THE FINDINGS OF THE UPPER PERMIAN IN THE CUOQIN BASIN, TIBET     

Shi He  Wang Chengshan  Ma Runze  Wang Hongfeng  Li Xianghui  Yin Haisheng  Wu RuizhongWT  ”BX 《地学前缘》2000,(Z1)

THE FINDINGS OF THE UPPER PERMIAN IN THE CUOQIN BASIN, TIBET  相似文献   

The North of Eastern Siberia: Refuge of Mammoth Fauna in the Holocene     

Gennady G. Boeskorov   《Gondwana Research》2004,7(2):451-455

The global climate changings at the end of Pleistocene led to extinction of the typical representatives of Mammoth fauna–mammoth, woolly rhinoceros, wild horse, bison, muskox, cave lion, etc.–on the huge territories of Northern Eurasia. Undoubtedly the Mammoth fauna underwent pressure from the Upper Paleolithic Man, whose hunting activity also could play the role in decreasing the number of mammoths and other representatives of megafauna (large mammals). Archaeological data testify that the typical representatives of Mammoth fauna were the Man's hunting objects only till the end of the Pleistocene. Their bone remains are not usually found on the settlements of Mesolithic Man. Formerly it was supposed that the megafauna of ‘Mammoth complex’ was extinct by the beginning of Holocene. Nevertheless the latest data testify that the global extinction of the Mammoth fauna was sufficiently delayed in the north of Eastern Siberia. In the 1990s some radiocarbon data testified that the mammoths on the Wrangel Island existed for a long time during the Holocene from 8000 till 3700 y. BP. The present radiocarbon data show that wild horses inhabited the north of Eastern Siberia (the lower stream of the Enissey river, the Novosibirskie Islands, the East Siberian sea-shore) 3000–2000 y. BP. Musk-oxen lived on the Taimyr Peninsula and the Lena River delta about 3000 y. BP. Some bison remains from Eastern Siberia belong to the Holocene. The following circumstances could promote the process of preservation of the Mammoth fauna representatives. The cool and dry climate of this region promotes the maintenance of steppe associations – habitats of those mammals. The Late Paleolithic and Mesolithic settlements are not found in the Arctic zone of Eastern Siberia from the Taimyr Peninsula to a lower stream of the Yana River; they are very rare in the basins of the Indigirka and Kolyma Rivers. So, the small number of the Stone Age hunting tribes on the North of Eastern Siberia was another factor in the long-term preservation of some Mammoth fauna representatives.  相似文献   

岩鹭在厦门海岸带的分布及其生态考察   总被引：7，自引：0，他引：7  

陈小麟 《台湾海峡》1999,18(3):355-358

岩鹭是我国二级保护鸟类,处于稀有的濒危状态。１９９３年３￣５月,１９９３年９月至１９９４年９月和１９９５年５￣１０月的考察结果。证实岩鹭在厦门的居留时间为１０月上旬至６月上旬。厦门的岩鹭分布于东部海岸,该区域人为干扰和污染少,潮间带底质以砂砾,岩石为主,厦门的岩鹭为灰黑色型,单独活动,种群总数量只有３￣５只,本文根据岩鹭的生态需求、行为习怀和种群数量特点,对岩鹭的保护也进行了讨论。  相似文献   

Distribution and temporal variation of mega‐fauna at the Regab pockmark (Northern Congo Fan), based on a comparison of videomosaics and geographic information systems analyses     

Yann Marcon  Heiko Sahling  Anne‐Gaëlle Allais  Gerhard Bohrmann  Karine Olu 《Marine Ecology》2014,35(1):77-95

The Regab pockmark is a large cold seep area located 10 km north of the Congo deep sea channel at about 3160 m water depth. The associated ecosystem hosts abundant fauna, dominated by chemosynthetic species such as the mussel Bathymodiolus aff. boomerang, vestimentiferan tubeworm Escarpia southwardae, and vesicomyid clams Laubiericoncha chuni and Christineconcha regab. The pockmark was visited during the West African Cold Seeps (WACS) cruise with RV Pourquoi Pas? in February 2011, and a 14,000‐m² high‐resolution videomosaic was constructed to map the most populated area and to describe the distribution of the dominant megafauna (mussels, tubeworms and clams). The results are compared with previous published works, which also included a videomosaic in the same area of the pockmark, based on images of the BIOZAIRE cruise in 2001. The 10‐year variation of the faunal distribution is described and reveals that the visible abundance and distribution of the dominant megafaunal populations at Regab have not changed significantly, suggesting that the overall methane and sulfide fluxes that reach the faunal communities have been stable. Nevertheless, small and localized distribution changes in the clam community indicate that it is exposed to more transient fluxes than the other communities. Observations suggest that the main megafaunal aggregations at Regab are distributed around focused zones of high flux of methane‐enriched fluids likely related to distinct smaller pockmark structures that compose the larger Regab pockmark. Although most results are consistent with the existing successional models for seep communities, some observations in the distribution of the Regab mussel population do not entirely fit into these models. This is likely due to the high heterogeneity of this site formed by the coalescence of several pockmarks. We hypothesize that the mussel distribution at Regab could also be controlled by the occurrence of zones of both intense methane fluxes and reduced efficiency of the anaerobic oxidation of methane possibly limiting tubeworm colonization.  相似文献   

Effects of substratum type on fish assemblages in shallow areas of a tropical estuary     

José Amorim Reis‐Filho  Alexandre Clistenes de Alcântara Santos 《Marine Ecology》2014,35(4):456-470

While there is already a comprehensive understanding of the effects of environmental variables, such as dissolved oxygen, temperature and salinity, on the structure, biomass and metabolism of aquatic biota in estuarine habitats, the effect of sedimentation, a harmful underlying factor, remains unclear. The aim of this study was to assess the differences in fish assemblages along the freshwater to salt water gradient of a large tropical estuary, and to evaluate the effects on them of habitat disturbance associated with shallow water sedimentation in the intertidal areas. Fish and environmental variables were recorded in the upper, middle and lower salinity zones of the estuary at ebb tide in both the dry and wet seasons. Sediment samples associated with different levels of habitat disturbance were analysed using granulometry, and their organic content and dissolved oxygen levels were quantified. Water temperature, salinity, pH and dissolved oxygen levels were also measured. Habitat disturbance was found to be correlated with the density, biomass and richness of fish assemblages. A total of 77 species were recorded, forming two distinct fish assemblages, with the Eleotridae family dominating in the upper zone, and Gerreidae, Gobiidae and Tetraodontidae the most common in the middle and lower estuary. Changes in the structure of fish assemblages, including reductions in density, biomass and richness, were associated with disturbance to natural features, where muddy sediment was replaced by sandy sediment and the quantity of organic matter fell. Atherinella brasiliensis was the species which showed a preference for the disturbed areas in the middle and lower zones, while Dormitator maculatus showed a preference for them in the upper estuary. They may be taken as indicators of habitat disturbance due to shallow sedimentation.  相似文献   

陕北贾大峁遗址出土动物遗骸的锶同位素比值分析     

赵春燕  胡松梅  杨苗苗  郭小宁  杨瞳 《第四纪研究》2022,42(1):59-68

史前时期动物驯养技术的跨大陆交流与传播是令人瞩目的 前沿课题.陕北地区位于欧亚草原早期青铜文化和中原地区古代文化交汇碰撞的前沿地带.贾大峁遗址位于陕西省横山县,年代为距今约4500～4300年的龙山早期.作为陕北地区目前发现的最早出现牛和羊的考古遗址之一,牛和羊是当地驯养抑或外来的,是值得我们探讨的问题.本文通过热电离...  相似文献   

中朝古陆的解体与华北、华泰二克拉通的确立   总被引：1，自引：0，他引：1  

王荃 《地质学报》2012,86(10):1553-1568

半个世纪之前,黄汲清和任纪舜等将华北、东北南部以及西北的阿拉善这类凡有前寒武纪结晶基底出露的地区确定为单一的中朝古陆(或准地台).这种观念一直被沿用迄今.近年,构造地层地体的研究发现原称之“中朝古陆”是由华北和华泰两个克拉通构成,计 11个地块或地体.重新厘定的华北克拉通,其范围只限于辽宁省西部和北部、河北省、内蒙古南...  相似文献   

北吕宋岛菲律宾活动带蛇绿岩及其上覆浊积岩的放射虫研究新进展     

Keisuke ISHIDA  Shigeyuki SUZUKI  Carla DIMALANTA  Graciano YUMUL JR.  Karlo QUEA?O  Decibel FAUSTINO-ESLAVA  Edanjarlo MARQUEZ  Noelynna RAMOS  Rolando PE?A 《地球学报》2012,33(S1):29-31

The basement of the Philippine Mobile Belt (PMB) is mainly composed of ophiolites that are mostly overlain by Paleogene to Miocene turbidites in central Luzon. To clarify the geological development of the PMB with respect to the initial stage of the arc volcanism (eg. Yumul et al., 2003, 2008; Dimalanta and Yumul, 2003; Suzuki et al., 2011), radiolarian dating was examined in siliceous sediments associated with the ophiolites and turbidites. The samples were collected from sites identified with the Zambales and Montalban ophiolites, basic tuff phyllites in NW Din-galan, and their overlying formations.  相似文献   

Macrobenthic polychaete assemblages of the continental shelf and upper slope off the west coast of the South Island,New Zealand     

P. K. Probert  G. B. Read  S. L. Grove  A. A. Rowden 《新西兰海洋与淡水研究杂志》2013,47(5):971-984

Polychaete assemblages are described from replicate box‐core samples collected in summer 1983 at 18 stations on the continental shelf and upper slope (28–943 m) off the west coast of the South Island, New Zealand, south‐eastern Tasman Sea (c. 41–43°S, 169–172°E). Three main station groupings were identified by multivariate analysis: (1) inner shelf sandy stations characterised by Prionospio australiensis, Aricidea (Acesta) sp., Magelona cf. dakini, Paraprionospio aff. pinnata, Aglaophamus sp., Heteromastus filiformis, and Magelona sp.; (2) middle to outer shelf muddy stations characterised by Levinsenia cf. gracilis, Prionospio australiensis, Paraprionospio coora, Aglaophamus verrilli, and Auchenoplax mesos; and (3) upper slope sandy mud or mud stations characterised by Prionospio ehlersi. A combination of water depth and sediment clay content provided the best correlation with the biotic pattern. Spionidae was the most abundant family (49% of polychaete individuals), which may reflect the scope for opportunistic species in a shelf environment characterised by a high input of terrigenous sediment and episodic upwelling.  相似文献   

Population surveys of toheroa (Mollusca: Eulamellffiranchiata) on Northland Beaches, 1962–67     

J. P. C. Greenway 《新西兰海洋与淡水研究杂志》2013,47(2):318-338

Surveys made each year between 1962 and 1967 to estimate populations of toheroa (Amphidesma ventricosum Gray) on the three main west coast beaches of Northland, New Zealand, are described. The surveys were carried out as close as possible to the beginning and ending of each gathering season. There were striking changes in the surveyed areas, probably mainly due to natural causes and not as a direct result of gathering. One beach, Muriwai 1963, even showed an improvement in population after the gathering season, but numbers of toheroas on this beach have usually been erratic and small during the surveyed period. The other beaches showed marked declines, which were mostly sudden and unsynchronised between beaches; these declines were too big to be accounted for solely by gathering. A private commercial survey, carried out annually during the gathering season on a leased portion of Dargaville Beach, shows very similar results to the equivalent departmental surveys.  相似文献