全文获取类型
收费全文 | 45篇 |
免费 | 13篇 |
国内免费 | 5篇 |
专业分类
地球物理 | 5篇 |
地质学 | 45篇 |
海洋学 | 2篇 |
综合类 | 4篇 |
自然地理 | 7篇 |
出版年
2021年 | 1篇 |
2020年 | 1篇 |
2019年 | 2篇 |
2018年 | 2篇 |
2017年 | 4篇 |
2016年 | 3篇 |
2015年 | 3篇 |
2014年 | 1篇 |
2013年 | 6篇 |
2011年 | 2篇 |
2010年 | 1篇 |
2009年 | 2篇 |
2008年 | 2篇 |
2007年 | 3篇 |
2004年 | 4篇 |
2003年 | 1篇 |
2002年 | 1篇 |
2001年 | 4篇 |
2000年 | 7篇 |
1999年 | 3篇 |
1998年 | 5篇 |
1997年 | 1篇 |
1996年 | 1篇 |
1995年 | 1篇 |
1991年 | 1篇 |
1989年 | 1篇 |
排序方式: 共有63条查询结果,搜索用时 484 毫秒
41.
野外填图和室分析表明,福建顺昌北部溪东一带存在1种英云闪长质片麻岩体,并获得颗粒锆石U-Pb年龄705.9Ma。它是中(酸)性深成岩体经受强烈变形变质作用改造的产物,属晋宁期侵入岩。它为研究福建省晋宁运动提供了重要资料。 相似文献
42.
43.
44.
Pliocene age deposits of the palaeo‐Orinoco Delta are evaluated in the Mayaro Formation, which crops out along the western margin of the Columbus Basin in south‐east Trinidad. This sandstone‐dominated interval records the diachronous, basinwards migration of the shelf edge of the palaeo‐Orinoco Delta, as it prograded eastwards during the Pliocene–Pleistocene (ca 3·5 Ma). The basin setting was characterized by exceptionally high rates of growth‐fault controlled sediment supply and accommodation space creation resulting in a gross basin‐fill of around 12 km, with some of the highest subsidence rates in the world (ca 5 to 10 m ka?1). This analysis demonstrates that the Mayaro Formation was deposited within large and mainly wave‐influenced shelf‐edge deltas. These are manifested as multiple stacks of coarsening upward parasequences at scales ranging from tens to hundreds of metres in thickness, which are dominated by storm‐influenced and wave‐influenced proximal delta‐front sandstones with extensive, amalgamated swaley and hummocky cross‐stratification. These proximal delta‐front successions pass gradationally downwards into 10s to 100 m thick distal delta front to mud‐dominated upper slope deposits characterized by a wide variety of sedimentary processes, including distal river flood and storm‐related currents, slumps and other gravity flows. Isolated and subordinate sandstone bodies occur as gully fills, while extensive soft sediment deformation attests to the high sedimentation rates along a slope within a tectonically active basin. The vertical stratigraphic organization of the facies associations, together with the often cryptic nature of parasequence stacking patterns and sequence stratigraphic surfaces, are the combined product of the rapid rates of accommodation space creation, high rates of sediment supply and glacio‐eustasy in the 40 to 100 Ka Milankovitch frequency range. The stratigraphic framework described herein contrasts strikingly with that described from passive continental margins, but compares favourably to other tectonically active, deltaic settings (for example, the Baram Delta Province of north‐west Borneo). 相似文献
45.
High‐resolution swath bathymetry and TOPAS sub‐bottom profiler acoustic data from the inner and middle continental shelf of north‐east Greenland record the presence of streamlined mega‐scale glacial lineations and other subglacial landforms that are formed in the surface of a continuous soft sediment layer. The best‐developed lineations are found in Westwind Trough, a bathymetric trough connecting Nioghalvfjerdsfjorden Gletscher and Zachariae Isstrøm to the continental shelf edge. The geomorphological and stratigraphical data indicate that the Greenland Ice Sheet covered the inner‐middle shelf in north‐east Greenland during the most recent ice advance of the Late Weichselian glaciation. Earlier sedimentological and chronological studies indicated that the last major delivery of glacigenic sediment to the shelf and Fram Strait was prior to the Holocene during Marine Isotope Stage 2, supporting our assertion that the subglacial landforms and ice sheet expansion in north‐east Greenland occurred during the Late Weichselian. Glacimarine sediment gravity flow deposits found on the north‐east Greenland continental slope imply that the ice sheet extended beyond the middle continental shelf, and supplied subglacial sediment direct to the shelf edge with subsequent remobilisation downslope. These marine geophysical data indicate that the flow of the Late Weichselian Greenland Ice Sheet through Westwind Trough was in the form of a fast‐flowing palaeo‐ice stream, and that it provides the first direct geomorphological evidence for the former presence of ice streams on the Greenland continental shelf. The presence of streamlined subglacially derived landforms and till layers on the shallow AWI Bank and Northwind Shoal indicates that ice sheet flow was not only channelled through the cross‐shelf bathymetric troughs but also occurred across the shallow intra‐trough regions of north‐east Greenland. Collectively these data record for the first time that ice streams were an important glacio‐dynamic feature that drained interior basins of the Late Weichselian Greenland Ice Sheet across the adjacent continental margin, and that the ice sheet was far more extensive in north‐east Greenland during the Last Glacial Maximum than the previous terrestrial–glacial reconstructions showed. Copyright © 2008 John Wiley & Sons, Ltd. 相似文献
46.
In the latest Early to Middle Miocene section of the Kingfish 8 well, offshore Gippsland Basin, the characteristically deep‐marine ostracod genus Zabythocypris is a conspicuous component of ostracod assemblages dominated by species of the genera Argilloecia, Krithe and Parakrithe. The taphonomy and taxonomic composition of the assemblages suggests that they accumulated in an upper bathyal environment (500–1000 m water depth) occurring in a lower continental slope setting. Supporting evidence for these deep‐marine ostracod assemblages occurring near the upper limit of their palaeobathymetrical range is the broadly coincident occurrence of the deep‐marine taxa Legitimocythere sp. and Neonesidea whatleyi Warne, in what would otherwise be considered an outer‐shelf (120–160 m) ostracod fauna at Fossil Beach, Mornington. Ostracod occurrences indicative of dysaerobic sea‐floor conditions in the Kingfish 8 well and Fossil Beach sections, when considered together, appear to record a shallowing of the oceanic oxygen‐minimum zone during the latest Early Miocene to earliest Middle Miocene transgressive phase of southeast Australia. 相似文献
47.
重庆巫山张家湾遗址2000年来的环境考古 总被引:15,自引:4,他引:15
通过对重庆巫山张家湾西汉遗址T911剖面进行粒度、磁化率等环境替代指标的分析研究,结果表明,汉代该区发达的农业、手工业生产使人们盲目砍伐树木,使该区植被严重退化,使生态环境恶化,降水集中、坡地表面松散沉积丰富、缺乏植被保护等使流水侵蚀、坡地径流发育,导致水土流失严重,该区的人类文明因此而衰落,同时研究发现,该区在竺可桢划分的中国4次温暖期与4次寒期扣的第2次寒冷期(公元初至公元600年)仍为温暖期,这是由于该区西北面与东南面均有高大山脉包围,一定程度上阻挡了来自北方的冷空气进入本区的缘故,该区气候演变在一定程度上可能受西南季风的影响,至少该区在汉代气候演变与西南季风的强弱有某种相关关系,作为一个相对独立的气候变化单元,研究其气候变化与人类文明发展的耦合关系具有重要的理论意义与实际意义。 相似文献
48.
《Sedimentology》2018,65(3):851-876
The Sarah Formation is a glaciogenic sedimentary unit deposited along the Gondwana margin during the latest Ordovician ice age and represents a major hydrocarbon reservoir in northern Saudi Arabia. Large‐scale glacial palaeo‐valleys cut into the Qasim Formation and were infilled by the Sarah Formation. Post‐glacial transgression in the earliest Silurian resulted in the deposition of the Qusaiba Shale Member and associated organic‐rich basal source rocks, which cap the Sarah Formation infilled palaeo‐valleys. This unique setting makes the Sarah Formation an important emerging exploration target in Saudi Arabia. This study focuses on the facies and depositional architecture in seismic‐scale outcrops of the Sarah Formation in north‐western Saudi Arabia. The Rahal Dhab palaeo‐valley provides a 100 km long dip‐oriented cross‐section which has been covered by 24 vertical sections, sedimentary architectural analyses at metre to kilometre scale and by three cored shallow boreholes. In the Rahal Dhab palaeo‐valley, the Sarah Formation was deposited in a proglacial setting that ranged from marginal marine to offshore prodelta and is made up of three units: (i) the Sarah Sandstone; (ii) the Sarah Shale; and (iii) the Uqlah Member. This study shows the relationships between these three units and architectural controls on reservoir quality in this system. This paper contributes to the regional understanding of the Sarah Formation, and the new depositional model of the Rahal Dhab palaeo‐valley provides an outcrop‐reservoir analogue for hydrocarbon exploration in adjacent areas. 相似文献
49.
50.