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Geochemical Characteristics and Tectonic Setting of the Laohushan Basalts, North Qilian Mountains

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Acta geologica Sinica(English Edition) 2001年第4期75卷 452-457页

作者： QIAN Qing and ZHANG Qi institute of geology and Geophysics, CAS, P. O. Box 9825, Beijing 100029 CAS Inst Geol & Geophys Beijing 100029 Peoples R China

The Ordovician Laohushan ophiolite, located in the eastern part of the North Qilian Mountains, is mainly composed of meta-peridotites, gabbros and basalts alternating with sediments. The sediments are mainly turbidites, including sandstones, siltstones, cherts etc. Major elements show that the basalts are subalkaline tholeiites and may be analogous to ocean-floor basalts. Except a few N-MORBs, most of the basalts are E-MORBs as indicated by incompatible element ratios such as (La/Ce)N, La/Sm, Ce/Zr, Zr/Y and Zr/Nb. Negative Nb anomaly is common but negative Zr, Hf and Ti anomalies are quite rare. Based on the geochemical characteristics, it is suggested that the Laohushan basalts were formed in a back-arc basin. ENd (t) of the basalts ranges between +3.0 and +8.9 and (87Sr/86Sr), ranges between 0.7030 and 0.7060, indicating a depleted mantle source which was mixed with more or less enriched mantle components. Furthermore, the petrography of the sandstones and geochemistry of the cherts suggest that the sediments were deposited near a continental margin.

关键词： North Qilian Mountains Laohushan basalts sediments geochemistry

Determining burn degree of fire-damaged concrete constructions by thermoluminescence

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Chinese Science Bulletin 1997年第21期42卷 1829-1833页

作者： Pei, JX Han, Y Sun, XH Chinese Acad Sci Inst Geol Beijing 100029 Peoples R China

NOWADAYS there are many skyscrapers in cities. If fire-damaged, the only way to lessen

关键词： determining of thermolominescence concrete constructions.

The white schist assemblage in the kyanite quartzite from the ultrahigh-pressure metamorphic belt, eastern Dabie Mountains

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Chinese Science Bulletin 1998年第19期43卷 1651-1655页

作者： Laili Jiang Shutong Xu Yican Liu Weiping Wu Wen Su Anhui inst geol Hefei 230001 Peoples R China

The kyanite quartzite from the ultrahigh-pressure metamorphic belt in the eastern Dabie Mountains is composed mainly of quartz, kyanite, talc and epidote, which contains a typical mineral assemblage of white schist. It suffered an eclogite facies metamorphism of P =(2 4±0 3) GPa and T =630℃ together with coexisting eclogite. The protolith may be an aplite replaced by high-pressure fluid of eclogite facies.

关键词： Dabie Mountains ultrahigh pressure white schist assemblage

A New Genus of Psittacosauridae (Dinosauria: Ornithopoda) and the Origin and Early Evolution of Marginocephalian Dinosaurs

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Acta geologica Sinica(English Edition) 2003年第1期77卷 15-20页

作者： YOU Hailu institute of geology, Chinese Academy of geological Sciences, Beijing 100037XU Xing and WANG Xiaolininstitute of Vertebrate Paleontology and Paleoanthropology Chinese Academy of Sciences, Beijing 100044 Chinese Acad geol Sci Inst Geol Beijing 100037 Peoples R China Chinese Acad Sci Inst Vertebrate Paleontol & Paleoanthropol Beijing 100044 Peoples R China

An almost complete juvenile dinosaur skull with lower jaw was discovered fromthe Early Cretaceous Yixian Formation in Beipiao, Liaoning Province, China. Here, the specimen isdescribed and a cladistic analysis is performed in order to find its phylogenetic relationships. Theresult shows that this specimen represents a new genus of Psittacosauridae, Hongshanosaurus houi,gen. et sp. nov., and confirms the monophyletic status for Ceratopsia and Marginocephalia. However,Heterodontosaurus is found to be the sister taxon to Marginocephalia, rather than a basalOrnithopoda.

关键词： Dinosauria Marginocephalia Hongshanosaurus houi, gen. et sp. nov. Yixian Formation Liaoning Province

Rare Earths, Niobium and Tantalum Minerals in Bayan Obo Ore Deposit and Discussion on Their Genesis

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Journal of Rare Earths 2002年第2期20卷 81-86页

作者：张培善陶克捷杨主明杨学明宋仁奎 inst. of geol. and Geophys. Chinese Acad. of Sci. Beijing 100029 China

Bayan Obo ore deposit is endowed with and lie hidden in the Proterozoic strata. The localities and occurrences of the minerals in the ore deposit were described. It is obviously that some minerals are strata minerals and some are post strata minerals. The rare earths, niobium and tantalum minerals are exactly the post strata minerals. In these minerals the hydrothermal metasomatic phenomena distinctly reveal their metallogenic characteristics. According to tectonic movement, magma activity, mineral paragenesis, hydrothermal metasomatism, geological age and lasting time scale of metallogenesis, and some other factors, it is supposed that genesis of rare earths, niobium and tantalum minerals in Bayan Obo ore deposit are closely related with hydrothermal metallogenic solution which is differentiated from silica acid and carbonic acid magma and derived from deep seated source, and then intruded into Proterozoic strata and metasomatized. It is recognized that the metallogenesis of Bayan Obo ore deposit is undergoing a long geological period and many episodes.

关键词： rare earths niobium and tantalum mineral genesis Bayan Obo

Experimental study of the metamorphic reaction involving melt under high temperature and high pressure

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Chinese Science Bulletin 1998年第3期43卷 249-253页

作者： Fulai Liu Qihan Shen Yuansheng Geng Xuechun Xu Rui Ma Chinese Acad Geosci Inst Geol Beijing 100037 Peoples R China Changchun geol Coll Open Lab Changchun 130021 Peoples R China

High P_T experiment with natural massive rock sample of garnet biotite plagioclase gneiss indicates that the metamorphic reaction involving melt (reaction between relic mineral phase and melt) is the most important re... 详细信息

关键词： metamorphic reaction involving melt natural massive rock garnet biotite plagioclase gneiss high_temperature and high_pressure experiment.

Discovery of granulite from the Fuping area in southern Qinling Mountains and its geological significance

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Chinese Science Bulletin 1998年第16期43卷 1358-1362页

作者： Chunjing Wei Chonghui Yang Shouguang Zhang Rongshe Li Peking Univ Dept Geol Beijing 100871 Peoples R China Chinese Acad geol Sci Inst Geol Beijing 100037 Peoples R China Bur geol & Explorat Shaanxi Prov Xianyang 712000 Peoples R China

Two-pyroxene-bearing granulites were discovered for the first time in the Hercynian-Indosinian metamorphic belt of the southern Qinling Mountains. The granulites occur in the lower part of the Fuping complex and are dominated by intermediate-acidic rocks intercalated with a small amount of bands and lenses of basic granulites. The main metamorphic minerals include orthopyroxene, clinopyroxene, biotite, plagioclase and quartz, and orthopyroxenes are often retrogressively transformed into amphiboles. The metamorphic conditions have been estimated to be %T%=720-780℃ and %P%=0.6 GPa. The granulite-bearing Fuping complex probably belongs to early Proterozoic in age. Whether it occurs as the crystalline basement of the southern Qinling Hercynian-Indosinian orogenic belt or as a thrusted slice in the collisional process needs further study.

关键词： granulite Fuping complex Qinling orogenic belt.

Discovery of ophiolite in southeast Yunnan,China

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Chinese Science Bulletin 1999年第1期44卷 36-41页

作者： Dalai Zhong Genyao Wu Jianqing Ji Qi Zhang Lin Ding Chinese Acad Sci Inst Geol Beijing 100029 Peoples R China

The Babu ophiolite in Malipo County, SE Yunnan, consists of three units: ultramafic, mafic and basaltic rocks. Studies of geological mapping, petrology and geochemistry reveal that the gabbro is similar to that in the Troodos ophiolite, and the diabase and basalt belong to a normal MORB-type,analogous to the Shuanggou ophiolite in west Yunnan. The ophiolite studied as a thrust tectonic slab,was overthrust northwards onto the Late Paleozoic-Triassic deep marine deposits of continental *** is inferred to be relics of Paleotethyan ocean; namely, a branch of Paleotethys occurs in South China, where the tectonic nature and evolutional history of the area should be reconsidered.

关键词： ophiolite geochemistry Babu in SE Yunnan.

U-series dating on late Quaternary sediments from Balikun Lake

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Chinese Science Bulletin 1998年第17期43卷 1434-1441页

作者： Jiaqi Liu Zhibang Ma Chinese Acad Sci Inst Geol Beijing 100029 Peoples R China

The U-series component-dating method has been employed to date the sediment core B-194 from Balikun Lake. 230Th/ 232Th and 234U/ 232Th ratios in various components of the samples dissolved in different concentration acids were measured respectively. The results indicate that there is a good relationship of the isotopic ratios between the solutions and the residues, and that uranium and thorium isotopic fractionations did not occur during acid leaching. Based on the U-series ages obtained by using component-dating method, a 144-ka time sequence was established corresponding to the upper 25-m interval of the B-194 core, which is in agreement with palaeomagnetic dating results. The fact that the palaeoclimatic and palaeoenvironmental record labeled with U-series ages is correlative with the deep-sea δ 18O SPECMAP also demonstrates that the U-series component-dating method can be used to date lake sediments.

关键词： Balikun Lake sediments component-dating model U-series age.