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| 1 | 内蒙古狼山地区早志留世石英闪长岩体的厘定及其地质意义显示文摘内蒙古狼山山脉西侧分布有零星的早古生代岩浆岩,早志留世侵入体主要出露于哈日音熬瑞-迈罕陶勒盖一带.该岩体岩性为石英闪长岩,LA-ICP-MS锆石U-Pb年龄显示,其^(206)Pb/^(238)U加权平均年龄为440±1Ma.岩石富集大离子亲石元素Rb、K、Pb,不同程度地亏损高场强元素Nb、Ta、P、Ti;轻稀土富集,重稀土亏损,具有弱的负Eu异常,显示了岩浆弧的地球化学特征ε.Hf(t)值为-12.1~-8.8及TDM2在1 973~2 182Ma之间,反映了源区以古元古代古老地壳为主,闪长质包体中的斜长石斑晶及矿物成因判别图解显示了岩体在形成过程中受到了岩浆混合作用.构造判别图解及Hf同位素特征表明该岩体可能形成于大陆边缘弧的构造背景.对比达茂旗、白乃庙地区新近发表的有关数据,早志留世石英闪长岩的岩石地球化学特征与之十分相似,由此可见,华北地块北缘早古生代俯冲带从白乃庙地区可以延伸到狼山地区. | 滕学建 田健 刘洋 张永 滕飞 段霄龙 | 2019 | 地球科学2019,44,4: | 6 |
| 2 | Effect of Beam Current and Diameter on Electron Probe Microanalysis of Carbonate Minerals显示文摘The effect of operating conditions on the time-dependent X-ray intensity variation is of great importance for the optimal EPMA conditions for accurate determinations of various elements in carbonate minerals. Beam diameters of 0, 1, 2, 5, 10, 15, and 20 μm, and beam currents of 3, 5, 10, 20,and 50 nA were tested. Ca, Mg, Zn, and Sr were found to be more sensitive to electron beam irradiation as compared to other elements, and small currents and large beam diameters minimized the timedependent X-ray intensity variations. We determined the optimal EPMA operating conditions for elements in carbonate: 10 μm and 5 nA for calcite;10 μm and 10 nA for dolomite;5 μm and 10 nA or 10 μm and 20 nA for strontianite;and 20 nA and 5 μm for other carbonate. Elements sensitive to electron beam irradiation should be determined first. In addition, silicate minerals are preferred as standards rather than carbonate minerals. | Xing Zhang Shuiyuan Yang He Zhao Shaoyong Jiang Ruoxi Zhang Jing Xie | 2019 | Journal of Earth Science2019,30,4: | 3 |
| 3 | 内蒙古头道桥地区蓝闪石片岩和相关变质岩石岩石学特征及其构造意义显示文摘内蒙古头道桥地区出露了一套经高压变质形成的岩石组合。本次研究通过岩相学和矿物化学分析,根据矿物组合的不同,识别出蓝片岩、绿片岩两种不同类型的岩石类型。其中,蓝片岩的矿物组合为角闪石(蓝闪石、蓝透闪石)+绿帘石+钠长石+绿泥石+石英+赤铁矿±多硅白云母±方解石±榍石;绿片岩的矿物组合为绿泥石+钠长石+石英±绿帘石±角闪石(阳起石、镁角闪石、蓝透闪石、冻蓝闪石等)±多硅白云母±赤铁矿。确定了蓝片岩的峰期变质级别为绿帘-蓝闪片岩相,峰期变质温度为400~600℃,压力为1.2~1.4GPa。绿片岩的峰期变质级别为绿帘-角闪岩相。结合前人研究成果,认为蓝片岩和绿片岩的形成与额尔古纳地块和兴安地块的碰撞拼合有关。 | 赵立敏 刘永江 滕加雨 李伟民 | 2018 | 吉林大学学报(地球科学版)2018,48,2: | 1 |
| 4 | Age, Geochemistry, and Tectonic Implications of Dulaerqiao Granite, Inner Mongolia显示文摘Dulaerqiao granite is located at the Xinlin-Xiguitu-Toudaoqiao suture zone between the Erguna massif and the Xing'an massif, northeast of Inner Mongolia. The rocks are mainly composed of K-feldspar, quartz, and plagioclase. Zircon LA-ICP-MS U-Pb data show that this granite was deposited in the Late Carboniferous Period(308.7±2.0 Ma). The samples are rich in alkali, Fe, and Al and low in Mg, Ca, and P. Chondrite-normalized REEs exhibit right-inclined patterns with significant negative Eu anomalies. Additionally, the granite shows high quantities of trace elements such as Zr, Hf, Th, K, and Rb and decreased quantities of Sr, P, and Ti. The chemical characteristics identified herein and a series of diagrams that distinguish different types of granite show that Dulaerqiao alkali-feldspar granites belong to the aluminous A-type granite group. Meanwhile, the initial magma crystallizes under hightemperature, low-pressure conditions resulting from a tectonic extension setting. The formation of Dulaerqiao aluminous A-type granite is related to the rejuvenation of the ancient Xinlin-Xiguitu-Toudaoqiao suture zone, which was activated by the interaction between the combined Erguna-Xing'an massif and the Songnen massif in the Late Paleozoic Era. This aluminous A-type granite was deposited about 30 Ma after the collision. | Anxia Chen Duo Zhou Qingkui Zhang Zhongzhu Yang | 2018 | Journal of Earth Science2018,29,1: | 1 |
| 5 | Timming of Lithospheric Extension in Northeastern China:Evidence from the Late Mesozoic Nianzishan A-Type Granitoid Complex显示文摘New zircon U-Pb dates obtained by laser ablation inductively coupled plasma mass spectrometry(LA-ICP-MS),whole-rock geochemical data and Sm-Nd and Rb-Sr isotopic data are presented for miarolitic alkaline granites,porphyritic syenite and rhyolites of the Nianzishan A-Type granitoid complex(NAGC)in the Great Xing'an Range-Songliao Basin in Northeast(NE)China.New crystallization ages of 112.95±0.93 and 114.1±1.71 Ma for granite and 118.6±0.51 Ma for porphyritic syenite were determined by high-precision LA-ICP-MS.The εNd(t)of the rocks range from +1.85 to+2.06,with Nd model ages(T(DM1))from 671 to 821 Ma,indicating that the NAGC originated from juvenile source rocks and exhibits geochemical characteristics of A1-and A-Type granite which formed in an extensional setting.We attribute the magmatism to regional extension and lithospheric thinning caused by the subduction of the western Pacific Plate about 120 to 100 Ma. | Jinhua Qin Cui Liu Yuchuan Chen Jinfu Deng | 2019 | Journal of Earth Science2019,30,4: | 0 |