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131.
132.
基于气候变化特征的红层划分对比——以东营凹陷南坡为例 总被引:1,自引:0,他引:1
首次利用气候变化特征,对由于缺少特征古生物化石资料而长期难以进行地层划分的东营凹陷南坡始新统沙河街组四段下亚段——孔店组一段的红层进行了有效划分。采用基于孢粉化石Ephedripites相对含量约束下的测井数据法恢复相对古气候变化,首先根据Ephedripites相对含量的变化确定气候变化拐点(最干旱点)的位置段,再根据能谱测井数据或常规测井数据计算出的连续粘土矿物组成确定气候拐点的具体点,即为层位界线。根据标准井测井数据建立的数学模型,可以对该井附近新钻探井的红层进行划分对比,其科学性、合理性已被之后的勘探成果所证实。该方法为缺少古生物化石数据的"哑地层"划分提供了一种新思路。 相似文献
133.
再论华南志留系红层的时代 总被引:2,自引:0,他引:2
牙形刺P.eopennatus带的确立和P.celloni带、P.amorphognathoides带的细分,使华南Llandovery统的划分和对比发生了变化,以往归入P.celloni带的地层,极大多数都要归属到P.eopennatus带,层位变低。依据牙形刺生物地层的分析,溶溪组(下红层)的时代可能为埃隆期晚期,... 相似文献
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利用淮南市朱集东矿井新生界松散层供水水文地质勘探成果和抽水试验资料,查明了区内新生界松散层供水含水层的供水水文地质条件,认为第一含水层埋藏浅,易受污染,水量随季节变化大,不宜作为生活饮用水供水水源,第三含水层水质较差,亦不作为生活饮用水供水水源,确定了第二含水层为矿区主要供水层位。采用解析法对第二含水层的水量进行了计算,并设计了布井方案,计算了井群水量;水位预报结果表明,开采50a后,3#、4#井中的水位最大降深为35.229m,小于其顶板埋深,说明拟建井群布置是合适的。评价结果为矿井供水设计提供了依据。 相似文献
138.
G. Neef 《Australian Journal of Earth Sciences》2013,60(5):647-660
The Early Devonian, Maccullochs Range beds (new) of the Winduck Interval largely comprise non-marine fine-grained sheet-flood-deposited sandstones which lie in the southeast sector of the Darling Basin Conjugate Fault System. Deposition of the >2.5 km-thick sequence occurred on the Wilcannia, Towers and Coolabah Bore alluvial fans, that were sourced largely from lightly indurated sandstone caps overlying a large basement high lying north of the Darling River Lineament, and also from west of Maccullochs Range (Coolabah Bore Fan). Four lithofacies are recognised. Lithofacies 1, massive sandstone, is proximal and was deposited from hyperconcentrated sheet floods. The more distal lithofacies 2 is partly massive, partly laminated and partly affected by soft sediment slumping during its deposition. It contains 1.3 – 3.5 m-thick sheet-flood successions that rarely show cross-bedding. Lithofacies 3 and 4 are minor: lithofacies 3, stream-flood deposited, comprises coarse-grained, pebbly sandstone and lithofacies 4, transient playa lake deposits that are locally intercalated with lithofacies 2. In lithofacies 2, thick massive fine-grained sandstone is commonly overlain by laminated sandstone that was deformed when soft. Incised channel deposits in lithofacies 2 deposits are rare and palaeosols were not discovered. Permanency of the positions of two of the alluvial fans, and by inference their feeder streams, remained unchanged for ~9 million years. The fans overlie probable floodplain deposits observed in a quarry in the easternmost part of the study area. Marine fossils are very minor in the range—the brachiopod Howellella jaqueti at one locality indicates an Early Devonian age for one of the brief marine incursions into what was normally an alluvial-fan environment. Very brief marine incursions elsewhere in the group are deduced from the presence of very rare fossil gastropods. 相似文献
139.
In western Victoria, a widespread stratiform style of gold enrichment in Palaeozoic black mudstone and chert—clearly different from the classic mesothermal quartz vein deposits of the Victorian goldfields—has been confirmed by whole-rock geochemistry and Laser Ablation Inductively Coupled Plasma Mass Spectrometry (LA-ICPMS). This enrichment pre-dates compaction, deformation and low-grade metamorphism of the sedimentary host-rocks, and therefore possibly developed diagenetically during slow deposition of the thin carbonaceous black mudstone beds and the thinner layers of chert. These paired strata have been documented at many locations in three regional outcrop areas of chevron-folded Cambrian and Lower Ordovician metasediments in the Stawell and Bendigo Zones, where they are interbedded with quartz-rich turbidites. The layers were named ‘indicators’ by the early miners, who found locally rich nuggety gold deposits at intersections between these layers and mesothermal quartz veins. Gold is present in euhedral pyrite crystals in both black shale and chert. LA-ICPMS analysis of individual pyrite crystals in the indicator beds shows that pyrite is enriched in Au, As, Sb, Se, Te and Bi. The Au content of pyrite varies from 0.03 to 2.69 ppm with a mean of 0.58 ppm and shows a positive correlation with As, which varies from 1000 to 6000 ppm. Many pyrite crystals show enrichment of gold in their cores and depletion in their rims, confirming the likely syngenetic or syndiagenetic accumulation of gold during pyrite formation in the sediments. Prior to regional metamorphism, folding and faulting, the many indicator strata in the outcrop areas were parts of an extensive marine sequence of Late Cambrian and Early Ordovician age. The former primary source of this mineralisation is considered to have been one or more contemporaneously exhalative submarine hydrothermal systems. Thus, the older Palaeozoic sediments of the western Lachlan Fold Belt were significantly enriched in syngenetic gold in the Early Palaeozoic, at least 40 million years before emplacement of the quartz – gold vein deposits of the goldfields. 相似文献
140.
在对赛汉陶来地区19口石油及煤田钻井地层岩性组合特征分析的基础上,总结了中生代不同构造单元的地层分布特征、含煤层段岩性特征及煤岩物理化学特征。含煤层段岩性组合为沉火山碎屑岩或再搬运的沉火山岩、泥岩夹煤层,具有典型裂谷盆地沉积特征。该套地层横向分布稳定,不同构造单元之间可进行对比,单井平均可采煤层的厚度为4.77m。煤岩演化程度较低,为不粘煤。含煤层段沉火山角砾岩获得的锆石年龄为295.0Ma±1.3Ma~303.4Ma±2.8Ma,对应地层为上石炭统—下二叠统干泉组。银额盆地赛汉陶来地区石炭系—二叠系含煤地层的发现不仅指示了良好的煤炭资源前景,并且对石炭纪—二叠纪盆地构造演化、沉积体系,以及石炭系—二叠系沉积埋藏史等基础地质问题的研究具有重要意义。 相似文献