齐大山铁矿黑云变粒岩单锆石年龄及意义   总被引：3，自引：1，他引：3  

王守伦  张瑞华 《矿床地质》1995,14(3):216-219

齐大山特大型鞍山式铁矿的成矿时代，以往都是根据铁矿的构造和建造特征，以及与铁矿伴生的花岗岩类岩体的同位素年龄数据间接推断的。本文最近获得了该铁矿的黑云变粒岩中，单颗粒锆石Ｕ－Ｐｂ同位素年龄为（２５３３±５３）×１０￣６ａ。这是迄今为止研究该矿床成矿时代较为可靠的直接测年数据。  相似文献   

广东兴宁铁山嶂铁矿床地质特征及成因探讨     

黄云皇 《地质论评》1993,39(1):23-30

本文讨论了矿区夕卡岩和铁矿成因。夕卡岩主要受围岩岩性控制,有固定的层位,属层控夕卡岩。铁矿赋存于有火山岩、含泥镁质灰岩夹层的碎屑岩中,受地层、岩性控制。它是在沉积或火山—沉积作用的基础上,经过改造而成的矿床。矿床具多层性,矿体呈层状、顺层整合产出。它们不论沿走向还是向深部延伸都受一定地层层位和岩性控制。属沉积或火山—沉积热变质改造的层控矿床。  相似文献   

海洋沉积物可溶铁测定条件的探讨     

陈荣星  王维法  何琳琳  吴金珍 《上海国土资源》1993,(4)

海洋沉积物可溶铁Fe~(3+)/Fe~(2+)比值,已被海洋地质工作者作为海洋油气化探的一项间接指标应用于东海油气化探中。这种铁的含量受提取酸的种类、浓度、样品微沸时间、放置时间等条件的影响。必须采用统一的可溶铁测定方法,只有在同一标准条件下测定的海洋沉积物可溶铁结果才有对比意义。  相似文献   

凉山州富铁矿资源的分布及开发     

陈广蓉  汪成开 《四川地质学报》1993,(1)

凉山州境内的富铁矿按成因可分为火山型、热液型、沉积变质型、沉积型等类型,本文逐一对其分布、地质特征及规模等方面进行了叙述和总结;对主要富铁矿产地和储量作了统计,并介绍了主要矿区开发现状及经济效益。提出了今后矿山开发、资源保扩及寻找富铁矿的建议。  相似文献   

Stable Eocene Magnetization Carried by Magnetite and Iron Sulphides in Marine Marls (Pamplona-Arguis Formation,Southern Pyrenees,Northern Spain)     

Larrasoaña  J.C.  Parés  J.M.  Pueyo  E.L. 《Studia Geophysica et Geodaetica》2003,47(2):237-254

In order to establish the magnetic carriers and assess the reliability of previous paleomagnetic results obtained for Eocene marine marls from the south Pyrenean basin, we carried out a combined paleo- and rock-magnetic study of the Pamplona-Arguis Formation, which crops out in the western sector of the southern Pyrenees (N Spain). The unblocking temperatures suggest that the characteristic remanent magnetization (ChRM) is carried by magnetite and iron sulphides. The ChRM has both normal and reversed polarities regardless of whether it resides in magnetite or iron sulphides, and represents a primary Eocene magnetization acquired before folding. Rock magnetic results confirm the presence of magnetite and smaller amounts of magnetic iron sulphides, most likely pyrrhotite, in all the studied samples. Framboidal pyrite is ubiquitous in the marls and suggests that iron sulphides formed during early diagenesis under sulphate-reducing conditions. ChRM directions carried by magnetic iron sulphides are consistent with those recorded by magnetite. These observations suggest that magnetic iron sulphides carry a chemical remanent magnetization that coexists with a remanence residing in detrital magnetite. We suggest that the south Pyrenean Eocene marls are suitable for magnetostratigraphic and tectonic purposes but not for studies of polarity transitions, secular variations and geomagnetic excursions, because it is difficult to test for short time differences in remanence lock-in time for the two minerals. The presence of iron sulphide minerals contributing to the primary magnetization in Eocene marine marls reinforces the idea that these minerals can persist over long periods of time in the geological record.  相似文献   

陇西民和黄土CaCO3和有机碳总量的含量变化及其气候指标的局限性   总被引：4，自引：0，他引：4       下载免费PDF全文

谢远云  李长安周 嘉殷鸿福 《中国地质》2003,30(1):99-104

民和黄土地处黄土高原与青藏高原东北缘的交接部位,对气候反应较敏感,对该黄土1.87-0.70Ma BP段进行了CaCO3和有机碳总量（TOC）的采样分析。民和黄土CoCO3含量在5.89%-18.63%之间变化,平均11.41%;有机碳含量较低,在0.007%-0.452%之间,平均0.088%。民和黄土中的CaCO3含量明显高于兰州、洛川和西安等地,而有机碳含量则远低于上述地区。黄土中CaCO3和有机碳含量变化反映了该区1.87Ma BP以来气候变干冷的趋向。分别受复杂的CaCO3来源与类型、困难的采样、地区上的差异对比等和有机碳保存条件、沉积速率以及“埋藏效应”的影响,黄土中的CaCO3和有机碳的波动变化作为气候变化的替代性指标存在一定的局限性。文章最后指出,在实际应用中,黄土（特别是黄土高原西北部）中CaCO3和有机碳气候指标应结合其他环境指标共同使用,才能从中提取正确的古气候信息。  相似文献   

五台山区构造对铁矿的控制规律浅析   总被引：2，自引：2，他引：0       下载免费PDF全文

李朝辉  张文亮 《地质找矿论丛》2002,17(3):191-194,202

五台山区富含铁矿资源。区域构造以多期次运动叠加的褶皱为主,后期构造对前期构造进行了改造。构造外貌总体呈“之”字型展布。区域构造以及其次级构造对矿体（床）有明显的控制作用,表现为区域构造控制矿体（床）的分布,二级构造控制矿体（床）的形态,三级以下构造对矿体（床）起局部控制或改造作用。区域铁矿床亦受“之”字型的控制。  相似文献   

Geochemistry of ice-covered, meromictic Lake A in the Canadian High Arctic     

John A. E. Gibson  Warwick F. Vincent  Patrick Van Hove  Claude Belzile  Xioawa Wang  Derek Muir 《Aquatic Geochemistry》2002,8(2):97-119

The geochemical processes occurring within meromictic Lake A (maxdepth 120 m) on northern Ellesmere Island, Canada, were investigated to determinethe history of the lake and to provide a baseline for future studies. The lake contained seawaterdiluted by freshwater input that had been mixed prior to the lake's isolation from tidalaction. Input of freshwater after isolation of the lake created vertical stratification resultingin the creation of distinct oxic, suboxic and anoxic zones. Dissolved oxygen was present to 13 m,and sulphide beneath 32 m. Manganese and iron cycling dominated the redox chemistrybetween these depths. Total manganese concentrations reached 176 M, higher thanin most other natural stratified lake or marine environments.  相似文献   

The Influence of Oxalate on Fe-Catalyzed S(IV) Oxidation by Oxygen in Aqueous Solution     

A. Wolf  F. Deutsch  P. Hoffmann  H. M. Ortner 《Journal of Atmospheric Chemistry》2000,37(2):125-135

This study demonstrates that oxalate has a strong inhibiting effect onFe-catalyzed S(IV) oxidation by oxygen in aqueous solution. While thepseudo-first order rate constant of S(IV) oxidation was determined to be1.6 × 10³ M^-1 s^-1 in experimentswithout oxalate, the oxidation of S(IV) was totally inhibited at a molarconcentration ratio of iron:oxalate = 1:5 at an oxalate concentration of 4M. Under these conditions, the Fe(II)/Fe(III) ratio remained nearlyconstant during the observed reaction time. The determined rate constants wereindependent of the initial oxidation state of iron. However, with increasingconcentrations of oxalate, a longer induction period is observed forexperiments with iron initially in the Fe(II) oxidation state.  相似文献   

A Basic Water Quality Model for the River Neckar: Part 2 – model‐based analysis of the oxygen budget and scenarios     

Ingo Haag 《洁净——土壤、空气、水》2006,34(6):549-559

In this paper the Basic Water Quality Model (BWQM) for the central part of River Neckar is used to analyse the oxygen budget and to assess the potentials of various measures to prevent or mitigate critical dissolved oxygen (DO) declines. It is shown that the oxygen budget is mainly governed by phytoplankton dynamics. The excessive growth of algae and the sudden break down of the resulting algal blooms may cause episodic DO depressions. Therefore, to stabilise the oxygen budget in a sustainable way, eutrophication has to be controlled within the central part of River Neckar and the upstream regions. The only feasible way to reach this goal appears to be a further drastic reduction of phosphorus emissions. In addition, it is indispensable to hold the very high standards of biochemical oxygen demand and ammonium retention at the wastewater treatment plants. A worse performance of the treatment plants would dramatically aggravate critical DO declines which may be caused by algae dynamics. As long as the oxygen budget is not completely stabilised, weir and turbine aeration can be used to mitigate DO depressions. It could be shown that the potentials of these measures suffice to keep DO at a tolerable level. However, due to the long travel times in River Neckar, it is important to start aeration up to several days before the DO minimum is reached.  相似文献