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| 1 | Genesis of the Changba–Lijiagou Giant Pb-Zn Deposit, West Qinling, Central China: Constraints from S-Pb-C-O isotopes显示文摘The extensive Changba-Lijiagou Pb-Zn deposit is located in the north of the Xihe–Chengxian ore cluster in West Qinling. The ore bodies are mainly hosted in the marble, dolomitic marble and biotite-calcite-quartz schist of the Middle Devonian Anjiacha Formation, and are structurally controlled by the fault and anticline. The ore-forming process can be divided into three main stages, based on field geological features and mineral assemblages. The mineral assemblages of hydrothermal stage I are pale-yellow coarse grain, low Fe sphalerite, pyrite with pits, barite and biotite. The mineral assemblages of hydrothermal stage II are black-brown cryptocrystalline, high Fe shalerite, pyrite without pits, marcasite or arsenopyrite replace the pyrite with pits, K-feldspar. The features of hydrothermal stage III are calcite-quartz-sulfide vein cutting the laminated, banded ore body. Forty-two sulfur isotope analyses, twenty-five lead isotope analyses and nineteen carbon and oxygen isotope analyses were determined on sphalerite, pyrite, galena and calcite. The δ34 S values of stage I(20.3 to 29.0‰) are consistent with the δ34 S of sulfate(barite) in the stratum. Combined with geological feature, inclusion characteristics and EPMA data, we propose that TSR has played a key role in the formation of the sulfides in stage I. The δ34 S values of stage II sphalerite and pyrite(15.1 to 23.0‰) are between sulfides in the host rock, magmatic sulfur and the sulfate(barite) in the stratum. This result suggests that multiple S reservoirs were the sources for S2-in stage II. The δ34 S values of stage III(13.1 to 22‰) combined with the structure of the geological and mineral features suggest a magmatic hydrothermal origin of the mineralization. The lead isotope compositions of the sulfides have 206 Pb/204 Pb ranging from 17.9480 to 17.9782, 207 Pb/204 Pb ranging from 15.611 to 15.622, and 208 Pb/204 Pb ranging from 38.1368 to 38.1691 in the three ore-forming stages. The narrow and symmetric distributions of the lead isotope values reflect homogenization of granite and mantle sources before the Pb-Zn mineralization. The δ13 CPDB and δ18 OSMOW values of stage I range from-0.1 to 2.4‰ and from 18.8 to 21.7‰. The values and inclusion data indicate that the source of fluids in stage I was the dissolution of marine carbonate. The δ13 CPDB and δ18 OSMOW values of stage II range from-4 to 1‰ and from 12.3 to 20.3‰, suggesting multiple C-O reservoirs in the Changba deposit and the addition of mantle-source fluid to the system. The values in stage III are-3.1‰ and 19.7‰, respectively. We infer that the process of mineralization involved evaporitic salt and sedimentary organic-bearing units interacting through thermochemical sulfate reduction through the isotopic, mineralogy and inclusion evidences. Subsequently, the geology feature, mineral assemblages, EPMA data and isotopic values support the conclusion that the ore-forming hydrothermal fluids were mixed with magmatic hydrothermal fluids and forming the massive dark sphalerite, then yielding the calcite-quartz-sulfide vein ore type at the last stage. The genesis of this ore deposit was epigenetic rather than the previously-proposed sedimentary-exhalative(SEDEX) type. | WEI Ran WANG Yitian MAO Jingwen HU Qiaoqing QIN Siting LIU Shengyou YE Dejin YUAN Qunhu DOU Ping | 2020 | Acta Geologica Sinica(English Edition)2020，94，4： | 4 |
| 2 | The first discovery of eclogite and Palaeoproterozoic granitoids in the Beishan area,northwestern Gansu Province,China显示文摘The eclogite, discovered in Liuyuan, occurs as lenticular enclave within granitic gneiss. It has typical features of eclogite in petrology and mineralogy. The eclogite provides an important wirdow to reconstruct the tectonic border of the Tarim block. The granitoids, located in Baihu area, yield U-Pb zircon ages of 1 660—2 000 Ma (Palaeoproterozoic), which irrplies an early Precambrian basement in the area. | Hualin Mei Haifeng Yu Quan Li Songnian Lu Huimin Li Yicheng Zuo Guochao Zuo Dejin Ye Jincheng Liu | 1999 | Chinese Science Bulletin1999，44，4： | 1 |
| 3 | Temporo-Spatial Distribution and Evolution of Ore Deposits in the West Sector of the Northern Qilian Mountains显示文摘The west sector of the northern Qilian Mountains is well-known for the Jingtieshan-type iron deposits. A new breakthrough has been made in prospecting for gold and copper in recent years. In this paper, the distribution characteristics of ore deposits in the study area are discussed from the viewpoint of tectonic evolution. It is suggested that there are 9 stages of mineralization from the Palaeoproterozoic to Indosinian. Four minerogenetic series and two minerogenetic subseries of ore deposits are recognized. Iron mineralization occurred in several stages, while most of the metals were accumulated in large amounts in the Caledonian. The enrichment and mineralization of gold is related to large-scale shear-strike-slip faults and the ascent and unloading of deep-seated fluids. | MAO Jingwen ZHANG Xiaoyu ZHANG Zhaochong REN Fengshou ZUO Guochao ZHANG Zuoheng YANG Jianmin WANG Zhiliang YE Dejin | 1999 | Acta Geologica Sinica(English Edition)1999，73，2： | 1 |
| 4 | Treatment for arteriovenous malformation of the brain Comparison between microsurgery and gamma knife显示文摘BACKGROUND: Microsurgery and gamma knife are the mainly ways to treat arteriovenous malformation of brain in grade Spetzler-Martin Ⅰ–Ⅲ; however,therapeutic effects of them need to be further studied. OBJECTIVE: To compare the therapeutic effects between microsurgery and gamma knife on the treatment of arteriovenous malformation of brain in grade Spetzler-Martin Ⅰ–Ⅲ. DESIGN: Retrospective analysis. SETTING: Department of Neurosurgery,the Third Hospital Affiliated to Sun Yat-sen University; Guangdong Microinvasion Center. PARTICIPANTS: A total of 86 patients with arteriovenous malformation of the brain were selected from the Department of Neurosurgery,the Third Hospital Affiliated to Sun Yat-sen University and Guangdong Microinvasion Center from January 1997 to February 2007. After DSA,CT and/or MRI examinations,patients were evaluated in grade Spetzler-Martin Ⅰ–Ⅲ. All patients were divided into microsurgery group (n = 34) and gamma knife group (n =52). There were 22 males and 12 females in the microsurgery group and their mean age was 26 years,while there were 34 males and 18 females in the gamma knife group and their mean age was 28 years. The grade of Spetzler-Martin was comparable in the two groups. All their relatives provided the confirmed consent and the study was allowed by ethics committee of our hospital. METHODS: Under complete anesthesia,patients were given microsurgery and the operative approach was chosen based on diseased regions. Firstly,feeding artery was blocked; secondly,it was separated along band of gliosis between malformation vessel mass and brain tissue; finally,draining vein was cut off and malformation vessel mass was resected. On the other hand,patients in the gamma knife group received Leksell-2300B gamma knife treatment. Leksell-G stereotaxis headframe was installed; GE1.5TMR scanning device was used for localization; r-Plan5.2 workstation was used for target design and dosage program; Leksell B gamma knife was used during the whole operative procedure. The target was 1–4 and peripheral dosage was 12–28 Gy. At 0.5,1 and 2 years after operation,angiography was used to detect vascular occlusion in the two groups. Meanwhile,focal hemorrhage and new neurological function defect (including hemiplegic paralysis,language disorder,cerebellar function disorder,increasing frequency of epilepsy,etc.) were also observed. MAIN OUTCOME MEASURES: Rate of vascular occlusion,focal hemorrhage and neurological function defect at different time points after operation. RESULTS: All 86 patients were involved in the final analysis. Vascular nest of patients in the microsurgery group disappeared completely; while,two patients (6%,2/34) had new neurological function defect but did not have rehaemorrhagia and death after operation. On the other hand,vascular nest of 43 patients (83%,43/52) in the gamma knife group disappeared completely,and 8 (15%,8/52) had new neurological function defect. There was significant difference between the two groups (χ2=2.63,P < 0.05). Six patients (12%,6/52) in the gamma knife group had rehaemorrhagia after operation,and one (2%,1/52) died. CONCLUSION: Both microsurgery and gamma knife have great effects on the treatment of arteriovenous malformation of brain in grade Spetzler-Martin Ⅰ–Ⅲ; however,the therapeutic effects of microsurgery are superior to those of gamma knife. | Dejin Shi Ying Guo Wen sheng Li Zhuopeng Ye Hui Wang Gang Chen Shengling Wu | 2007 | Neural Regeneration Research2007，2，10： | 0 |
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