Geochemical,mineralogical and textural nature of beach placers,north-east Sri Lanka: Implications for provenance and potential resource     

Samikshya Mohanty  Madurya Adikaram  Debashish Sengupta  Nishara Madhubashini  Chelaka Wijesiri  Somnath Adak  Biswajit Bera 《国际泥沙研究》2023,38(2):279-293

The Pulmoddai placer sands in Sri Lanka(9°3’23.65’’-8°51’38.83’’N and 80°55’22.91’’-81°3’32.65’’E) is considered to be one of the major rare earth element(REE) prospects world-wide. This deposit has a global significance in terms of strategic economic resources and can provide valuable insight for resource estimation and for its economic use. A detailed study of the geochemical, mineralogical, and textural properties of the heavy minerals of this region is undertaken applying the scanning electr...  相似文献   

Provenance,depositional process,and tectonic setting of gold placer from the Bétaré-Oya Gold District(East-Cameroon,Central Africa)along the Precambrian Sanaga fault     

Milan Stafford Tchouatcha  Arnaud Patrice Kouske  Primus Azinwi Tamfuh  Epimarc Gildas Tchameni Ngouabe  Gerald Chuye Yango 《国际泥沙研究》2023,38(4):576-596

The Bétaré-Oya Gold District is one of the three gold districts in East Cameroon with varied types of mining. The study site is an open-cast mine located in an alluvial plain. The strata succession globally consists of two positive sequences represented by three facies associations and seven lithofacies: massive clast-supported(Gcm), massive trough-cross bedded(Gtm), and massive matrix-supported(Gmm)conglomerates; massive sands(Sm); and massive(Fm), heterolothic(Fhl), and convolute and heterolit...  相似文献   

大兴安岭漠河砂金富集区岩金找矿思路   总被引：6，自引：2，他引：4  

陈满  刘涛  徐伦先  梁海军  宋丙剑 《地质与资源》2006,15(1):33-37

大兴安岭漠河地区砂金极为丰富,充分研究区内的地质构造特征、砂金分布和富集规律、区域剥蚀深度等,利用砂金信息寻找岩金是区内岩金找矿工作的有效手段之一.利用砂金矿只能寻找剥蚀残留的那一部分岩金矿.对物源区剥蚀程度和探矿构造分析研究,是在砂金富集区内圈定岩金找矿靶区的关键.溶蚀系数可指示砂金是近或远原生源金矿.Pb同位素可指示成矿母岩,利用矿石、岩浆岩、地层和基底铅同位素全方位对比来判别铅同位素的来源是一种近年来国际上认同的办法,砂矿评价中利用铅同位素寻找母岩已获得成功.本区砂金Pb同位素特征值与源区极为相似,可做为砂金富集区寻找岩金的指示元素.本文旨在论述砂金富集区内砂金与岩金空间位置关系、成因上的联系及岩金成矿特点,为下一步岩金找矿工作提供思路和方法.  相似文献   

阿尔泰山“东山区”的古冰川作用与砂金矿     

乌尔坤  叶玮 《冰川冻土》1992,14(1):63-72

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山门金银矿床重砂异常特征及找矿意义     

徐曼  杨复顶  李任时  李楠 《吉林地质》2014,(1):93-96

本文通过对山门金银矿床自然重砂矿物的系统研究,揭示了山门金银矿床自然重砂异常的分布特征,优选出具有重要找矿指示作用的重砂矿物,并确定标型矿物组合,结合地质特征建立山门金银矿床的自然重砂找矿模式,为找矿预测提供重要依据。  相似文献   

Occurrence and Emplacement of Chromite Ores in Sindhudurg District,Maharashtra, India     

Sridhar D. IYER  Elapavalooru V.S.S.K. BABU  Premchand G. MISLANKAR  Anup R. GUJAR  Navso V. AMBRE  Victor J. LOVESON 《《地质学报》英文版》2010,84(3):515-527

<正>In the present study,we present the occurrence and emplacement of chromite ore deposits from two abandoned mines(Kankavali[Janoli]and Wagda) in the Sindhudurg district of Maharashtra,India.These ores,that occurred as lenses and are associated with metamorphic and ultrabasic rocks,consist of octahedral grains of chromite,while clinochlore is present between the interstices of these grains.The Kankavali(Janoli) and Wagda ores revealed a dominance of Cr_2O_3 followed by FeO and variable proportions of A1_2O_3,MgO,and SiO_2.The former deposits have a slightly higher Cr_2O_3(average 52 wt%) and FeO(～18 wt%) than those from Wagda(Cr_2O_3～50 wt%,FeO～25 wt%).The similar Cr~# values(0.73 for Kankavali[Janoli],0.74 for Wagda) correspond to those reported for typical podiform-type chromite deposits.We suggest that the ores were emplaced as phacoliths in folded outcrops with a steep easterly dip and a northwest-southeast trend.We postulate the continuation of the fold structure from Janoli to Wagda(～4.5 km apart) and the probable (sporadic) occurrence of chromite along this stretch.The possibility of the contribution of chromite grains from these areas to the coastal placer deposits cannot be ruled out.  相似文献   

江苏新沂金刚石砂矿地质特征及供源方向探讨   总被引：1，自引：0，他引：1  

施建斌  曹强  蔡承刚 《化工矿产地质》2010,32(1):39-43

江苏省新沂金刚石砂矿赋存于更新统王圩组地层中,平面上受古沂河流域控制,垂向上则主要位于王圩组底部的砾石层中,并于古沂河的有利部位沉积,形成了本区的第四系金刚石砂矿。金刚石的物质来源一是古沂河上游山东的金刚石原生矿和古砂矿,二是本区的可能存在的金刚石原生矿。  相似文献   

凌云县下甲水晶矿区砂金的发现及找矿意义     

蒋承欢  吴实忠  李正合 《南方国土资源》2000,13(3):23-26

文章对凌云县下甲水晶砂矿中民采发现砂金进行介绍,分析研究了当地成矿地质条件,认为砂金与水晶砂矿来源一样,其母体都是含晶石英-方解石脉,属于岩溶型水晶-砂金矿.此发现对寻找广西砂金矿,拓宽金矿资源的思路,具有现实意义.  相似文献   

对博山区夏庄一带新近纪白彦组的初步认识     

鲁峰  孙斌  宋建华  熊玉新  梁太涛  沙启文 《山东国土资源》2011,27(1)

通过野外地质调查、采样化验及区域地质资料对比研究,初步认定赋存在淄博凹陷南缘夏庄、五福峪、马家庄等地下古生代寒武-奥陶纪灰岩、白云岩岩溶负地形中的砾岩层,其综合地质特征符合山东省岩石地层新近纪白彦组的现在定义,砾岩含金而未见金刚石.该地层的发现弥补了该区原有区域地质资料的不足,有助于对该区地质构造发展史的研究,也为今后的找矿工作提供了有价值的线索.  相似文献   

Offshore Occurrences of Heavy-Mineral Placers,Northwest Galicia,Spain     

Malcolm Richard Gent  Mario Menéndez Alvarez  Jesús José María García Iglesias  Javier TaraÑo Álvarez 《Marine Georesources & Geotechnology》2013,31(1-2):39-59

ABSTRACT

Results of offshore water-jet sediment sampling demonstrate the potential for interstadial placer deposits of industrial minerals in the shore-face to inner-shelf of Cape Ortegal, NW Spain. Placer deposition is interpreted to have occurred during glacial interstadials since the Last Glacial Maximum, and deposits sampled at 24 to 42 m. BSL were formed during the Younger Dryas, and subsequently preserved as a result of very rapid rising sea-levels. The sediments are almost entirely terrestrially derived with a particularly high heavy mineral content (Sp. Gr. >2.9), of more than 75% in all samples. Reworked garnet from earlier-sedimentary deposits constitutes an important fraction of the placer deposits identified but is generally absent in other sediments. Indications of the presence of +5 m-thick paleo-placer deposits with sections include:

• Placer garnet + spinel grades increase with depth in those sediments at 24 to 42 m BSL to the ocean-floor.

• The d50 of sediments with background grades decrease with depth while those of placer deposits do not display any significant trend.

• Garnets in non-mineralized sediments are almost entirely angular, whereas in placer enriched sediments they vary in form from well-rounded to angular. Some grains in the latter display surface morphologies typical of reworked sediment while none of the former do.

Sediments deposited during glacial interstadials at depths of up to 130 m BSL may represent important, undeveloped exploration targets for offshore placer deposits of industrial minerals. Industrial mineral exploration should extend the depths of investigations to those corresponding to major interstadial periods.  相似文献