共查询到19条相似文献，搜索用时 765 毫秒
1.
曲边冰洲石的发现及其矿床成因的探讨 总被引：2，自引：0，他引：2
在各类型冰洲石矿床中发现了大量的冰洲石弯晶，通过冰洲石矿床野外考察的归纳总结，联系到晶体生长和材料力学的有关知识，提出冰州石矿床的成因极可能是原矿床中方解石受到的构造运动强烈影响后，在长期的水淋滤改造作用下发生冰洲石化，并由此而形成冰洲石矿床。 相似文献
2.
１９９０年在黔西南发现冰洲石─方解石超巨晶群体，最大单晶达２５ｔ，如此巨大的晶体成群出现，实为稀世之宝。巨晶赋存地层为中三叠统石灰岩，断裂、裂隙及古溶洞为主要容矿、控矿构造。巨晶整体呈半透明一透明，几何形态以菱面体为主，自形程度较高。冰洲石纯度高、质量好，ＣａＣＯ３含量达９９．９５％，仅含微量杂质。自然界冰洲石矿床并不多见，尤其是浅成低温条件下形成巨晶更为罕见。作者研究认为，这种冰洲石一方解石巨晶形成的条件是：①有大型且封闭良好的结晶空间；②有纯洁丰富的矿物源供应；③热动力条件是温度缓慢降低及温度较长时期稳定环境，其结晶温度主要稳定在８０～１００℃范围内；④有微过饱和具卤水属性的成矿溶液以及具有长时间缓慢生长速度的条件。此外，据野外观察，方解石脉膨大的核部是巨晶成长发育的特定位置。冰洲石─方解石巨晶矿床是浅成、低温热液条件下，以溶蚀作用为主导成矿作用的产物，属岩溶矿床成困类型。 相似文献
3.
冰洲石系透明如水的方解石,CaCO_3含量达99.95％,县高折射率,用于制作各种偏光仪器,是现代高科技工业的重要矿物原料。我省碳酸盐岩分布地区赋存岩溶型、脉型、裂隙破碎带型冰洲石矿床。在古岩溶与节理裂隙相结合地段及方解石脉膨胀部位于成矿有利,光学材料晶体获得率较高。冰洲石的精选是以台灯聚光,在暗室里重点鉴定节瘤、管道、包体、剔出缺陷部分,获取商品晶体。四川地区现已发现有待勘查开发的冰洲石矿点30余处,建议加强地质勘查工作,对冰洲石资源进行保护性开采。 相似文献
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我国首次发现冰洲石－方解石巨晶、超巨晶群体及形成机制探讨 总被引：1，自引：0，他引：1
文章在阐明冰洲石－方解石巨晶、超巨晶群体的地质特征和矿物学特点的基础上,着重讨论了其巨型晶的形成条件和岩溶成矿机制问题。 相似文献
6.
我们在贵州西南部,研究冰洲石及宝石矿物经济开发课题,于4月20—5月25日,经过野外及室内反复研究,并经有关专家核实,证实某矿床有冰洲石巨晶群体。经计算,多数单晶达数吨重,一般都在10t以上,最大单晶竞达25t重。据悉,如此巨大冰洲石单晶及其成群出 相似文献
7.
对3种贵珊瑚方解石的FTIR光谱的测量以及与无机成因方解石的FTIR光谱的对比分析,结果表明生物成因方解石与无机成因方解石的FTIR光谱存在差异。生物成因方解石样品的υ2,υ3和υ4带的平均值与标准无机方解石υ2,υ3,υ4带的位移达到2.5cm-1,6.5 cm-1和6.2 cm-1。方解石中的υ2,υ3和υ4带可用于区分方解石的生物或无机成因。生物成因方解石的FTIR光谱频移特征可能与其低结晶度、纳米粒径和晶格畸变有关。 相似文献
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开发甘肃黄渚关冰洲石矿资源的建议王长宪（白银有色金属公司研究所兰州７３０９００）冰洲石具有最高的双折射率。主要用于光学、国防、电子诸多高科技领域，制造特种光学仪器。甘肃黄渚关地区蕴藏丰富的冰洲石矿产资源。１黄渚关冰洲石矿产出概况黄渚关冰洲石矿位于陇南... 相似文献
10.
黔西南某冰洲石矿床矿体形态，矿石的矿物成分和结构构造均简单，但含晶矿物晶体巨大光学级冰洲石赋存于晶洞和巨晶体中。由于冰洲石物理性质的特殊性，因而开发利用时必须选择适宜的采，选方法，才能使矿物资源得到合理利用。 相似文献
11.
A. R. Geptner 《Lithology and Mineral Resources》2009,44(3):205-228
Distribution, timing, and sequence of hydrothermal mineralization in the Iceland rift zone are discussed. Vein and pore mineralization in basalts confined to the fissure-dike swarm is considered. Intermittent formation of siliceous and other hydrothermal minerals is established at a sufficiently prolonged existence of hydrothermal system. Formation of parallel-layered smectite-zeolite segregations in the course of extension and origination of open fissures and groundwater level fluctuations is analyzed. Local concentration of silica in the plateau basalt-hosted fissures and cavities, as well as accumulation of banded siliceous segregations (onyxes), is ascribed to the multiple intermittent inputs of solutions into the basalt mineralization zone. 相似文献
12.
冰岛是欧洲的第二大岛屿,在成因类型上,是由于地幔柱上涌而形成的碱性玄武岩区,属于周期性的海底岩浆活动和海底火山喷发而形成的火山岛。全岛主要由玄武岩组成,并可分为4个主要地层单元,分别为中新世—早上新世岩层、晚上新世—早更新世岩层、晚更新世岩层及冰后期岩层。构造方面,冰岛火山断裂系统发育,可分为3个火山侧翼带和4个火山裂谷带。冰岛地热资源极丰富,其具有分布广、类型多、温度高、地热流体多为淡水等特征。近年来,冰岛发现了一系列金矿(化)点,主要分布在冰岛沿海地区,可分为3个成矿带,与地热系统具有密切的时空分布关系,成因类型多为浅成低温热液型金矿床,与中国新疆西天山地区阿希金矿床具有相似的成矿环境和地质特征。在系统收集前人资料的基础上,简要介绍了冰岛地质特征及演化历史,阐述了冰岛地热、金矿资源分布规律,旨在为中国地质科技人员了解冰岛的地质和矿产资源特征提供参考依据。 相似文献
13.
The mineralization of bacterial organic matter in the groundwater of Iceland is discussed. Structural relationships between
secondary minerals in cavities within a Pleistocene basaltic sill and the general sequence of their precipitation allowed
us to recognize five stages of the secondary mineral formation. Two stages of layer silicate formation separated by a stage
of zeolite and apophyllite formation were pointed out. The composition and structure of clay minerals formed at different
stages as a result of the interaction between groundwater and basalt with an active participation of bacteria have been investigated.
Clay minerals of the second stage are similar in composition and microstructure to biomorphic structures previously studied
in Miocene plateau basalts. The last stage of mineralization is related to the fossilization of filamentous microbiota residing
in open cavities and covering all older secondary minerals 相似文献
14.
Yarrow Axford Gifford H. Miller slaug Geirsdttir Peter G. Langdon 《Quaternary Science Reviews》2007,26(25-28):3344-3358
The Holocene temperature history of Iceland is not well known, despite Iceland's climatically strategic location at the intersection of major surface currents in the high-latitude North Atlantic. Existing terrestrial records reveal spatially heterogeneous changes in Iceland's glacier extent, vegetation cover, and climate over the Holocene, but these records are temporally discontinuous and mostly qualitative. This paper presents the first quantitative estimates of temperatures throughout the entire Holocene on Iceland. Mean July temperatures are inferred based upon subfossil midge (Chironomidae) assemblages from three coastal lakes in northern Iceland. Midge data from each of the three lakes indicate broadly similar temperature trends, and suggest that the North Icelandic coast experienced relatively cool early Holocene summers and gradual warming throughout the Holocene until after 3 ka. This contrasts with many sites on Iceland and around the high-latitude Northern Hemisphere that experienced an early to mid-Holocene “thermal maximum” in response to enhanced summer insolation forcing. Our results suggest a heightened temperature gradient across Iceland in the early Holocene, with suppressed terrestrial temperatures along the northern coastal fringe, possibly as a result of sea surface conditions on the North Iceland shelf. 相似文献
15.
slaug Geirsdttir Jrunn Hardardttir rny E. Sveinbjrnsdttir 《Quaternary Science Reviews》2000,19(17-18)
Reconstruction of the paleoenvironment of South Iceland based on lithofacies and chronological studies of the Búdi morainal complex, lacustrine deposits at Ófærugil and a sediment core from Lake Hestvatn, South Iceland, revealed evidence for repeated catastrophic flood (jökulhlaup) activities during the late Younger Dryas (YD) and the early Preboreal (PB) chronozones. During this time, thin and lobate outlet glaciers from the retreating Iceland Ice Cap extended from major valleys and calved into the paleobay of southern lowlands of Iceland where relative sea level was at least 70 m higher than today. A number of ice-marginal lakes formed during the stepwise retreat of the South Iceland ice sheet at the transition of the YD and PB. Primary geomorphic and sedimentologic impact of the jökulhlaups was erosion of multiple channels downstream from the most prominent moraines in South Iceland and through the coastal sediment, accompanied by net aggradation of chaotically stratified sand and silt lenses. At the ice-distal environment, these floods accumulated in the form of recurrent turbidity currents. Volcanic eruptions, supplemented by a catastrophic release of the ice-marginal lakes, are postulated as the main triggers for the jökulhlaup activity. The jökulhlaup events evidenced in this study and subsequent break-up of the partly marine-based glacier may have contributed to the ice-rafting events found in the North Atlantic paleoenvironmental record. 相似文献
16.
Precise distance measurements made on four networks of permanent benchmarks situated on the active axes of Iceland during the four-year period 1968–1972 showed that a combination of left-lateral and extensional movement is occurring on the Reykjanes Peninsula in southwest Iceland at a rate of about 9 mm per year. Elsewhere in Iceland, the movements, if they exist, are too small to be detected. Measurements from a geothermal area in southwest Iceland showed also that large horizontal movements occur in the vicinity of producing geothermal wells. 相似文献
17.
Four major ash zones recorded in piston cores raised from the Iceland Plateau north of Iceland are shown to be coincident with the last four interglacial isotopic stages. Their geochemical composition links the ashes to volcanic events on Iceland. The occurrence of these ash layers, which record events orders of magnitude larger than the ‘normal’ Holocene volcanic eruptions, can not be explained by changes in sea ice cover and atmospheric circulation alone. It is suggested that these events are related to pressure releases in the magma chambers resulting from major deglaciations of the Icelandic Ice Cap. 相似文献
18.
M. R. Fisk J. -G. Schilling H. Sigurdsson 《Contributions to Mineralogy and Petrology》1980,74(4):361-374
Tholeiite basalts from 60° N to 65° N on the Mid-Atlantic Ridge were melted and recrystallized at atmospheric pressure in a CO2-H2 gas mixture. Seven basalts are from the Langjokull-Thingvellir volcanic zone and the Reykjanes Peninsula of Iceland and nine are from the Reykjanes Ridge. The crystallization sequence in both Iceland and Reykjanes Ridge basalts with (Total Fe as FeO)/(Total Fe as FeO+ MgO) [F/F + M] less than 0.6 is olivine, plagioclase, clinopyroxene. Chromian spinel crystallizes before plagioclase in one Iceland and one Reykjanes Ridge basalt with F/F+M less than 0.57. Chemical differences of the two groups of basalts (lower SiO2 and higher alkalis in Iceland basalts) can not simply be a result of low pressure fractional crystallization. Liquidus temperatures of the seven Iceland basalts decreases from 1,230° C to 1,170° C as the F/F+M of the rock increases from 0.52 to 0.70. The liquidus temperatures of the Reykjanes Ridge basalts are about 10° C lower than those of the Iceland basalts for the same F/F+M value. The profile of measured liquidus temperatures from 65° N on Iceland to 60° N on the Reykjanes Ridge has a minimum value at 63.2° N on the Reykjanes Ridge just south of Iceland. Model calculations of the pressure of phenocryst crystallization indicate that olivine and plagioclase in Langjokull basalts could have equilibrated between 2.0 and 6.2 kb (200 to 620 MPa). Phenocryst assemblages in Reykjanes Ridge basalts at 60° N could have crystallized together at greater than 2 kb (200 MPa) and probably less than 8 kb (800 MPa). A minimum in the equilibrium pressure of phenocryst crystallization occurs between 62.9° and 64° N and coincides with the minimum in the experimentally determined liquidus temperatures. The more extensive fractionation at low pressure in this area could be related to the shift of the Mid-Atlantic Ridge axis along the leaky transform fault from the Reykjanes Ridge to the Thingvellir volcanic zone. 相似文献
19.
H. Bungum 《Tectonophysics》1977,41(4):T15-T18
Strike-slip solutions have been obtained and are presented here for the focal mechanisms of one earthquake from Iceland and one from Svalbard, on 13 and 18 January 1976, respectively. A fault plane is suggested for the Iceland earthquake. 相似文献