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地质学的发展分为三个阶段，即启蒙阶段、分析阶段和综合阶段，三个阶段的地质学各具特色，总体显示地质学从分析到综合的发展轨迹。地质学的三个发展阶段，形成了人们不同的思维方式，思维方式的转换逐步与地球的客观实际相一致。当前，地质学正处于综合阶段，科学的思维方式促成了新学说和理论的产生和发展，但是，过去阶段的思维方式具有遗传性质，它对新的学说和理论具有阻碍作用。 相似文献
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Mt. St. Hilaire occurs as a small funnel-shaped intrusion in the Monteregian petrographic province of Quebec and consists of alkali gabbros and later nepheline syenites. Based on field relations, petrography, and geochemistry, five types of gabbro are recognized. In order of intrusion these are: leucogabbro, foliated gabbro, kaersutite-biotite gabbro, kaersutite gabbro, and a gabbro-melagabbro series. Based on analyses of the early-forming ilmenite-titanomagnetite, the gabbros crystallized under high fO2 conditions which lead to subsequent crystallization of olivines with high MnO contents. Fractionation of ilmenite and titanomagnetite was a major control on the Ti and A[TV]concentrations in the clinopyroxenes. Plagioclase compositions in the gabbros became richer in Ab contents in the sequence gabbro-melagabbro to leucogabbro. Whole-rock analyses suggest that the parental magma of alkali basaltic composition was fairly evolved prior to emplacement. Lack of olivine in the cumulate gabbro-melagabbros and low Ni and Cr in all gabbros may reflect either extreme olivine fractionation and/or a very low olivine content in the source material for these basalts. Differentiation of the gabbros occurred both pre- and post-emplacement, probably by a process of crystal-liquid fractionation at depths between 3-5 and 8 km. This is in accordance with geophysical measurements for other Monteregian intrusions. A model is presented for the mechanism of emplacement. 相似文献
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The Dalgaranga meteorite crater, 100 km northeast of Yalgoo, Western Australia, was one of the first impact structures identified in Australia, the smallest isolated crater found in Australia, and the only confirmed crater in the world associated with a mesosiderite projectile. Seventeen years passed before the Dalgaranga meteorites were described in the scientific literature, and nearly 40 years passed before a survey of the structure was published. The reasons for the time gap were never explained and a number of factual errors about the discovery and early history remain uncorrected in the scientific literature. Using historical and archival documents, and discussions with people involved in Dalgaranga research, the reasons for this time gap are explained by a series of minor misidentifications and coincidences. The age of the crater has yet to be determined, but using published data, we estimate the projectile mass to be 500–1000 kg. 相似文献
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新疆阿尔泰、准噶尔北缘铜、金、多金属资源现状及找矿前景分析 总被引：4，自引：1，他引：3
本文扼要地阐述了阿尔泰、准噶尔北缘铜、金、多金属资源现状,地质环境和矿带划分,并认为阿尔泰南缘、恰其海—喀拉通克、萨吾尔—索尔库都克、阿尔泰山区巴拉额尔齐斯复背斜倾伏端及两翼、阿克塔斯—萨尔布拉克分别是寻找块状硫化物矿床、岩浆型铜镍矿、斑岩型铜矿、“焦家式、河台式”金矿和低品位大矿量金矿的有利地段。 相似文献
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Silcretes on the N.S.W. coast near Ulladulla have long been attributed to. a sub‐basaltic origin, but field evidence is at odds with all variations of the sub‐basaltic hypothesis, and one site shows good evidence that the basalt post‐dates the silcrete. K‐Ar ages averaging 29.7 ± 0.5 Ma from the basalts provide a minimum age for silcrete development in this area. Furthermore, the K‐Ar dates, together with evidence for an erosional rather than tectonic origin of the coastal lowland, demonstrate that the adjacent tablelands reached their present elevation prior to the mid‐Oligocene. 相似文献
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湖南邵东下石炭统刘家塘组产丰富的介形类化石，计有１８属３５种（包括６新种），它们绝大多数可与国内外下石炭统介形类对比，其地质时代为早石炭世杜内期，刘家塘组介形类明显地可分成上、下两个不同组合。本文仅描述了刘家塘组介形类６属７种（包括６新种）。 相似文献
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新疆塔里木板块西部瓦吉里塔格地区二叠纪超镁铁岩的岩石成因与岩浆源区 总被引：10，自引：15，他引：10
瓦吉里塔格地区位于塔里木板块西部，前人在此区发现了晚二叠世形成的6个爆破角砾岩筒和32条岩脉。爆破角砾岩筒属火山口相和火山管道相，脉岩属次火山相。爆破角砾岩筒由角砾和胶结物组成。角砾的主要类型是纯橄榄岩、橄榄岩、橄榄辉石岩、辉石岩等；胶结物主要是麦美奇岩和苦橄岩。据岩石化学组成和液相线橄榄石的F0分子确定的原生岩浆的MgO含量分别是18．78％和18.8％。它们的CaO／Al2O3平均值为3．9，Al2O3／TiO2平均值为2．6。这些超镁铁岩都富集LREE、大离子亲石元素和Nb、Ta，而重稀土元素贫化，并有Zr、Hf负异常。不同样品间∑REE和(La／Yb)N的差异反映了橄榄石和单斜辉石堆晶作用的影响。依据实验岩石学研究成果，熔融深度应为450km～650km。副矿物组合异常复杂，其中，刚玉的结晶深度有可能大于575km。它们的εNd（t）= 3．3～ 5．4，εSr(￡)=-4．27～-10．78，^206Ph／^204Ph=18．47～22．78，^207Ph／^204Ph=15．52～15．90，^208Ph／^204Pb/38．45～39．62。Nd、Sr、Ph同位素组成与洋岛玄武岩和一些地慢柱组分相同或相近。综合各方面的研究成果可以证明，这些超镁铁岩很有可能源自于核一幔边界之上的D″层。源区本属于亏损型地幔，但在岩浆生成前不久被富含轻稀土元素和大离子亲石元素的流体交代。 相似文献
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黔西南水银洞层控超大型卡林型金矿床成矿模式及成矿预测研究 总被引：9，自引：0，他引：9
贵州省贞丰县水银洞金矿是一个近年来发现的、具较高品位、资源量已达超大型的层控卡林型金矿床。矿床受灰家堡背斜核部构造和有利岩性组合控制。金矿床具有低温成矿特征,出现去碳酸盐化、硅化、黄铁矿化和粘土化等围岩蚀变,特征的 Au-As-Hg-Tl 元素组合。成矿流体具有低温低盐度和较高压力和富挥发份的特点,均一温度在 220 ℃±,盐度在6±Wt% NaCl,压力为1.6±0.4Kbars。成矿物质主要来自深部。高压和富挥发份促使成矿流体从深部迁移至控矿背斜核部,并由于构造作用挥发份的快速逃逸,压力骤降,促使流体快速卸载,金快速沉淀,形成水银洞超大型层控卡林型金矿床。根据找矿标志及成矿和找矿模型,进行了成矿预测研究并取得很好效果,使水银洞金矿新增储量数十吨,并且预示该类型金矿找矿远景巨大,已经成为黔西南第一个超大型层控卡林型金矿床。 相似文献
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