Extension and subsidence of the Pearl River Mouth Basin, northern South China Sea

Abstract The uniform stretching model has been applied to seismic reflection profiles and well-log information from the Pearl River Mouth Basin on the northern flank of the South China Sea. Stretching factors were calculated from subsidence curves determined from the stratigraphy by using the backstripping technique to remove the effects of compaction and sediment loading. Variations in rift topography, palaeobathymetry and global sea-level v/ere taken into account. We argue that the Pearl River Mouth Basin formed by lithospheric extension by a factor of about 1.8, lasting from Late Cretaceous to late Oligocene times. Stretching factors calculated from subsidence agree with those determined from the geometry of normal faulting and from crustal thinning. Thus there is no indication of a significant discrepancy between the different estimates of stretching. The geometry of faulting suggests that considerable amounts of local footwall uplift occurred during the rifting period. Small differences between the observed and calculated subsidence curves (∽ 400 m in the middle Miocene) are best explained by minor amounts of extension ( β ∽ 1.1). The time-temperature history of sediments within the basin has also been calculated so that expected vitrinite reflectance and oil abundance could be determined. The results are consistent with each other and are in reasonable agreement with observations from wells.     

基于均一化观测序列的京津冀地区气候变化格局分析

利用1960~2015年京津冀地区88个国家级气象站观测资料（包括日平均气温、日最高气温、日最低气温、日降水、日平均风速等）,使用MASH（Multiple Analysis of Series for Homogenization）方法剔除台站迁址、仪器变更等因素所致偏差后,生成均一化的观测资料集。基于新资料集计算了各站气温、降水和凤速序列的线性趋势和Morlet小波等统计特征,分析了京津冀地区气候变化格局。结果表明:MASH方法能较准确地检测并校订观测序列中迁站、仪器变更等因素所导致的非均一性;1960~2015年期间京津冀年平均气温显著上升,上升幅度为0.261℃/10 a;降水减少,平均减少11.27 mm/10 a;风速显著减小,平均减小0.193 m s-1（10 a）-1。     

Aerosol properties over an urban site in central East China derived from ground sun-photometer measurements

Sun-photometer measurements at Hefei, an urban site located in central East China, were examined to investigate the variations of aerosol loading and optical properties. It is found that aerosol optical thickness (AOT) keeps higher in winter/spring and gets relatively lower in summer/autumn. The large AOT in winter is caused by anthropogenic sulfate/nitrate aerosols, while in spring dust particles elevate the background aerosol loading and the excessive fine-mode particles eventually lead to severe pollution. There is a dramatic decline of AOT during summer, with monthly averaged AOT reaching the maximum in June and soon the minimum in August. Meanwhile, aerosol size decreases consistently and single scattering albedo (SSA) reaches its minimum in July. During summertime large-sized particles play a key role to change the air from clean to mild-pollution situation, while the presence of massive small-sized particles makes the air being even more polluted. These complicated summer patterns are possibly related to the three key processes that are active in the high temperature/humidity environment concentrating on sulfate/nitrate aerosols, i.e., gas-to-particle transformation, hygroscopic growth, and wet scavenging. Regardless of season, the increase of SSA with increasing AOT occurs across the visible and near-infrared bands, suggesting the dominant negative/cooling effect with the elevated aerosol loading. The SSA spectra under varying AOT monotonically decrease with wavelength. The relatively large slope arises in summer, reinforcing the dominance of sulfate/nitrate aerosols that induce severe pollution in summer season around this city.     

新疆图拉尔根镁铁-超镁铁质杂岩体镍铜钴成矿岩浆作用过程:流体化学与碳同位素组成制约

东天山造山带的图拉尔根镁铁-超镁铁杂岩体为一个早古生代长期活动的幔源岩浆通道,大型铜镍钴硫化物矿体赋存于Ⅰ号超镁铁质岩体的顶部,不同类型岩石中辉石矿物的流体挥发份化学组成以H₂O为主（平均91%,5400.4mm³/g）,其次为H₂（2.0%）、H₂S（2.3%）和CO₂（2.1%）;赋矿角闪橄榄岩中CO₂和H₂S含量最高,辉长岩中流体挥发份含量低于辉石橄榄岩和橄榄辉石岩等岩浆早期结晶的岩石。CO₂和CH₄的δ¹³C值位于地壳与甲烷氧化的范围内,甲烷同系物的碳同位素组成具有正序分布模式,部分样品（TLG512）释出的CH₄和C₂H₆具有较重的δ¹³C值和反序分布特征。表明I号岩体不同类型岩石可能是不同期次岩浆活动的产物,成矿岩浆具有富H₂O和H₂S的特征,可能起源于被流体交代的亏损地幔源区,混染壳源组分可能为俯冲板片来源蚀变沉积有机质组分。     

塔里木盆地塔中地区奥陶系古岩溶包裹体特征及古环境意义

碳酸盐岩古岩溶型储层是油气勘探开发的重点领域,具有极强的非均质性,是世界级难题。古岩溶发育期次的确定一直都是古岩溶储层地质建模的技术难题。现有判别古岩溶发育期次的方法多以地表裸露古岩溶充填物特征为依据。在塔里木盆地塔中地区地质构造复杂,具有多期次古岩溶作用的叠加改造。本次利用古岩溶充填方解石流体包裹体均一温度法,研究塔中地区奥陶系碳酸盐岩古岩溶作用期次与古环境条件,揭示了4期古岩溶作用环境:加里东期古岩溶作用、海西晚期古岩溶作用、印支-燕山期古岩溶作用、喜马拉雅期古岩溶作用。该研究成果对后期岩溶储层预测具有重要意义。      

蜀南Z工区茅口组顶岩溶古地貌、古水系特征与刻画

蜀南地区茅口组灰岩岩溶储层较为发育,是蜀南地区重要的产层之一。但是该套储层非均质性强、缝洞充填程度高,储层预测具有较大困难。恢复岩溶古地貌、刻画古水系,可以摸清岩溶储层的发育分布规律,对蜀南地区茅口组油气勘探具有重要的指导意义。本文利用印模-趋势面法,以茅口组顶至长兴组顶的沉积厚度为标识,恢复了蜀南Z工区的岩溶古地貌,根据微地貌组合形态,划分了4类三级地貌单元,并结合岩溶水文地质学理论在Z工区刻画出南北向地表水系。分析认为不同的地貌位置,水动力条件具有较大差异;河流两侧位于径流区,水动力条件最强,溶蚀孔缝最发育,是下一步储层勘探方向。      

黏声介质平面波有限差分叠前深度偏移及在莺歌海盆地的应用

莺琼盆地诸探区中存在底劈现象,深层气源产生的气体沿底劈产生的裂隙通道向上漫溢.漫溢过程中,一是充填在遇到的砂体中形成气藏;二是弥漫在上溢通道中,使得通道中的纵波速度发生变化,进而纵波波阻抗差异变小,反射变弱.另外,通道中气体的存在,会加强地层的吸收衰减,使得地震波振幅变弱、高频成分损失导致同相轴分辨率降低.利用OBC数据进行多波地震勘探和利用黏声介质的叠前深度偏移都是改善模糊区成像质量的重要方法技术.为此,本文提出用黏声介质平面波有限差分法叠前深度偏移成像方法改善气体充填区域的成像质量.黏声介质成像目的是补偿地震波的吸收衰减;平面波偏移成像目的是适应海上单炮数量巨大,提高波动方程叠前深度偏移成像的效率;有限差分法叠前偏移的目的是适应该区浅层气分布局域性极强、Q值的空间变化大的情况.在莺歌海某探区的实际数据上的黏声介质平面波有限差分叠前深度偏移试验证明,本方法是改善模糊区成像质量的较为有效的途径.     

塔里木盆地塔北露头区的古岩溶发育模式

目前塔里木盆地海相碳酸盐岩的油气勘探已进入高峰期,为弥补钻井岩心资料不足,进一步认识井下岩溶发育规律及发育模式特征,开展塔北露头区奥陶系风化壳古岩溶缝洞系统发育特征及发育模式研究。研究表明,岩溶发育主要受控于岩性因素和不整合面,主要发育层位为一间房组地层;主要岩溶作用期为吐木休克组／一间房组沉积间断岩溶期。为井下岩溶缝洞系统的认识及岩溶地质模型的建立提供了重要理论依据。     

全球变暖背景下新疆地区近45 a来最大冻土深度变化及其突变分析

利用覆盖新疆大部分地区资料完整的93个站点资料,对1961-2005年新疆地区最大冻土深度进行了分析. 结果表明：新疆地区月最大冻土深度有明显的季节变化,低海拔区域(海拔<1 800 m)最大值出现在1月份,而高海拔区域(海拔≥1 800 m)的最大值出现在2月份,比低海拔区域要滞后. 新疆地区最大冻土深度的地理分布特征表现为北疆深于南疆,山区深于平原,且与气温的分布有很好的一致性. 全年和冬、春季最大冻土深度与气温场的空间相关系数分别为-0.795、-0.736和-0.848. 年际变化表明,近45 a来的最大冻土深度出现了较为明显的下降. 高海拔区域与低海拔区域年最大冻土深度的倾向率分别为-15.65 cm·(10a)^-1和-9.48 cm·(10a)^-1,且与气温的相关系数分别为-0.51和-0.69,均通过了0.001的信度检验. 同时发现,高海拔区域冬季下降多,而低海拔区域春季下降多. 新疆地区年最大冻土深度在近45 a有明显的突变现象,高海拔区域和低海拔区域突变发生年份分别为1996/1997年度和1978/1979年度,说明新疆地区高海拔区域的年最大冻土深度对气温变化的响应比低海拔区域要滞后. 突变年后高海拔区域与低海拔区域年最大冻土深度比突变年前的平均值分别降低了61.12 cm和26.67 cm.     

南京长江新济洲群湿地保护与恢复规划设计

以南京长江新济洲群湿地为例,分析了在长江中下游开展洲滩湿地生态恢复的重要意义和必要性,在分析了南京长江新济洲群湿地退化现状及其驱动因素的基础上,对其保护和恢复规划设计进行了探讨,希望为长江中下游洲滩湿地的保护和生态恢复提供思路和借鉴。