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Magma underplating and Hannuoba present crust-mantle transitional zone co.position: Xenolith petrological and geochemical evidence

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Science China Earth sciences 2005年第8期48卷 1089-1105页

作者： FAN Qicheng1,2, ZHANG Hongfu1, SUI jianli1, ZHAI Mingguo1, SUN Qian2 & li Ni2 1. institute of geology and geophysics, chinese academy of sciences, beijing 10002., China 2. institute of geology, China Seismological Bureau, beijing 10002., China institute of geology and geophysics Chinese Academy of Sciences Beijing China institute of geology China Seismological Bureau Beijing China

On the basis of mineral assemblage, mineralogy, petrology, and major, trace ele-mental and isotopic geochemistry of the underplated granulite- and eclogite-facies accumulate, peridotite and pyroxenite xenoliths entrained in Hannuoba Cenozoic basalts, this work co.-strained the petrological co.stituents for the crust-mantle transitional zone, which is supported by the results of high-temperature and pressure velocity experiments on rocks and geophysics deep survey. Present lower part of lower crust is mainly co.posed of granulite-facies mafic accumu-lates (dominantly plagioclase websterite) and crust-mantle transitional zone dominantly co.-posed of eclogite-facies pyroxenites with or without garnet and spinel lherzolites; Archaean ter-rain granulite is only nominally early lower crust. Magma underplating in the crust-mantle boundary led to the crustal vertical accretion and the formation of the crust-mantle transitional zone, which is a significant mechanism for the chemical adjustment of the crust-mantle boundary since the Phanerozoic.

关键词： magma underplating, xenolith petrology, geochemistry, cust-mantle boundary co.stituent, Hannuoba.

Ambient noise near the sea-route

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Science China(Physics,Mechanics & Astronomy) 2009年第1期52卷 40-45页

作者： HE li1,2, li Zhenglin1,3 & PENG Zhaohui1 1 National Laboratory of Aco.stics, institute of Aco.stics, chinese academy of sciences, beijing 100190, China 2 institute of geology and geophysics, chinese academy of sciences, beijing 10002., China 3 NanHai Laboratory of Aco.stics, institute of Aco.stics, chinese academy of sciences, Haikou 570206, China National Laboratory of Aco.stics Institute of Acoustics Chinese Academy of Sciences Beijing China institute of geology and geophysics Chinese Academy of Sciences Beijing China NanHai Laboratory of Aco.stics Institute of Acoustics Chinese Academy of Sciences Haikou China

Ambient noise data measured in an experiment co.ducted in shallow water near a sea-route were analyzed. It was observed that, at low frequency, the horizontal co.relation has an obvious difference from that predicted by the classical ambient noise model. The theoretical analyses show that this phenomenon is caused by wind noise together with the discrete shipping noise nearby. An ambient noise model was proposed to include the effects caused by both the noise sources. Data measured at different times verify that the proposed model can be used to forecast the ambient noise field in shallow water near the sea-route.

关键词： ambient noise model horizontal co.relation discrete ships

A new species of Leptocycas (Zamiaceae) from the Upper Triassic sediments of liaoning Province,China

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Journal of Systematics and Evolution 2010年第4期48卷 286-301页

作者： 1,2,3jian-Wei ZHANG 2jian-Xin YAO 1jia-Rui CHEN 1Cheng-Sen li 1(State Key Laboratory of Systematic and Evolutionary Botany,institute of Botany,chinese academy of sciences,beijing 100093,China) 2(State Key Laboratory of Stratigraphy and Paleontology,institute of geology,chinese academy of Geological sciences,beijing 100037,China) 3(Graduate university,chinese academy of sciences,beijing 100049,China) (State Key Laboratory of Systematic and Evolutionary Botany Institute of Botany Chinese Academy of Sciences Beijing 100093 China) (State Key Laboratory of Stratigraphy and Paleontology Institute of Geology Chinese Academy of Geological Sciences Beijing 100037 China) (Graduate university Chinese Academy of Sciences Beijing 100049 China)

A new cycad,Leptocycas yangcaogouensis ***.,was found in sediments from the Late Triassic in western liaoning,*** pinnately co.pound leaves(Pseudoctenis type)are screwed in a crown on the stem *** leaflets are linear,with parallel veins and decurrent bases on the *** leaf bases are *** cataphylls intermix with the *** female co.e is ovoid in *** characteristics of the new plant are more similar to those of Leptocycas gracilis,a Triassic cycad from North America,but the new species differs from *** in the size of its stem(7–8 vs.3–5 cm in diameter,respectively),leaves(length×width 100×16 vs.30×7 cm,respectively)and leaf density along the stem(4–6 vs.1–2 bases/1 cm length,respectively).Both *** and ***,having leaves of the Pseudoctenis type,show a closer relationship to the extant Dioon of *** present study provides evidence for the origin of the genus Dioon,which may have co.e from Leptocycas plants of the *** would be assumed that the extent cycads in Zamiaceae originate from the pteridosperms in the Late Paleozoic and have evolved through the stage of *** and *** in Late Triassic,and reaching the extant Dioon.

关键词： China Cycadales Leptocycas Upper Triassic Zamiaceae

Si-and alkali-rich melt inclusions in minerals of mantle peridotites from eastern China:Implication for lithospheric evolution

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Science China Earth sciences 2006年第1期49卷 43-49页

作者： FAN Qicheng1, SUI jianli2, XU Ping2, li Ni1, SUN Qian1 & WANG Tuanhua1 1. institute of geology, China Seismological Bureau, beijing 10002., China 2. institute of geology and geophysics, chinese academy of sciences, beijing 10002., China institute of geology China Seismological Bureau Beijing China institute of geology and geophysics Chinese Academy of Sciences Beijing China

Minerals of spinel- and garnet-facies mantle xenoliths entrained in Cenozoicbasalts from eastern China (North China, Northeastern China and Southeastern China co.stal area)co.tains lots of melt inclusions. Studies on these melt inclusions show that the glass inclusionsare rich in SiO_2 (60%—68%) and alkalis (K_2O+Na_2O = 5%—11%, especially for K_2O) as well asvolatiles such as H_2O and co.2 (2%—7%), which belong to dacites and andesites of the high-K calcicalkali series rocks with few shoshonites. High Al and Ca diopside in melt inclusion is the productof melt crystallization at high temperature and pressure, rather than the product ofdevitrification. Results show that these K-rich (in general K_2O > 3%) intermediate-acidic silicatemelt inclusions have characteristics of co.tinent without a genetical link to host basalts and theirphenocrystic minerals. Thus, these trapped melt inclusions represent melts of Mesozoic lithosphericmantle-crust interaction and imply that the co.tinental lithospheric mantle beneath eastern Chinahad undergone fragmentation and recreation processes during the Mesozoic and Cenozoic periods. Thisresult undoubtly provides important implication for the evolution of sub-co.tinental lithospherebeneath eastern China. We propose that these Si- and alkalis-rich melts should be responsible forthe mantle chemical heterogeneity underneath eastern China.

关键词： Si- and alkali-rich melt inclusion, mantle peridotite, lithospheric evolution, eastern China.

Carbon isotope co.position and its implications of Lower Cretaceous Aptian-Albian shallow water carbonates in the Cuoqin Basin, North Tibet

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Science China Earth sciences 2004年第3期47卷 247-254页

作者： ZHU Jingquan1, li Yongtie2, jiaNG Maosheng1 & CHEN Daizhao1 1. institute of geology and geophysics, chinese academy of sciences, beijing 10002., China 2. Research institute of Petroleum Exploration and Development, CNPC, beijing 100083, China institute of geology and geophysics Chinese Academy of Sciences Beijing 100029 China Res. Inst. Petroleum Explor./Devt. CNPC Beijing 100083 China

The d 13C values of Lower Cretaceous Aptian-Albian platform-type carbonates in the Cuoqin Basin, North Tibet vary between 2.48 and 5.46. The mean value is 3.93. The values are not only provided with positive excursion, but also 1.17 higher than those of co.-temporaneous pelagic carbonates which possess pretty high d 13C values. The origin is ap-proached. During the oceanic anoxic events, a great number of organisms were rapidly buried, causing the increase of the d 13C value of oceanic total dissolved carbon (TDC) and generally promoting the values of marine carbonates. After that, owing to the organisms undergoing dif-ferent isotopic fractionation in the paleo-ocean with stratified structure, d 13C values of shallow sea carbonate were obviously higher than those of pelagic carbonates.

关键词： shallow water carbonate, stable carbon isotope, paleooceanography, Aptian-Albian stage, Cuoqin Basin.

Crustal structure of Gondwana-and Yangtze-typed blocks:An example by wide-angle seismic profile from Menglian to Malong in western Yunnan

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Science China Earth sciences 2005年第11期48卷 1828-1836页

作者： ZHANG Zhongjie1, BAI Zhiming1, WANG Chunyong2, TENG Jiwen1, Lü Qingtian3, li Jiliang1, SUN Shanxue1 & WANG Xinzheng1 1. institute of geology and geophysics, chinese academy of sciences, beijing 10002., China 2. institute of geophysics, chinese Seismological Bureau, beijing 100081, China 3. institute of Deposition Resource, chinese academy of Geological sciences, beijing 100037, China institute of geology and geophysics Chinese Academy of Sciences Beijing China institute of geophysics Chinese Seismological Bureau Beijing China institute of Deposition Resource Chinese Academy of Geological Sciences Beijing China

The wide-angle seismic profile between Menglian and Malong crosses the Baoshan block (Gondwana-typed), and Simao and southwestern Yangtze blocks (Yangtze-typed). By in-terpreting the wide-angle seismic data, we obtained the seismic crust/upper mantle structure of P-wave velocities together with the seismic reflections of these three blocks, Changning- Menglian and Mojiang suture zones among the mentioned three blocks. Our interpreting results demonstrate that the P-wave crustal velocity of Simao block is slower than that of Baoshan and southwestern Yangtze block and the crustal thickness gradually thickens from the Baoshan block, Simao to southwestern Yangtze block. Crustal reflection patterns of these three blocks have dis-tinct differences too. For the Gondwana-typed blocks, seismic reflections in the upper crust are well developed while in middle-lower crust they are very weak. The crustal reflections in the Yangtze block are very well developed. The crustal reflection patterns in Simao and southwest-ern Yangtze blocks are distinguishable. The average thickness of the crust in the studied area is about 40 km. And we make some discussions on the crustal thickening model of the three blocks in western Yunnan and tectonic setting of seismic developing and interaction of Gondwana and Yangtze blocks.

关键词： Gondwana blocks,Yangtze blocks,wide-angle profile,crustal structure,tectonic setting

Typical basin-fill sequences and basin migration in Yanshan, North China ——Response to Mesozoic tectonic transition

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Science China Earth sciences 2004年第2期47卷 181-192页

作者： li Zhong, liU Shaofeng, ZHANG Jinfang & WANG Qingchen1. institute of geology and geophysics, chinese academy of sciences, beijing 10002., China 2. China university of Geosciences, beijing 100083, Chinaco.respondence should be addressed to li Zhong (email: lizhongd@***) institute of geology and geophysics Chinese Academy of Sciences Beijing China China university of Geosciences Beijing China

Basin-fill sequences of Mesozoic typical basins in the Yanshan area, North China may be divided into four phases, reflecting lithosphere tectonic evolution from flexure (T3), flexure with weak rifting (J1+2), tectonic transition (J3), and rifting (K). Except the first phase, the other three phases all start with lava and volcaniclastic rocks, and end with thick co.rse clastic rocks and/or co.glomerates, showing cyclic basin development rather than simple cyclic rift mechanism and disciplinary basin-stress change from extension to co.pression in each phase. Prototype basin analysis, based on basin-fill sequences, paleocurrent distribution and depositional systems, shows that single basin-strike and structural-line direction co.trolling basin development had evidently changed from east-west to northeast in Late jurassic in the Yanshan area, although basin group still occurred in east-west zonal distribution. Till Early Cretaceous, main structural-line strike co.trolling basins just turned to northeast by north in the studied area.

关键词： Yanshan, Mesozoic, basin-fill, paleocurrent, tectonic transition.

The age of the plant fossil assemblage in the liuqu co.glomerate of southern Tibet and its tectonic significance

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Progress in Natural Science:Materials international 2006年第1期16卷 55-64页

作者： FANG Aimin1, YAN Zhen1, liU Xiaohan2, PAN Yusheng1, li Jiliang1, YU liangjun1, HUANG Feixing2 and TAO junrong3 (1.Laboratory of lithosphere Tectonic Evolution, institute of geology and geophysics, chinese academy of sciences, beijing 10002., China 2. institute of Tibet Plateau Research, chinese academy of sciences, beijing 100085, China 3. institute of Botany, chinese A cademy of sciences, beijing 100093, China) Laboratory of lithosphere Tectonic Evolution Institute of Geology and Geophysics Chinese Academy of Sciences Beijing 100029 China institute of Tibet Plateau Research Chinese Academy of Sciences Beijing 100085 China institute of Botany Chinese A-cademy of Sciences Beijing 100093 China

The liuqu co.glomerate, situated to the south of Yarlung Tsangbo Suture Zone (YTSZ), is a suit of molasse formed in a foreland basin of the Himalayan orogenic belt after the co.lision between the two plates of the Indian and Eurasion, It is of great significance in co.straining the younger limit time of the co.lision of the two plates and providing stratigraphic evidence to reveal the post-co.li sional tectonic evolution and uplifting history of the Tibet plateau. However, the age of this molasse suit and its co.relation to other synchronous strata distributed in southern Tibet have been in great disputes for a long time. Especially in recent years, argues on its ages are growing violently with the reco.nition of the great sedimentary tectonic significances of this molasse. During the field work carried out recently on this molasse suit, a lot of plant fossils were found preserved in fairly good co.ditions in the upper part of this strata, which is of great help in determining its age. By identification, the assemblage of the plant fossils belongs to a tropic to subtropic flora developed in the southern margin of the Northern Hemisphere superco.tinent during the Middle to Later Eocene, which can provide good co.straint on its formation age. This paper is to give a brief introduction of the plant assemblage and its age, and to discuss their tectonic significances.

关键词： liuqu co.glomerate plant fossils age Eocene Tectonic implications.

Jinning granodiorite and diorite deeply co.cealed in the central Tarim Basin

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Science China Earth sciences 2005年第12期48卷 2061-2068页

作者： li Yuejun1, 2, SONG Wenjie2, WU Genyao1, WANG Yifen1, li Yuping2 & ZHENG Duoming2 1. institute of geology & geophysics, chinese academy of sciences, beijing 10002., China 2. Tarim Oil-field co.pany, PetroChina, Korla 841000, China institute of geology & geophysics Chinese Academy of Sciences Beijing China Tarim Oil-field co.pany PetroChina China

The 7200-m-deep Well Tacan 1 in the central Tarim Basin is the deepest in China. Purplish gray medium-grained granodiorite co.taining dark gray fine-grained diorite xenolith is revealed at the base of the well (7169―7200 m), and they are results of the Jinning magmatic activities. Trace-element geochemistry and REE profiles of both rock types are similar, indicating that they are calc-alkaline series I-type granitoid. Proxies of diorite signify the development of a magmatic arc due to subduction at ca. 1200 Ma. The granodiorite was formed before 890―932 Ma. However, more study is needed to clarify if the arc diorite represents a ca. 300 Ma extension of the subduction or a reactivation during the orogenic co.lision event at ca. 900 Ma.

关键词： diorite, granodiorite, magmatic arc, Jinning orogeny, Tarim Basin.