辽西朝阳盆地早白垩世一新的无齿翼龙化石   总被引：12，自引：1，他引：12  

董枝明  孙跃武  伍少远 《世界地质》2003,22(1):1-8

采自辽西朝阳盆地早白垩世九佛堂组的一翼龙化石被记述。化石材料是一接近完整骨架的无齿的翼龙，带有一不完全的头骨。作者将其归于翼手龙类(Pteroclactyloidea)，并建一新属、新种一无齿吉大翼龙(Jidapterus edentus gen．et sp．nov．)。  相似文献   

西昆仑山阿卡孜岩体锆石SHRIMP定年及其地球化学特征   总被引：12，自引：3，他引：12  

张传林  王中刚  沈加林  毕华  郭坤一  王爱国 《岩石学报》2003,19(3):523-529

西昆仑山阿卡孜岩体是该区已知的最古老侵入体。岩体侵入于太古代赫罗斯坦群(TTG岩系)中。获得最新的单颗粒锆石SHRIMP年龄为2426±46Ma。岩石地球化学研究表明,岩石具有高碱度富K特征;∑REE为409.94×10~(-6)～787.76×10~(-6),δEu为0.48～0.73;微量元素显示富集大离子元素。综合分析该岩体地质地球化学特征,认为该岩体形成于晚太古代～古元古代初期碰撞后拉张背景,是TTG岩系(赫罗斯坦群)重熔的结果。这对研究西昆仑山早前寒武纪陆壳增生及构造演化提供了重要的地质资料。  相似文献   

Post-caldera activity in the Alban Hills volcanic district (Italy): 40Ar/39Ar geochronology and insights into magma evolution     

F. Marra  C. Freda  P. Scarlato  J. Taddeucci  D. B. Karner  P. R. Renne  M. Gaeta  D. M. Palladino  R. Trigila  G. Cavarretta 《Bulletin of Volcanology》2003,65(4):227-247

We present 24 ⁴⁰Ar/³⁹Ar ages for the youngest volcanic products from the Alban Hills volcanic district (Rome). Combined with petrological data on these products, we have attempted to define the chronology of the most recent phase of activity and to investigate the magma evolution of this volcanic district. The early, mainly explosive activity of the Alban Hills spanned the interval from 561±1 to 351±3 ka. After approximately 50-kyr of dormancy, a mainly effusive phase of activity took place, accompanied by the strombolian activity of a small central edifice (Monte delle Faete). This second phase of activity spanned the interval 308±2 to 250±1 ka. After another dormancy period of approximately 50-kyr, a new, hydromagmatic phase of activity started at 200 ka at several centers located to the southwest of the Monte delle Faete edifice. After an initial recurrence period of approximately 50-kyr, which also characterized this new phase of activity, the longest dormancy period (approximately 80-kyr) in the history of the volcanic district preceded the start of the activity of the Albano and Giuturna centers at 70±1 ka. Results of our study suggest a quasi-continuous magmatic activity feeding hydromagmatic centers with a new acme of volcanism since around 70 ka. Based on data presented in this paper, we argue that the Alban Hills should not be considered an extinct volcanic district and a detailed re-assessment of the volcanic hazard for the area of Rome is in order. Published online: 4 April 2003 Editorial responsibility: J. Donnelly-Nolan  相似文献   

GIS在西部生态环境建设中的应用初探   总被引：1，自引：0，他引：1  

黄芳 《北京测绘》2003,(3):13-16,24

GIS与西部生态环境建设的有机结合将是一项长期的、复杂的系统工程。笔者在严格论证了该项目实施的可行性之后,在可持续发展理论的指导下,运用空间分析方法,提出了项目实施的方案。在该方案中,对生态环境信息数据进行了分类,详述了空间数据文件存贮结构,查询管理子系统的开发,最后得出生态环境地理信息系统的总体结构,并简述了其功能。  相似文献   

Chemical, Isotopic, and Fluid Inclusion Evidence for the Hydrothermal Alteration of the Footwall Rocks of the BIF-Hosted Iron Ore Deposits in the Hamersley District, Western Australia     

Makoto Haruna    Takahiro Hanamuro    Kaoru Uyeda    Hirokazu Fujimaki  Hiroshi Ohmoto 《Resource Geology》2003,53(2):75-88

Abstract. The petrography, chemical, fluid inclusion and isotope analyses (O, Rb-Sr) were conducted for the shale samples of the Mount McRae Shale collected from the Tom Price, Newman, and Paraburdoo mines in the Hamersley Basin, Western Australia. The Mount McRae Shale at these mines occurs as a footwall unit of the secondary, hematite-rich iron ores derived from the Brockman Iron Formation, one of the largest banded iron formations (BIFs) in the world. Unusually low contents of Na, Ca, and Sr in the shales suggest that these elements were leached away from the shale after deposition. The δ¹⁸O (SMOW) values fall in the range of + 15.0 to +17.9 per mil and show the positive correlation with calculated quartz/sericite ratios of the shale samples. This suggests that the oxygen isotopic compositions of shale samples were homogenized and equilibrated by postdepositional event. The pyrite nodules hosted by shales are often rimmed by thin layers of silica of varying crystallinity. Fluid inclusions in quartz crystals rimming a pyrite nodule show homogenization temperatures ranging from 100 to 240C for 47 inclusions and salinities ranging from 0.4 to 12.3 wt% NaCl equivalent for 18 inclusions. These fluid inclusion data give direct evidence for the hydrothermal activity and are comparable to those of the vein quartz collected from the BIF-derived secondary iron ores (Taylor et al, 2001). The Rb-Sr age for the Mount McRae Shale is 1,952 ± 289 Ma and at least 200 million years younger than the depositional age of the Brockman Iron Formation of ∼ 2.5 Ga in age. All the data obtained in this study are consistent with the suggestion that high temperature hydrothermal fluids were responsible for both the secondary iron ore formation and the alteration of the Mount McRae Shale.  相似文献   

滇西南洞穴考察     

张帆  刘宏 《云南地理环境研究》1996,8(1):90-96,F003

云南西南部地区由于地质构造等方面的原因，喀斯特洞穴不象滇东地区那样分布广泛和发育强烈，在以往对云南喀斯特与洞穴的研究与开发中并未引起人们足够的重视，有关喀斯特与洞穴学的探测和研究工作在滇西地区进行得不多，可以说还是一块“处女地”。１９９３年至１９９４年间，笔者等人在滇西保山市、施甸县和景谷县等地的洞穴进行了实地综合调查。调查结果表明，滇西南地区的洞穴由于所处的地理位置和特殊的自然环境，有着丰富的喀  相似文献   

滇西石缸河锡矿床的成因探讨     

张文源 《矿产与地质》1996,10(3):159-164

石缸河锡矿床在空间上，时间上和成因上与志本山花岗岩演化分异晚期形成的浅色细粒白云母花岗岩有着密切联系，属岩浆期后热液矿床。  相似文献   

大别山西部熊店加里东期榴辉岩——同位素地质年代学的证据   总被引：19，自引：6，他引：19       下载免费PDF全文

简平  杨巍然  李志昌  周慧芳 《地质学报》1997,71(2)

以UP-Pb单颗粒锆石同位素稀释法、角闪石~(40)Ar—~(39)Ar坪年龄和Sm-Nd全岩及矿物等时线相结合的研究方法,系统地研究了大别造山带西部熊店榴辉岩的峰变质年龄,可能的原岩年龄和退变质年龄,建立了这一榴辉岩的构造-变质时间序列,提出了大别地区存在加里东期榴辉岩的确凿证据。  相似文献   

辽西中生代燕鸟化石新材料的补充研究     

袁崇喜 《地质学报》2004,78(4):464-467

本文记述了一件产自辽宁锦州义县早白垩世九佛堂组燕鸟 (Yanornis)化石的新标本。研究标本不但自身保存非常精美 ,而且其嘴里还完整地保存了它捕获的最后一件猎物——吉南鱼 (Jinanichthys longi-cephalus)。该标本的研究 ,不仅对燕鸟的生存环境、生活习性、捕食类型等研究提供了直接的证据 ,而且对于探讨辽西热河生物群中脊椎动物的“集群死亡”的原因也具有重要的意义  相似文献   

Sampling Fauna in Stream Sediments as well as Groundwater Using One Net Sampler     

Susanne I. Schmidt  Hans J. Hahn  Gerald D. Watson  Robert J. Woodbury  Thomas J. Hatton 《洁净——土壤、空气、水》2004,32(2):131-137

Groundwater bores act as traps. Net samplers are regularly used for sampling this type of trap for fauna. To enable direct comparisons of faunal communities in groundwater bores and stream sediments, stream sediment tubes were built similar to groundwater bores and were sampled with net samplers for fauna. These stream sediment tubes consisted of a tube anchored in the stream sediment, also called interstitial space. To test the efficacy of this trap method in stream sediments, it was compared to another type of trap, Hahn's trap. Faunal communities sampled by a net in the stream sediment tubes did not differ hugely from fauna in Hahn's trap samples. Physical and chemical factors of sampled water in both the stream sediment tubes, the surrounding interstitial sediments and the second type of traps, Hahn's traps, showed that water in both the tubes and Hahn's traps was closely related to interstitial water. The net sampler is inexpensive and easy to handle. It is suggested that sampling stream tubes with nets may be an appropriate method for long‐term monitoring studies.  相似文献