渤海湾盆地车镇凹陷古近系构造样式对沉积及储集层的影响*

近年来,构造对沉积的控制作用研究成为当前国际地质和油气勘探研究中的一个热点,但构造对储集层质量影响的研究相对较缺乏。在对车镇凹陷构造、沉积、储集层研究的基础上,讨论了不同构造样式中沉积充填和储集层发育特征。构造样式对沉积充填类型及特征具有重要影响,其中板式构造样式区仅发育近岸水下扇及少量滑塌浊积扇;铲式构造样式区除在边界断裂根部附近发育近岸水下扇外,其前端湖底扇常较发育;断阶式和坡坪式构造样式区受次级断裂控制,陆上与水下沉积常常共生,沉积类型多样,从冲积扇、扇三角洲到近岸水下扇、湖底扇均可发育。构造样式通过影响砂砾岩体的垂向叠置方式、规模和沉积类型及砂体结构,最终影响了其储集层质量。综合研究认为,断阶式和坡坪式构造样式区沉积类型丰富,为有利储集层最发育区;铲式构造样式区湖底扇发育,砂砾岩单层薄,为次级有利区;而板式构造样式区砂砾岩展布窄、单层厚度大,储集层质量最差。该认识为中低勘探程度的含油气断陷盆地中优质储集层发育带的预测提供了思路。     

铅山—上饶“石溪组下段”砾岩层的层位探讨

本文依据大量的野外观察资料,综合分析了江西铅山—上饶地区“石溪组下段”砾岩层及有关地层的地质特征,论证了“石溪组下段”砾岩层实属周家店组底部的砾岩层。     

砂砾岩储集层的成岩作用及孔隙演化——以准噶尔盆地红车拐地区三叠系百口泉组为例

准噶尔盆地三叠系百口泉组油气勘探潜力巨大,但储集砂体物性较差,非均质性较强,优质储层形成原因尚未明确,成岩相关特征认识模糊,限制了该区油气的勘探开发。基于三叠系百口泉组岩芯观察,结合薄片分析、扫描电镜以及物性分析等资料,分段分岩性对储层成岩作用以及孔隙演化进行了详细分析。结果表明,研究区百口泉组岩石类型以砂砾岩为主,储层按岩性可划分为砂砾共同支撑储层和砂质颗粒支撑储层,储集空间整体以原生粒间孔为主,储层物性较差,属于低孔低渗型。储集层的成岩阶段为中成岩B期。基于定量分析,发现压实作用和胶结作用对储集层物性破坏较大,溶蚀作用增孔能力受控于岩石支撑类型,对砂砾共同支撑的储集层岩石增孔影响较大,对砂质颗粒支撑的储集层岩石增孔影响较差。     

U–Pb dating of detrital zircon from Permian successions of the South Kitakami Belt,Northeast Japan: Clues to the paleogeography of the belt

The South Kitakami Belt in the northeast Japan is unique in presence of a thick Paleozoic–Mesozoic sedimentary rocks. The Permian sedimentary succession in the Maiya area of this belt is divided into the Nishikori, Tenjinnoki, and Toyoma formations, in ascending stratigraphic order. The Tenjinnoki Formation includes the Yamazaki Conglomerate Member containing granitic clasts. We performed U–Pb dating for detrital zircon of one sample of tuffaceous sandstone from the Nishikori Formation, six samples of sandstone from the Tenjinnoki and Toyoma formations, and five granitic clasts from the Yamazaki Conglomerate using laser ablation-inductively coupled plasma-mass spectrometry. Our dating results show that the tuffaceous sandstone sample has two age peaks at 287 and 301 Ma for the Nishikori Formation, three age peaks at 320–300, 290, and 270 Ma for the Tenjinnoki and Toyoma Formation, and ages of 311, 300, and 270 Ma from granitic clasts of the Yamazaki Conglomerate. In addition, older ages of 452–435 and 380 Ma were obtained from some zircon grains of the sandstone and granitic clasts. Our results suggest igneous activity in these periods. The South Kitakami Belt's origin with respect to continental blocks has been discussed in regard of the margin of North China Block or South China Block. Based on the stratigraphic ages and timing of igneous activity, we conclude that during the Permian the South Kitakami Belt was located at the margin of the South Central Asian Orogenic Belt, near the Solonker-Xra Moron-Changchun suture and the North China Block in East Asia.     

藏南柳区砾岩的沉积环境及物源分析:对雅鲁藏布缝合带古近纪隆升的约束

沿雅鲁藏布江缝合带分布的柳区砾岩是喜马拉雅造山作用过程中重要的沉积记录。然而,目前对该套地层的构造属性仍存在不同的认识,因为尚未发现来自冈底斯中酸性的火山岩砾石,部分学者认为其是在印度和洋内岛弧碰撞形成的。本次工作对柳区出露的柳区砾岩进行了详细的剖面实测、沉积学观察和物源区分析。地层由厚层的砾级到巨砾级的砾岩以及相对较薄层的砂岩和泥岩组成,砾石包括硅质岩、基性-超基性岩、石英砂岩、岩屑砂岩以及板岩和千枚岩。砾岩分选差,磨圆差,颗粒支撑和基质支撑均发育,根据岩相组合判断其形成于冲积扇和辫状河环境。较大的砾径以及极低的结构成熟度表示为近源堆积,暗示雅鲁藏布江蛇绿岩带为该套砾岩的重要源区,而特提斯喜马拉雅带为板岩和片岩的主要源区。岩屑砂岩的碎屑颗粒统计结果显示岩屑的含量为82%~85%,其中沉积岩屑为主(82%~95%),石英颗粒以单晶石英为主。碎屑锆石U-Pb年龄有453~579Ma和737~889Ma二个主要的范围,而缺少200~400Ma的锆石年龄。上述观测都说明日喀则弧前盆地、雅鲁藏布蛇绿岩带和特提斯喜马拉雅为柳区砾岩的重要物源区。由于柳区砾岩内部含有日喀则弧前盆地提供的物源,所以柳区砾岩是印度-欧亚板块碰撞之后沉积的。而柳区砾岩内各成分的变化反应源区对物源贡献的变化,同时记录了造山带隆升的历史,具体表现为印度-欧亚板块碰撞后,首先雅鲁藏布江蛇绿岩带和日喀则弧前盆地相对较快隆升,并遭受剥蚀,为柳区砾岩的沉积提供初始的物源,随着印度板块的俯冲,特提斯喜马拉雅带开始隆升,成为了柳区砾岩的物源,主要提供板岩和千枚岩。进一步的俯冲使得蛇绿岩带大幅度隆升而阻碍了日喀则弧前盆地和冈底斯继续提供物源,使得柳区砾岩上段石英砂岩中缺少火山岩石英和再旋回的石英颗粒。     

西客站管理委员会办公楼基坑支护工程问题分析及处理

文章简要分析和论证了在第三系砾岩、粘土岩中施工时遇到的问题和处理方法,以及地下水对边坡稳定性的影响。对今后在该地区施工有参考和借鉴价值。     

胶莱盆地砾岩型金矿的发现及经济地质意义

１砾岩型金矿的发现及特征近期作者在山东省牟平宋家沟—发云夼地段,发现了砾岩型金矿。金矿位于胶莱盆地东北端。赋矿围岩为灰色、深灰色及灰黑色砾岩及砂质砾岩,地层属下白垩统莱阳群一段,是一套不整合在胶东地块前寒武系基底变质杂岩之上以巨砾、砾石为主的粗碎屑岩...     

The Ridgeway Conglomerate Formation of SW Wales,and its implications. The end of the Lower Old Red Sandstone?

The Devonian Old Red Sandstone Ridgeway Conglomerate Formation crops out in Pembrokeshire, SW Wales. It was deposited as part of a dryland alluvial fan, axial fluvial valley deposystem. It conformably overlies the mid Lochkovian Freshwater West Formation and probably predates deposition of the Lower Cosheston Group Mill Bay Formation indicating an Early Devonian (latest Lochkovian to earliest Pragian) age, rather than a Middle Devonian age as suggested by previous workers. It therefore represents the youngest preserved formation of the Milford Haven Group south of the Ritec Fault. The Formation thickens drastically into the Ritec Fault, indicating its control on sedimentation. The half‐graben topography initiated deposition of a hangingwall alluvial fan that was sourced from a southerly Lower Palaeozoic/Precambrian provenance within the present‐day Bristol Channel. The Formation is heterolithic in nature, with deposits on the fan reflecting a mixture of processes. Conglomerates were deposited primarily by laterally extensive sheetfloods, and as bars in low‐relief, laterally accreted channels. Sandstones were also predominantly deposited by sheetfloods. Gritty mudrocks in comparison demonstrate deposition by cohesive debris flows. The fan prograded northward and interfingered with a low‐gradient, high‐sinuosity fluvial channel system dominated by inclined and non‐inclined heterolithic stratification. Thinly laminated mudstone and sandstone interbeds were deposited in ephemeral fan‐toe and axial valley lakes that may have developed during sub‐humid climatic episodes. The lacustrine heterolithic association has associated matgrounds and possible ‘algal roll‐up’ structures. Calcretized peetee structures and root traces comprise a lake margin calcrete association. Fan gravels prograded into the axial fluvial valley during periods of increased sediment flux that may represent semi‐arid conditions and/or episodes of tectonic activity. Calcretes of varying development were established in both the fan and axial valley zones. Calcretes with lower stages of development are more proximal to the Ritec Fault reflecting decreased soil residence times and high deposition rates within the axial valley. More strongly developed soil profiles on the fan may indicate sequence boundaries associated with low sediment flux, or increased soil residence time due to active fan‐channel migration (the pedofacies concept). Groundwater calcretes have sharp‐based and layer‐bound calcrete profiles. Gully‐bed cements are locally developed within the fan gravels. Copyright © 2007 John Wiley & Sons, Ltd.     

碎屑岩压裂缝的特征、成因与油气勘探意义

碎屑岩压裂缝是一种岩石受到纵向或侧向应力时,碎屑岩中颗粒接触点处承受较大的压强而产生的颗粒内部裂缝,这种裂缝的分布大部分限于碎屑颗粒的内部,从而有别于由构造应力产生的构造裂缝。对我国西部地区油气盆地中碎屑岩压裂缝的研究表明,这种压裂缝的发育程度与粒级、碎屑颗粒组分、填隙物含量有密切的关系。它多发育于粗砂岩和砾岩中,发育压裂缝的碎屑颗粒主要为刚性颗粒及凝灰岩岩屑和火山岩岩屑,在相同粒级和碎屑颗粒组份构成相当情况下,压裂缝发育程度与岩石中填隙物所占的百分数成反比关系,填隙物占岩石的百分数越少,压裂缝越发育。此外这种压裂缝在没有构造应力而仅有纵向岩柱压力的条件下也可以产生,从而为油气聚集提供了新的储集空间和渗流通道,拓宽了深部油气勘探的领域;同时对提高油气采收率也有重要的意义。     

山东牟平宋家沟金矿床地质特征及矿床成因初探

宋家沟金矿床是胶东地区新近发现的金矿床之一,矿体赋存在胶莱盆地东北缘拆离断层带上盘的莱阳组砾岩中,为区内火山活动前期在大气水的参与下形成的蚀变砾岩型金矿床。初步的类比研究表明,宋家沟式金矿不同于传统意义上的砾岩型金矿,也不同于胶东地区的玲珑式和焦家式金矿床,而与南非兰德金矿床具有一定的可比性,是胶东地区新发现的金矿类型。其找矿远景巨大。