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周口店河谷地区发现古宽谷地形及其相关的沉积物——Ⅳ阶地砾石层。砾石层形成于早更新世,是地表槽状流水作用的结果,命名为“捐兵湾组”。此地层的发现完善了周口店地区晚新生代地层系统,为重建北京猿人先期的古地理环境提供了科学依据。 相似文献
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凤阳县石门山-清塘一带不整合于古近纪定远组之上,上为中更新世泊岗组角度不整合覆盖的一套松散的槽状交错层理发育的砂砾层,为典型的河流相沉积.上述砂砾层与下草湾组、定远组岩性及成岩程度上相差甚远,与南京地区"六合组"岩性相近,但时代不同,故新建"石门山组". 相似文献
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格吉格音乌拉火山机构主要由集块岩、角砾集块熔岩和碱性橄榄玄武岩组成。玄武岩中含有二辉橄榄岩包体,岩石属大陆内部碱性玄武岩系列。玄武岩层平覆于中新统通古尔组之上,是阿巴嘎玄武岩底部层位。玄武岩全岩钾—氩稀释法同位素年龄１２９９Ｍａ。综合分析认为：阿巴嘎玄武岩早期喷发活动最晚始于上新世。 相似文献
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重庆凉风垭飞仙关组风暴流沉积 总被引：5，自引：0，他引：5
本文根据重庆中梁山凉风垭下三叠统飞仙关组中风暴岩的特征,讨论了在风暴作用下的沉积环境中形成一系列独特的沉积物类型和沉积标志。一个完整的风暴流沉积序列,由底部、中部和顶部三个部分六个层段组成。并根据剖面上各单元风暴层各层段发育程度和滞留砾石特点不同,划分出原地型滞留砾石近积风暴岩、异地型滞留砾石近积风暴岩和迭加型近积风暴岩三种类型。 相似文献
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赣杭构造带中、新生代红色粗碎屑岩发育,对红层中砾石组构分析有助于理解红盆形成、演化过程.运用砾组分析方法,对江西抚崇盆地晚白垩世—古新世莲荷组砾岩层的砾性、砾度、砾态及砾向进行分析,并在此基础上对研究区红盆砾岩的物质来源、成因和形成条件等进行综合判断.研究结果表明,莲荷组砾岩为晚白垩世—古新世半干旱—干旱条件下的一套冲积扇相粗碎屑沉积,具有多物源和快速堆积的特点.总体上,砾石成分复杂,风选程度较差,呈次棱角—次圆状,风化程度较低.盆地不同地区砾石成分组合特征具有明显差别,反映了盆地周围复杂的物源供应条件.根据盆地周边出露基岩地层和扁平状砾石产状统计玫瑰花图判断,莲荷组沉积时期,物源主要来自盆地内部的基岩地层以及盆地西南部、西部和东北部. 相似文献
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区内氧化锰矿皆赋存于含锰层系中,呈似层状或透镜状产出,且与围岩略具同步褶曲,表明锰矿系-古风化型锰矿经后期的进一步氧化、富集所形成的.这一认识对指导区域找矿取得了较好的效果. 相似文献
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Sediment production and transport in a proglacial stream: Hilda Glacier, Alberta, Canada 总被引：2，自引：0，他引：2
KATHLEEN M. HAMMER NORMAN D. SMITH 《Boreas: An International Journal of Quaternary Research》1983,12(2):91-106
Hilda Glacier, a small cirque glacier in the Canadian Rocky Mountains, yields two principal types of sediment: ablation till, deficient in fine material and produced by rockfalls and avalanches falling on to the glacier surface, and basal lodgement till, rich in fines and formed mainly by subglacial erosion. Recent recession from its Neoglacial maximum has exposed large areas of basal till with thin veneers of ablation till which, when combined with present subglacial and supraglacial debris, provide abundant material for erosion and transport by the mcltwatcr stream. Sediment transport measurements over two summers (1977–1978) showed that bed load and suspended load occur in approximately equal proportions and that dissolved loads are minor. Local source variations, especially bank slumps, are a major cause of scatter in sediment rating curves. Suspended-sediment concentrations are greater early in the melt season due to availability of loose sediment produced by freezing and thawing. Other contributors to scatter in suspended-sediment rating curves include rain showers and diurnal hysteretic effects. Although the distinction between bed load and suspended load is never sharp, available data suggest that the sand/ gravel grain-size boundary (-1ø) approximates the suspendcd-load/bed-load division for characteristic Hilda flows transporting gravel. This approximation, combined with till grain-size analyses, suspended-sediment measurements, and spatial distributions of till types, leads to the following computations of fluvial sediment sources: for suspended load - 6% supraglacial, 47% subglacial, 47% channel banks; for bed load - 46% supraglacial, 27% each subglacial and channel banks. Supraglacial debris provides only about one-fourth of all fluvial sediment, but nearly half of the bed load. 相似文献