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1.
长江源各拉丹冬地区晚二叠世乌丽群类生物组合 总被引：4，自引：0，他引：4
长江源各拉丹冬地区二叠系乌丽群中的晚二叠世类化石 ,可分为两个组合 ,产于乌丽群下部那益雄组的Palaeofusulina parafusiformis- N anlingella simplex组合 ,产于乌丽群上部拉卜查日组的 Gallowayinella meitienen-sis- Palaeofusulina sinensis组合 ,这两个类化石组合属种分异度低 ,丰度高。该生物群属于特提斯动物群 ,在羌塘盆地及华南地区具有广泛的区域对比性。各拉丹冬及其邻近地区的二叠纪类生物群均为暖温型 ,属华夏特提斯区的分子 相似文献
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The location of the Palaeo-tethys suture in Tibet has been in great dispute for past two decades. The Longmucuo-Shuanghu suture has long been considered as the Palaeo-tethys in Tibet. Restudy of the Carboniferous and Permian sequences in the north and south of this suture reveal that: (1) the Carboniferous and Permian se-quence of the North Qiangtang Block is characterized by containing compound corals and intact fusulinids zones from Moscovian Fusulinella, Fusulina to Changhsingian Palaeofusulina zones; (2) the Early Permian of the South Qiangtang Block is dominated by diamictites and the Middle Permian carbonates found there may deposit on the oceanic seamount. 相似文献
3.
华南二叠系长兴阶灰岩的碳同位素地层对比 总被引：4，自引：1，他引：3
以浙江长兴煤山长兴阶层型剖面、江西上高七宝山剖面、陕西汉中梁山剖面为代表的华南长兴阶碳酸盐岩碳同位素地层,清楚地显示出长兴阶顶、底为碳同位素低值区,其中Ｐ－Ｔ界线附近的碳同位素出现强烈负异常事件。在长兴阶内部两次碳同位素低值异常区,将长兴阶碳同位素演化曲线由下至上明显分为３个旋回,其中长兴阶顶,也即Ｐ－Ｔ界线,碳同位素强烈负异常与生物绝灭事件有关,时间短,变化幅度大,是全球界线对比的重要标志。而其它碳同位素负漂移和由此构成的３个旋回,在华南可以追踪对比。上旋回与长兴阶上段煤山段相当;而中、下旋回则与下段葆青段相当,并将其两分。碳同位素地层对比表明江西上高地区长兴组的中、上部可能属长兴阶,而下部厚约９０ｍ的含Ｇａｌｏｗａｙｉｎｅｌａ灰岩可能属吴家坪晚期。 相似文献
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西藏羌塘北部上二叠统热觉茶卡组 类动物群的特征 总被引：1，自引：0，他引：1
西藏羌塘北部热觉茶卡组的 类动物群共3属11种（不含未定种）,包括：Palaeofusulina sinensis Sheng, P. fusiformis Sheng,P. nana Likharev, P. laxa Sheng, P. wangi Sheng, P. minima Sheng et Chang, P. simplex Sheng et Chang, Parananlingella acervula (Sheng et Rui), Reichelina changhsingensis Sheng et Chang, R. pulchra K. M.-Maclay, R. gaqoiensis Wang, Sheng et Zhang。根据 类沿剖面的分布,建立了Palaeofusulina 带,由下至上划分为2个亚带：Palaeofusulina minima亚带和Palaeofusulina sinensis亚带。该 类化石带属种丰度高,所含的 类动物群属华夏特提斯型分子,为晚二叠世的代表分子和典型分子,与中国华南长兴阶 类化石带可进行对比。 相似文献
5.
<正>苏浙皖接壤地区有许多好的二叠系界线部面，著名的长兴煤山界线候选层型部面就出露在这里(盛金章1983;Sheng et al.1994)。因为本区长兴组岩相多变，在研究 相似文献
6.
二叠系长兴阶全球界线层型剖面和点位 总被引：2，自引：0，他引：2
二叠系乐平统长兴阶底界全球界线层型和点位(GSSP)确立在我国浙江长兴煤山D剖面长兴灰岩的下部、4a-2层之底,以牙形石演化序列Clarkina longicuspidata-C.wangi中C.wangi的首现为标志。该点位位于长兴组底界之上88cm处,与长兴期特征的■类化石Palaeofusulina sinensis和大巴山菊石类的首次出现层位一致。界线层的碳同位素存在明显的负漂移,正磁极性带出现在吴家坪晚期的反极性带之上。在煤山D剖面以西300m处的C剖面出露较多的龙潭组地层,清晰地反映出龙潭组—长兴组连续的沉积序列,被列为辅助层型剖面。 相似文献
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在长江源区各拉丹冬一带晚二叠世地层中建立了2个腕足类生物组合，下部为Spinomarginifera cf.kueichowensis-Tschernyschewia cf.sinensis-Tyloplecta cf.yangtzeensis组合，见于乌丽群下部的那益雄组；上部为Leptodus nobilis-Perigeyerella costellata-Enteletes subequivalis组合，见于乌丽群上部的拉卜查日组。两个组合生物群属于特提斯动物群，均可与华南地区同期地层中的生物群相对比。 相似文献
8.
华南二叠系长兴阶层型剖面碳酸盐岩的碳氧同位素地层 总被引：14，自引：3，他引：11
华南长兴阶层型剖面４０多米厚的地层主要由泥晶灰岩组成,从中系统采集了１５９个碳酸盐岩样品进行碳氧同位素地层学研究,清楚地识别出同位素的变化规律,划分出８个序列和３个旋回。３个碳氧同位素地层旋回由上至下为：长兴早期的Ｐａｌａｅｏｆｕｓｕｌｉｎａｍｉｎｉｍａ旋回,长兴中期的Ｃｒｕ－ｒｉｔｈｙｒｉｓ－Ｇｅｉｎｉｔｚｉｎａ－Ｃｌａｒｋｉｎａｓｕｂｃａｒｉｎａｔａ旋回,长兴晚期的Ｐａｌａｅｏｆｕｓｕｌｉｎａｓｉｎｅｎｓｉｓ旋回。碳酸盐岩碳同位素的异常变化与有机碳的贮藏和氧化相关,而这些变化可能具同时性,记录于整个古华南海水中,从而成为地层对比的良好标志。长兴阶高分辨率碳氧同位素地层的建立,提高了地层的划分精度,为长兴阶进一步的精细地层对比提供了可能。 相似文献
9.
Nathan D. Sheldon Ramananda Chakrabarti Gregory J. Retallack Roger M. H. Smith 《Sedimentology》2014,61(6):1812-1829
The end of the Palaeozoic is marked by two mass‐extinction events during the Middle Permian (Capitanian) and the Late Permian (Changhsingian). Given similarities between the two events in geochemical signatures, such as large magnitude negative δ13C anomalies, sedimentological signatures such as claystone breccias, and the approximate contemporaneous emplacement of large igneous provinces, many authors have sought a common causal mechanism. Here, a new high‐resolution continental record of the Capitanian event from Portal Mountain, Antarctica, is compared with previously published Changhsingian records of geochemical signatures of weathering intensity and palaeoclimatic change. Geochemical means of discriminating sedimentary provenance (Ti/Al, U/Th and La/Ce ratios) all indicate a common provenance for the Portal Mountain sediments and associated palaeosols, so changes spanning the Capitanian extinction represent changes in weathering intensity rather than sediment source. Proxies for weathering intensity chemical index of alteration, ?W and rare earth element accumulation all decline across the Capitanian extinction event at Portal Mountain, which is in contrast to the increased weathering recorded globally at the Late Permian extinction. Furthermore, palaeoclimatic proxies are consistent with unchanging or cooler climatic conditions throughout the Capitanian event, which contrasts with Changhsingian records that all indicate a significant syn‐extinction and post‐extinction series of greenhouse warming events. Although both the Capitanian and Changhsingian event records indicate significant redox shifts, palaeosol geochemistry of the Changhsingian event indicates more reducing conditions, whereas the new Capitanian record of reduced trace metal abundances (Cr, Cu, Ni and Ce) indicates more oxidizing conditions. Taken together, the differences in weathering intensity, redox and the lack of evidence for significant climatic change in the new record suggest that the Capitanian mass extinction was not triggered by dyke injection of coal‐beds, as in the Changhsingian extinction, and may instead have been triggered directly by the Emeishan large igneous province or by the interaction of Emeishan basalts with platform carbonates. 相似文献
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拉萨地块晚二叠世-三叠纪地层的研究对认识青藏高原前新生代特提斯演化具有重要意义,但目前对该时期的沉积充填序列及古地理环境尚未形成统一认识.通过对西藏昂仁县孔隆地区开展的详细地层和牙形石相关研究,在木纠错组上部发现了晚三叠世诺利期Epigondolella sp.牙形石分子,在下拉组顶部发现了时代跨越晚二叠统长兴阶和早三叠统印度阶的牙形石Hindeodus typicalis;从而将研究区木纠错组时代重新厘定为晚二叠世长兴期至晚三叠世诺利期,指示拉萨地块西部三叠纪应仍为连续的浅海相沉积. 相似文献
12.
Paleo‐fires and Atmospheric Oxygen Levels in the Latest Permian: Evidence from Maceral Compositions of Coals in Eastern Yunnan,Southern China 总被引：1，自引：0，他引：1
Inertinite maceral compositions of the Late Permian coals from three sections in the terrestrial and paralic settings of eastern Yunnan are analyzed in order to reveal the paleo-fire events and the atmospheric oxygen levels in the latest Permian. Although the macerals in the studied sections are generally dominated by vitrinite, the inertinite group makes up a considerable proportion. Its content increases upward from the beginning of the Late Permian to the coal seam near the Permian-Triassic boundary. Based on the microscopic features and the prevailing theory that inertinite is largely a by-product of paleo-fires, we suggest that the increasing upward trend of the inertinite abundance in the latest Permian could imply that the Late Permian peatland had suffered from frequent wildfires. Since ignition and burning depend on sufficient oxygen, a model-based calculation suggests that the O2 levels near the Wuchiapingian/Changhsingian boundary and the Permian-Triassic boundary are 27% and 28% respectively. This output adds supports to other discoveries made in the temporal marine and terrestrial sediments, and challenges the theories advocating hypoxia as a mechanism for the Permian-Triassic boundary crisis. 相似文献
13.
Zakharov Y. D. Biakov A. S. Horacek M. Goryachev N. A. Vedernikov I. L. 《Doklady Earth Sciences》2019,484(1):21-24
Doklady Earth Sciences - It is proposed that unstable temperature conditions in the Late Wuchiapingian and Early Changhsingian (Late Permian) changed in the Boreal Superrealm to less contrasting... 相似文献
14.
贵州紫云晚二叠世-早三叠世初火山作用与生物礁的沉积演化 总被引：1，自引：1，他引：0
晚二叠世长兴期是华南地区重要的成礁期,也是火山事件频发的一个时期。生物礁是一种对海洋环境十分敏感的生态系,晚二叠世的火山作用势必影响到当时生物礁的生长和沉积相的演化。然而,前人有关晚二叠世火山事件的研究主要集中在二叠系与三叠系界线附近,而对整个长兴期生物礁的演化与火山事件关系的研究则较少。选择贵州紫云的台地边缘礁为研究对象,通过大量磁化率的测试,分析整个晚二叠世生物礁的沉积演化与火山作用的关系。分析结果显示,长兴早期和末期岩石的磁化率值明显偏高,反映较强的火山活动。在这两个时期,造架生物相对不发育。长兴中期,岩石的磁化率值相较于长兴早期和长兴晚期总体偏低,表明火山活动相对较弱,导致生物礁的快速生长。但长兴中期生物礁灰岩中夹有几层生物碎屑灰岩,其磁化率值有小幅度的升高,说明短时期小规模的火山作用虽然导致了生物礁生长的暂时中断,但礁相动荡的环境使得火山灰中细小的铁磁性物质难以沉积下来。研究发现,尽管早三叠世早期泥岩具有高的磁化率值,但泥质岩中多层火山黏土具有异常高的磁化率值,火山灰物质对磁化率大小的影响远远超过陆源物质的贡献。 相似文献
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Hathaithip THASSANAPAK Mongkol UDCHACHON FENG Qing-lai Chongpan CHONGLAKMANI 《地球学报》2012,33(S1):67-68
Bedded cherts collected from northern Thailand, including Chiang Dao, Lamphun and Den Chai contain Middle Triassic radiolarian faunas. The faunas from Chiang Dao can be divided into two assemblages. The first assemblage includes Eptingium and other co-occurring species such as Cryptostephanidium cornigerum Dumitric?, Plafkerium antiquum Sugi-yama, Pseudostylosphaera compacta (Nakaseko and Nishimura), P. longispinosa Kozur and Mostler, P. acrior (Bragin), P. japonica (Nakaseko and Nishi-mura), Parasepsagon sp. cf. P. variabilis (Nakaseko and Nishimura), Hozmadia sp. cf. H. gifuensis Sugi-yama, Triassospongosphaera multispinosa (Kozur and Mostler), Celluronta donax Sugiyama, Oertlispongus sp. cf. O. diacanthus Sugiyama, Paroertlispongus multispinosus Kozur and Mostler, etc. The second as-semblage consists of Triassocampe deweveri (Na-kaseko and Nishimura), Yeharaia annulata Nakaseko and Nishimura, Hindeostylosphaera spinulosa (Na-kaseko and Nishimura), Plafkerium contortum Dumitric?, Kozur and Mostler, Pseudostylosphaera goestlingensis (Kozur and Mostler), P. timorensis Sa-shida and Kamata and Paroertlispongus rarispinosus Kozur and Mostler. These assemblages indicate upper and uppermost Anisian, respectively. 相似文献
16.
通过地层、古生物、地震相、地震属性分析,笔者发现了利川和石柱地区存在晚二叠世长兴期台内盆地的证据,并分别命名为利川台内盆地和石柱台内盆地。基于上述证据和前人研究成果,对鄂西—渝东地区的古地理格局及生物礁展布提出了新的认识:利川台内盆地、石柱台内盆地及鄂西盆地共同控制了鄂西—渝东地区晚二叠世长兴期台盆相间的古地理格局,生物礁主要沿这3个盆地边缘呈带状展布;鄂西盆地在长兴组一段沉积时期形成,该台地边缘坡度较陡,发育陡坡型生物礁;利川台内盆地和石柱台内盆地分别形成于长兴组一段和组二段沉积时期,其台地边缘坡度较缓,分别发育长一期和长二期缓坡型生物礁。与缓坡型生物礁相比,陡坡型生物礁横向及纵向发育规模更大。 相似文献
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论河北南部太原组的时代问题 总被引：10，自引：1，他引：9
<正> 近年来,本文作者在太行山东麓峰峰至元氏一带对晚古生代主要含煤地层作了比较系统的研究,采集了大量的动、植物化石,于原上石炭统太原组上部的野青灰岩层中,发现了大量二叠纪的非有孔虫Geinitzina,Pachyphloia,类Nankinella 及其砂泥岩夹层中发现常见于山西组、下石盒子组的Lobatannularia等植物证明了本区石炭、二叠系的界线应重新厘定,二叠系之底界应置于野青灰岩层之下。 相似文献
18.
对四川广元上寺剖面大隆组的放射虫动物群进行了详细的鉴定和丰度、分异度的统计。发现该放射虫动物群丰度和分异度均较低,以泡沫虫和内射虫为主,含少量十字多囊虫的分子;其丰度和分异度与长兴期海平面变化具有很好的耦合关系:放射虫丰度、分异度较大的层位对应于长兴早期和长兴晚期两次最大海侵事件发生的层位。相对长兴晚期而言,长兴早期放射虫的丰度和分异度较大,这与长兴早期水体相对较深有关。此外,有孔虫与放射虫丰度变化呈现很好的负相关性,这与它们不同的生活习性和水深的变化有关。分析表明:水深的变化是上寺剖面放射虫动物群演变的主要控制因素。 相似文献
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报道了采自恩格尔乌苏缝合带的蛇绿混杂岩硅质外来岩块中的二叠纪阿尔拜虫目放射虫化石,包括3属7种,可以划分为2个放射虫化石组合,能够与日本、美国的放射虫化石带进行对比,其地质时代分别为早二叠世和中二叠世晚期-晚二叠世早期。恩格尔乌苏缝合带位于华北板块和塔里木板块之间,这些放射虫化石的发现为研究恩格尔乌苏缝合带的构造演化提供了新的证据。鉴于其中最新的放射虫组合的地质时代为中二叠世晚期-晚二叠世早期,认为华北板块与塔里木板块之间自中二叠世晚期-晚二叠世早期曾经存在古海洋,即华北板块和塔里木板块的拼合时间是晚二叠世晚期。 相似文献