北康盆地沉降作用与构造运动

在地质构造特征研究的基础上,采用地层回剥法和局部均衡模式,研究北康盆地的构造沉降作用,并探讨该盆地构造演化与区域构造运动的关系。北康盆地是一个拉张性盆地,经历了3次快速沉降作用。中始新世沉降作用占总构造沉降量的28％～34％,沉降速率为234～325m／Ma,拉伸系数最大达1.72,它是43Ma时印度板块和欧亚板块碰撞的结果。上始新世—早渐新世构造沉降作用速率较慢,幅度也较小,为西卫运动影响下的越东—万安走滑断裂发生走滑拉张活动所致。上新世—第四纪的沉降速率极快,幅度很大,可达整个构造沉降的40％以上,可能是太平洋板块与欧亚板块相互作用所引起的整个南海区域沉降在盆地中的反映。     

1.5 Ma以来南海南北上部水体温度变化对比

浮游有孔虫表层海水古温度转换函数、表层暖水种属种含量比值,以及次表层暖水种含量的变化,表明南海北部1．5Ma以来表层、次表层海水温度逐渐降低,其主要变化阶段为0．86～0．94Ma和0．64～0．68Ma。与南海南部西太平洋暖池区的17957站研究结果对比．发现南海南部1．5Ma以来表层、次表层海水温度逐渐增加．发生的主要时间为1．23～1．3Ma和0．64～0．68Ma。南海北部的上部海水结构变化主要受东亚冬季风影响,而南海南部则主要受西太平洋暖池影响,因此,南海南、北上部海水温度的变化说明0．9Ma后尤其是0．68Ma以来东亚冬季风强化,西太平洋暖池加强。     

波动分析约束下的原型盆地剥蚀量恢复——以惠民凹陷为例

为准确的恢复原型盆地剥蚀量，提出在波动分析法约束下，恢复原型盆地剥蚀量的新思路。即通过波动分析法界定剥蚀的区域和厚度范围，再精确计算原型盆地剥蚀量。并以惠民凹陷新生代为例，首先运用波动分析原理，得出反映凹陷形成与发展的主周期波为57，27和7．5Ma，根据7．5Ma的周期波反映凹陷内不同沉积期间断面的剥蚀情况，来确定区域的剥蚀范围。然后根据惠民凹陷的地质特点及资料情况，采用沉积速率法、镜质体反射率差值法、地层对比法等来恢复局部地层的剥蚀量。在波动分析法的约束下，参考地质沉积史和构造演化分析的结果，综合加权平均得到最终的地层剥蚀厚度，以确保计算结果精确。研究结果表明：受波动旋回的影响，沙四段和孔店组地层普遍存在剥蚀，剥蚀厚度较大的区域主要集中在凹陷边缘或靠近隆起区，剥蚀量最小的区域是阳信洼陷，说明该区沙四上亚段和孔二段烃源岩没有遭受破坏，具有较大的勘探潜力。     

基于Fisher算法的江汉盆地钻孔岩芯沉积阶段划分及其意义

“Fisher算法”是对有序样品进行最优化分段的1种数学方法.应用有序聚类法中次序不变的特点,以江汉盆地ZL钻孔46个地球化学测试样品为研究对象,在有序聚类的数学理论基础上,借助DPS软件包将钻孔沉积物垂直剖面进行分层.研究结果表明,江汉盆地第四纪以来沉积演化大致经过4个阶段:2.77～2.68 Ma B.P.、2.68～2.23 Ma B.P.、2.23～1.25Ma B.P.及1.25 Ma＆P.以来,4个阶段微量元素比值变化特征揭示了该地区河流由不稳定到成熟水系的演化过程.     

新疆博格达山中新生代隆升--热历史的裂变径迹记录

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。     

晚新生代青藏高原北缘构造变形和剥蚀变化及其与山脉隆升关系

青藏高原的差异性隆升是一个涉及高原隆升过程和机理的重要科学问题，利用青藏高原北部塔里木盆地，柴达木盆地与河西走廊盆地的地层沉积序列推算了高原北缘西昆仑山、阿尔金山和祁连山系晚新生代以来的山脉剥蚀幅度化特征，得到了青藏高原北缘山系隆升运动差异的传播比，它们基本上反映了晚新生代西昆仑山、阿尔金山和祁连山隆升运动的差异程度。高原北缘山系垂直运动速率的计算值与实测资料对比是相吻合的，进而研究了青藏高原北缘山系构造缩短变形，剥蚀变化与山脉隆升的关系。研究表明，青藏高原二期隆升时祁连山的高度在2400-3100m的范围内。     

琼东南盆地新生代沉降特征

利用回剥技术对琼东南盆地进行了沉降史计算和分析,主要包括北部坳陷带的崖北凹陷、崖南凹陷,中央坳陷带的乐东凹陷,和南部坳陷带的华光凹陷.按照地震测线的分布和凹陷特征,我们共选取了30口模拟井进行一维沉降史计算,并展示了具有代表性的8口井,分析他们在小同时期的构造沉降速率与总沉降速率.分析结果表明,新生代以来,琼东南盆地主要经历厂三个主要的沉降幕:(1)始新世至渐新世,盆地处于裂陷期,构造沉降速率较大,平均为81m·Ma-1,沉降中心位于中央坳陷带.(2)早中新至中中新世,盆地由裂陷期向坳陷期转化,平均构造沉降速率减小至68m·Ma-1;(3)晚中新世以后,瓮地进入新一期的沉降阶段,平均构造沉降速率增加至84m·Ma-1;上新世以后,中央坳陷带发生快速沉降,达到了110m·Ma1.     

万安盆地新生代构造运动与构造样式关系研究

本文详细描述了万安盆地形成演化进程中几期主要构造运动，以及各构造层内的构造样式，并对两者关系进行动力学成因解释。研究表明，万安盆地新生代主要有三期构造运动，早期的礼乐运动造就了现今盆地构造格局的最初雏型；稍后发生的西卫运动使早期的陆级张裂断陷范围进一步扩大，转化为渐新一中中新世的断坳沉积；而最终的万安运动则导致盆内地层强烈挤压、隆升剥蚀、产生构造反转、断块及褶皱、是盆内圈闭构造最发育的时期。伴随万     

苏皖下扬子区晚白垩世以来的构造-热历史：浦口组砂岩磷灰石裂变径迹证据

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。     

喜马拉雅前渊和孟加拉湾盆地形成演化

通过区域地质、地球物理、板块重建及地球动力学背景综合研究,揭示了喜马拉雅前渊和孟加拉湾盆地形成演化及动力学背景。喜马拉雅前渊与孟加拉湾盆地被西隆(Shillong)高原分隔。喜马拉雅前渊位于西隆高原北侧,主要以拉萨地块前白垩系为基底,晚白垩世—早始新世为新特提斯洋向洋内岛弧、拉萨板块俯冲形成的弧前和弧后盆地;中始新世—中新世早期,新特提斯洋逐渐俯冲消亡,印度板块与拉萨地块的陆陆碰撞逐渐加剧,形成前陆盆地;中新世中期以来,随着印度板块与欧亚板块陆陆碰撞的加剧,喜马拉雅前陆盆地隆升、剥蚀,只保留了前陆盆地的前渊。孟加拉湾(Bengal)盆地位于西隆高原南侧,其西北部以印度板块的前寒武系为基底,石炭—二叠纪为裂谷盆地,三叠纪为剥蚀区,侏罗纪—早白垩世以火山作用为主,晚白垩世—早始新世为被动大陆边缘盆地,中始新世以来随着印度板块向拉萨板块俯冲加剧,印度洋板块向缅甸大陆俯冲,孟加拉湾盆地演化为陆缘碎屑供应逐渐增强的残留洋盆。孟加拉湾东南部的基底为前古近系洋壳,始新世以来形成巨厚的残留洋盆充填序列。     

川西高原甘孜黄土与印度季风演化关系

川西高原甘孜黄土地层的磁化率、土壤颜色、碳酸盐含量综合分析表明，早在1.15Ma前，印度季风就已影响本地区，并且印度季风与同期影响黄土高原的东亚夏季风相比，似有共同的盛衰变化，尤其是0．5Ma前更为相似，说明印度季风与东亚季风有共同的驱动机制；但0．5Ma以后，印度季风对本地区的影响呈逐步衰减之势，这可能与青藏高原又隆升到一个新的临界高度有关，从而阻挡了印度季风的水汽输入。另外，黄土高原揭示的L9、L15极端冷干事件，甘孜黄土反映较弱。而黄土高原反映的L6冷干事件，甘孜黄土表现的却是极端冷湿事件，青藏高原东北部若尔盖湖心记录也有同样反映。     

柴达木盆地达布逊湖地区3万年来气候演化的微古生物记录

柴达木盆地第四系富含各种生物化石，尤以介形类最为丰富。以盆地东部达布逊湖东南岸的达参1井浅部的介形类特征为基础，划分出了3万a来的9个古气候演化阶段，其中I1－I5对应于冰后期，Ⅱ1－Ⅱ4对应于末次冰期的晚冰期。这9个阶段中，26．3－20．0、12．2－10．1、8．0－4．5、3．8－2．5kaBP4个阶段生物丰度和分异度都较高，反映了当时气候温暖湿润，适于生物生长。20．3和2．8kaBP是晚更新世以来的两次气候极适宜时段，生物丰度和分异度都达到了最高，而30kaBP左右的生物突然大量灭绝和盐层开始析出是全球性的气候变冷以及青藏高原的第5次隆升的结果。     

临夏盆地王家山剖面沉积物地球化学元素特征与季风演化

位于青藏高原东北边缘临夏盆地王家山剖面（上新统以上段）的沉积物地化元素含量波动特征表明，上新世气候频繁、剧烈和大幅度波动体现了上新世气候演化的过渡性特征，与第四纪早期相对稳定的湖相沉积地球化学元素的波动明显不同。这种差异的产生具有深刻的环境及构造背景，一定程度上反映了亚洲季风从上新世开始不稳定过渡到第四纪早期相对稳定的动态过程，与青藏高原隆升有密切的内在关系。     

青藏高原洞穴次生方解石的裂变径迹年代及地貌学意义

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,     

晚更新世以来山东半岛北部沿海地区的构造抬升速率

根据构造地貌与新构造特征,推算了晚更新世以来山东半岛北部沿海地区的构造抬升速率。结果表明,晚更新世以来不同地段平均构造抬升速率不同,金牛山断裂以东地区为０．１５ｍｍ／ａ,断裂以西地区为０．５０ｍｍ／ａ,龙口盆地２．４万年前后曾发生过幅度７￣９ｍ的断陷。此外,同一地段不时段的抬升速率也有差异,但非常接近平均速率。     

Low-Temperature Thermal History Using Fission Track Dating in Three Wells in Southern Alaska Offshore Basins: Lower Cook Inlet,Shelikof Strait,and Stevenson Trough

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.     

黄土高原河谷阶地黄土地层结构模式

流经黄土高原的黄河及其支流因受地壳不断间歇性隆升的影响而形成了5—6级阶地,这些阶地多系黄土覆盖阶地。以六盘山为界,河谷阶地黄土地层结构可分为东、西阶地地层区。六盘山以西河流阶地一般为6级。第6级阶地(T6)冲积黄土状土之上全系无层理黄土,厚310~505 m,含21—23层古土壤,是迄今世界上最厚的黄土剖面,黄土开始堆积的时间不早于1.43 MaBP。T5上的黄土厚200~400 m,含14—16层古土壤,黄土最早是在1.23 MaBP开始堆积的。T4上的黄土厚100~200 m,含5—6层古土壤,开始沉积时间为0.62 MaBP。T3上的黄土包括L1和S1,厚40~65 m,形成于0.12 MaBP。T2冲积黄土状土之上的风积黄土厚20~35 m,形成时间约为0.03 MaBP。T1冲积黄土状土之上为S0、L0及MS,厚1.5~2.5 m,形成时间不早于0.01 MaBP。六盘山以东的河谷阶地一般为5级。T5风积黄土厚70~90 m,含11—16层古土壤,黄土开始堆积时间不早于1.23 MaBP。T4黄土厚40~70 m,含8—9层古土壤,形成时间不晚于0.80 MaBP。T3的黄土包括L1—S6之间的土层,厚25~45 m,形成于0.62 MaBP。T2的黄土由L1和S1构成,厚10~17 m,形成于0.12 MaBP。T1冲积黄土状土之上为S0、L0及MS,厚1.5~2.5 m,形成时间不早于0.01 MaBP。     

Morphology and Evolution of the Remnant Colville and Active Kermadec Arc Ridges South of 33°30′ S

Swath MR1 data from the remnant Colville and active Kermadec arc margins, south of 33°30 S (SW Pacific), record the structural morphology and evolution of the rifted, and now separate portions, of the proto-Colville–Kermadec arc flanking the actively widening southern Havre Trough back-arc basin associated with Pacific-Australian plate convergence. Both the remnant Colville and active Kermadec arc margins comprise opposing, asymmetric, partially basement exposed, segmented ridges. Differences in morphology between the two ridges are, however, observed. The single, near linear, border fault system, with relief of 1000 m, along the western edge of the Kermadec margin is interpreted to be the exposed fault escarpment of a major, west-dipping, detachment fault. In contrast, two major zig-zag border fault systems along the eastern edge of the Colville Ridge, bounding a back-tilted ridge flank terrace, are interpreted as major antithetic faults between the remnant arc and back-arc region. This contrast in structural morphology coincides with, respectively, lesser and greater degrees of both active tectonism and channel-canyon erosion, on the remnant Colville and active Kermadec margins. These differences are interpreted to reflect the progressive trenchward collapse and associated greater rift flank uplift and incisive erosion of the Kermadec foot-wall contrasting with the non-collapse and relatively lesser rift flank uplift and ridge erosion of the Colville hanging-wall. The data provide further constraints on the early evolution of the Havre Trough in particular, and back-arc basins in general.     

台湾海峡地区新生代的构造演化

根据采集反射剖面,结合区域地质资料,分析了晋江凹陷、九龙江凹陷、新竹凹陷、台中凹陷和台湾凹陷为半地堑结构。新竹凹陷和台中凹陷下拗,演变为前陆盆地。晋江凹陷和九龙江凹陷因岩石圈上隆,其沉积较薄。这种模式决定了在台湾海峡地区,西部的生油气层为下第三系,而东部的生油气层为下第三系和上第三系。     

Morphology of the Blanco Transform Fault Zone-NE Pacific: Implications for its tectonic evolution

The right-lateral Blanco Transform Fault Zone (BTFZ) offsets the Gorda and the Juan de Fuca Ridges along a 350 km long complex zone of ridges and right-stepping depressions. The overall geometry of the BTFZ is similar to several other oceanic transform fault zones located along the East Pacific Rise (e.g., Siquieros) and to divergent wrench faults on continents; i.e., long strike-slip master faults offset by extensional basins. These depressions have formed over the past 5 Ma as the result of continual reorientation of the BTFZ in response to changes in plate motion. The central depression (Cascadia Depression) is flanked by symmetrically distributed, inward-facing back-tilted fault blocks. It is probably a short seafloor spreading center that has been operating since about 5 Ma, when a southward propagating rift failed to kill the last remnant of a ridge segment. The Gorda Depression on the eastern end of the BTFZ may have initially formed as the result of a similar occurrence involving a northward propagating rift on the Gorda ridge system. Several of the smaller basins (East Blanco, Surveyor and Gorda) morphologically appear to be oceanic analogues of continental pull-apart basins. This would imply diffuse extension rather than the discrete neovolcanic zone associated with a typical seafloor spreading center. The basins along the western half of the BTFZ have probably formed within the last few hundred thousands years, possibly as the result of a minor change in the Juan de Fuca/Pacific relative motion.