琼东南盆地中央峡谷天然气成藏特征及其主控因素   总被引：1，自引：0，他引：1  

许怀智  张迎朝  林春明  裴健翔  刘云芝 《地质学报》2014,88(9):1741-1752

基于地震、测井、岩芯、岩屑和天然气样品分析化验等资料,研究了中央峡谷天然气成藏特征,探讨了成藏主控因素与成藏模式。研究结果表明,晚中新世—早上新世沿琼东南盆地中央坳陷发育一条大型海底峡谷,称之为中央峡谷,峡谷内充填了多期相互叠置的浊积砂岩,平均孔隙度为15%~33%,渗透率为11×10-3~971.3×10-3μm2,为较好的储层;发育了岩性和构造-岩性复合两大类圈闭。峡谷的气源来自于崖城组的煤系地层,属于煤型气。烃源岩的有机质类型为Ⅱ2和Ⅲ型,以Ⅲ型为主;热演化程度处于成熟—高成熟阶段,晚中新世—上新世达到生烃高峰。琼东南盆地中央坳陷是一个高温高压的坳陷,实测地温梯度平均值高达4.2~4.6℃/100m,实测压力系数为1.20~2.15。在高温高压的环境下,盆地内孕育众多的底辟构造,而峡谷下伏的底辟构造与谷内相互叠置的复合砂体在空间上有效的配置构成了天然气垂向与侧向运移的输导体系,成为峡谷天然气成藏的关键因素。  相似文献   

A proposed Laramide proto-Grand Canyon     

C.A. Hill  W.D. Ranney   《Geomorphology》2008,102(3-4):482-495

The absence of “rim gravels” north of Grand Canyon and of “Canaan Peak-type” gravels south of Grand Canyon suggests that a paleocanyon, which intersected the transport of these gravels north and south, may have begun forming in the Laramide in approximately the same position as today's central Grand Canyon. This Laramide-age canyon is envisioned as having flowed generally from the SW to NE; from the Peach Springs Canyon area to Mile 197 where it was captured by karst; then along a N. 60°E joint system to the Kanab Point area where it converged with drainage coming off the west side of the Kaibab arch. From there it flowed north along the west flank of the Kaibab arch to Paleogene Lake Claron. The critical idea suggested by this proposed model is that the modern Colorado River utilized Laramide paleotopography in establishing its course through the central Grand Canyon, with younger sections of the canyon integrating with it later, in the middle to late Miocene. This paleocanyon route, in association with headward erosion from the Grand Wash Cliffs toward the Kaibab arch after 16–17 Ma, helps account for the total volume of rock eroded from Grand Canyon, which cannot be explained by present-day incision rates.  相似文献   

Tectonics and Seismicity of the Yarlung Tsangpo Grand Canyon Region     

Shao Cuiru  You Huichuan  Cao Zhongquan  Wang Chunyong  Tang Fangtou  Zhang Decheng  Lou Hai  Xu Guangyin  Yang Qiyan  Mei Tuo  Xie Ping  Yu Gang 《中国地震研究》2009,23(2):144-160

The Yarlung Tsangpo Grand Canyon region is located in the frontal zone of the eastern Himalayan syntaxis, where neo-tectonics and seismicity are intensive and closely related to each other. In the region, two sets of fault structures have developed, striking NNE-NE and NWW-NW, respectively. Investigation shows that they differ markedly in terms of scope, property, active times and intensity. The NWW-NW trending faults are large in size, and most are thrust and thrust strike-slip faults, formed in earlier times. The NEE-NE-strike faults are relatively small in size individually, with concentrated distribution, constituting the NNE-trending shear extensional fault zone, which is relatively younger with evident late Quaternary activities. Strong earthquakes occur mainly in the areas or zones of intensive differential movement of the Himalayas, e.g. along the deep and large fault zones around the crustal blocks. Most earthquakes of M≥7.0 are closely related to tectonics, where large-scale Holocene active faults are distributed with complicated fault geometry, or the faults of multiple directions intersect. Among them, earthquakes of M≥7.5 have occurred on the NW and NE-trending faults with a greater strike-slip component in the fault tectonic zones.  相似文献   

Influence of an oxygen minimum zone and macroalgal enrichment on benthic megafaunal community composition in a NE Pacific submarine canyon          下载免费PDF全文

Lia Domke  Myriam Lacharité  Anna Metaxas  Marjolaine Matabos 《Marine Ecology》2017,38(6)

Megafaunal diversity in the deep sea shows a parabolic pattern with depth. It can be affected by factors such as low oxygen concentration, which suppresses diversity, or the presence of submarine canyons, which enhances it. Barkley Canyon, located off the west coast of British Columbia, Canada, is a submarine canyon that extends from the continental margin (200 m) into the deep ocean (2,000 m). This canyon receives drift kelp from shoreline kelp forests and contains an oxygen minimum zone (OMZ) at 500 to 1,500 m depth. Our study investigated the abundance and diversity of epibenthic megafauna over a range of depths (200–2,000 m) and oxygen concentrations (0.5–5.0 ml/L) within Barkley Canyon, as well as changes in abundance near detrital kelp. Video was collected using the remotely operated vehicle ROPOS along seven 1‐km cross‐canyon (i.e., across the axis of the canyon) transects and three 40‐m perpendicular cross‐transects over kelp. Taxonomic groups were associated with depth, temperature, and the presence of pebbles. The OMZ restricted pennatulids, and edge effects along OMZ boundaries were observed for ophiuroids. The geomorphology of the sea floor affected the distribution of taxa across the canyon, with Porifera mainly found along the walls and Echinoidea within the canyon axis. Expected richness exhibited a bimodal pattern, peaking at 300 and 2,000 m, possibly due to the combined effect of the OMZ and the submarine canyon. Echinoidea aggregated near drift kelp at 200 and 300 m. We found that faunal communities in Barkley Canyon were influenced by several confounded factors including depth, oxygen and substrate. Understanding faunal patterns is paramount with increased exploitation and a changing climate.  相似文献   

Difference infiltrometer: a method to measure temporally variable infiltration rates during rainstorms     

John A. Moody  Brian A. Ebel 《水文研究》2012,26(21):3312-3318

We developed a difference infiltrometer to measure time series of non‐steady infiltration rates during rainstorms at the point scale. The infiltrometer uses two, tipping bucket rain gages. One gage measures rainfall onto, and the other measures runoff from, a small circular plot about 0.5‐m in diameter. The small size allows the infiltration rate to be computed as the difference of the cumulative rainfall and cumulative runoff without having to route water through a large plot. Difference infiltrometers were deployed in an area burned by the 2010 Fourmile Canyon Fire near Boulder, Colorado, USA, and data were collected during the summer of 2011. The difference infiltrometer demonstrated the capability to capture different magnitudes of infiltration rates and temporal variability associated with convective (high intensity, short duration) and cyclonic (low intensity, long duration) rainstorms. Data from the difference infiltrometer were used to estimate saturated hydraulic conductivity of soil affected by the heat from a wildfire. The difference infiltrometer is portable and can be deployed in rugged, steep terrain and does not require the transport of water, as many rainfall simulators require, because it uses natural rainfall. It can be used to assess infiltration models, determine runoff coefficients, identify rainfall depth or rainfall intensity thresholds to initiate runoff, estimate parameters for infiltration models, and compare remediation treatments on disturbed landscapes. The difference infiltrometer can be linked with other types of soil monitoring equipment in long‐term studies for detecting temporal and spatial variability at multiple time scales and in nested designs where it can be linked to hillslope and basin‐scale runoff responses. Published 2012. This article is a U.S. Government work and is in the public domain in the USA.  相似文献   

Assessing potential environmental influences on killer whale (Orcinus orca) distribution patterns in the Bremer Canyon,south-west Australia     

Alexandra Jones  Eleanor Bruce  Kevin P. Davies  Michelle Blewitt  Scott Sheehan 《The Australian geographer》2019,50(3):381-405

ABSTRACT

Submarine canyons play an important role in the regional distribution, abundance and dispersal of marine biota and are increasingly being recognised as geomorphic features of high conservation significance along Australia’s continental margin. Certain canyons have been described as foraging ‘hotspots’ attributable to the high abundance of apex cetacean species aggregating in these areas. Anecdotal evidence of large seasonal aggregations of killer whales in the Bremer Canyon, south-west Australia, has attracted significant research attention in the last decade. To identify important environmental drivers influencing aggregation patterns, a predictive spatial habitat model using the Maxent model was developed based on presence-only whale sighting data. In addition, remotely sensed sea surface temperature and chlorophyll-a concentrations were assessed to investigate the spatio-temporal variation in sea surface conditions. Habitat preference was predicted in areas between canyon heads, with the most influential predictor variables being depth and distance from the continental shelf break. Analysis of remote-sensing data highlighted low localised variability in surface waters and illustrated the seasonal trends of the Leeuwin Current. This study demonstrates the influence of bathymetry and submarine geomorphology on enhanced cetacean abundance and highlights the need for recognition of this potential foraging area in marine reserve planning.  相似文献   

论大峡谷生态环境的脆弱性     

杨逸畴 《云南地理环境研究》1999,11(2):1-8

分析了大峡谷的基本特点, 把它看作是内外作用营力的现阶段表现。提出了内营力的地质基础是破碎的、不良的、不稳定的; 外营力的水汽通道带来强大水热作用的负面影响, 它们结合在一起, 组成了生态环境本质极为脆弱的基础。并把历史上的重大山地灾害当作是一面镜子; 而把现实看到的破坏作为人类参与下正在长鸣的警钟, 提醒人们要建立大峡谷生态环境是极为脆弱的基本概念, 一切要以环保为基础, 以可持续发展为根本目标。  相似文献   

世界第一大峡谷--雅鲁藏布大峡谷科学考察新进展   总被引：4，自引：1，他引：3  

张文敬  高登义 《山地学报》1999,17(2):99-103

介绍了首次徒步穿越世界第一大峡谷科学探险考虑活动观察到的新资料和新发现。  相似文献   

黄河晋陕峡谷河流阶地和鄂尔多斯高原第四纪构造运动   总被引：47，自引：5，他引：42       下载免费PDF全文

程绍平  邓起东  闵伟  杨桂枝 《第四纪研究》1998,18(3):238-239

本文通过黄河晋陕峡谷河段21个地点的阶地横剖面观察和阶地对比研究,确定出6级宽谷阶地序列,同时,依据17个放射性测年数据对阶地定年。6级宽谷阶地序列揭示了鄂尔多斯高原第四纪区域造陆隆起和局部构造变形,区域造陆隆起的发生时间比之青藏高原隆起要滞后0．113～0．25Ma,而且,平均区域造陆隆起量比之青藏高原的内部和边缘的隆起量小得多。晋陕峡谷河段发生过3期加积作用幕,指示着造陆隆起景观中的气候变化时间线。渭河盆地北缘的韩城断裂悬崖带记录着构造基准面下降,影响的河流长度仅为21～127km。  相似文献   

“Of outstanding universal value”: The challenge of scale in applying the World Heritage Convention at national parks in the US   总被引：1，自引：0，他引：1  

Helen Hazen 《Geoforum》2008,39(1):252-264

This paper explores the operation of the international World Heritage Convention in the national context of the United States. Although an early advocate of the national park idea and among the earliest proponents of the Convention, the US has shown increasing ambivalence towards the World Heritage Program since the mid-1990s. Through in-depth interviews with expert informants and a questionnaire survey of 406 visitors at four US World Heritage Sites, this study considers whether combining national and international conservation designations provides valuable reinforcement of conservation goals, or leads to unnecessary overlap and even challenges to sovereignty. The majority of my expert informants were supportive of the Convention, related to philosophical and practical benefits that they believed to be associated with the World Heritage label, although most identified few tangible influences of the World Heritage Program itself. Several noted hostility to the Program from a nationalist fringe, which fears international involvement in land use decisions. Such concerns were reflected in questionnaire responses, which revealed some distrust of the Convention and misunderstandings of its operation. I conclude that the scalar mismatch of implementing an international convention at the national scale inevitably involves challenges, but that country-specific factors are important in explaining why the Convention has been particularly controversial in the US. Education is integral to addressing these challenges, as well as reengagement with the Program by both the National Park Service and the federal administration. Intangible values associated with World Heritage mean that the Convention still enjoys considerable support in the US, providing a solid foundation for such a reengagement.  相似文献