共查询到20条相似文献，搜索用时 62 毫秒
1.
宋友桂 《海洋地质与第四纪地质》2003,23(2):79-84
对石膏裂变径迹测年的可行性及研究方法进行了探讨，研究表明，无论矿物结构特征还是铀含量与年龄关系均说明石膏可用于裂变径迹测年，其测定的年龄能较好地与古地磁、地层学、古生物学上的证据吻合，裂变径迹年龄与自发径迹密度和诱发径迹密度比值(ρs/ρi)相关分析进一步证明石膏测定的裂变径迹年龄是可信的。同时发现在中子通量相同的情况下，石膏裂变径迹年龄与铀含量并不存在特定的相关关系。为了进一步提高石膏裂变径迹测年数据的可靠性、精确度和可比性，今后研究中应加强最佳蚀刻条件、退火机制的研究和标准年龄对比法的应用。 相似文献
2.
东海西湖凹陷反转构造定量研究:来自裂变径迹分析数据的约束 总被引：7，自引：0，他引：7
对来自东海陆架盆地西湖凹陷反转构造带上的 5口钻井 (XL1,XL2 ,XH,XY,XT)的 17个样品 (11个磷灰石、6个锆石样品 )进行了系统的裂变径迹年龄测定。样品的地层年代介于渐新世和上新世之间。锆石裂变径迹年龄表明 ,各样品所经历的最大埋藏温度小于 (2 2 5± 2 5 )℃。磷灰石裂变径迹的年龄则比锆石的要复杂。南侧 XT和XY两口井的磷灰石裂变径迹年龄大于相应的地层年龄 ,而北侧的 3口井的磷灰石裂变径迹年龄则小于相应的地层年龄。磷灰石年龄的分布表明西湖凹陷南部第三系地层所经历的最大沉积埋深小于北部 ,反转程度南弱北强。对于裂变径迹年龄小于地层年龄的样品 ,对地层剥蚀量进行了初步的估算 相似文献
3.
青藏高原洞穴次生方解石的裂变径迹年代及地貌学意义 总被引：8，自引：1，他引：7
古岩溶洞穴中残留的次生方解石晶体可以作为裂变径迹测年的材料。通过测定遍及青藏高原的２０组洞穴次生方解石晶体的裂变径迹年代,结果表明,晚第三纪青藏高原的古岩溶过程和缓慢构造抬升过程相伴进行,其间大约１０ＭａＢ．Ｐ．、１２ＭａＢ．Ｐ．和１９ＭａＢ．Ｐ．时溶穴次生化学沉积较为发育。由于地表切割程度的差异,晚第三纪岩溶过程在高原南部较为强烈,相对于第四纪期间的强烈抬升来说,高原晚第三纪的抬升速率较为缓慢, 相似文献
4.
磷灰石裂变径迹作为一种低温热史重建的研究手段,现已用来约束断裂带的活动时限。但是,通过分析发现,在磷灰石裂变径迹——断裂带活动时限研究过程中仍然存在诸多制约因素,以致对研究结果造成比较大的干扰。其中,诸如矿物自身特征(如矿物成分、各向异性等)、实验操作及解译模型的选取,这都无疑增加了磷灰石热史重建的难度;岩石热导率、火山等构造活动、地层孔隙水含量等因素,更是造成了地温变化的多种解释;在目标断裂构造运动解译过程中,更是需要排除气候、周边断层构造活动的影响。最后以实验操纵、自然热冷却、周边断层构造运动因素为例,基于前人研究提出相应的解决方法,尽量消除上述影响因素关于断裂带研究的干扰,以提高解释的科学性、合理性。 相似文献
5.
对苏皖下扬子区上白垩统浦口组（K2P）的三个砂岩样品进行了磷灰石裂变径迹（AFT）研究。结果显示：2个样品的AFT合并年龄为（88．8±4．4）Ma（径迹长度为（12．0±0．3）μm）和（82．1±6．8）Ma（径迹长度为（14．4±0．3）μm）与浦口组沉积年龄相近,说明它们沉降的幅度达到但没有超过AFT部分退火区间,1个样品的AFT合并年龄（117．3±5．9）Ma（径迹长度为（13．3±0．3）μm）大于浦口组沉积年龄,代表物源区抬升、剥露的冷却年龄。根据热历史模拟结果,识别出黄桥事件（110～90Ma）、仪征事件（70～60Ma）和三垛事件（35～22Ma）三期重要的构造事件,并将下扬子区晚白垩世以来的盆地演化划分为四个阶段：110～70Ma断坳复合型伸展盆地、70～35Ma拉张断陷盆地、35～22Ma挤压抬升阶段和22Ma至今坳陷盆地。 相似文献
6.
新疆博格达山中新生代隆升--热历史的裂变径迹记录 总被引：13，自引：0，他引：13
5个磷灰石样和4个锆石样的裂变径迹测年证据以及热历史的定量模拟研究表明,博格达山自晚侏罗世末—早白垩世开始隆升,总体表现为持续的隆升过程,具有4个主要期次的演化阶段,起始时间分别为150~106、75~65、44~24、13~9 Ma。其中44~24 Ma之前,博格达山南、北缘隆升速率近于一致。之后,博格达山的隆升转为区段性,南、北缘形成差异隆升。北缘在42~11 Ma为近于稳定的状态,隆升速率为1 m/Ma,11 Ma至今隆升速率为190.6 m/Ma;而南缘在26~9 Ma间隆升较快,速率为41.2 m/Ma,9 Ma至今隆升速率为162.9 m/Ma。这种差异性的隆升可能一方面与印度板块和欧亚板块碰撞的远程效应有关,另一方面也是更主要的原因可能受博格达山不同段深部差异性动力学过程所控制。 相似文献
7.
盆山沉积耦合原理在定量恢复造山带隆升剥蚀过程中的应用 总被引：4，自引：1，他引：3
造山带的隆升剥蚀过程研究一直是地学界研究的热点和难点,而与造山带毗邻的沉积盆地则真实地记录了造山带隆升剥蚀演化历史。因此,通过对沉积盆地中沉积物的研究可以反演山地隆升剥蚀历史。基于这种思路,介绍了两种定量恢复造山带隆升剥蚀的方法,即裂变径迹热年代学方法和质量平衡法。前者利用样品碎屑单颗粒的裂变径迹年龄的统计分析确定其源区,并量化源区的抬升剥露及热演化历史,但要求对样品的沉积时代有很好的年代学控制,沉积后样品没有遭受热重置。后者则假定在一定时间间隔内,盆山耦合系统中物源区的地形变化总和与沉积区的碎屑沉积质量总和成正比,即隆升过程中产生侵蚀总量与毗邻盆地的沉积总量之间质量守恒,从而通过研究盆地中相应时间段的沉积总量、沉积速度来定量恢复古地形,反演造山带的演化,但盆山系统的界定以及地层定年的精度直接影响到恢复造山带隆升剥蚀过程的可靠性。 相似文献
8.
9.
国际大洋钻探计划自１９８３年以来，已成功地实施了６６个航次的深海钻探作业，获取钻探岩芯逾１０００００ｍ。在关于大陆边缘的构造演化，海洋地壳的形成与发展，地壳流体循环和壳幔相互作用海洋沉积结构和古海洋学，地球大气圈、水圈、冰圈、生物圈的长期变化等众多研究领域取得了一系列重大科研成果。 相似文献
10.
由徐脉直研究员等编著的《海洋固体矿产》一书 ,已由青岛海洋大学出版社出版发行。该书在前人研究的基础上 ,结合我国近年来的调查研究成果 ,从历史与发展的角度 ,全面地、系统地介绍了各类海洋固体矿产的研究历史和现状 ,科学地阐述了海洋多金属结核、富钴结壳、热液硫化物、海底磷钙土、滨海砂矿等海洋固体矿产的成因、类型、地球化学特征及分布规律。该书还对海洋固体矿产进行了技术经济评价 ,并对开发前景进行了预测。作者认为 ,海洋固体矿产资源开发虽投资巨大且有风险 ,但却是一项获利极大的事业。但是 ,由于陆地资源仍可满足人们对资… 相似文献
11.
Three wells, all offshore, in southern Alaska studied using apatite fission track dating make a transect southward from Lower Cook Inlet to the Kodiak Shelf and include ARCO Lower Cook Inlet COST #1 well (LCI well), Chevron OCS-0248 #1A well (Shelikof Strait), and Kodiak COST KSSD #1 OCS 77-1 well (Stevenson Basin, Kodiak). The ages of deep partially annealed samples from Lower Cook Inlet well suggest that the region cooled between ~100 and 75 Ma and or sometime after. Two scenarios are presented: (1) maximum heating before cooling in Late Creta ceous times and (2) maximum heating before cooling during mid-Tertiary times. Which is better is uncertain from the thermal and age data alone, but mid-Tertiary or later uplift, erosion, and cooling is preferred because data from Shelikof well suggests that the mid-Cretaceous unconformity was minor relative to the mid-Tertiary unconformity. Finally, because of the ~12 C warmer past than present bottom-hole temperature, the base of the LCI well is now ~500 m shallower than during maximum, burial (12 C/24 C/km geothermal gradient). Single-grain apatite fission track ages (20-25 Ma) from deep in the Shelikof well approach the age of the overlying mid-Tertiary (Miocene; ~23 Ma) unconform ity, suggesting significant and rapid exhumation. This suggests that strongly annealed, once deeply buried strata were uplifted and cooled quickly prior to onlap of the unconformity. The Miocene unconformity, therefore, is interpreted to be the major unconformity in the Shelikof well section. In this scenario the section was buried deepest, and was therefore hottest, until the onset of mid-Tertiary erosion. Approximately 665 m of late Tertiary and Quaternary strata have since been deposited in Shelikof Strait and have reburied the Shelikof section to within ~536 m of its original maximum burial depth. Including modern water depth, the Shelikof well section has experienced ~1 km of burial+submergence since ~25 Ma (832 m section+166 m water=998 m). It follows that the depth to the base of the well is now ~290 m shallower than it would have been during maximum burial. Single-grain apatite fission track ages deep in the Kodiak KSSD1 well are as young as 20-25 Ma and approach the age of overlap of a mid-Miocene regional unconformity (<23 Ma). The deepest Eocene samples were exhumed to within 574 m of the Miocene unconformity surface during Miocene time and were reburied by ~1.7 km of late Tertiary strata. The total section before exhumation was ~5 km; this suggests that Oligocene-age deposits may have existed in the Stevenson Basin. Together with the known Eocene strata, such deposits were exhumed during ~4.4 km of uplift and erosion during a short interval culminating in early to middle Miocene times (>25-23 Ma). Unique and anomalous apatite compositions (high F-, low Cl-, moderate OH-) from the Eocene section could provide a chemical tracer for determining their sediment source along the northeast Pacific rim prior to translation and accretion. 相似文献
12.
Close interactions among vertically stacked pairs of counter-rotating eddies under sea ice were investigated in numerical experiments. The numerical model contains a stratified ocean capped by an ice layer. Under the ice layer, a shallow brine source produces a top cyclone and a submerged anticyclone, while a shallow freshening source generates a top anticyclone and a submerged cyclone. Ice-exerted friction would dissipate the top eddy, leaving the submerged one in lone existence. In this work the winning vorticity is sought from group settings. Arrays of equally spaced salinity sources and sinks, alternate in sign but equal in strength, are employed to produce rows of vertically stacked eddy pairs. Fission occurs when adjacent vortex centers are separated by less than one Rossby radius. This process ejects parcels of density anomalies to the ambient ocean in upper depths. Low salinity anomalies are quickly dispersed into a thin surface layer and are unable to regenerate submerged eddies. High salinity parcels, being difficult to disperse, often maintain or regenerate submerged anticyclones below. Fission is particularly effective if a single row of salinity forcing is used. With multiple rows, fission is active only in the outer rows. The strong interaction among closely packed eddies operates in time scales of tens of days, helping explain the predominance of submerged anticyclones under Arctic sea ice. 相似文献
13.
It is desired to track the location of an underwater acoustic source with range difference measurements from a stationary passive array. Many times, the array has only one or two sensors, and the multipath and intersensor range difference measurements are insufficient to localize and track a source moving along an arbitrary path [1]. Here, we propose to track sources with one- or two-sensur stationary passive arrays by making the simplifying assumption that the source's path can be described by a small set of so-called track parameters. Range difference information can then be used to estimate the track parameter set rather than the source location as a function of time. In this paper, we choose the track parameters to specify a straight-line constant-velocity constant-depth path. Cramer-Rao bounds are presented for estimating these track parameters from the time history of multipath and intersensor range difference measurements. It is shown that this track parameter set cannot be accurately estimated from the time history of a single multipath range difference without side information (an independent velocity estimate, for instance), although multipath and intersensor range difference measurements from a two-sensor array are generally sufficient to estimate the track parameter set. Computationally efficient techniques are presented which estimate track parameters from range difference measurements taken from one- and two-sensor arrays. Monte-Carlo simulations are presented which show that these techniques have sample mean-square error approximately equal to the Cramer-Rao bound when a single multipath range difference and an independent velocity estimate are available. The sample mean-square error is shown to be in the range of two to ten times the corresponding Cramer-Rao bounds when these techniques are applied to two-sensor range difference data. 相似文献
14.
本文导得了1个研究内波分裂的射线型二维KdV方程。利用这一方程的一维退化方程进行了实验室尺度下孤立子型内波分裂的数值研究。数值结果表明,深水区的初始内孤立波和实测的内孤立波(内潮)在通过陆坡区时都会产生分裂,并在陆架上(浅水区)生成一内孤立子波列。这表明在实际海洋条件下,深海区内潮的分裂是陆架上海洋内孤立子波包(或波列)生成的主要机制之一。 相似文献
15.
16.
利用1°×1°NCEP再分析资料、卫星云图和中尺度自动站等气象资料,分析了环流背景对台风莫拉菲的路径和降水变化的影响,并对莫拉菲的降水过程的物理量特征进行诊断分析.结果表明,500 hPa副热带高压带状分布,副高南缘偏东气流加强,台风北侧最大东风风速与南侧最大西风风速之差增大是造成台风路径变化并稳定向西北偏西方向移动的主要原因;莫拉菲在向西北偏西方向移动过程中,其水汽通量相对散度、垂直速度、涡度等各物理量场均表现出有利于强降水出现的特征,也揭示了此次台风造成的强降水出现地区性差异的主要原因. 相似文献
17.
18.
船舶监控系统中实现了船只航迹线的动态绘制,发过程中涉及到偏转角度算法和距离插值两个核心算法,视化表现方面取得了良好的效果。系统能够根据船只航行方向动态显示航行轨迹,程序开系统开发实践表明,这两个算法的合理应用在航迹线可 相似文献
19.
Wilmut M.J. Chapman N.R. Heard G.J. Ebbeson G.R. 《Oceanic Engineering, IEEE Journal of》2007,32(4):940-947
This paper describes a simple approach for inferring the depth and track of a sound source at short ranges by inversion of acoustic field data at a set of sea bottom hydrophones. At short ranges, the acoustic field consists of a dominant Lloyd mirror (LM) signal from the direct and surface-reflected ray paths and a series of bottom-reflected paths that modulate the LM signal. A computationally efficient propagation model based on the method of images is developed to calculate replica fields for the inversion. The matched field inversion method for inferring the source depth and track is demonstrated using data from an experiment carried out in shallow water off the east coast of Canada. The estimated values were in very good agreement with independent measurements taken during the experiment. 相似文献
20.
A novel efficient track initiation method is proposed for the harsh underwater target tracking environment (heavy clutter and large measurement errors): track splitting, evaluating, pruning and merging method (TSEPM). Track initiation demands that the method should determine the existence and initial state of a target quickly and correctly. Heavy clutter and large measurement errors certainly pose additional difficulties and challenges, which deteriorate and complicate the track initiation in the harsh underwater target tracking environment. There are three primary shortcomings for the current track initiation methods to initialize a target: (a) they cannot eliminate the turbulences of clutter effectively; (b) there may be a high false alarm probability and low detection probability of a track; (c) they cannot estimate the initial state for a new confirmed track correctly. Based on the multiple hypotheses tracking principle and modified logic-based track initiation method, in order to increase the detection probability of a track, track splitting creates a large number of tracks which include the true track originated from the target. And in order to decrease the false alarm probability, based on the evaluation mechanism, track pruning and track merging are proposed to reduce the false tracks. TSEPM method can deal with the track initiation problems derived from heavy clutter and large measurement errors, determine the target’s existence and estimate its initial state with the least squares method. What''s more, our method is fully automatic and does not require any kind manual input for initializing and tuning any parameter. Simulation results indicate that our new method improves significantly the performance of the track initiation in the harsh underwater target tracking environment. 相似文献