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本文针对我国第四纪内陆有孔虫化石群的出现及其存在问题,提出有没有非海相有孔虫以及第四纪内陆有孔虫化石群是否都与海水入侵有关等问题。作者从我国现代海岸带有孔虫群调查着手,结合国外资料,说明弱海相性有孔虫群的分布及特征,分析我国第四纪内陆有孔虫化石群的生态环境,指出弱海相性有孔虫群具有一定的指相意义,是一类非正常的海相有孔虫群,不仅存在于海岸带,也可出现在内陆环境,出现有孔虫群不一定证明有海水入侵,只要有适宜的水化学条件也可出现。推论第四纪内陆有孔虫群有的与海水有关,有的可能无关。 相似文献
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在第四纪海陆过渡相环境研究中,有没有能够确定古盐度的定量标志?本文作者针对中国东部第四纪海陆过渡相地层中常见的两种有孔虫Ammonia beccarii(Linne)vars.和Protelphidium glabrum(Ho, Hu et K. Wang)进行现代样品的碳同位素分析。在现代样品研究的基础上,确定了碳同位素与盐度存在线性关系,运用这一结果于第四纪几个钻孔样,并综合有孔虫化石群其他特征,推导古环境特点。 相似文献
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在第四纪海陆过渡相环境研究中,有没有能够确定古盐度的定量标志?本文作者针对中国东部第四纪海陆过渡相地层中常见的两种有孔虫Ammonia beccarii(Linne)vars.和Protelphidium glabrum(Ho, Hu et K. Wang)进行现代样品的碳同位素分析。在现代样品研究的基础上,确定了碳同位素与盐度存在线性关系,运用这一结果于第四纪几个钻孔样,并综合有孔虫化石群其他特征,推导古环境特点。 相似文献
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江苏武进漕桥地区第四纪更新世海侵初步研究 总被引：2，自引：1，他引：1
根据漕桥地区更新世沉积物不同层位中产出的微体古生物,对该地区的更新世海侵问题作了初步研究。从有孔虫复合分异度的变化,介形虫与有孔虫化石群比值的变化等,阐明了太湖海侵旋回、湖海侵旋回的海侵与海退过程,结合微体古生物的生态类型及丰度,论述了古地理环境。 相似文献
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本文论述了铁山港海区表层沉积物的沉积类型、碎屑重矿物、贝壳类,有孔虫和介形虫群的分布特征。根据岩芯中微体化石群,岩性特征和14C测定年代数据,确定沉积相及其年代,并讨论沉积物来源和运移。 相似文献
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本文以生物事件的观点论述和探讨了上新统一更新统界线在南海北部的划分。南海北部陆架有跨越上新统一更新统界线的海相地层,其中莺歌海一琼东南盆地的海相第四系厚达2000m左右,是我国除台湾省外研究海相更新统下界的最佳地点。该盆地钻孔中的浮游有孔虫与钙质超微化石群的垂向序列,与意大利Vrica上新统一更新统界线国际层型剖面可以对比,得出1.64Ma的界线值,但在界线上下岩性和化石群均无明显变化,难以在实践中使用。相反,界线下的Globorotalia multicamerata sensu lato末现面上下,浮游有孔虫占有孔虫全群的比例和壳体保存状况发生剧变,地震剖面上亦显示下削上超的接触关系,代表着大约2.00—2.50Ma前一个重要的沉积间断面,此面还可追索到珠江口盆地和北部湾盆地。西太平洋等地海相地层中与此期相应也有明显的沉积环境变化。为此,建议以此面作为划分南海北部上新统一更新统的界线。 相似文献
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化石群落与层序地层的耦合关系研究——以塔里木盆地西部中新生代有孔群落与层序地层关系研究为例 总被引：3，自引：1，他引：2
本文研究的是大陆边缘海以底栖有孔虫为主的化石群落与层序地层的关系。海平面变化是控制化石群落演替和识别划分层序的主要因素。化石群落在一个完整海水进退诈回中呈机会种群落、平衡种群落、终极种群落演替变化,在化石丰度、多样度、均衡度、成壳类型等方面分异显著,与层序地层的三级层序的海进体系域、凝缩期沉积、高位体系域具有密切的耦合关系。化石群落的替变化是对海洋环境变迁的能动反映。因此,化石群落的研究可以帮助识别和优化层序、沉积体系域和层序界面,从而为层序地层的准确识别划分提供新的思路。 相似文献
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本文研究的是大陆边缘海以底栖有孔虫为主的化石群落与层序地层的关系。海平面变化是控制化石群落演替和识别划分层序的主要因素。化石群落在一个完整海水进退旋回中呈机会种群落、平衡种群落、终极种群落演替变化,在化石丰度、多样度、均衡度、成壳类型等方面分异显著,与层序地层的三级层序的海进体系域、凝缩期沉积、高位体系域具有密切的耦合关系。化石群落的演替变化是对海洋环境变迁的能动反映。因此,化石群落的研究可以帮助识别和优化层序、沉积体系域和层序界面,从而为层序地层的准确识别划分提供新的思路。 相似文献
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正世界一流的有孔虫标本模型在中国地质科学院地质所区域地质与编图研究室完成装架并长期展示。这架有孔虫标本模型(图1,见第139页)系由郑守仪院士亲自雕制并监督制作,一共有120个属种,每个种都是标准的环境指相种。标准有孔虫是地层时代的定年器(世界性浮游有孔虫化石带)、古海洋的温度计、盐度计和深度计(浮游与底栖有孔虫),对它的鉴定必须准确无误。如果误定,对年代和环境信息的解译将会发生错误。因为有孔虫是小如灰尘的微体动物,一般小于1.0毫米,只能借助高倍实体显微镜才能看到其 相似文献
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杨瑞东 《沉积与特提斯地质》1998,18(1):43-47
本文以沟鞭藻生态为基础,结合我国东部第三纪盆地的地球化学、古生物、岩相古地理、区域地质和全球海平面变化,论证东部含油气盆地在第三纪时不存在海水侵进。出现有“海相”沟鞭藻、有孔虫和钙质超微化石是由于当时湖泊咸化及富养料造成的。同时认为沟鞭藻是广盐性生物,其最适应于半咸水环境。 相似文献
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对我国西北和东北（内蒙古东部）36个地点的新生代-现代陆相咸化湖泊沉积中的433块标本进行了采样分析，在其中15个地点38块标本中发现钙质超微化石10个属：Coccolithus, Reticulofenestra, Cyclicargolithus,Quadrum, Discoaster, Gephyrocapsa, Calcidiscus, Umbilicasphaera,Cotonocyclus, Watznaueria等，多数为原地沉积，也有一部分属于再沉积来源。由此可见，不能笼统地把所有钙质超微化石的发现都当作海相或海侵的证据。陆相咸化湖泊沉积中钙质超微化石的特点是：丰度低，数量稀少；属种分异度低；常与陆相喜盐水生生物共生。第四系和现代陆相咸化湖泊沉积中发现的钙质超微化石属种往往是海相第四系或现代海洋中常见类型。在青海柴达木盆地七个泉构造七心1井中-上始新统下干柴沟组上段岩心中，发现Reticulofenestra bisecta。这是海相中始新世-渐新世沉积中标志化石。看来，利用钙质超微化石进行海、陆相地层对比探索已取得一定进展，但离“统”一级的地层对比还有很大距离。 相似文献
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南海北部秋季活体浮游有孔虫的组成与分布 总被引：2，自引：0，他引：2
对2004年9月采自南海北部海区19个站位40个垂直浮游拖网样品中的活体浮游有孔虫进行了定量分析, 探讨了该区秋季现代有孔虫的组成、分布及其影响因素.研究表明, 该区秋季现代浮游有孔虫以热带暖水群落为主, 呈现出明显的区域变化.浮游有孔虫的丰度主要呈西北高、东南低的分布格局.浅层水种G. sacculifer和G. ruber的高含量主要出现在近岸带; N. dutertrei的高含量主要出现在外陆架和陆坡区域; G. menardii的高含量主要出现在深水区域; G. calida和G. aequilateralis两水种的含量分布有明显的相似性, 主要出现在深水区, 在越南岸外站位其含量远高出区域其他站位.研究认为, 南海北部秋季水体浮游有孔虫的分布主要受初级生产力和水深的共同制约, 高初级生产力水平下浮游有孔虫的丰度明显要高, 水深则对中深层水种G. menardii、G. calida和G. aequilateralis的分布有明显的制约作用.南海北部秋季温跃层的温盐结构对中层水种N. dutertrei、G. glutinata、G. calida和G. aequilateralis的分布有一定的影响.此外, 暖涡水体对浮游有孔虫的丰度和组成也有明显影响, 位于暖涡中心区的浮游有孔虫丰度明显增高, 特征属种G. sacculifer的含量明显高出周边站位.P. obliquiloculata的高含量主要出现在东北部黑潮分支影响区. 相似文献
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文章通过青海诺木洪—格尔木高速公路盐渍土路段勘察实例,指出了公路盐渍土勘察中应注意的事项,分析了高原盐渍土的成因,提出了盐渍土的重要物理力学指标、盐渍土路基的处理方法等。为西部高速公路勘察与设计提供了新的思路和方法,并对高原盐渍土勘察提供了范例。 相似文献
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A rich foraminiferal assemblage, consisting of abundant Aulotortus sinuosus and A. tumidus in association with Lamelliconus multispirus, Endoteba ex gr. controversa, E. ex gr. badouxi, Endotebanella kocaeliensis, Endotriada tyrrhenica, Endotriadella wirzi, Malayspirina fontainei, Ammobaculites rhaeticus, Diplotremina astrofimbriata, Agathammina austroalpina, and others, was found in the Doi Long Formation of the Triassic Lampang Group, Northern Thailand. These foraminifers suggest that the formation is referable to the Carnian (early Late Triassic), which is consistent with the age estimated by ammonoids. In microfacies, peloidal grainstone, bioclastic grainstone, sponge-microbial boundstone, and oolitic grainstone were recognized in the Doi Long Formation. Based on microfacies, three depositional facies, the lagoon facies, reef facies, and shoal facies, are recognized in this formation. These lines of evidence are suggestive that the Doi Long Formation was deposited in a reef or bank setting rather than a ramp setting. 相似文献
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Qian Jianxing 《《地质学报》英文版》1995,8(2):209-219
Abstract Based on a comparison between the oxygen isotope records of benthic and planktonic foraminifers from core 8KL of the South China Sea and sea-level change records derived from the Huon Peninsula, New Guinea, it is found that both records are very similar from 72 Ka B.P. to the present, especially for the benthic oxygen isotope record. The linear regression shows that δ<sup>18</sup>O changes (0.9995‰ for benthic foraminifers and 1.022‰ for planktonic foraminifers) are equal to 100 m in sea-level fluctuation. After making temperature correction in the δ<sup>18</sup>O record of benthic foraminifers from 72 to 120 Ka B.P., the curve of sea-level oscillation of the South China Sea since 186 Ka B.P. has been reconstructed. The lowermost sea-level that occurred in the last glacial maximum and oxygen isotope stage 6 is approximately - 130 m. 相似文献
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The Guevgueli Ophiolite Complex near Demir Kapija (Eastern Vardar Ophiolitic Unit) was studied for the age and facies of the overlying sediments. Cherts in direct contact with basalts are dated to late Bathonian–early Callovian with radiolarians. The post-obduction sequence, here informally named the Demir Kapija group, is composed of polymictic conglomerate, probably Kimmeridgian in age, and a more than 350-m thick carbonate succession. The carbonate succession consists of hemipelagic, slope and platform margin facies and contains algae and benthic foraminifers indicative of the Tithonian age. These new data support the previously proposed palaeogeographical connection between the Guevgueli and South Apuseni ophiolite complexes. 相似文献
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Cores from the salt marshes along the drowned melt-water valley of river Varde Å in the Danish Wadden Sea have been dated and analysed (litho- and biostratigraphically) to reconstruct the Holocene geomorphologic evolution and relative sea level history of the area. The analysed cores cover the total post-glacial transgression, and the reconstructed sea level curve represents the first unbroken curve of this kind from the Danish Wadden Sea, including all phases from the time where sea level first reached the Pleistocene substrate of the area. The sea level has been rising from − 12 m below the present level at c. 8400 cal yr BP, interrupted by two minor drops of < 0.5 m at c. 5500 cal yr BP and 1200 cal yr BP, and one major drop of ∼ 1.5 m at c. 3300 cal yr BP. Sediment deposition has been able to keep pace with sea level rise, and the Holocene sequence consists in most places of clay atop a basal peat unit overlying sand of Weichselian age and glacio-fluvial origin. In its deepest part, the basal peat started to form around 8400 cal yr BP, and reached a thickness of up to 3.5 m. This thickness is about half of the original, when corrected for auto-compaction. The superimposed clay contains small (63-355 μm) red iron stains in the top and bottom units, and foraminifers of the calcareous type in the middle. The fact that iron stains and foraminifers in no cases coexist, but always exclude each other is interpreted as a result of the difference between salt-marsh facies (iron stains) and tidal-flat facies (foraminifers). This represents a novel and easy way to distinguish between these two otherwise often undistinguishable sedimentary facies in the geological record. 相似文献
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微体古生物分析已经证明是沿海平原和陆架海侵研究的最重要手段之一。由于我国第四纪海侵研究大量工作是在海陆过渡相地层中进行,而对于过渡相化石群古生态和埋葬学方面复杂性认识不足,往往会导致微体化石的错用。河口微体化石的溯流搬运,海岸带低pH环境下钙质壳体的溶解作用,氯化钠型盐湖中有孔虫的产出以及河床摆动造成与海侵、海退相似的化石序列,都可能引起微体化石在海侵研究中错误解释和应用。本文通过澳大利亚和中国的实例进行论证,并提出今后研究工作的建议。 相似文献
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Arindam Chakraborty Amit K. Ghosh Abhijit Mazumder 《Journal of the Geological Society of India》2017,90(4):428-436
Petrographic thin section analysis of the samples collected from the type section of Neil West Coast Formation, situated in the west coast of Neil Island yielded moderately preserved coralline red algae, benthic and planktic foraminifers, coral fragments, echinoid spines and gastropod shells. The coralline red algae are represented by both non-geniculate and geniculate forms. The non-geniculate forms belong to melobesids, lithophylloids and mastophoroides. The geniculate forms are represented by species of Amphiroa, Corallina, and Jania. However, the diversity and abundance of coralline algal forms are less in comparison to the benthic foraminifers those are represented by Amphistegina, Neorotalia, Ammonia, Elphidium, Operculina, Assilina, Amphisorus and texularids. Planktic foraminifers like Globigerinoides and other biogenic components viz., gastropod shells, echinoid spines and coral fragments are also common. A foraminiferal-algal grainstone facies has been recognized as observed in the field as well as in thin section analysis. The overall assemblage of the biogenic components and facies analysis indicate intertidal to near shore environment of deposition with high energy condition and increased hydrodynamic activity. 相似文献