准噶尔盆地东部石炭纪富火山岩海相油气盆地原型:一个工作假说

准噶尔盆地石炭系中发现自生自储的大型火山岩油气藏,这不仅大大拓宽了油气勘探领域,而且从含油气盆地原型恢复角度为我们提出了一个新的命题。本文对准噶尔盆地东部的石炭纪盆地进行了剖析,在井间地层对比和锆石U-Pb同位素年代学测定基础上,确定了准噶尔盆地石炭系划分方案,建立了准东地区及邻区石炭系的5条联井对比骨干地质剖面,进而把准东地区石炭系盆地的充填过程划分为两个旋回、7个阶段,其中第一旋回为早石炭世,进一步分为4个阶段,第1至第3阶段以各种火山岩发育为特征,第4阶段为火山活动的间歇期,发育了暗色泥质岩。第二旋回为晚石炭世,进一步分为3个阶段,第5和第6两个阶段以发育中基性火山岩为特征,第7阶段以沉火山凝灰岩和与泥质岩、砂岩互层发育为特征。文中归纳了准东地区石炭纪盆地及其中火山岩油气藏烃源岩和储层的发育特点,建立了其盆地原型,指出准东地区石炭系在沉积时的构造古地理以多岛洋为特征,受准噶尔洋的持续向北东方向俯冲的影响,准东地区盆地基底向南西方向倾斜,造成了沉积中心的向南西迁移。考虑到盆地位于增生型造山带内,将其原型盆地称为增生楔盆地。文中特别指出,任何构造位置上形成的盆地都有形成大油气田的潜力,能否形成大油气田的关键在于有没有优质烃源岩、优质储层和有效圈闭。准东增生楔盆地中烃源岩与火山岩储层的空间关系十分密切,二者往往形成互层状或穿插状,这一特征决定了盆地中油气产出具有近源性,而圈闭的形成则因火山岩储层的成层性差而呈形态和类型的多样性。     

长江-淮河流域短时暴雨洪涝灾害危险性预警评估及验证

洪涝灾害危险性预警分析是防灾减灾的重要基础,在灾害发生前进行预警,可以有效减轻灾害带来的影响。本文以2020年6—8月长江-淮河流域洪涝灾害为研究案例,首次利用前3天累计降水量(前期状态),当前时次土壤湿度(当前状态)和预测日降水量(未来状态)作为致灾因子,基于改进的层次分析法建立危险性预警分析模型。通过县域灾情信息验证表明,评估正确率达74.46%,遗漏率仅5.59%,评估结果与实际灾情吻合性好;同时对预警准确性和时相一致性进行评价,最大值(县内最高指数)的预警率达到81.6%;“特大型”暴雨洪涝灾害中的预警达到77.3%以上,且灾害在前3~5天危险性指数普遍提升,存在有效预警。本文方法对于长江—淮河流域短时暴雨洪涝灾害危险性预警有较好的准确性和可靠性,可提供防灾减灾决策依据。     

鄂尔多斯盆地东南部延长组储层成岩体系研究

鄂尔多斯盆地东南部延长组具有丰富的油气资源,储集层为一套致密低渗透砂岩,油气的富集与致密低渗透背景下的高效储层有关。通过铸体薄片、背散射、扫描电镜及能谱分析,结合孔、渗测定,认为:①延长组高效储层的形成与绿泥石环边有密切关系,绿泥石环边的出现是三角洲前缘沉积环境、富黑云母的长石砂岩和咸—微咸水的湖泊水体在空间上耦合的产物;②绿泥石环边抵消了一部分埋藏过程中上覆地层的机械压实作用,减缓了由于压实作用而引起的原生孔隙的减低,而且有抑制石英次生加大的作用;③同生期形成的方解石可以使颗粒呈嵌晶接触,形成致密层,但是这部分方解石量小且分布不均匀;④自生石英在纵向上变化明显,封闭体系中形成的SiO2由于绿泥石环边的抑制作用,以雏晶的形式产出;而半封闭体系中形成的SiO2可向上发生运移,在绿泥石环边不连续或欠发育的层段以加大边的形式产出。通过成岩体系研究,可以明确高效储层的形成机理,指导岩性油气藏的勘探。     

华北北部不同构造单元地壳速度模型——均匀分层介质反射波走时反演的结果

从广义反演理论出发,对多层反射波的走时联合反演,可以同时获得所有的各层速度及厚度参数。其优点是在不需要把问题线性化过程的同时,统一考虑了各层反射波走时的离散对整个地壳模型的影响,又可兼顾观测数据的不同误差分布。本文将该方法进行了数值模拟并应用于华北北部的几个不同构造单元,反演得出了其反射P波速度结构,并与正演结果进行了对比。     

浙江省丽水地区白垩纪红层盆地火山岩年龄及其构造意义

为查明丽水地区火山活动与盆地形成、演化之间的关系,在碧湖盆地、章村盆地、丽水盆地等红层盆地区域地质调查基础上,对盆地内中性－酸性火山岩夹层进行了精确测年和岩石化学分析,火山岩岩石地球化学表明,碧湖盆地、丽水盆地、章村盆地岩石化学成分基本一致。火山岩LA-ICP-MS 锆石U-Pb测年表明：碧湖盆地朝川组火山岩年龄为(123±2) Ma,章村盆地馆头组火山岩年龄为(111±3)Ma,丽水盆地塘上组火山岩年龄为(95±1)Ma。该地区盆地间火山岩夹层存在28 Ma时差,反映了丽水-余姚断裂带的活动延续性。     

GEOMORPHOLOGY OF THE GYARING CO FAULT ZONAL DRAINAGE SYSTEM AND ITS STRUCTURAL IMPLICATIONS

Strike-slip faults and normal faults are dominant active tectonics in the interior of Tibetan plateau and control a series of basins and lakes showing extension since the Late Cenozoic, by contrast with the thrust faulting along the orogenic belts bordering the plateau. The late Neotectonic movement of those faults is key information to understand the deformation mechanism for Tibetan plateau. The Gyaring Co Fault is a major active right-lateral strike-slip fault striking~300° for a distance of~240km in central Tibet, in south of Bangong-Nujiang suture zone. The Gyaring Co Fault merges with the north-trending Xainza-Dinggye rift near the southern shore of Gyaring Co. From NW to SE, Dongguo Co, Gemang Co-Zhangnai Co, Zigui Co-Gyaring Co form the Gyaring Co fault zonal drainage basin. Some scholars have noticed that the formation of lakes and basins may be related to strike-slip faults and rift, but there is no analysis on the Gyaring Co fault zonal drainage basin and its response to regional tectonics. In recent years, a variety of quantitative geomorphic parameters have been widely used in the neotectonic systems to analyze the characteristics of the basin and its response mechanism to the tectonic movement. In this paper, we applied ASTER GDEM data on the ArcGIS platform, extracted the Gyaring Co fault zonal drainage basin based on Google Earth images (Landsat and GeoEye) and field work. We acquired basic geomorphic parameters of 153 sub-basin (such as grade, relief, average slope, area) and Hypsometric Index (HI) value and curve. Statistical results have indicated significant differences in scale(area and river network grade)in north and south sides of the fault. Southern drainage basins' relief, slope, HI value are higher than the northern basins, and the overall shape of hypsometric curve of northern basins are convex compared with southern concavity. Along the strike of the Gyaring Co Fault, average slope, and HI value are showing generally increasing trending and hypsometric curve become convex from west to east. By comparing and analyzing the lithology and rainfall conditions, we found that they have little influence on the basic parameters and HI value of drainage basins. Therefore, the changes of basin topographic differences between northern and southern side of fault and profile reveal the Gyaring Co Fault has experienced differential uplift since the late Cenozoic, southern side has greater uplift compared to the north side, and the uplift increased from NW to SE, thus indicate that normal faulting of the Gyaring Co Fault may enhanced by the Xainza-Dinggye rift. The early uplift of the Gangdise-Nyainqentanglha Mountain in late Cenozoic might provide northward inclined pre-existing geomorphic surfaces and the later further rapid uplift on the Gangdise-Nyaingentanglha Mountain and Xainza-Dinggye rift might contribute to the asymmetrical development of the Gyaring Co fault zonal drainage basin.     

Burial and exhumation history of the Xigaze forearc basin,Yarlung suture zone. Tibet

The Cretaceous-Eocene Xigaze forearc basin is a crucial data archive for understanding the tectonic history of the Asian continental margin prior to and following collision with India during the early Cenozoic Era. This study reports apatite and zircon(U-Th)/He thermochronologic data from fourteen samples from Albian-Ypresian Xigaze forearc strata to determine the degree and timing of heating(burial) and subsequent cooling(exhumation) of two localities along the Yarlung suture zone(YSZ) near the towns of Saga and Lazi. Thirty-seven individual zircon He ages range from 31.5 ± 0.8 Ma to6.06 ± 0.18 Ma,with the majority of grains yielding ages between 30 Ma and 10 Ma. Twenty apatite He ages range from 12.7 ± 0.5 Ma to 3.9 ± 0.3 Ma,with the majority of grains yielding ages between 9 Ma and 4 Ma. These ages suggest that the Xigaze forearc basin was heated to 140-200 ℃ prior to cooling in Oligocene-Miocene time. Thermal modeling supports this interpretation and shows that the samples were buried to maximum temperatures of ～140-200 0 C by 35-21 Ma, immediately followed by the onset of exhumation. The zircon He and apatite He dataset and thermal modeling results indicate rapid exhumation from ～21 Ma to 15 Ma, and at ～4 Ma. The 21-15 Ma thermochronometric signal appears to be regionally extensive, affecting all the lithotectonic units of the YSZ, and coincides with movement along the north-vergent Great Counter Thrust system. Thrusting, coupled with enhanced erosion possibly related to the paleo-Yarlung River, likely drove Early Miocene cooling of the Xigaze forearc basin.In contrast, the younger phase of rapid exhumation at ～4 Ma was likely driven by enhanced rock uplift in the footwall of north-striking rifts that cross-cut the YSZ.     

山西临汾盆地近期地震活动性分析

通过对临汾盆地内近期地震活动频度和地震活动图像的分析，认为未来中强地震最有可能发生在近期地震活动较稀少的地段，能量积累的优势层位为5km～15km。     

苏门答腊裂谷盆地带构造分带及其成藏模式

苏门答腊弧后裂谷盆地带是印尼乃至东南亚最大的油气产区,由于勘探程度高, 近十年来勘探成效差,盆地油气发现进入瓶颈期。为了指明苏门答腊弧后裂谷盆地带勘探方向,以盆地带构造演化为主线,以构造带为研究对象,在构造特征、构造对成藏模式控制作用等多方面研究的基础上,预测了苏门答腊盆地带有利勘探领域。根据构造特征分析,苏门答腊弧后裂谷盆地带可划分为近岛弧带、中央反转带和远岛弧带3个构造带。近岛弧带以继承性隆起为构造特征,油气主要通过断裂垂向运移,聚集在局部构造高部位生物礁和背斜之中,近岛弧带为旁生侧储型成藏模式,基底潜山圈闭是近岛弧带未来的勘探方向;中央反转带构造样式为挤压反转的半地堑、铲式正断层,中央反转带油气来自底部深凹陷,上部多层系做储层,垂向断层或侧向砂体发育,沟通烃源岩与圈闭,具有近水楼台的优势成藏条件,为下生上储型成藏模式,该带基底潜山圈闭和源内构造—岩性圈闭也具有较好的烃—运—储匹配关系,可能形成好的油气藏;远岛弧带以单斜构造背景为主,局部发育深洼陷,远岛弧带局部洼陷具有一定的生烃能力,该构造带钻井揭示了地层超覆油气藏,但目前勘探程度较低,尚存在较大勘探潜力。     

鄂尔多斯盆地中新生代峰值年龄事件及其沉积-构造响应

通过锆石-磷灰石裂变径迹年龄分布及其与粗碎屑沉积建造和地层不整合关系的综合分析,提供了鄂尔多斯盆地中新生代构造事件的年代学约束及其沉积响应特点。印支期构造事件主要发生在230～190Ma,包含215Ma和195Ma两个峰值年龄,在盆地西南缘发育晚三叠世粗碎屑类磨拉石建造及其与上覆地层的平行不整合。燕山期构造事件主要发生在燕山中晚期的150～85Ma,包含145Ma、120Ma和95Ma等3个峰值年龄,在盆地西南缘发育燕山中期的晚侏罗世和早白垩世的粗碎屑类磨拉石建造及其地层间的角度不整合。喜山期构造事件主要表现为盆地区域的多旋回构造隆升,至少包含55Ma、25Ma和5Ma等3个幕次的峰值年龄事件。其中,锆石和磷灰石叠合分布的峰值年龄(145Ma)和其相关的角度不整合、逆冲推覆和区域岩浆活动等,共同指示了鄂尔多斯盆地中新生代的一次关键构造变革事件。