercury variabilities,surface ozone concentrations at Nam Co are primarily attributed to stratospheric intrusion of ozone and peaked in May.The effects of the Indian summer monsoon and stratospheric intrusion on air pollutants in the inland Tibetan Plateau are complex and require further studies.  相似文献   

东昆仑中东段驼路沟钴（金）矿床钠铁矾的识别及其指示意义     

牛斯达  吴华英  牛向龙  王英超  白生龙  陈家浩  张敏  莫凌超 《矿床地质》2022,41(6):1232-1244

黄钾铁矾族矿物是干旱地区硫化物矿床氧化带中常见的表生矿物,是重要的示矿标志,其详细研究可以为解剖与之相关矿床的次生富集过程提供重要依据。东昆仑中东段驼路沟钴（金）矿床主要出露一套纳赤台群哈拉巴依组变火山-沉积岩,其中的石英钠长石岩是重要的含矿主岩,前人认为其为一套热水喷流沉积岩,并由此提出驼路沟为喷流沉积型钴（金）矿床。文章重点选择矿区内玉女沟矿段的黄褐色-赤红色土状-块状破碎氧化带为研究对象,通过野外地质调查、显微观察、扫描电镜、全成分分析、电子探针和X射线衍射技术,揭示氧化带中主要矿物有钠铁矾、白云母、钠长石、石英、石膏和赤铁矿,其中以钠铁矾发育为显著特征。矿区发育的黄铁矿和石英钠长岩在氧化淋滤过程中析出的S、Fe、Na为钠铁矾的形成提供了物质来源,钠铁矾可作为指示高原干旱地区热水喷流沉积型矿床氧化带的标型矿物。  相似文献   

Evaluation of the oil and gas preservation conditions,source rocks,and hydrocarbon-generating potential of the Qiangtang Basin: New evidence from the scientific drilling project     

《China Geology》2023,6(2):187-207

The Qiangtang Basin of the Tibetan Plateau, located in the eastern Tethys tectonic domain, is the largest new marine petroliferous region for exploration in China. The scientific drilling project consisting primarily of well QK-1 and its supporting shallow boreholes for geological surveys (also referred to as the Project) completed in recent years contributes to a series of new discoveries and insights into the oil and gas preservation conditions and source rock evaluation of the Qiangtang Basin. These findings differ from previous views that the Qiangtang Basin has poor oil and gas preservation conditions and lacks high-quality source rocks. As revealed by well QK-1 and its supporting shallow boreholes in the Project, the Qiangtang Basin hosts two sets of high-quality regional seals, namely an anhydrite layer in the Quemo Co Formation and the gypsum-bearing mudstones in the Xiali Formation. Moreover, the Qiangtang Basin has favorable oil and gas preservation conditions, as verified by the comprehensive study of the sealing capacity of seals, basin structure, tectonic uplift, magmatic activity, and groundwater motion. Furthermore, the shallow boreholes have also revealed that the Qiangtang Basin has high-quality hydrocarbon source rocks in the Upper Triassic Bagong Formation, which are thick and widely distributed according to the geological and geophysical data. In addition, the petroleum geological conditions, such as the type, abundance, and thermal evolution of organic matter, indicate that the Qiangtang Basin has great hydrocarbon-generating potential.©2023 China Geology Editorial Office.  相似文献   

Luminescence dating of shoreline sediments indicates a late deglacial lake-level rise of Selin Co on the central Tibetan Plateau     

《Quaternary Geochronology》2022

The palaeo-shorelines around the lakes on the Tibetan Plateau can be used to reconstruct water level variations, which serve as sensitive indicators of hydroclimate change. Extensive studies have been carried out to constrain the Holocene lake level fluctuations by dating shorelines with a variety of methods (e.g., luminescence, ¹⁴C, ¹⁰Be and U–Th series). In comparison, the timing of the lake level variations during the last glacial and subsequent deglaciation periods has been rarely studied. The driving factors of such changes, therefore, remain elusive. In this study, we performed a detailed luminescence dating investigation on six samples taken from a nearshore sedimentary outcrop in the south of Selin Co basin. The post-IR IRSL signals measured at 225 °C (pIRIR₂₂₅) on sand-sized K-feldspar grains demonstrated a generally good behavior and yielded reliable chronologies, while the optically stimulated luminescence (OSL) signals of quartz showed systematical age underestimation, which was attributed to anomalous fading. Six pIRIR₂₂₅ ages ranging from 15 to 10 ka suggested that the lake level of Selin Co during the last deglaciation reached up to 40–45 m high above the modern lake level. In view of the regional precipitation and temperature proxy records, we consider that the glacier meltwater supply has likely been the primary contributor to the lake highstands during the last deglaciation.  相似文献   

富钴结壳地球化学与古海洋学研究进展   总被引：7，自引：0，他引：7  

蔡毅华  黄奕普 《台湾海峡》2002,21(2):258-264

本文综述了近年来国内外富钴结壳地球化学与古海洋学研究的新进展，概述了富钴结壳地球化学的研究成果，阐述了富钴结壳中元素的扩散及与周围海水的交换，基岩和磷酸盐化事件对富钴结壳组成的影响，分别介绍了稳定同位素（Pb,Nd和Hf的稳定同位素），放射性同位素（Be,U和Th的放射性同位素）及元素（常量和微量元素，稀土元素）在富钴结壳古海洋学研究上的应用。  相似文献   

南海北部边缘盆地天然气成因类型及气源构成特点   总被引：12，自引：3，他引：9  

何家雄姚永坚  刘海龄万志峰 《中国地质》2008,35(5):1007-1016

南海北部边缘盆地油气地质现象丰富多彩,天然气成因类型及分布规律复杂。根据该区天然气勘探及研究程度,迄今为止勘探所发现烃类天然气可划分为生物气及生物-低熟过渡带气（亚生物气）、成熟-高熟油型气及煤型气以及高熟-过熟天然气等3大成因类型;非烃天然气CO2可划分为壳源型（有机/无机）、壳幔混合型及幔源型等3型4类。生物气及亚生物气在莺—琼盆地及珠江口盆地浅层广泛分布,气源来自上新统及第四系海相沉积;成熟油型气主要分布于北部湾、琼东南东北部及珠江口盆地,气源来自始新统中深湖相偏腐泥型烃源岩;成熟-高熟煤型气及高熟-过熟天然气,则主要展布于莺—琼盆地及珠江口盆地部分地区,前者气源主要由渐新统煤系和中新统海相偏腐殖型烃源岩所供给,后者气源则来自不同类型高熟-过熟烃源岩。CO2则主要富集于莺歌海盆地泥底辟带浅层及琼东南盆地东部和珠江口盆地部分区域,气源分别来自受泥底辟热流体活动影响强烈的中新统海相含钙砂泥岩和深部地幔活动。  相似文献