层序地层框架下的鲕粒滩形成样式:以北京西郊下苇甸剖面寒武系第三统为例   总被引：5，自引：0，他引：5  

马永生  梅冥相  周润轩  杨文 《岩石学报》2017,33(4):1021-1036

华北地台寒武系第三统,大致包括毛庄组、徐庄组、张夏组和崮山组,在其中上部大面积发育鲕粒滩相灰岩,从而不符合标准的威尔逊碳酸盐相带中"台地边缘颗粒滩相"的概念。在北京西郊下苇甸剖面,基于沉积相序列的层序地层划分表明,这些鲕粒滩相地层,常常构成层序的晚期高水位体系域或强迫型海退体系域,表现出层序地层框架下特别的鲕粒滩形成样式,成为相对快速沉降背景下的相对海平面缓慢下降的沉积响应,从而不符合标准的层序地层学模式,因为在标准的层序地层学模式中沉积作用主要发生在相对海平面上升和停滞阶段,而且在海平面下降期将形成一个连续的侵蚀作用不整合面。再者,与海侵作用期的陆棚相钙质泥岩和深缓坡相条带状泥晶灰岩、及其所代表的泥质碳酸盐沉积物主导的浅海陆架型台地相对应,强迫型海退过程之中发育的大面积分布的鲕粒滩,代表着寒武纪类型多样的碳酸盐台地类型中的一种新的碳酸盐台地类型,即鲕粒砂所主导的浅海碳酸盐陆架为特征的一种特别的碳酸盐台地,即浅海陆架被颗粒质的鲕粒沉积物大面积覆盖,向海一侧为缓坡、向陆一侧为潮坪。所以说,北京西郊下苇甸剖面的寒武系第三统,鲕粒滩的层序地层位置所代表的特别的形成样式,以及所蕴含的寒武纪碳酸盐台地的类型,将为更大区域的追索和对比、以及华北地台第三世的古地理重建提供重要的线索和思考途径。  相似文献   

定向电磁波传播随钻测量基本理论及其在地层界面预测中的应用   总被引：2，自引：0，他引：2       下载免费PDF全文

魏宝君  田坤  张旭  刘坤 《地球物理学报》2010,53(10):2507-2515

采用水平层状各向异性介质中的磁流源并矢Green函数计算定向电磁波传播随钻测量的幅度衰减和相位移.分析了定向电磁测量的探测范围和对地层界面的灵敏性,研究了地层各向异性、地层相对倾角和接收天线倾角对定向测量的影响.计算结果表明,频率越低、线圈距越大、目的层和围岩层电阻率对比度越大,定向电磁测量的探测范围越大.随着接收天线倾角的增加,定向幅度衰减在接近地层界面时的变化更加明显,对地层界面的灵敏性增加.采用对称天线结构可消除定向测量信号在远离地层界面处对地层各向异性和地层相对倾角的依赖,实现对地层界面的准确预测.  相似文献   

小型非开挖钻机在花岗岩地层穿越施工中的应用     

杨国发 《岩土钻凿工程》2009,(1):66-68

本文介绍了小吨位水平定向钻在岩石层的施工方法及施工机具配置,施工工艺,操作注意事项。  相似文献   

Long term monitoring for oil in the Exxon Valdez spill region   总被引：2，自引：1，他引：1  

Payne JR  Driskell WB  Short JW  Larsen ML 《Marine pollution bulletin》2008,56(12):2067-2081

In the aftermath of the 1989 Exxon Valdez oil spill, a Long Term Environmental Monitoring Program (LTEMP) has been regularly sampling mussels (and some sediments) for polycyclic aromatic and saturated hydrocarbons (PAH and SHC) at sites in Port Valdez, Prince William Sound, and the nearby Gulf of Alaska region. After 1999, a decreasing trend appears in total PAH (TPAH) in tissues at all sites with current values below 100 ng/g dry weight (many below 50 ng/g). Currently, most samples reflect a predominantly dissolved-phase signal. This new low in TPAH likely represents ambient background levels. Synchrony in TPAH time-series and similarities in the hydrocarbon signatures portray regional-scale dynamics. The five inner Prince William Sound sites show similar composition and fluctuations that are different from the three Gulf of Alaska sites. The two Port Valdez sites represent a unique third region primarily influenced by the treated ballast water discharge from the Alyeska Marine Terminal. Prince William Sound has reverted to a stable environment of extremely low level contamination in which local perturbations are easily detected.  相似文献   

Wave direction analysis from data buoys     

Min-Chih Huang  Jia-Yuan Chen 《Ocean Engineering》1998,25(8):621-637

This paper describes a new procedure of directional wave analysis from pitch-roll buoy measurements. The two previous procedures adopted by the National Data Buoy Center (NDBC) [Steele, K. E., Lau, J. C. K. and Hsu, Y.-H. L. (1985) Theory and application of calibration techniques for an NDBC directional wave measurement buoy. IEEE Journal of Oceanic Engineering OE-10(4), 382-396; Steele, K. E., Teng, C.-C. and Wang, D. W. C. (1992) Wave direction measurements using pitch-roll buoys. Ocean Engineering 19(4), 349-375] are relevant to our formulations. In these two studies, an estimate for the total phase shift of the sea surface displacement/slope spectra from the measured buoy heave/pitch and heave/roll spectra was calculated either by a weighted average method or a maximum heave/pitch quad-spectrum method. These two formulations were based on a fundamental assumption of symmetric hull-mooring effect on pitch and roll motions, which will never be true in the oceans. In the present study we essentially incorporate the basic formulations of NDBC, but calculate two estimates for this total phase shift.Examples of directional wave analysis from data measured by a 3 m diameter discus buoy during Typhoon Herb are presented in this paper. This data set was also analyzed by the weighted average method of Steele et al. (1985) which yielded unsatisfactory results of wave directions during severe wave climates.  相似文献   

浅海声传播和混响的选频衰减   总被引：2，自引：0，他引：2  

裘辛方  张仁和  李文华  朱柏贤  金国亮 《海洋学报》1998,20(1):41-49

在强负跃层浅海的爆炸声实验中,发现当声源和接收器都位于跃层之上时,平均混响强度和某一航向的声传播损失在频率1000-2000Hz之间出现强烈的异常衰减现象,而且很有意思的是发射和接收均无指向性的平均混响强度的异常衰减与该航向声传播损失的异常衰减具有中心频率相同、带宽一致、附加衰减值相近的窄带共振或选频衰减特权.显然,这一异常衰减现象无法用各向异性的机理(内波、海面或海底的有规律起伏等)来解释.根据本文实验所得的传播损失和混响强度的深度结构以及一些间接的证据,我们认为这一选频附加衰减是由分散活动干跃居上部的有鳔鱼(极可能是鱼)所引起的.  相似文献   

洞穴碳酸盐微层研究及其发展方向   总被引：4，自引：0，他引：4  

王先锋  刘东生 《地球科学进展》1999,14(3):286-291

近几年,在分辨率气候－环境变化研究中,洞穴碳酸盐微层逐渐受到人们重视。洞穴碳酸盐微层的类型较多,主要为年层。微层是在沉积条件发生高频率的周期性改变时形成的,要受到供水条件和碳酸钙浓度等多因素的控制。洞穴碳酸盐微层的稳定同位素组成,生长速率,微层结构与物质组分,微层厚度与灰度和光学特征等可以反映降水,温度,土壤成分及植被变化等信息。  相似文献   

Property rights on genetic resources: economic issues     

Josef Janssen   《Global Environmental Change》1999,9(4):197

Biodiversity loss is one of the major international environmental problems. This paper analyses the question of how the use of genetic and biochemical resources in biotechnological industries might affect biodiversity conservation. It is argued that the answer will significantly depend on the concrete regimes of property rights on genetic resources and related biotechnological knowledge. One of the main conclusions derivable from this analysis is that a tightening of intellectual property rights may either aggravate biodiversity loss or strengthen biodiversity conservation, depending on various conditions. This result has interesting parallels to the results of second best theory. Furthermore it sheds new light on the debate regarding the relationship between the WTO Agreement on trade-related aspects of intellectual property rights (TRIPs) and biodiversity loss.  相似文献   

On the measurement of directional wave spectra at the southern Brazilian coast     

J. H. G. M. Alves  E. Melo 《Applied Ocean Research》1999,21(6):539-309

The detailed reconstruction of the directional spectrum of wind waves from measurements of the wave field is an essential requirement for several applications, including the numerical modeling of wave evolution. Three reconstruction techniques that provide estimates of the directional distribution function D(f,θ), given the one-dimensional frequency spectrum, are compared using data from a coastal locality at the southern Brazilian coast. The techniques are the maximum entropy method (MEM), the Fourier Expansion Method using a cos² type function (FEM_cos) and the Fourier Expansion Method using a sech type function (FEM_sech). The main patterns of the wave climate at the study site are qualitatively assessed. Three main sea states, including swell, transition between local sea and swell, and directionally bimodal wind sea, are identified. Time series from three events associated with the main sea states provide test cases for inter comparison of the three reconstruction techniques. Maximum entropy estimates of D(f,θ) provide results that are more consistent than those obtained from the two FEM techniques in all cases considered.  相似文献   

A laboratory study of directional spectra with maximum likelihood mehod-Ⅱ Decaying swell     

Zhao Dongliang  Masuda Akir  Wen Shengchang  Guan Changlong 《海洋学报(英文版)》1999,18(1):75-85

INTRODUCTIONForavarietyofapplications,includingcoastalandoceanengineering,shiproutingandtheinterpretationofremotelysensedata,informationonthedirectionalwavespectrumisdesirable.Knowledegeoftheintegratedorone-dimensionalspectrumisconsiderable,duelargelytofieldmeasurementssuchasJONSWAP.Asimilarsituation,however,doesnotexistinthecaseofdirectionalsprectra.Thisislargelyduetotheaddedcomplexityandthecostofdirectionalmeasure1.InstituteofPhysicalOceanography,OceanUniversityofQingdao,Qingdao266…  相似文献