花岗岩的成岩时代、地球化学特征和成因青海祁漫塔格地区虎头崖矿床Ⅵ矿带     

姚磊  吕志成  于晓飞  庞振山  蔡煜琦  刘鹏  刘长城  王凤兰 《吉林大学学报(地球科学版)》2015,(3)

利用 LA ICP MS 锆石 U Pb 法,测得与成矿有关的青海祁漫塔格地区虎头崖矿床Ⅵ矿带花岗岩的成岩年龄为(233.6±1.8)Ma(MSWD=1.2,n=17)。地球化学特征显示：花岗岩属高钾钙碱性、弱过铝质花岗岩;样品的稀土元素组成以总体右倾,轻、重稀土分异明显和具明显的负铕异常为特征;微量元素具有富集 Rb、Th、U、La、Nd 等大离子亲石元素,亏损 Ba、Sr、Nb、P、Ti 等元素的特点。Sr Nd 同位素组成特征显示,花岗岩的源区可能是富集岩石圈地幔。初步研究认为,虎头崖矿床Ⅵ矿带花岗岩可能形成于中、晚三叠世碰撞后碰撞的构造背景下。  相似文献   

Sedimentary and hydrological studies of the Holocene palaeofloods in the Shanxi-Shaanxi Gorge of the middle Yellow River,China     

Xiaogang Li  Chun Chang Huang  Jiangli Pang  Xiaochun Zha  Yugai Ma 《International Journal of Earth Sciences》2015,104(1):277-288

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河北省重污染天气分型及其预报概念模型研究     

王琼  沈瑞珊  庞杨 《气象与环境科学》2020,43(4):107-114

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Slippage and re-initiation of (hydraulic) fractures at frictional interfaces     

K. Y. Lam  M. P. Cleary 《国际地质力学数值与分析法杂志》1984,8(6):589-604

The analysis of mechanisms which could control the growth of fractures in non-homogeneous regions is of paramount importance. One such mechanism is the behavior of the fracture as it reaches a frictional interface; coupled with this is the question of re-initiation, e.g. whether a fracture can be contained within the region of initiation. Though the problems of slippage have been dealt with by other investigators, the present paper gives a more comprehensive picture and detailed treatment: effects of various frictional models at an interface are considered for a crack which intersects it at any angle; specialization then allows comparison with existing results in the literature. The problem of re-initiation, after slippage has occurred at a frictional interface, is also considered, using two different models. First, by introducing microcracks in the adjacent stratum and looking at the effects on propagation criteria and, secondly, by examining the actual distribution of the stress tangential to the slip surface; detailed computations are performed and a simple criterion for re-initiation is given, relating the re-initiation stress dominantly to the confining stress on the interface.  相似文献   

EFFECTIVE TEMPERATURE COMFORT INDICES FOR SOME MALAYSIAN TOWNS     

Mohammed Ilyas  MSc.  Ph.D.    Pang Chong Yen  BSc.  Chan Ah Wah  BSc. 《Singapore journal of tropical geography》1981,2(1):27-31

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MULTI-DIMENSIONAL NUMERICAL STUDIES OF CONVECTION-RELATED STELLAR PROBLEMS     

Chan Kwing Lam 《紫金山天文台台刊》2003,(2)

1　IntroductionManybottlenecksinthetheoreticalstudyofstellarevolutionarisefromthelackofunder standingofsomehighlycomplicatedprocessesthatcannotbetreatedwithanalyticaltech niques .Alargeportionoftheseprocessesisrelatedtohydrodynamics,particularlyconvec tion .Theapplicationofmultidimensionalnumericalcomputationstotheinvestigationofthesedifficultproblemshasmadegreatprogressinrecentyears .Here ,weprovideasurveyoftherecentnumericalstudiesofconvectionrelatedproblems.Theobjectiveistoassistthosewhoar…  相似文献   

The Moho depth in the Canadian Basin and its tectonic implications          下载免费PDF全文

Ma Yuanyuan  Zhao Lihong  Ling Zilong  Yang Mingming  Pang Beibei 《极地研究》1988,31(3):284

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Organochlorines and dioxin-like compounds in green-lipped mussels Perna viridis from Hong Kong mariculture zones     

So MK  Zhang X  Giesy JP  Fung CN  Fong HW  Zheng J  Kramer MJ  Yoo H  Lam PK 《Marine pollution bulletin》2005,51(8-12):677-687

Concentrations of persistent organic pollutants including polychlorinated biphenyls (PCBs), organochlorine (OC) pesticides and dioxin-like compounds were measured in green-lipped mussels, Perna viridis, collected from seven mariculture zones in Hong Kong between September and October in 2002 in order to evaluate the status, spatial distribution and potential sources of pollution in these areas. Concentrations ranged from 300 to 4400 ng/g lipid weight for total OCs and 170–1000 ng/g lipid weight for total PCBs (based on 28 congeners). Relatively smaller DDT concentrations in mussels compared with previous studies suggest reduced discharges of DDTs from nearby regions into Hong Kong waters. Detection of a mixture of HCH isomers in the mussels indicated that Hong Kong waters were predominantly contaminated by technical HCHs rather than lindane. Mussel samples from all sampling locations elicited significant dioxin-like activity in the H4IIE-luc bioassay. The greatest magnitude of dioxin-like response (39 pg TEQ/g wet wt.) was detected in mussels from Ma Wan in the western waters of Hong Kong, which is strongly influenced by the Pearl River discharge. Human health risk assessment was undertaken to evaluate potential risks associated with the consumption of the green-lipped mussels. Risk quotient (RQ) for dioxin-like compounds was greater than unity suggesting that adverse health effects may be associated with high mussel consumption.  相似文献   

Polybrominated diphenyl ethers (PBDEs) and organochlorines in small cetaceans from Hong Kong waters: levels, profiles and distribution   总被引：9，自引：0，他引：9  

Ramu K  Kajiwara N  Tanabe S  Lam PK  Jefferson TA 《Marine pollution bulletin》2005,51(8-12):669-676

Polybrominated diphenyl ethers (PBDEs) and organochlorine compounds (OCs) were determined in the blubber, liver and kidney of Indo-Pacific humpback dolphins (Sousa chinensis) and finless porpoises (Neophocaena phocaenoides) stranded in Hong Kong coastal waters during 1995–2001. Among the organohalogen compounds analyzed, DDTs were the most dominant contaminants with concentrations ranging from 9.9 to 470 μg/g lipid wt. PBDEs in Hong Kong cetaceans, which are reported for the first time, were detected in all the samples with values ranging from 0.23 to 6.0 μg/g lipid wt., with a predominance of BDE-47. Results from this study suggest PBDEs should be classified as priority pollutants in Asia. Higher concentrations were found in humpback dolphins than in finless porpoises, and this was attributed mainly to differences in habitat. Elevated residues of PCBs and DDTs in some cetaceans suggest these species may be at risk.  相似文献   

Modeling of depuration of paralytic shellfish toxins in Chlamys nobilis and Perna viridis     

Yu KN  Choi MC  Shen X  Wu RS  Wang WX  Lam PK 《Marine pollution bulletin》2005,50(4):474-479

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