若尔盖黄河唐克段河岸沉积序列测年及地表过程变化

通过对若尔盖盆地进行野外考察,在盆地中部黄河唐克段右岸发现了包含深湖相的河岸沉积物,进行了细致的地层观测和系统年代学样品采集。在实验室利用光释光和AMS¹⁴C测年技术建立了年代框架,并结合各个层次的地层沉积相宏观特征和理化性质,分析探讨了若尔盖盆地内部从末次冰期古湖消亡以来的环境和地表过程变化规律。研究结果表明：古黄河在37 ka沿着玛曲断陷谷地溯源侵蚀,沟通了若尔盖古湖水系,盆地内部在30.9 ka之前为深湖环境,稳定地沉积了蓝灰色湖相淤泥层。30.9 ka之后,黄河贯穿若尔盖湖盆内部,古湖水外泄消失,原有的古湖水系转变成为黄河源水系。黄河从湖盆上游远距离搬运携带来的浊黄橙色泥沙大量沉积,覆盖了古湖相沉积层,湖盆内部风沙作用盛行。在末次冰盛期（Last Glacial Maximum, LGM）,盆地内部松散沉积物普遍地受到冰缘冻融作用的改造,形成了冻融褶皱现象。到了14.6~12.5 ka,响应B/A（B?lling-Aller?d）时期的温暖气候,盆地周边山地冰川消融,冰融水汇入盆地,古湖盆底部各种浅洼地形成了大小不等的浅湖,沉积了滨浅湖相的沙层。在12.5~11.7 ka,对应于全球性新仙女木（Younger Dryas,YD）事件,盆地气候再次变冷,转变为冰缘冻土环境,盆地内部滨浅湖相的沙层受到冻融作用和古地震扰动,形成复式褶皱现象。进入全新世,在11.7~4.8 ka气候逐渐变得温暖湿润,古湖盆底部浅洼地积水成为淤泥质沼泽环境,在全新世中后期4.8~1.8 ka则转变成为沼泽草甸环境,在1.8 ka之后,盆地内沼泽面积收缩,风沙活动盛行,河岸台地的近源沙尘暴沉积物经过成壤改造形成亚高山草甸黑土类现代土壤。     

塔河六七区鹰山组-巴楚组混积特征研究

受加里东期-海西期构造运动及持续海平面升降变化影响,塔河油田六七区沉积环境复杂多变,中下奥陶统鹰山组和下石炭统巴楚组发育陆屑-碳酸盐混积岩。结合岩心、薄片及测井资料综合分析,混积岩据混积强度分为混积型碳酸盐岩、混积型碎屑岩、高度混积岩。据沉积背景及沉积特征,混积岩成因类型可分为岩溶穿插再沉积型(岩溶型)和相缘渐变型(相变型)。其中,混积型碳酸盐岩和混积型碎屑岩为岩溶成因,高度混积岩为相变成因。此外,混积岩储集空间发育,储集类型主要包括原生粒间孔、次生溶蚀孔缝和构造裂隙,岩溶型混积岩较相变型混积岩储集性能较好。混积岩孔缝中见含油显示,相关油气意义值得进一步研究。     

新仙女木期黄河晋陕峡谷古风成沙层年代及其物质来源

通过对黄河晋陕峡谷壶口至龙门段开展广泛细致的野外考察,发现了典型的晚更新世以来黄土—土壤层夹古风成沙层剖面—北桑峪剖面（BSY）。结合不同类型沉积物的野外宏观特征、磁化率、粒度成分、石英颗粒表面特征和地球化学元素的对比分析,确定黄河晋陕峡谷壶口至龙门段BSY剖面中所夹古风成沙层的性质为中沙质细沙,是在干旱多风环境下形成的沙质沉积物。基于光释光（OSL）测年数据,确定其沉积年代为12.5-11.6 ka,记录了黄河中游发生在末次冰消期的极端干旱事件,其与相邻区域沙漠/黄土过渡带中湖沼沉积和风成黄土—古土壤剖面记录的新仙女木事件相对应。该剖面中古风成沙沉积物的物质来源,主要来自黄河晋陕峡谷的古河床相沙层物质。这是因为该河段处于干旱半干旱季风气候区,在新仙女木时期,黄河晋陕峡谷处于极端干冷的环境之中,冬季风强盛、夏季风衰弱,黄河水位下降明显,河漫滩和江心洲将大面积出露,大量的沙物质在风力作用下向岸边输移,成为河谷两侧缓坡台地上古风成沙沉积层出现的主要沙源地。这个研究成果对于进一步揭示黄河中游流域极端干旱事件发生的时间性规律及其与季风气候变化的关系,具有重要的科学意义。     

滇西南普洱强震群地区地壳形变的数值模拟

滇西南普洱一带地质构造复杂,中-强地震成群活动特征明显,地壳的形变特征与形变机制引起了地学界的广泛关注和深入研究。在参考、借鉴以往研究成果的基础上,本文构建了普洱一带包含活动断裂的二维板有限元模型,以GPS测量得到的块体年运动量作为模型区域的边界约束,模拟计算获得了普洱地区的构造形变空间分布,以NEE、NNW 2个方向、从数值模拟角度对普洱地区的水平形变特征和区域地壳垂直形变场进行了分析和探讨。结果表明:在青藏高原东南缘扩展、高原物质重力滑塌型南东向移动的动力学背景下,研究区内NEE向断裂的活动带动牵引NNW向断裂共轭运动,隆升性质的垂直形变场与60年的大区域水准测量结果相吻合,沿NNW向形变场的分布无规律,应是区域应力累积和震后调整双重作用的结果。沿NEE向形变场呈现了较明显的西部大于东部的分布图像,特别是西北部高值区对应了2014年景谷6.6级强震,最后对研究区的区域动力学问题进行了初步探讨。     

我国低序次扭动构造体系控油模式研究

以地质力学理论为指导,通过开展塔里木、准噶尔-吐哈、走廊、鄂尔多斯、四川、松辽、渤海湾等8个（地区）构造体系控油作用研究,深刻认识到油气田分布主要受各类低序次扭动构造体系的控制,在此基础上,发展和建立了五类低序次扭动构造体系控油模式,包括帚状构造体系、旋扭构造体系、雁列构造体系、入字型构造体系和反"S"型构造体系。文章分别以具体典型实例系统概述了其各类低序次构造体系的形成特征、油气成藏条件及分布规律,认为构造体系的形成受不同构造环境和应力场控制;不同低序次扭动构造控制油气田分布规律各异。这些控油模式的建立对当前和今后油气勘探和油气田发现有重要指导意义。      

Isolation of sea surface salinity maps on various timescales in the tropical Pacific Ocean

To isolate sea surface salinity (SSS) maps on seasonal, ENSO, decadal, and long-term trend timescales in the tropical Pacific Ocean, the ensemble empirical mode decomposition (EEMD) is applied on an SSS data set covering 1950–2009, concerning three key regions including the western equatorial Pacific Warm Pool (WP), South Pacific Convergence Zone (SPCZ), and Inter Tropical Convergence Zone (ITCZ); then a self-organizing map is performed on the intrinsic mode function maps decomposed by the EEMD, concerning the whole basin. The ENSO and decadal signals concern mainly the western Pacific, in contrast to the seasonal signal mostly notable in the east. (1) The modulated annual cycle has smaller (larger) amplitudes during El Ni?o (La Ni?a) years and later appearance of minima during El Ni?o years; one unique annual cycle is observed at the northwestern edge of the ITCZ lagging the well-known ITCZ cycle by ~3?months. (2) The pronounced 1999–2001 SSS-related La Ni?a event in the SPCZ was reinforced twice by the decadal shift in the 1990s; the eastern Pacific and central Pacific ENSO-related SSS features are compared. (3) The contrasted anomalies between the western equatorial and non-equatorial regions were pronounced during 1977–1996, whereas they were less pronounced during 1971–1976, 2005–2008, and a roughly opposite pattern appeared with strong and abrupt decrease shift prevailing in large areas over the southwestern basin during 1997–2004. (4) The freshening at the western equator and the saltening located east of the SPCZ SSS front together amplify the geographical SSS contrasts exhibited by the WP and SPCZ SSS fronts.     

灵山岛早白垩世软沉积物变形构造触发机制及其古环境意义探讨

灵山岛早白垩灵山岛组发育丰富的软沉积物变形构造。野外踏勘船厂、灯塔和千层崖三个剖面,根据沉积外观可分为变形层段和非变形层段两个部分。软沉积物变形构造在变形层段和非变形层段均有发育。其中,变形层段中可见褶皱变形、变形层理及大型负载构造。非变形层段可见火焰构造、同沉积布丁构造和同沉积微断层。研究发现,变形层段软沉积物变形构造尺度大(厚度可至十多米,长度可至数百米),侧向连续性好;非变形层段软沉积物变形构造尺度小(厚度仅几个厘米),侧向连续性差。且变形层段和未变形层段厚度统计数据表明,变形层段软沉积物变形构造与砂岩厚度无必然联系,而非变形层段软沉积物变形构造多出现在粒序砂岩层底部或旋回砂岩层变厚过程中。沉积环境表明,非变形层段和变形层段为一深水低角度斜坡沉积产物。软沉积物变形构造发育形态和数量受到斜坡地形的控制。结合沉积环境及沉积特征分析,认为变形层段软沉积物变形构造触发机制为地震,而非变形层段软沉积物变形构造触发机制为负载作用。锆石测年数据表明灵山岛组与上覆流纹岩沉积时间相近,因此地震活动可能与岩浆侵入或早期火山喷发活动相关。此外,汇总早白垩世重要事件,发现灵山岛组沉积、变冷事件、恐龙迁移、海平面变化和同位素偏移具有时间一致性,因此推断这些事件可能共同对应了早白垩世一次与火山活动相关的短期灾难性事件(如早白垩世缺氧事件)。     

云南普洱-宁洱地区变形及应力场的有限元模拟

为研究普洱-宁洱地区强震频发与构造应力场和变形场的相关性,以1997—2007年GPS数据计算得到的云南普洱-宁洱块体年运动量为边界约束,建立云南普洱-宁洱地区包含红河断层及澜沧江断层等10个断层的三维摩擦接触有限元模型,计算在GPS年运动速率约束下棋盘式构造格局的变形位移场、应变场及应力场分布,并将计算结果与GPS计算结果进行比较。通过计算发现:普洱-宁洱断层群会使澜沧江及红河断层包围区域变形及应力场更复杂,普洱-宁洱地区复杂变形及应力场可能是该地区中强地震频发的主要原因;镇远-普洱断层可能是影响普洱-宁洱地区变形及应力场的主要断层;普洱-宁洱地区走向共轭断层交汇处,存在较大变形及应力值;变形场与应力场会随断层走向变化而发生变化,在断层走向变化剧烈部位有较大值。     

Holocene palaeoflood events recorded by slackwater deposits along the lower Jinghe River valley,middle Yellow River basin,China

Palaeoflood slackwater deposits (SWDs), are the natural record of overbank flooding and are often found within aeolian loess‐soil profiles along the river valleys of the middle Yellow River basin. These pedo‐stratigraphic sequences are studied using a multi‐disciplinarily approach to reconstruct Holocene hydro‐climatic variations. Our field investigations along the lower Jinghe River valley have identified palaeoflood SWDs at several sites along the riverbanks based on sedimentological criteria. Analytical results, including magnetic susceptibility, particle‐size distribution and concentrations of chemical elements, indicate that these well‐sorted palaeoflood SWD beds were deposited from the suspended sediment load in floodwaters. We identify two episodes of extraordinary palaeoflood events along the Jinghe River valley. These hydro‐climatic events were dated to 4200–4000 and 3200–2800 a BP, by using the optically stimulated luminescence method in combination with archaeological dating of retrieved anthropogenic remains, and with pedo‐stratigraphic correlations with the previously studied Holocene pedo‐stratigraphy in the Jinghe River drainage basin. The flooding events are therefore considered to be a regional expression of known climatic events in the northern hemisphere and demonstrate Holocene climate was far from stable. This study provides important data in understanding the interactions between regional hydro‐climatic systems and global change in semi‐arid and sub‐humid regions. Copyright © 2012 John Wiley & Sons, Ltd.     

我国古生代海相碳酸盐岩成藏理论的新进展

近年来在中国古生界新发现大中型油气田40多个,其中大型油气田16个。在长期研究中国古生代海相沉积特征的基础上,总结归纳近几年来新发现的海相烃源岩,提出对碳酸盐岩有效烃源岩的新认识。从有效烃源岩、古岩溶储集体、油气成藏期次和成藏模式等四个方面概述油气成藏理论方面的新进展;根据油气成藏史研究,结合区域构造演化史、生烃史等,提出塔河油田奥陶系有四个成藏期:加里东中晚期至海西早期;海西晚期;燕山期-喜马拉雅早中期;喜马拉雅晚期。