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81.
At present, researches on climate change of the Heihe River basin mainly focus on the relationship between basin climate change
and regional water resources, regional desertification and dynamic climatic seasons of sandstorm, but less on climate change
of oasis region, where there are more intense and frequent human activities. Based on data of precipitation, temperature,
strong wind and dust events frequencies obtained from the six meteorological stations of Zhangye region in Heihe River basin,
the features of climate change during 1968–2005 were carefully studied. Results show that the regional temperature rise rate
exceeded the average level of China. The annual precipitation changed a little, but the precipitation had a slowly increasing
trend in spring and winter. Frequencies of strong wind and sandstorm days show obviously descending trends, which had a close
correlation with the regional temperature rise and the precipitation increase in spring and winter. Meanwhile, further human
economic activities and exploitations to the oasis in the inland valley of arid regions also affected the climate change of
this region, which has a sensitive and fragile eco-environment.
__________
Translated from Journal of Desert Research, 2007, 27(6): 1048–1054 [译自: 中国沙漠] 相似文献
82.
Rock magnetic record of Cenozoic lake sediments from the Linxia basin and aridification of the Asian inland 总被引:1,自引:0,他引:1
High resolution research of rock magnetic records and quartz sands from the Maogou Section in the Linxia basin reveals that
after a relatively stable environment between 13.07 Ma and 8.6 Ma, the basin was gradually influxed by eolian dusts at about
8.6 Ma, with two rapid increases at about 6.4 Ma and 5.3 Ma, respectively. The study suggests that drying of northwest China
began at 8.6 Ma and strengthened rapidly at about 6.4 Ma and 5.3 Ma.
__________
Translated from Marine geology & Quaternary geology, 2007, 27(4): 103–110 [译自: 海洋地质与第四纪地质] 相似文献
83.
华北克拉通东部早白垩世伸展盆地的发育过程及其对克拉通的破坏 总被引:1,自引:0,他引:1
在晚侏罗世华北克拉通东部破坏之初出现了区域性隆起,全区缺失上侏罗统沉积。在早白垩世早期,出现了区域性的伸展活动,断陷盆地形成,克拉通南、北缘伸展活动最强,北部燕山构造带以出现变质核杂岩为特征,南部出现宽裂谷型盆地。早白垩世中期华北克拉通东部普遍出现了火山活动与岩浆侵入。早白垩世晚期克拉通上以出现窄裂谷型盆地为特征,沿北北东走向的郯庐断裂带断陷活动最强。这些断陷盆地的演化过程揭示,经历地表抬升后,克拉通破坏之初的岩石圈热而弱,从而形成变质核杂岩或宽裂谷型盆地。这期间的破坏强度在空间上具有不均匀分布的特征,受控于早期岩石圈地幔的结构。经过早白垩世中期的大量岩浆活动之后,早白垩世晚期克拉通岩石圈温度降低、强度变大,从而利用早期大型断裂构造形成窄裂谷型盆地。这现象支持华北克拉通东部晚中生代的岩石圈减薄是以逐渐拆沉机制为主。 相似文献
84.
鸡西盆地被平麻断裂分割成南、北两个条带,多数研究者将南带1煤之下的海相层叠伏于北带海相层或底砾岩之下,称为“城子河组下段”或“石河北组”。利用事件地层学的原理,分析盆地内城子河组早期盆地裂陷、海侵、火山喷发、聚煤等重大事件在地层精细对比方面的意义,甄别出了盆地中重大事件的地层记录.以等时层为基础建立对比框架。通过大量钻井资料追溯对比,认为盆地中坳陷部位的渴湖海湾沉积是南北两带的沉积过渡类型,根据微体古生物研究,南北两带海相层中的沟鞭藻类化石面貌基本一致,南北带的海相层应是同一层位,初步实现了盆地内南、北两个条带城子河组的精细对比,为恢复盆地古地理环境奠定了可靠的基础。 相似文献
85.
四川盆地泸州古隆起嘉陵江组储层特征研究 总被引:1,自引:0,他引:1
对研究区嘉陵江组沉积背景认识的基础上,通过岩心观察、岩石薄片确定了不同类型的储集岩和储集空间,得出本地区储层岩石类型和储渗空间类型均多样化的特点。从成因角度识别出来了溶蚀孔隙型储层、膏溶孔洞型储层、裂缝型储层等三类储层。研究不同类型储层的孔、渗特征及关系表明,溶蚀孔隙型储层物性要优于膏溶孔洞型储层,而溶蚀孔隙型储层中的颗粒云岩溶蚀孔隙型储层物性最好、颗粒灰岩溶蚀孔隙型物性其次、粉晶云岩溶蚀孔隙型储层物性最差,其原因是不同储层受沉积环境和成岩作用控制和影响。 相似文献
86.
87.
R. S. Bradley M. J. Retelle S. D. Ludlam D. R. Hardy B. Zolitschka S. F. Lamoureux M. S. V. Douglas 《Journal of Paleolimnology》1996,16(2):97-110
A comprehensive study of meteorological, hydrological, limnological and sedimentological conditions in the watersheds of density-stratified (meromictic) lakes around Taconite Inlet, Northern Ellesmere Island, N.W.T., Canada was carried out from 1990–1992. Lakes C1 and C2 contain seawater trapped by isostatic uplift as the former embayments became isolated from the sea. These lakes, and Lake C3, contain varved sediments which provide an annually resolvable paleoclimatic record. By studing the major systems influencing sedimentation in one of these lakes (Lake C2) a better understanding of the climatic controls on varve formation, and hence on the paleoclimatic signal in the varved sediment record, was obtained. The varves of Lake C2 provide a proxy record of summer temperature for the region.This is the first in a series of papers published in this issue on the Taconite Inlet Lakes Project. These papers were collected by Dr R. S. Bradley. 相似文献
88.
本文根据层序地层学的基本原理,立足东部箕状断陷盆地的特点,以冀中拗陷和二连盆地为重点研究对象,提炼出陆相断陷盆地层序地层学模式,在缓坡带,以风暴浪基面作为“陆架边角”的参照物,层序地层特征相似于海相被动大陆边缘背景;在陡坡带则截然不同,并以湖面与边界断裂的交点取代“陆架边角”,各体系域所含沉积体系与海相模式不尽相同,在盆地形成初期的层序,低水位体系域发育,湖泊消亡以后,主要发育高水位体系域。此外,本文还探索了层序地层与油气赋存的关系,指出富砂的“盆底扇”是今后勘探开发的重要方向。 相似文献
89.
During the Late Carboniferous to Early Permian, a rift was formed by post-collisional extension after ocean closure or an island arc-related basin formed by Paleo-Asian Ocean (PAO) subduction in the Xi Ujimqin area. Nevertheless, the closure time of the PAO is still under debate. Thus, to identify the origin of the PAO, the geochemistry and U-Pb age of zircons were analyzed for the extra-large deep marine, polymict clastic boulders and sandstones in the Shoushangou Formation within the basin. The analyses revealed magmatic activity and tectonic evolution. The conglomerates include megaclasts of granite (298.8 ± 9.1?Ma) and granodiorite porphyry (297.1 ± 3.1?Ma), which were deposited by muddy debris flow. Results of this study demonstrated that the boulders of granitoids have the geochemistry of typical I-type granite, characterized by low Zr + Nb + Ce + Y and low Ga/Al values. The granitoid boulders were formed in island arc setting, indicating the presence of arc magmatism in the area that is composed of the Late Carboniferous to Early Permian subduction-related granitoid in southern Xi Ujimqin. Multiple diagrams for determining sedimentary provenance using major and trace elements indicate that Shoushangou sediments originated from continental island arc-related felsic rocks. Detrital zircon U-Pb age cluster of 330–280?Ma was obtained, indicating input from granite, ophiolite, Xilin Gol complex, and Carboniferous sources to the south. The basin was geographically developed behind the arc during the Early Permian period because the outcropped intrusive rocks in the Late Carboniferous to Early Permian form a volcanic arc. The comprehensive analyses of source areas suggest that Shoushangou sediments developed in a backarc basin in response to the northward subduction of the PAO. The backarc basin and intrusive rocks, in addition to previously published Late Carboniferous to Early Permian magmatic rocks of arc unit in Xilin Gol, confirm the presence of an Early Permian trench-arc-basin system in the region, represented by the Baolidao arc and Xi Ujimqin backarc basin. This study highlights the importance and potential of combined geochemical and geochronological studies of conglomerates and sandstone for reconstructing the geodynamic setting of a basin. 相似文献
90.
本文通过对祁连山南部地区三叠纪沉积充填特征的研究,建立了盆地形成过程中沉积充填与区域构造演化的关联。依据沉积充填特征、构造接触关系及区域地质背景,认为祁连山南部地区三叠纪盆地具有弧后前陆盆地的构造属性;综合分析年代学、沉积物性和盆地内部填充单元的差异划分出与柴达木岛弧带和祁连山南部弧后前陆盆地相关的区域大地构造单元。认为早三叠世-中三叠世中期,南部遭受俯冲作用持续向北挤压推覆导致盆地挠曲沉降;中三叠世中期-晚三叠世中期发生弧(东昆仑-柴北缘)-陆(巴颜喀拉地块)碰撞,祁连山南部盆地挠曲沉降增大,其间形成区域性断裂和不整合等盆地记录的地质事件;晚三叠世晚期祁连山南部盆地发生过补偿陆相填充,弧后前陆盆地消亡。 相似文献