共查询到20条相似文献，搜索用时 15 毫秒
1.
《International Geology Review》2012,54(12):1053-1070
A database on a number of elements in oceanic volcanic rocks is presented, including the principal major-element oxides-SiO2, TiO2, Al2O3, Fe2O3(T), MnO, MgO, CaO, Na2O, K2O, and P2O5 (where T refers to total iron)–and the trace elements–Ba, Ce, Cr, Cu, Ni, Sc, Sr, V, Pb (mainly by isotope dilution), Yb, Zn, and Zr. Interpretations are given for transition metals, with emphasis on Mn, Sc, and V, in order to determine the concentration of the elements in primitive melts and assess their trends in magmatic differentiation. Transition metals are not enriched in plagioclase, so all are incompatible with pure plagioclase removal–that is, they become enriched in the melt. Both Cr and Ni are known to be highly compatible with olivine separation-i.e., they are depleted in the melt early in differentiation. Also, Sc is compatible with clinopyroxene (Cpx) removal from the melt and is depleted by separation of Cpx. Copper does not fit well in any of the principal silicates, but Cu, like Ni, is greatly enriched in sulfides that may remain in the source or separate from the magma. Decreasing Ni abundances and increasing Cu contents during differentiation are a sign of olivine separation. In the analysis presented herein, V–in the absence of Cpx separation–is found to behave remarkably like the moderately incompatible element Zn, and these two elements add to the list of element pairs of similar incompatibility whose ratios are insensitive to differentiation and to submarine weathering as well. Both are enhanced in titanomagnetite, so both would be compatible during titanomagnetite separation. When Cpx separates, however, V becomes compatible like Sc, but Zn remains incompatible. Thus, decreasing V (and Sc) contents and increasing Zn contents during differentiation are a sign of Cpx separation. Manganese often behaves much like Zn and therefore is moderately incompatible, but Mn is less compatible than Zn and V in titanomagnetite. Thus, decreasing Zn and V with increasing Mn is an indication of titanomagnetite removal. Dual compatible and incompatible trends with differentiation are found chiefly for Cu, Sc, and Sr. Distinguishing mid-ocean ridge basalts (MORB), oceanic-island volcanic rocks (OIV), and island-arc volcanic rocks (IAV) may be accomplished by plots of Ce/Yb versus Ba/Ce, where OIV plot to higher values of Ce/Yb than do MORB, and IAV data plot to higher values of Ba/Ce than do those of MORB. These ratios do not seem to be significantly affected by submarine weathering. 相似文献
2.
《International Geology Review》2012,54(4):346-350
Industrial development of the Angara region has necessitated geological exploration for available resources. The Angara River flows north from Lake Baikal, intersecting the mountains surrounding it; passes through the 'Irkutsk Amphitheater, ' part of the central Siberian platform; and, near Bratsk, flows across a diabase intrusion, forming the Bratsk rapids (approximately 300 kilometers long). The Angara river basin is underlain by crystalline basement (the Siberian craton) composed of schists, gneisses, marble, and Archean and Proterozoic granites. These rocks dip sharply from the Sayan and Baikal ranges, where they outcrop, toward the Irkutsk Amphitheater, where they reach 3000 meters depth. The craton is covered by sediments ranging in age from Cambrian to Quaternary. Lower Cambrian rocks over 2500 meters thick are overlain by Middle Cambrian strata which are generally eroded. In the Irkutsk coal basin, north of Lake Baikal, Mesozoic rocks 600 meters thick are covered unconformably by Tertiary sediments. Quaternary deposits are known to occur; the Angara River terraces are probably pre-Quaternary. Regional tectonics involved fracturing within the Irkutsk Amphitheature and in the surrounding mountains. Geophysical survey and drilling revealed a wide horizontal protrusion (the 'Angara swell') in the Siberian craton; this protrusion divides the Irkutsk Amphitheater in the Pre-Baikal and Pre-Sayan depressions. Overlying Cambrian sediments are folded in conformity with these basement-complex dislocations. Jurassic deposits, generally horizontal, are disturbed only near the younger uplifts of Sayan and Baikal. The southwestern part of a large trap-rock intrusion crosses the Irkutsk Amphitheater; concordant intrusions, e. g. sills, entered lower Paleozoic sediments along with dikes, during late Permian and, principally, Triassic times. Mineral deposits are rich and varied: Precambrian rocks contain magnetic iron ore (of the Krivoy Rog type); talc; magnesite; pure crystalline limestone; and, possibly, phosphates. Paleozoic rocks contain large marine and lacustrine salt deposits, gypsum, phosphatized shell rock, and, possibly, oil: as well as carbonaceous rocks with lead and zinc minerals. Hydrogen-sulfide -saturated and saline mineral waters as well as subsurface water with high potassium content occur in Cambrian rocks. Siberian trap rocks are rich in magnesium and iron; magnesium-magnetite ores occur in volcanic necks as large veins of pure ore, associated with tuffs and aureoles. Trap rock (diabase) may be used in the new stone-melting industry. Jurassic deposits include saprolitic-bog and humus coals as well as extensive fire-clay and high-quality kaolin deposits. Cambrian fossils include trilobite and brachiopod remains, reefs, and molluscs; fish, insects, ostracods, and numerous fossil plant traces, are representative of the Mesozoic. The Angara River terraces, 25 to 30 meters thick, contain mammal remains, brackish-water molluscs, and, from the Middle Paleolithic, Azilian and Solutrean artifacts. -- D. D. Fisher 相似文献
3.
马达加斯加前寒武纪变质基底特征综述 总被引：3，自引：0，他引：3
马达加斯加岛是全球重要的前寒武纪变质单元之一,是冈瓦纳大陆重要的组成部分.对其地质调查过程从19世纪初至今主要经历了4个阶段,上世纪90年代至今20几年新理论和新方法的应用使得其基础地质研究得到飞跃发展.根据现有研究,将马达加斯加岛构造单元划分为：太古宙Antongil块体、太古宙-元古宙Antananarivo块体、太古宙Tsaratanana绿岩带、南部元古宙块体和北部新元古宙块体5个部分,每个部分又可进一步细分不同的构造单元.该岛整体上经历中新太古代变质基底形成和新元古代构造活化两个阶段,其中新元古代构造活化与冈瓦纳大陆形成密切相关. 相似文献
4.
5.
6.
《International Geology Review》2012,54(1):69-70
A brief summary of the geological history and structural elements of the Kuznetz coal basin is given. The coal beds overlie Tournaisian limestones and were deposited in a gradually subsiding graben, which existed until the end of the Paleozoic. Continental deposition commenced in the Mesozoic and has continued to the present. Coal reserves in the Kuznetz basin have been estimated at 400 billion tons. --M. Russell. 相似文献
7.
《International Geology Review》2012,54(6):79-85
The U. S. S. R. -IGY Antarctic station, Mirnyy [66°31'S. 93°E.], is situated on four outcrops of Precambrian charnockitic granite, crystalline schist, and gneiss. The four mounds contain numerous angular xenoliths, generally dark schist and gneiss, denoting a palingenetic origin for the bedrock. Quartz veins and sulfide mineralization indicate later hydrothermal activity. The mounds are cut by two major fissure systems perpendicular to each other and several secondary fissure systems. In general, the offshore islands (the Haswell Islets) and the mounds are similar to the ancient Antarctic shield and are, therefore, considered to be a part of it. --Editor. 相似文献
8.
Mapgis在地质学中的应用 总被引：7，自引：0，他引：7
简要讨论了Mapgis的主要功能，重点阐述了Mapgis的地质制图技术、空间分析技术以及二次开发能力在地质学领域中的应用，并举例论述之。Mapgis的地质制图技术将纷繁复杂的传统地质制图过程简化，而且美观精确；空间分析技术可以将矢量数据和栅格数据综合制作出各种图形和图象文件，方便分析；地质工作者也可以运用Mapgis的二次开发能力来开发面向特定领域的系统。 相似文献
9.
湖北省西南部地質構造形態,可以分別為華夏式與新華夏式。華夏式構造為本區主要構造形式,走向東北——西南。顯著的褶縐有十一個背斜(看附圖F2-4,F6,F8,F11,F13-15,F17,F21),十二個向斜(F1,F5,F7,F9-10,F11F16,F19,F20-22,F26);還有九個逆掩斷層(T3-11)。褶縐形狀是寬而長,各軸向略呈平行,有向兩端延長達幾百公里的,有向一端延展的,或兩端傾消的。較新地層居向斜中部,較老地層居背軸軸部。向斜軸部地層傾斜平緩（傾角15°—30°）,在兩翼傾斜較陡（傾角35°—70°）,有時直立。至於逆掩斷層(T3-11),斷層走向與褶縐走向相同,T3（看附图）是最顯著的,向兩端延長达60公里,斷層面傾向西北,上衝體從西北向东南推動。其餘斷層延長較短,上衝體有從西北向東南,亦有從東南向西北推動,情况不一。新華夏式構造在本區內居次。褶縐走向北北东—南南西,成狭而長的形狀。向斜軸部地層傾斜較陡（傾角45°—80°）,而在背斜軸部傾斜較緩。属於此系的逆掩斷層,T1在齊嶽山之东麓,T2在川利縣之西,T9在咸豐縣之南,T11及T12都在F18向斜西翼。斷層走向都是北北東-南南西,舆褶縐走向相同。 華夏式與新华夏式二系構造干涉現象異常顯著,如向斜（F1）軸部被逆掩斷層（T2）截割為二,背斜(F13)的西南段被逆掩斷層阻切,向斜與背斜原來都成東北—西南走向,被成北北東—南南西向的逆掩斷層所阻切。亦有褶縐受阻撓而折轉成北北東—南南西向,如F7,F8,F10;可以證明華夏式構造受新華夏式構造所阻切。 華夏式被新華夏式所截切或干涉,二者造山運動時期,自然前者較早,約在白堊纪的後期;後者較晚,在白堊紀之後,可能在第三紀初期。 相似文献
10.
张家坪子金矿地质特征初探 总被引：2，自引：0，他引：2
四川省冕宁县张家坪子金矿产于T2.3的一套绿片岩、变质玄武岩、火山角砾岩夹蚀变交代白云岩中的矿床,受金河—程海深断裂影响,金矿化主要位于蚀变带内.经燕山中晚期深源的富Au的多金属地幔流体侵入,在构造有利部位发生交代作用,使Au进一步富集,至喜山期,又发生一次富金热液作用,在有利部位进一步加富而形成矿体. 相似文献
11.
佳木斯中间地块前寒武纪地质研究 总被引：4，自引：0，他引：4
刘静兰 《吉林大学学报(地球科学版)》1988,(2)
本文对前人确定的黑龙江群与麻山群的界限、接触关系及两群变质地体的性质提出疑义。笔者认为,两群变质地体的界限不在湖南营组(原黑龙江群顶部)与西麻山组(原麻山群底部)之间,而在湖南营组与下伏的原山嘴子组之间;它们不呈整合过渡接触,而是呈构造接触。本文重新认识和研究了黑龙江群变质地体的性质,认为不是区域变质地层单元,而且存在大型韧性剪切带,并论述了大型韧性剪切带的糜棱岩、微构造、变质作用等性质。 相似文献
12.
《International Geology Review》2012,54(9):42-46
The discovery of ultrabasic rocks and of diamonds in Upper Triassic-Lower Jurassic kimberlite pipes in the Siberian platform gave impetus to the search for diamond deposits in this area. Also, the discovery of diamond placers in Mesozoic and Cenozoic marine and nonmarine sediments in 1948 intensified the search. The geology of the area is characterized, as is that of the African diamond fields, by considerable faulting and heterogeneous composition of the basement, the development of large depressions, and a magmatic cycle dominated by basic and ultrabasic magmas. Many unexplored areas within the platform, undoubtedly having similar characteristics, are potential diamond producers. --G. E. Denegar. 相似文献
13.
14.
大规模工程建设给城市提出了新的工程地质和环境工程问题.本文简要介绍了西安城市建设中的几个工程地质问题,以期引起对类似城市地质环境问题的重视和研究. 相似文献
15.
周文革 《大地构造与成矿学》2002,26(4):459-461
总结了浏阳市城区第四系的分布范围、厚度、韵律(层序)及其阶地分布;指出了其基底风化残余粘土层的厚度变化、岩溶现象和断裂发育情况;探讨了与之有关的工程地质注意事项。 相似文献
16.
网格技术在地学中的应用 总被引：1，自引：0，他引：1
网格技术是一门新兴的信息技术，努力完善技术的同时，也将投入各种实用领域。本文介绍网格技术的发展基本特征，探讨网格技术在地学中的应用，首次提出地学网格新概念。 相似文献
17.
卫星遥感技术应用在公路选线中，具有常规方法无可比拟的优势。在湖南省常德-吉首高速公路初勘研究中，以正射航空相片，Landsat-TM数字图像为主要信息源，通过数据处理和地学遥感判释，并综合分析其它资料，对常吉公路沿线地区进行了地质构造。地层，地貌。地表水，第四系等遥感专题调查。探讨分析了不良地质现象分布规律。形成背景及发展演化趋势。在此基础上比较各设计线路之优缺点。并提出科学合理的建议线路方案。方法对自然条件十分复杂的西部公路建设有较好的借鉴意义。 相似文献
18.
19.
在复杂的工程地质条件下,由于岩土体地质特征在空间分布及其连续性变化大,如何选用合理、经济的手段进行岩土工程勘察是非常重要的.本文通过工程实例讨论了地质雷达技术在类似条件下进行岩土工程勘察中的有效应用,该项技术以其高分辨率和图象的实时表现等优势,将其与地质钻探方法相结合、同时采用合适的工作流程可以有效地查明地下介质结构信息的空间组合及其变化特征,为岩土工程特征的合理评价提供重要信息,使勘察工作获得事半功倍的效果. 相似文献
20.
《International Geology Review》2012,54(5):570-577
New data collected since 1955 on the geology of the Lovozero massif, considerably detailing and supplementing existing ideas as to its structure and geochemistry, are presented. As a result of these investigations the thickness of the ore-bearing stratified rock complex has been traced to a depth of 1700 m. Laws governing the vertical alteration of rock composition of individual series have been established as well as the fact that the amount of titanium-bearing minerals increases with depth.—Auth. English summ. 相似文献