准噶尔盆地玛湖凹陷下二叠统风城组含碱层段韵律特征及成因^*          下载免费PDF全文

余宽宏  操应长  邱隆伟  孙沛沛  杨勇强  曲长胜  万敏 《古地理学报》2016,18(6):1012-1029

准噶尔盆地玛湖凹陷早二叠世风城组沉积时期为典型的碳酸盐型咸化湖盆,湖盆咸化过程中析出大量的碱矿(钠碳酸盐类矿物)。通过含碱层段主量元素、碳氧同位素分析,结合岩心宏观及微观矿物岩石特征,探讨了含碱层段韵律特征及形成机理。研究层段碱矿与沉凝灰岩互层,形成明暗相间的咸化韵律。浅色碱矿层质地较纯,主要为苏打和小苏打,主量元素表现为 Na₂O含量高,CaO、MgO、SiO₂和Al₂O₃含量低;暗色层段主要为含斑点状碳钠钙石的沉凝灰岩,主量元素表现为Na₂O含量低,CaO、MgO、SiO₂和Al₂O₃含量高。浅色碱矿层和暗色沉凝灰岩段碳氧同位素值均为正,表明其沉积水体具高盐度特征。浅色含碱层段具有更高的 δ¹⁸O 值,反映了碱矿层沉积时期强烈蒸发的气候条件。根据δ¹⁸O/δ¹³C值的波动将研究层段划分为炎热干旱和相对湿润的气候条件,并据此解释不同韵律层盐类矿物形成机理。暗色的沉凝灰岩沉积代表地表流水注入量大于蒸发量,沉凝灰岩中盐类矿物含量少或者呈斑点状从颗粒间的卤水中析出;随着蒸发量的增高以及古气候由温暖潮湿转变为干旱炎热,地表流水注入量急剧减少,强烈蒸发控制了碱矿的沉积,形成浅色质地较纯的碱矿层。气候的频繁交替形成了风二段碱矿与沉凝灰岩频繁互层的特征。  相似文献   

1976年唐山MS7.8地震余震序列持续时间及对地震危险性分析的意义   总被引：1，自引：0，他引：1       下载免费PDF全文

仲秋  史保平 《地震学报》2012,34(4):494-508

1976年7月28日唐山MS7.8大地震对唐山及其周边地区造成了重大的人员伤亡和财产损失. 主震之后约15小时滦县又发生了MS7.1地震; 同年11月15日宁河也发生了MS6.9地震. 唐山MS7.8主震后的余震一直持续至今,使该区域至今保持了与主震前相比具有较高的地震活动性．如何估计余震的持续时间,并进一步将余震从主震目录中去除,一直是地震学中所关注的问题．该文通过对数线性回归和理论计算,从不同角度求取并讨论了1976年唐山MS7.8大地震的余震持续时间．结果表明,由对数线性回归计算得到的余震持续时间约为80 a．而基于Dieterich的余震触发理论所得到的余震持续时间则与区域剪应力变化率有关．区域剪应力变化率可有几种不同方法求得: ① 根据剪应力变化率和静态应力降Delta;tau;e及地震回复周期tr之间的关系求取应力变化率,该方法所得到的余震持续时间约为70——100 a;② Ziv和Rubin对Dieterich的方法进行了修正,给出了通过远场加载速率和断层宽度求取应力变化率, 该方法得到的余震持续时间约为80 a;③ 由背景场地震活动性求取远场剪应力速率, 可以得到该地区二维分布式的余震持续时间,此方法得到的研究区域内余震持续时间为130——160 a．综上,唐山地区余震持续时间约为70——140 a,据此, 该地区现今所发生的地震仍为MS7.8唐山地震所触发的余震．   相似文献   

鄂尔多斯盆地环县地区上三叠统延长组长6₃砂层组沉积微相特征及新认识          下载免费PDF全文

付金华  高振中  牛小兵  文佳涛  梁晓伟  程文  王成玉  邱安南 《古地理学报》2012,14(6):695-706

通过岩心的详细观察,结合测井、录井资料综合分析,在环县地区上三叠统延长组长6₃砂层组中,识别出了三角洲前缘、前三角洲和深湖3种亚相,和水下分流河道、支流间湾、河口砂坝、远砂坝、前三角洲泥、砂质碎屑流沉积、浊流沉积、液化流沉积、滑塌沉积和深湖泥10种微相。编绘了一系列沉积微相连井剖面图和长6₃砂层组的沉积微相平面展布图,表明研究区西部、北部及东北部发育三角洲前缘亚相,研究区中部和东南部发育深湖亚相。在深湖亚相中除了深湖泥外,发育大量的砂质碎屑流和浊流等重力流沉积。作者首次提出了源于浅水区的砂级沉积物是通过前三角洲上的一系列水道搬运至深湖区形成重力流沉积的。综合以上研究成果,建立起了该区的沉积模式。论文最后分析了研究区的油气潜力,指出水下分流河道和砂质碎屑流沉积两种微相的储集性能最好。由于本区砂体横向尖灭现象普遍,可形成一些规模较大的岩性圈闭,是岩性油气藏勘探的有利目标区。  相似文献   

Study on SST front disappearance in the subtropical North Pacific using microwave SSTs     

Chunhua Qiu  Hiroshi Kawamura 《Journal of Oceanography》2012,68(3):417-426

We investigated the processes relating to the weakening of the SST front in the subtropical front (STF) zone using the Advanced Microwave Scanning Radiometer for the Earth Observing System SSTs for 7?years with temporal/spatial resolutions of 1?day/12.5?km. In April, the SST front is strong with a high gradient magnitude (GM) and Jensen–Shannon divergence (JSD) band; in August, SSTs become uniform (28–30?°C), together with small GMs (<0.8?°C/100?km) and JSDs (<0.75). Since the SST front features become invisible in GM/JSD snapshots and weekly–monthly averaged images, we call this phenomenon ‘SST front disappearance (SFD)’. The SFD occurs in August, but the number of high SSTs (>30?°C) in August is smaller than that in July, which indicates that the SFD results from not only the increase in lower SSTs but also the decrease in higher SSTs. In June and July, the GM distributions have quite large standard deviations compared to those in May and August. We also investigated the vertical profile of STF using in situ temperature/salinity profiles. It was revealed that the SFD influence extends to 50?m depth. The area of high integrated heat flux and shallow mixed layer depth were found to correspond to the area where the GM decreases from 0.9 to 0.6?°C/100?km during June–August. Quantitative analyses confirmed that the SFD mechanism may be attributable to the establishment of the shallow mixed layer by the high integrated heat flux from May to July. From July to August, the SST heating/cooling in the north/south of the SST front may accelerate the SFD.  相似文献   

A long-term numerical model of morphodynamic evolution and its application to the Modaomen Estuary   总被引：1，自引：0，他引：1  

莫文渊  韦惺  邱立国 《中国海洋工程》2012,26(1):123-138

Because of the influence of human activities,the evolution of the Modaomen Estuary is no longer a purely natural process.We used a long-term morphodynamic model(PRD-LTMM-10) to study the evolution of the estuary from 1977 to 1988.The model incorporated modules for riprap-siltation promotion and waterway dredging.The model can simulate the morphodynamic evolutionary processes occurring in the Modaomen Estuary during the period of interest.We were able to isolate the long-term influences of various human engineering activities and the roles of natural factors in estuarine evolution.The governance projects had the largest effect on the natural development of the estuary,resulting in larger siltation on the west side.Installation of riprap and reclamation of submerged land resulted in scouring of the main Hengzhou Channel causing deep trough out-shift.Severe siltation narrowed the upper end of the Longshiku Deep Trough.  相似文献   

Complementary zoning frameworks for sustainable management of eco-economic capital: a case study of Lijiang, China     

Dewei Yang  Quanyi Qiu  Wenjuan Liu 《山地科学学报》2012,9(6):760-769

We propose two zoning frameworks for regional decision-makers to regulate eco-economic capital in Lijiang,southwest China,using an index system,layer overlay,and GIS spatial analysis.The frameworks include eco-economic zoning and major function-oriented zoning,with an emphasis on ecoeconomic capital and human activities.The two frameworks share common advantages in top-down resource regulation by a certain function and the pursuit of competitiveness,sustainability and welfare fairness.Their differences in development orientation,functional links and scale suitability provide a complementary approach for regional decisionmakers.The frameworks will help to understand complex eco-economic resource patterns and foster appropriate regional regulation strategies.  相似文献   

Plant Species Richness Affected Nitrogen Retention and Ecosystem Productivity in a Full‐Scale Constructed Wetland     

Si‐Xi Zhu  Peili Zhang  Hai Wang  Han‐Liang Ge  Jie Chang  Scott Chang  Zhi Qiu  Hongbo Shao  Ying Ge 《洁净——土壤、空气、水》2012,40(4):341-347

The effects of plant species richness (SR; i.e., 1, 2, 4, 8, and 16 species per plot) on substrate nitrate and ammonium retention and ecosystem productivity in a full‐scale constructed wetland (CW) with high nitrogen (N) input were studied. Substrate nitrate (0.1–16.4 mg kg^?1) and ammonium concentrations (1.3–9.2 mg kg^?1) in this study were higher than those in other comparable biodiversity experiments. Substrate nitrate concentration significantly increased while ammonium concentration significantly decreased with the increase of plant SR (p = 0.008 and 0.040, respectively). The response of ecosystem productivity to increasing SR was unimodal with four species per plot achieving the greatest productivity. Transgressive overyielding, which was compared to the most productive of corresponding monocultures, did not occur in most polycultures. We conclude that substrate N retention was enhanced by plant SR even with high N input, and plant SR could be managed to improve the efficiency of N removals in CWs for wastewater treatment.  相似文献   

页岩气富集带地质控制因素及地震预测方法   总被引：1，自引：0，他引：1       下载免费PDF全文

杨瑞召  赵争光  庞海玲  李聪聪  仇念广  宋向辉 《地学前缘》2012,19(5):339-347

首先对页岩气富集带的地质控制因素及各家的评价指标进行了探讨,认为页岩气的评价指标可以分为两大类：一类是评价页岩气量的多少,即资源因素,它决定了该区页岩气资源潜力及储量的多少,是页岩气资源评价、有利区块优选的关键指标。主要包括页岩厚度、有机质（TOC）丰度、干酪根类型、成熟度(Ro)、天然气含量及状态（游离、吸附）等。另一类决定了页岩气能否经济地开采出来,以及产量的高低,即所谓的“核心区”或“甜点”区。包括埋藏深度、页岩本身的矿物成分、脆度、孔隙度（裂缝）、渗透率以及原始地应力大小、方向及差异等。这两类指标共同控制了页岩气的富集和最终产量。因此,在页岩气勘探开发过程中,应首先利用地质和地球化学方法对第一类指标进行评价,从中优选出有利区块。在有利区块内,可以利用地震相关技术对第二类指标预测和评价,从中优选出适合钻井和开采的页岩气富集带或“甜点”区。根据对页岩气富集带（甜点）地质控制因素的讨论,可以将页岩气划分为“裂隙” 型页岩气藏及“脆性”型页岩气,两种类型均需位于弱应力各向异性区,以便于压裂过程中得到理想的复杂网状裂缝系统。笔者认为,对于“裂隙”型页岩气藏,几何地震属性分析技术（包括相干体、蚂蚁体、曲率体等）可以很好地刻画断层、隐伏断层及裂缝发育带,对这些成果的解释可以以玫瑰图的方式展示,从而可以揭示该区域的裂缝的主要发育方向及次要方向,进而推断该区的局部主应力方向,为水平井位部署提供依据。而对于“脆性”型页岩气藏,叠前反演技术、叠后反演技术可以揭示低泊松比(υ),纵横波速比等来进行有利目标（甜点）识别。曾经在常规油气勘探中发挥重要作用的地震技术,在页岩气等非常规油气资源勘探开发中,仍然是一种不可或缺的关键技术。  相似文献   

我国地应力观测与地震预报   总被引：4，自引：2，他引：2  

谢富仁  邱泽华  王勇  苏恺之  欧阳祖熙 《国际地震动态》2005,(5):54-59

我国是最早开展地应力连续观测并将其用于地震预报的国家,回顾40年的发展历程,总结经验教训,分析国际发展趋势,提出了我国地应力监测与地震预报发展构想。  相似文献   

基于神经网络奇异谱分析的ENSO指数预测   总被引：2，自引：1，他引：1  

严军  刘健文 《大气科学》2005,29(4):620-626

采用奇异谱分析方法研究了ENSO指数及相关序列, 结果表明奇异谱分析能很好的对原始序列进行信噪分离, 增大了ENSO指数的可预报性.在此基础上, 提出了人工神经网络和奇异谱分析相结合的ENSO指数预测方法, 进行了不同因子组合的预报试验, 预报效果明显优于持续性预报, 超前4季的Nio 3区、 Nio 4区预报相关系数仍高于0.5.  相似文献