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991.
992.
红牛矿属印支晚期义敦岛弧带南段、中甸弧主弧期远程熔体(岩浆)—溶液改造型矽卡岩矿床,赋存于上三叠统曲嘎寺组第二段地层中。除典型矽卡岩铜矿床特征外,出现成矿温度较高的辉钼矿,推测矿区深部应发育含矿性较好的中酸性侵入体,具有寻找大—超大型矽卡岩—斑岩复合型铜钼多金属矿床的找矿前景。 相似文献
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"改造成矿作用"是涂光炽院士提出的新理论。这一理论有如下基本论点和鲜明特色:矿质来源的广泛性;成矿流体的特殊性;成矿元素的活泼性;改造作用的内生性;断裂构造的主导性;赋矿岩石的多样性;改造矿床的普遍性;成矿作用的独特性与应有地位——矿床分类的四分法。滇中大姚-牟定式砂岩铜矿是典型的沉积-成岩-后生-改造成因。其主要论据与以下要素有关:裂谷成矿背景;矿源层(K、J)、矿源岩(元谋古陆);矿体受地层层位、岩相、岩性控制,其生成与煤系(提供有机质)、盐层(提供卤素)密切相关;矿体形态产状、矿石结构构造、成矿流体性状与水的来源、有机质类型及其作用在不同成矿期、成矿阶段显著不同。从岩石学的名词概念来解读和划分"改造成矿作用"的上限与下限:上限确定在后生作用之后,下限在变生作用之末。 相似文献
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东辛油田沙三中亚段发育大量与三角洲前缘滑塌相伴生的坡移浊积扇、滑塌浊积扇、远源浊积岩以及洪水成因的水下碎屑流,发育岩性油藏及岩性-构造油藏。纵向上,湖退体系域早期准层序组PS7~PS5是最主要的油气富集层位,其次为湖侵体系域PS8;平面上,各准层序组西部油气富集程度好于东部,含油储层主要为滑塌浊积扇及部分远源浊积岩,其次为坡移浊积扇。油气分布主要受宏观沉积相带、构造、微观储集物性和成岩作用等多种因素控制,距油源远近控制油藏纵向有利层位,砂体成因类型控制着平面有利区带。 相似文献
999.
JULIEN BOURGET SEBASTIEN ZARAGOSI NADINE ELLOUZ‐ZIMMERMANN NICOLAS MOUCHOT THIERRY GARLAN JEAN‐LUC SCHNEIDER VALENTINE LANFUMEY SIGFRIED LALLEMANT 《Sedimentology》2011,58(2):376-406
This study investigates the morphology and Late Quaternary sediment distribution of the Makran turbidite system (Makran subduction zone, north‐west Indian Ocean) from a nearly complete subsurface mapping of the Oman basin, two‐dimensional seismic and a large set of coring data in order to characterize turbidite system architecture across an active (fold and thrust belt) margin. The Makran turbidite system is composed of a dense network of canyons, which cut into high relief accreted ridges and intra‐slope piggyback basins, forming at some locations connected and variably tortuous paths down complex slopes. Turbidite activity and trench filling rates are high even during the Holocene sea‐level highstand conditions. In particular, basin‐wide, sheet‐like thick mud turbidites, probably related to major mass wasting events of low recurrence time, drape the flat and unchannellized Oman abyssal plain. Longitudinal depth profiles show that the Makran canyons are highly disrupted by numerous thrust‐related large‐scale knickpoints (with gradients up to 20° and walls up to 500 m high). At the deformation front, the strong break of slope can lead to the formation of canyon‐mouth ‘plunge pools’ of variable shapes and sizes. The plunge pools observed in the western Makran are considerably larger than those previously described in sub‐surface successions; the first insights into their internal architecture and sedimentary processes are presented here. Large plunge pools in the western Makran are associated with large scoured areas at the slope break and enhanced sediment deposition downstream: high‐amplitude reflectors are observed inside the plunge pools, while their flanks are composed of thin‐bedded, fine‐grained turbidites deposited by the uppermost part of the turbidity flows. Thus, these architectural elements are associated with strong sediment segregation leading to specific trench‐fill mechanisms, as only the finer‐grained component of the flows is transferred to the abyssal plain. However, the Makran accretionary prism is characterized by strong along‐strike variability in tectonics and fluvial input distribution that might directly influence the turbidite system architecture (i.e. canyon entrenchment, plunge pool formation or channel development at canyon mouths), the sedimentary dynamics and the resulting sediment distribution. Channel formation in the abyssal plain and trench‐fill characteristics depend on the theoretical ‘equilibrium’ conditions of the feeder system, which is related closely to the balance between erosion rates and tectonic regime. Thus, the Makran turbidite system constitutes an excellent modern analogue for deep‐water sedimentary systems with structurally complex depocentres, in convergent margin settings. 相似文献
1000.
Propagation of the Storegga tsunami into ice‐free lakes along the southern shores of the Barents Sea
Deposits in coastal lakes in northernmost Norway reveal that the Storegga tsunami propagated well into the Barents Sea ca. 8100–8200 years ago. A tsunami deposit – found in cores from five coastal lakes located near the North Cape in Finnmark – rests on an erosional unconformity and consists of graded sand layers and re‐deposited organic remains. Rip‐up clasts of lake mud, peat and soil suggest strong erosion of the lake floor and neighbouring land. Inundation reached at least 500 m inland and minimum vertical run‐up has been reconstructed to 3–4 m. In this part of the Arctic coastal lakes are usually covered by >1 m of solid lake ice in winter. The significant erosion and deposition of rip‐up clasts indicate that the lakes were ice free and that the ground was probably not frozen. We suggest that the Storegga slide and ensuing tsunami happened sometime in the summer season, between April and October. Copyright © 2011 John Wiley & Sons, Ltd. 相似文献