共查询到18条相似文献,搜索用时 93 毫秒
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利用气相色谱-质谱联用仪(GC-MS)对连续取样的洛川黄土剖面弱古土壤层(L1 SS1)和相邻黄土层(L1LL1,L1LL2)的分子化石进行了检测,获得正构烷烃、正烷基-2-酮和酰胺等种类众多、丰度较高的分子化石。W草/植=nC31/(nC27+nC29+nC31),W木/植=(nC27+nC29)/(nC27+nC29+nC31)和W木/草=(nC27+nC29)/nC31记录了草本与植被、木本与植被、木本与草本比例变化规律的古植被信息。检测样品的CPI值为5.60~11.50,地质作用影响较小;通过磁化率、粒度和分子化石指标的相关性分析,认为磁化率、粒度记录了环境变化及主要气候事件(相关系数达-0.81);而分子化石能较好地反映古植被变化。当气候环境由干冷向温湿变化、水热配置条件改善时,植被变化响应较迅速;当环境恶化、转向干冷时,响应较弱或滞后,这种现象可能是由于植被生态系统稳定性造成的结果。整个研究剖面段样品以nC31为主峰的高碳数优势,分子化石表明末次冰期间冰段洛川地区(黄土高原)发育草本植被而没有出现以森林为主的植被。 相似文献
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重力梯度测量的现状及复兴 总被引:19,自引:3,他引:16
评述重力梯度测量的发展史,介绍重力梯度的各种应用,预测重力梯度测量的前景.由于重力梯度值或重力高次导数具有比重力本身高的分辨率,特别适合于探测或研究局部的小地质体及其细节;由于美国海军秘密重力梯度仪技术的公开,并投入工业应用,以及多种新型重力梯度仪正在加速研究,重力梯度测量在石油、金属矿勘探和小地质体探测以及研究方面必将起更重要的作用. 相似文献
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大兴安岭诺敏河石榴石橄榄岩捕虏体的发现及其地质意义 总被引:4,自引:4,他引:0
在重力梯度带北端的大兴安岭诺敏河第四纪火山岩中发现石榴石相和尖晶石相地幔橄榄岩捕虏体,其矿物组成分别为Ol40~55Opx20~35Cpx0~10Grt5~25和Ol45~65Opx30~40 Cpx0~15Sp0~10。两种地幔相橄榄岩均以方辉橄榄岩为主,说明研究区上地幔具有难熔的特点。其高Mg#橄榄石Fo91~92和高Cr#31~47尖晶石特征与南区哈河的地幔橄榄岩特征一致。在橄榄石含量与Fo图解上,敏河橄榄岩包体落在太古代和元古代地幔区域,揭示大兴安岭地区岩石圈地幔可能保留了较多古老的残余地幔。根据石榴石橄榄岩的平衡温压条件(1114~1168℃和2.14~2.33GPa),推测来源深度为70~75km。这些数据暗示研究区具有较高的地温梯度,与中国东部新生代火山岩区的地温梯度相似。 相似文献
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利用实测重力垂直梯度反演长白山地区一剖面的深部构造 总被引:3,自引:0,他引:3
针对重力梯度高分辨率的特点,利用在长白山地区实测的重力垂直梯度数据,采用梯度空间参量图反演其深部构造。台阶模型试验表明: 重力梯度空间参量图能给出构造倾角和倾面的信息,结合重力梯度剖面和梯度空间参量图可以构建出地下构造的几何模型,进而对一些复杂构造进行解释。通过对比实测布格重力异常和实测重力梯度异常,重力梯度比重力异常的分辨率更高; 将梯度法应用到实测重力梯度数据的处理中,结果表明: 该方法对确定密度变化界面的水平位置和深度具有非常好的效果。 相似文献
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利用重力梯度反演南海西南海盆深部构造 总被引:2,自引:0,他引:2
重力梯度异常反映的是重力异常的变化,其分辨率比重力异常高。重力梯度空间参量图能给出构造倾角和倾面的信息,结合重力梯度剖面和梯度空间参量图可以构建出地下构造的几何模型,进而对一些复杂构造进行解释。本文利用重力梯度异常对南海西南海盆进行了解释,得到大致以西南海盆北东向扩张轴为对称轴的穹隆状构造面。该构造面在西南海盆下6~15km处形成一个密度界面,此界面可能是西南海盆北西-南东向海底扩张期间地幔上隆所引起的。 相似文献
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Least squares collocation is a very comprehensive method for gravity field modelling, since it may use known noise characteristics of the data. In many earlier applications the errors affecting the data were considered uncorrelated, mainly due to the difficulty in estimating the systematic character of such kind of errors. In this study, error covariance functions of airborne gravity gradiometer data are estimated by comparing model covariance functions with empirical covariance functions of the gravity gradiometer data. The model covariance functions were estimated from accurate surface gravity data and continuated upward to the height of the airborne measurements using the covariance propagation law. The estimated error covariance functions were modeled as finite ones and used as an additional information for the prediction of gravity anomalies from gravity gradiometer data. The assessment of the prediction results was made by comparing the gravity values predicted from the airborne gradient data and showed up to 25% improvement compared to not using correlated errors. 相似文献
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基于磁测的边坡深部大变形监测方法 总被引:2,自引:0,他引:2
现有边坡深部变形监测仪器易受雨水、泥石流、滚石等环境的影响,仪器布设较繁琐,且无法监测边坡深部滑移的中后期变形。基于磁场定位理论,采用磁性物质制作智能石头,在边坡深部布置智能石头,通过智能石头和全张量磁力梯度仪建立边坡深部大变形监测系统。基于磁场梯度张量缩并定位对智能石头进行三维定位,实现边坡深部的中后期大变形监测。针对全张量磁力梯度仪的精度和地球磁场梯度的影响,由三维磁感应强度和磁场梯度的分析,其有效监测距离为35 m;在磁场定位试验中,监测精度为0.06 m。可为磁测在边坡深部大变形监测的进一步研究和应用提供参考。 相似文献
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An analysis of modern developments in the area of space-based gravitational-wave detectors is presented, and possible applications of key technologies for future space-based measurements of the gradient of the Earth’s gravitational field are considered. The structure of a space-based gradiometer based on free masses is presented, together with proposals for the reduction and calibration of measurements from such a device.
相似文献15.
Manik Talwani 《Central European Journal of Geosciences》2011,3(4):424-434
All gradiometers currently operating for exploration in the field are based on Lockheed Martin’s GGI gradiometer. The working of this gradiometer is described and a method for robust non linear inversion of gravity gradients is presented. The inversion method involves obtaining the gradient response of a trial body consisting of vertical rectangular prisms. The inversion adjusts the depth to the tops or bases of the prisms. In the trial model all the prisms are not required to have the same area of cross section or the same density (which can also be allowed to vary with depth). The depth to the tops and bottoms of each prism can also be different. This response is compared with the observed values of gradient and through an iterative procedure, the difference is minimized in a least square sense to arrive at a best fitting model by varying the position of the tops or bottoms of the prisms. Each gradient can be individually inverted or one or more gradients can be jointly inverted. The method is extended to invert gravity values individually or jointly with gradient values. The use of Differential Curvature, a quantity which is directly obtained by current gradiometers in use and which is an invariant under a rotation in the horizontal plane, is emphasized. Synthetic examples as well as a field example of inversion are given. 相似文献
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航空重力梯度勘探中,载体自身产生的重力梯度效应对于超高精度的重力梯度仪而言是一种严重的干扰。由于载体结构复杂,用常规的载体建模并正演难以精确去除这种干扰。本文从统计学角度出发,用多元线性回归来处理自身梯度效应,不需要对载体模型做出任何假设与近似,用纯数据驱动的方式来校正自身梯度的干扰。回归诊断与模型仿真验证了这种校正方式有较高的准确性,并且当实际的转角落在地面标定的范围内时具备预测能力。 相似文献
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本文概要介绍了中国航空物探(航磁、航空电磁、航空重力、航空伽马能谱)技术现状,近年来在仪器研制、测量技术、数据处理、解释方法与软件研发等方面的最新进展,分析了中国航空物探技术发展存在的主要问题.对中国航空物探技术的发展趋势进行了探讨.预测航空物探技术将向提高对探测目标的分辨能力和探测深度的方向发展,航空重力测量技术将得到广泛的应用.提出了以国家需求为导向,重点发展航磁多参数测量方法技术、航空重力测量和重力梯度测量技术、大探测深度时间域航空电磁测量技术,突破高温超导探测器研制的关键技术,发展航空重、磁、电的各种反演技术与三维可视化技术,建立物探仪器重点实验室,完善航空物探动态试验场,加快标准化建设,加快发展与航空物探相关行业(如通用航空)等建议. 相似文献
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《International Geology Review》2012,54(9):39-41
A two-dimensional formula using gravitational and/or magnetic observations of both the unmapped body and an exposed anomalous object located at the same depth along a line of common extension is devised to decrease error in determining the depth of an anomalous deposit. Practically, the same effect can be achieved by simply adding to an anomalous field with insufficient extension isoanomalies of identical fields on either side. --G, E. Denegar. 相似文献