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云南金平晚二叠纪玄武岩特征及其与峨眉地幔柱关系——地球化学证据 总被引：17，自引：4，他引：17
分布于哀牢山－红河断裂带西南侧的金坪上二叠统玄武岩属于低钛拉斑玄武岩（LT）（Ti/Y＜500）。其地球化学特征总体与洋岛玄武岩（OIB）相似，根据其岩相学、主量元素，微量元素特征，将其划分为LT1和LT2两个地球化学亚类型，它们的分布和主要地球化学标志为：LT1分布于下部，高Mg^#(48-63),SiO2(50%-56%)，高∑REE(118-145μg/g）、低Fe2O3（1．36％－1．63％），Na2O(1.88%-3.17%)，TiO2(1.37%-1.92%)，高Th、U，低Nb,Ta和Sr负异常；LT2分布于上部，低SiO2(47%-56%)，Sr强负异常，二者地球化学特征的差异是同一母岩浆经不同的分离结晶和同化混染作用的结果，金平与宾川峨眉山的化学地层学对比表明，金平LT1和LT2玄武岩与宾川峨眉山玄武岩下部的LT1、LT2十分相似，它们可能是同时，或在类似的环境下形成，金平玄武岩属于峨眉山大火山岩省的一部分，同为峨眉地幔柱早期活动的产物。新生代哀牢山－红河断裂的左滑剪运动导致了宾川与金平玄武岩的错位。 相似文献
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The Jinping–Fan Si Pan (JFP) Cenozoic magmatic and Cu–Mo–Au metallogenic belt in the southeastern part of the Ailao Shan shear zone host the Tongchang, Chang′an, Habo, and Chinh Sang Cu–Mo–Au deposits. These deposits form an integrated epithermal-porphyry regional mineralization system associated with 40–32 Ma high-K alkaline magmatism. The magmatic rocks in the belt have relatively low TiO2 (<0.73 wt%), P2O5 (<0.29 wt%), and FeO* (<4.99 wt%), and high Na2O (2.86–4.75 wt%) and K2O (4.01–7.98 wt%). They also have high contents of incompatible trace elements, and are enriched in LILE (Rb, Ba, K, Sr) and LREE. They have marked Nb, Ta, Ti and P depletion in primitive mantle-normalized spidergrams, and plot close to the EMII mantle field in the Sr–Nd isotopic diagram. These characteristics are similar to those of the Eocene high-K alkaline rocks along the northern Ailao Shan belt, eastern Tibet plateau. The sulfur and lead isotope analyses of sulfide minerals from both the ores and related magmatic rocks confirm the involvement of a magmatic ore fluid. The Cenozoic alkaline intrusions and Cu–Mo–Au mineralization in the JFP were formed prior to the initiation of left-lateral shearing along the Ailao Shan shear zone. The magmas appear to have been derived from enriched mantle, possibly with mixing of materials from the buried Tethyan oceanic lithosphere, and/or crust. 相似文献
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脆性作为岩石的重要的力学指标,对深部岩体性态评价以及灾害预防具有重要意义。岩石应力−应变曲线能够很好地表征岩石的脆性。考虑到现有基于应力−应变曲线的脆性指标大多都只对曲线的一部分进行分析,且少有指标能够准确地应用于岩石II类曲线中,对整体判断的缺乏可能会导致工程应用上适应性及可靠性不足的情况。针对现有脆性指标普遍存在的物理意义模糊、评估结果与岩石脆性的关系非连续等问题,综合考量岩石应力−应变曲线中峰前应力上升速率、峰后应力跌落速率以及峰值点应变值对岩石脆性的影响,提出了一种物理意义明确、计算结果与岩石脆性之间的关系是单调且连续的岩石脆性指数计算方法。选取国内外常用脆性指标对锦屏II级水电站大理岩和某铁路隧道花岗岩、变质砂岩以及片麻岩的单轴压缩试验数据进行脆性评价后进行比较,验证了指标的适用性。进一步将提出的指标应用于常规三轴试验条件下大理岩脆性分析,结果表明,该指标不仅能够量化和分类不同岩石的脆性特征,还能表征围压对岩石脆性的抑制作用。 相似文献
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西南三江地区是我国重要的成矿区带之一,具有复合叠加成矿特征。阿德博独居石矿床位于云南省金平县境内,印度地块、哀牢山-金沙江断裂带南侧,属于哀牢山隆起的东南延伸部分。该矿床赋存于花岗质风化壳中,岩性主要有片麻状花岗岩、二长花岗岩、花岗片麻岩;矿体中主要含有独居石,少量磷钇矿、锆石、金红石、钛铁矿、榍石。岩体中片麻状花岗岩的锆石U-Pb谐和年龄为31.40±0.16Ma(MSWD=7.8),二长花岗岩的锆石U-Pb谐和年龄为34.52±0.22 Ma(MSWD=1.3),表明阿德博岩体形成于新生代古近纪,与三江地区构造体制转换阶段富碱斑岩体的成矿时期一致。片麻状花岗岩中45个锆石Hf同位素数据结果较均一,(~(176)Hf/~(177)Hf)i比值范围为0.282583～0.282712,平均为0.282633,εHf(t=31.40 Ma)范围为-6.00～-1.44,平均值为-4.21。二长花岗岩中13个锆石Hf同位素数据结果变化范围较大,(~(176)Hf/~(177)Hf)i=0.282484～0.282814(平均值为0.282681),εHf(t=31.40 Ma)=-9.43～2.22(平均值为-2.45);其中有8粒锆石的εHf(t)为负值,5颗锆石的εHf(t)为正值,暗示岩体的源区主要为地壳物质的部分熔融,可能有地幔物质的混合。 相似文献
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哀牢山-金沙江岩带透辉石花岗岩锆石SHRIMP U-Pb年龄及地质意义--以玉召块、马头湾和十里村岩体为例 总被引：11，自引：2，他引：9
位于哀牢山—金沙江新生代钾质碱性岩浆岩带南段的玉召块、马头湾和十里村透辉石花岗岩锆石SHRIMP定年结果为 38Ma、34Ma和 37Ma,相当于渐新世,属于喜马拉雅期,结合岩石化学、微量元素、稀土元素和Sr、Nd、Pb同位素组成等,对控岩机制、岩石的属性和成因以及锆石的成因进行探讨。 相似文献
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The Jinping terrane is situated in the southern segment of the Ailaoshan ore belt, Sanjiang Tethyan Orogen (SW China). The Paleogene intrusions in Jinping consist of syenite porphyry, fine-grained syenite and biotite granite stocks/dikes, and contain relatively low TiO2 (0.21–0.38 wt%), P2O5 (0.01–0.35 wt%), and high Na2O (2.00–4.62 wt%) and K2O (4.48–7.06 wt%), belonging to high-K alkaline series. Paleogene gold mineralization in Jinping comprises four genetic types, i.e., orogenic, alkali-rich intrusion-related, porphyry and supergene laterite. The NW–NNW-trending faults and their subsidiaries are the major ore-controlling structures. The orogenic Au mineralization, dominated by polymetallic sulfide-quartz veins, occurs in the diorite and minor in Silurian-Devonian sedimentary rocks. It contains a CO2-rich mesothermal fluid system generated from the mixing of mantle-derived fluids with crustal-derived metamorphic fluids, and the ore-forming materials were upper crustal- or orogenic-derived. The alkali-rich intrusion-related Au mineralization is hosted in the Ordovician-Silurian sedimentary rocks and minor in the Paleogene alkaline intrusions, and the Au orebodies occur predominantly in the alteration halos. It contains a CO2-bearing, largely metamorphic-sourced mesothermal fluid system, and the ore-forming materials were derived from the ore-hosting rocks and minor from the alkali-rich intrusions. The porphyry Cu-Mo-Au mineralization occurs in the granite/syenite porphyries and/or along their contact skarn, with the mineralizing fluids being magmatic-hydrothermal in origin. The former two hypogene Au mineralization types in Jinping were mainly formed in the late Eocene (ca. 34–33 Ma) and slightly after the porphyry Cu-Mo-Au mineralization (ca. 35–34 Ma), which is coeval with the regional Himalayan orogenic event. Subsequent weathering produced the laterite Au mineralization above or near the hypogene Au orebodies. 相似文献
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深埋隧洞极强岩爆段隧道掘进机半导洞掘进岩爆风险研究 总被引：3，自引：0，他引：3
深埋隧洞TBM（隧道掘进机）全断面掘进时,在局部超高应力集中的完整硬脆性岩体洞段将直面极强岩爆的风险,设备和人员的安全将遭受极大的威胁。在锦屏II水电站3#引水隧洞极强岩爆段实施了“先半导洞+TBM联合掘进”实验,结合微震实时监测信息对TBM半导洞掘进的岩爆风险开展了研究。监测结果表明,（1）TBM半导洞掘进期间,日平均微震事件数、日平均辐射微震能、微震大事件数及实际岩爆发生次数和强度均远远低于TBM全断面掘进;（2）能量指数对数值和累积视体积的时域演化表明,TBM半导洞掘进强烈岩爆发生的风险远低于TBM全断面掘进,现场实际开挖也证明了这一点;（3）半导洞洞段微震事件的空间集结程度、总数、震级大小与能量辐射均远小于全断面洞段。因此,TBM半导洞掘进的岩爆风险远远低于TBM全断面掘进,在具有施工条件的情况下采用先半导洞预处理,然后TBM半断面掘进极强岩爆段,以期控制岩爆风险的方案是可行的。 相似文献