应力松弛作用对未固结砂岩等效弹性性质的影响     

邓继新  韩德华 《吉林大学学报(地球科学版)》2011,41(1):283-291

未固结碎屑砂岩储层是国内外重要的油气储层类型之一,其物理本质是由离散颗粒组成的软凝聚态物质.在地震勘探中通常使用Hertz-Mindlin等效介质模型来计算未固结砂岩的地震弹性特征,但该模型在使用中通常会得到明显偏高的剪切模量值.基于3D离散元技术,对颗粒介质在单轴压缩与纯剪两种过程中的力学响应进行离散元数值模拟,从微...  相似文献   

海上地震勘探GI枪子波数值模拟     

李国发  曹明强  陈浩林  倪成洲 《吉林大学学报(地球科学版)》2011,41(1):277-282

GI枪震源已经逐步成为海上地震勘探的主要激发方式。常规气枪只有一个腔室,而GI枪具有G腔和I腔2个腔室,能够较好地压制气泡振荡。基于自由气泡振动理论,分析GI枪的激发机制,在考虑气泡壁的热传导作用和流体粘度对气泡振动影响的基础上,建立了海上勘探GI枪子波数值模型,并对气泡的振动过程和远场地震子波进行了数值模拟。结果表明:当G腔内气体释放所形成的气泡体积达到最大时,I腔内气体的释放有效地抑制了气泡的收缩,气泡壁运动速度明显减小,气泡变得稳定;GI枪激发所产生的子波具有明显的峰值和较小的旁瓣,有利于高分辨率海上地震勘探。  相似文献   

辽宁北票四合屯地区早白垩世早期鸟类集群死亡原因探析   总被引：3，自引：0，他引：3  

张立军  巩恩普 《地质论评》2003,49(4):347-354

通过大规模系统挖掘,在对四合屯7个含鸟层进行澄清的基础上,以四合屯剖面为主,黄半吉沟剖面为辅,分别在含鸟层的底板、含鸟层、含鸟层顶板,不含鸟沉积层及含鸟层底部的火山岩系统取样,进行多项相关元素分析。应用元素地球化学理论,根据其环境地球化学场特征,结合相关地质资料,重点对鸟类集群死亡原因进行了探讨。结果表明包括二氧化硫(SO2)、硫化氢(H2S)、铅(Pb)的卤化物盐(PbBr2、PbBrCl、Pb(OH)Br、(PbO)2PbBr2)及汞(Hg)蒸汽等有毒气体是导致鸟类集群死亡的主要原因;含鸟化石密集的原因是由于火山口在四合屯附近。  相似文献   

Cosmogenic nuclide constraints on glacial chronology in the source area of the Urumqi River,Tian Shan,China   总被引：1，自引：0，他引：1  

Yingkui Li  Gengnian Liu  Ping Kong  Jon Harbor  Yixin Chen  Marc Caffee 《第四纪科学杂志》2011,26(3):297-304

Cosmogenic nuclide surface exposure dating of boulders and erratics provides new constraints for a glacial chronology in the source area of the Urumqi River, Tian Shan, China. ¹⁰Be exposure ages of 15.0 ± 1.3–17.1 ± 1.5 ka from the Upper Wangfeng (UWF) moraines agree well with their previous relative age assignments to marine isotope stage (MIS) 2, but are younger than published AMS ¹⁴C and electron spin resonance (ESR) ages (from 22.8 ± 0.6 to 37.4 ka). This difference may result from variations in techniques, or could reflect the impact of surface erosion and sediment/snow cover on surface exposure dating. ¹⁰Be ages from the Lower Wangfeng (LWF) moraines (18.7 ± 1.8 and 16.2 ± 1.5 ka) are indistinguishable from the UWF exposure ages, but are significantly younger than previously reported thermoluminescence (TL) and ESR ages (37.7 ± 2.6–184.7 ± 18 ka). Either these two groups were formed during the same period (MIS 2) and there are problems with TL and ESR ages, or the moraines were of very different ages and the similar exposure ages result from different degrees of degradation. Erratics on rock steps and a drumlin along >8 km of the main glacial valley above the UWF have internally consistent and slightly decreasing ¹⁰Be exposure ages indicating glacier retreat >2.5 m a^?1 after MIS 2 and before middle or late Holocene glacier re‐advances. This retreat rate is similar to rates observed from modern glaciers. Copyright © 2011 John Wiley & Sons, Ltd.  相似文献   

Paleo-climate of the central European uplands during the last glacial maximum based on glacier mass-balance modeling     

Barbara M. Heyman  Jakob Heyman  Thomas Fickert  Jonathan M. Harbor 《Quaternary Research》2013,79(1):49-54

During the last glacial maximum (LGM), glaciers existed in scattered mountainous locations in central Europe between the major ice masses of Fennoscandia and the Alps. A positive degree-day glacier mass-balance model is used to constrain paleo-climate conditions associated with reconstructed LGM glacier extents of four central European upland regions: the Vosges Mountains, the Black Forest, the Bavarian Forest, and the Giant Mountains. With reduced precipitation (25–75%), reflecting a drier LGM climate, the modeling yields temperature depressions of 8–15°C. To reproduce past glaciers more severe cooling is required in the west than in the east, indicating a strong west–east temperature anomaly gradient.  相似文献   

IMPACTS OF URBANIZATION ON SURFACE HYDROLOGY,LITTLE EAGLE CREEK,INDIANA, AND ANALYSIS OF LTHIA MODEL SENSITIVITY TO DATA RESOLUTION     

Matt Grove  Jon Harbor  Bernie Engel  Suresh Muthukrishnan 《自然地理学》2013,34(2):135-153

Land-use change in urbanizing areas can significantly alter the hydrology of a watershed and can have serious impacts on wetland water balances, downstream flooding, and groundwater recharge. Most currently available models used in determining the hydrologic impacts of urbanization are not well suited to long-term hydrologic analysis or are too complex and data intensive for widespread practical application. The Long-Term Hydrologic Impact Assessment (LTHIA) model run on a Geographic Information System (GIS) is a relatively simple, user-friendly model that uses the Curve Number method to estimate changes in surface runoff between different stages of development. Application of the model to a large, rapidly urbanizing watershed near Indianapolis, Indiana, suggests that average annual runoff depths increased by more than 60% from 1973 to 1991, with even greater increases for some individual sub-basins. These results are consistent with runoff changes estimated from historical stream flow data in the watershed. A sensitivity analysis to determine minimum data requirements shows that a precipitation record length of 15 years or more is required to produce consistent results with LTHIA and that the highest possible resolution land-use and soils data should be used. The LTHIA model is now available on the Internet at http://www.ecn.purdue.edu/runoff. [Key words: hydrology, urbanization, modeling, GIS.]  相似文献   

SHRIMP Age of Exotic Zircons in the Mengyin Kimberlite, Shandong, and Their Formation     

YIN Zuowei  LU Fengxiang  CHEN Meihua Gemmological Institute  China University of Geosciences  Wuhan  Hubei  Earth Science Department  China University of Geosciences  Wuhan  Hubei 《《地质学报》英文版》2005,79(5):654-661

1Introduction Due to its special properties and ubiquitous occurrence,zircon can be found in the crust,mantle,lunar rocks,meteorites,etc.And it is the ideal mineral to test the formation age of rocks(Xie et al.,2001).However,zircons are an exceptionally rare component of kimberlites.They have various sources and courses of formation.Zircons crystallized from kimberlitic magma are usually have large sizes and a maximum diameter of20mm was reported.Typically,they have low contents of U and Th,…  相似文献   

《地质论评》新增栏目启事     

编辑部 《地质论评》2019,65(1):65010039-65010039

正第40届编委会第一次会议讨论决定,《地质论评》自2019年起,在原有"问题讨论"、"科技述评"、"研究进展"、"通讯资料"、"消息报道"和"新书介绍"6个专栏的基础上,新增两个栏目:"专题细解"和"窥斑速报"。"专题细解"(Theme Paper)专栏为一组对同一专题进行研究的文章,一般由4～7篇组成,一般应当包括一篇评述,其余为专题研究或讨论。"窥斑速报"(Express Letter)专栏快速发表对重要地质问题有关证据或重要地质体的新发现,该栏文章的格式与正  相似文献   

POLYCULTURE OF SCALLOP CHLAMYS FARRERI AND KELP LAMINRIA JAPONICA IN SUNGO BAY     

方建光  孙惠玲  燕敬平  匡世焕  李锋  GaryF.Newkirk  Jon Grant 《中国海洋湖沼学报》1996,(4)

Several polyculture models of scallop Chlamys farreri and kelp Laminaria japonica currently employedin Sungo Bay and other parts of northern China are described in this paper. Economic benefits of differ-ent polyculture models are analysed based on the growth rate, culture density and market price. In addi-tion, site selection, critical environmental conditions and polyculture problems are discussed in detail.  相似文献   

Fluid Inclusion Studies and Geochemistry of Rare Earth Elements of Hydrothermal Fluorites from Pohrenk, Kirsehir, Central Turkey     

Sükrü KOC  Ali RECBER 《《地质学报》英文版》2001,75(1)

Fluorite mineralization occurs along fractures and cracks of Middle Eocene and Pliocene limestones and marls in the north and northeast of the Pohrenk region (Qicekdagi, Kirsehir). Tb/Ca - Tb/La and Y/Ho ratios were obtained from REE contents of fluorites which have revealed that mineralization is of hydrothermal type. Negative Ce anomalies and positive Eu anomalies reflect that hydrothermal solutions once had high oxygen fugacity. Fluid inclusion studies indicate that homogenization temperatures of mineralization varied between 90℃ and 200℃, and hydrothermal solutions are composed of NaCl + KCl + MgCl2 + H2O. In addition, salinity measurements show that hydrothermal solutions were mixed with meteoric or rock formation water. Geologic setting, REE geochemistry and fluid inclusion studies suggest that mineralization was deposited from a solution generated by mixing of magmatic and meteoric water under epithermal conditions.  相似文献