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元古代晋宁期本区发生了一次裂谷-大洋过程,形成扬子板块西部的被动大陆边缘。古生代扬子板块由南向北漂移,寒武纪末—奥陶纪初本区到达南纬9°左右。这时古边界断层重新活动,分异地幔发生2—5%部分熔融所产生并聚集在莫霍面附近的碱性橄榄玄武岩浆沿断裂带上升,形成上部岩浆房。随后岩浆在不同压力下结晶,分别形成基性岩体和基性-超基性岩体;同时由于氧逸度高,铁钛氧化物早期晶出并堆积在岩浆房底部形成早期岩浆矿床。岩浆多次脉动贯入曾使正常的结晶作用多次中断和反复,形成两个以上的Ⅱ级韵律层和相应的钒钛磁铁矿层。由于双扩散作用,结晶锋面以上的岩浆发生对流和分层又使正常的结晶层序复杂化。 相似文献
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绿铬矿发现于四川渡口的石墨矿床中。矿物呈浅绿-墨绿色,条痕淡绿色,包裹于3T白云母中,结晶化学式Cr-1:(Cr_(1.99)Mn_(0.004)Fe_(0.0035)Ti_(0.001)Mg_(0.003))_(2.0015)0_(2.997);Cr-2:(Cr_(1.99)Mn_(0.0026)Fe_(0.005)Ti_(0.005)Mg_(0.003))_(2.0011)O_(2.996);晶胞参数α=0.495nm;c=1.360nm;V=28.858nm~3;Z=6;D_x=5.24g·cm~( 相似文献
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自1984年起, 在我国北方最大淡水湖泊——山东省南四湖的滨湖洼地上, 创建丫生态工程的三种模式, 即台田-鱼池联合生产甩、果林-蔬菜-鱼塘分层多级利用胡、农-牧-渔再循环利用沏, 经五年的调查研究, 现场实验及生产实践, 结果证明其生态环境条件得到了改善, 促进了物流的良性循环, 实现了物质及能量的多层分级利用, 在生产上减少了投入、增加了产出。同步取得经济、生态环境及社会效益。这些生态工程模式提出了改良和利用湖泊滩地的一些途径, 并树立了典型, 现在在南四湖地区较广泛地推广中。 相似文献
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The area studied had developed into an inactive continental margin on the western edge of the Yangtze plate during the Jinning period in Proterozoic time.The Yangtze plate drifted from the south northwards in Paleozoic time and reached about 9oS between Late Cambrian and Early Ordovician .The alkalic olivine basalt magma,which was produced via 2-5% partial melting of a fractionated mantle and was accumulated in a deep-seated magma chamber near the Moho.found its way upward along the reviving boundary faults into the upper crust.Two types of layered intrusions,basic and ultrabasic-basic,crystallized from the magma at different pressures.The high initial oxygen fugacity of the magma provides a favorable condition for the deposition of Fe-Ti oxides in the early stage of magmaevolution,resulting in large-sized early magmatic deposits.Magma crystallization may have been interrupted and repeated as a result of pulsative magma influx,giving rise to rhythmic cycles (including the corresponding V-Ti-magnetite ore beds).The magma was stratified owing to double diffusion at the crystallization front and convection was thus occasioned by the density gradient.This has greatly complicated the sequence as would be expected from normal crystallization. 相似文献
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