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421.
LI Qiuli LI Shuguang HOU Zhenhui HONG Ji''''an & YANG Wei School of Earth Space Sciences University of Science Technology of China Hefei China Institute of Geology Geophysics Chinese Academy of Sciences Beijing China 《科学通报(英文版)》2005,50(5):459-465
Methods recently advanced for discrimination on the genesis of metamorphic zircon, such as analysis of mineral inclusions and trace elements, provide us powerful means to distinguish zircon overgrowth during high-pressure metamorphism. Zircons in ultrahigh-pressure eclogite from Qinglongshan in the Sulu terrane were studied by the SHRIMP U-Pb method in combining with trace element and mineral inclusion analyses. No inherited core was identified in the analyzed zircons by means of cathodoluminescence images. The occurrence of high-pressure metamorphic mineral inclusions in zircon, such as garnet, omphacite, rutile, and the flat HREE pattern in zircon indicate that the zircon formed at high-pressure metamorphic conditions. Therefore, a weighted average U-Pb age of 227.4±3.5 Ma obtained from such a kind of zircon is interpreted to represent the timing of peak nietamorphism for the Qinglongshan eclogite. 相似文献
422.
XIE Lei WANG Rucheng CHEN Xiaoming QIU Jiansheng & WANG Dezi State Key Laboratory for Mineral Deposits Research Department of Earth Sciences Nanjing University Nanjing ? China 《科学通报(英文版)》2005,50(8):809-817
Zircon is one of the most common accessory minerals in igneous rocks, especially in granites. It exists through the crystallization and evolution of grantic magma be-cause of stable physicochemical properties. Trace element abundances (e.g. Hf, Th, U, Y) in zircon are very sensitive to the crystallization environments[1]. Therefore, zircon plays an important role in the granite research. However, although A-type granites are given more and more regards by the geologists owing to their charac… 相似文献
423.
QIU Zhili WU Fuyuan YU Qingyuan XIE Liewen YANG Shufeng 《科学通报(英文版)》2005,50(22):2602-2611
Cenozoic basalts are widely distributed in eastern China, and some of them contain zircon megacrysts which are considered to be constituent mineral of the subcontinental lithospheric mantle (SCLM) and petrogenetically related to mantle metasomatism induced by addition of crustal materials. Using the Laser Ablation Multiple Collector Inductively Coupled Plasma Mass Spectrometry (LA-MC-ICPMS), zircon megacrysts from the Cenozoic basalts at Changle in Shandong, Mingxi in Fujian, and Penglai in Hainan provinces have been used for Hf isotopic analyses. The data indicate that there is no significant deviation for the different zircon grains in each locale, except those from Penglai. The obtained ^176Hf /^177Hf ratios are 0.28302- 0.28308 for Changle, 0.28297-0.28300 for Mingxi, and 0.28288-0.28293 for Penglai, with corresponding ear values of 8.7-10.8, 7.0-7.9, and 3.9-5.7, respectively. These data display that there existed some regional heterogeneity, but the Hf model ages clustere in the Phanerozoic. Therefore, it is inferred that metasomatism of the lithospheric mantle beneath eastern China took place in the Phanerozoic, most probably in the Mesozoic-Cenozoic. However, the formation time of the iithospheric mantle is not clearly constrained based on the present Hf isotopic data. 相似文献
424.
Shifts of the Kuroshio axis over the last 20 000 years 总被引:5,自引:0,他引:5
Core 255 from the southern Okinawa Trough was selected to monitor the shift of the Kuroshio axis over the last 20 000 years.
During the last glacial maximum the Kuroshio axis had ever shifted outside the Okinawa Trough. It entered the Okinawa Trough
again at about 6 500 a BP, leading to abrupt increase of sedimentation rate, distinctly coarser sediment and remarkably increased
abundance of foraminiferal indicators of the Kuroshio in the core. But, during about 4 000-3 000 a BP the abundance of the
Kuroshio indicatorPulleniatina obliquiloculata sharply decreased again, indicating that the Kuroshio axis had ever shifted casterly for a short period or the Kuroshio was
weakened and that moment. 相似文献
425.
The study of the sediment of Core M1 from Jianghan Plain suggests that the sediment source of this area changed in the Holocene,
which corresponds with thr south moving of the Yangtze River. Since then, the sediment source has been mainly from the Hanshui
River. 相似文献
426.
近年,应用~(14)C年龄测定法测定了一批广东、福建、海南等省的考古及地质样品的年龄,涉及多种类型的样品,对人类考古学、第四纪地质学及地貌学有一定的参考价值。 相似文献
427.
428.
张京良 《山东科技大学学报(自然科学版)》1989,(4)
本文主要通过磁化率各向异性即磁性组构的研究,证明山东蒙阴金伯利岩矿床是属于侵入成因,并阐述了用磁性组构取代岩石学组构测量是地质学发展的一种新趋势。根据视极移曲线及同位素测定岩石年龄的方法,确定岩体的形成时代为加里东期岩浆活动,以此对燕山期岩浆活动的结论提出质疑。 相似文献
429.
430.
山东昌乐与碱性玄武岩有关刚玉巨晶中锆石包裹体的发现及其意义 总被引:3,自引:0,他引:3
山东昌乐蓝宝石矿是我国最大的与新生代碱性玄武岩有关的蓝宝石矿床,但对其成因仍有不同的认识[1,2].本文根据昌乐刚玉巨晶中发现的锆石包裹体,探讨刚玉巨晶的成因.1 地质背景与山东昌乐蓝宝石矿床有关的碱性玄武岩的产出主要受沂沐断裂(郯庐断裂山东段)及其次级断裂——... 相似文献