论"三叠纪初"的一次海侵

论述二叠纪末生物大灭绝事件后的一次全球性快速海侵。以往认为该海侵发生在三叠系底部,但新的材料表明属二叠纪末期。在国际标准层型剖面浙江长兴煤山地区海侵高潮(海平面快速上升)见于26层黑色页岩,层内含菊石Hypophiceras组合,双壳类Claraia? baoqingensis和二叠纪牙形刺;在浙江黄芝山剖面海侵见于大灭绝层之上的Claraia cf.bioni层,此层也可与克什米尔Guryul Ravine剖面E_1层(Claraia bioni带)对比;在北极区,海侵层相当于Otoceras Concavum 层。还讨论了康滇古陆东缘和华北古陆南缘此次海侵的影响,这些古陆边缘地区陆相沉积(“卡以头段”和石千峰群)中夹的海相层不是三叠纪,而是二叠纪。     

江西信丰铁石口剖面晚二叠世的牙形石动物群

对江西省信丰县铁石口剖面晚二叠世长兴阶至铁石口阶下部的牙形石动物群有了新的认识。基于牙形石的研究,将该地区晚二叠世的地层划分为3个牙形石生物带,自上而下分别是：Clarkina changxingensis yini带;Clarkina postwangi带;Clarkina changxingensis带。探讨了浙江长兴煤山标准剖面晚二叠世长兴组至殷坑组下部的牙形石生物带的划分,将这段地层划分为4个牙形石带,自上而下分别是：Clarkina meishanensis meishanensis带; Clarkina changxingensis yini-Clarkina meishanensis zhangi带;Clarkina postwangi和Clarkina subcarinata-Clarkina changxingensis组合带,而最下部的一个带又分为2个亚带,即上部的Clarkina changxingensis亚带和下部的Clarkina subcarinata-Clarkina wangi亚带。最后将铁石口剖面与煤山剖面进行了牙形石生物地层对比,认为铁石口剖面除了长兴组下部被第四纪河床覆盖之外,晚二叠世上部的地层可以完全与煤山剖面进行对比。     

A detailed Lower Triassic conodont biostratigraphy and its implications for the GSSP candidate of the Induan–Olenekian boundary in Chaohu, Anhui Province

Chaohu is located in a deep part of carbonate ramp on the Lower Yangtze Block, which belonged to the low-latitude eastern Tethyan archipelago during the Early Triassic. Fossils were very rich in the Lower Triassic of Chaohu. Bivalves, ammonoids, conodonts were very common throughout the Lower Triassic, while fish fossils were generally rich in some beds of the upper part. It is one of the most typical sections for the Early Triassic chronostratigraphy in the world. Although various fossils had been studied in the 1980s and 1990s, recent studies based upon new and more detailed collections from the Lower Triassic of Chaohu showed that the conodont zonation needs revision. We collected Lower Triassic conodont fossils from continuous sections of the West Pingdingshan, North Pingdingshan and South Majiashan, Chaohu, Anhui Province, and updated zonations were made for each section. Eight conodont zones have been distinguished. They are, in ascending order, Hindeodus typicalis zone, Neogondolella krystyni zone, Neospathodus kummeli zone, Neospathodus dieneri zone, Neospathodus waageni zone, Neospathodus pingdingshanensis zone, Neospathodus homeri zone, and Neospathodus anhuinensis zone. The first occurrence of Neospathodus waageni eowaageni of the N. w. eowaageni subzone （i.e. the base of the N. waageni zone） is suggested as the marker to define the Induan-Olenekian boundary.     

黔西南三叠系永宁镇组牙形石研究—兼论下,中三叠统界线

本文首次系统描述了贵州贞丰县龙场、关岭县永宁镇的永宁镇组牙形石5属12种;在永宁镇组中识别出4个牙形石组合带(层)(由下而上):1. Pachycladina obliqua-Parachirognathus delicatulus带,2. Neospathodus homeri-Neospathodus triangularis.带,3. Neogondolella cf. jubata-Neospathodus timorensis带,4. Neogondolella navicula navicula-Neogondolella constricta层;首次将下、中三叠统的界线置于 Neogondolella navicula navicula-Neogondolella constricta层之底,即永宁镇组第4段之底。两统之间为整合接触。     

中国三叠纪含牙形刺地层

十年来,中国三叠纪牙形刺地层的研究取得了很大的成绩。1.三叠纪含牙形刺地层主要分布在中国南方,尤其在昆仑-秦岭一线以南,此地层发育程度由西向东逐渐减弱,例如:西部珠峰地区分布在整个三叠系地层中,向东到下扬子地区,主要分布在下三叠统中。2.中国三叠纪牙形刺很丰富,已发现39属,230种,可划分成24个带。3.在奥伦尼阶,我国牙形刺根据生态可划分为两种类型:(1)盆地型(珠峰类型),(2)台地型(湖北利川类型)。     

江西信丰县铁石口地区二叠—三叠纪牙形石动物群的发现及其地质意义

本文首次报道并描述了江西信丰县铁石口地区的二叠—三叠纪的牙形石动物群;根据牙形石和菊石、双壳类、腕足类,将“铁石口系”划分为三部分:下部(层1～10)、中部(层11～20)、上部(层21～23),它们分别相当于Griesbachian阶、Nammalian阶、Spathian阶。层2～8中发现了二叠纪型和三叠纪化石伴生的混生动物群。三叠系与二叠系之间可暂时以层1厚约3cm的黄白色粘土岩为界线,二系为整合关系。     

推荐一条GSSP的辅助剖面

该文赞同以Ｈｉｎｄｅｏｄｕｓ ｐａｒｖｗｓ的首次出现作为划分二叠－三叠系界经的生物标志，笔者强调只有以正模及其描述为准所厘订的Ｈ、ｐａｒｖｕｓ，且以主齿、细齿保存完美、距界线粘土层顶面位置最低以及其顶面至界线生物面之上均为单一岩相的Ｈ、ｐａｒｖｕｓ的首次出现点位，才有可能成为二叠－三叠系全球界线层型剖面点的位置、东岭剖面可以它典型的Ｈ．ｐａｒｖｕｓ距界线粘土层顶面仅高出１３ｃｍ，化石保存完好以及界     

江西信丰县铁石口剖面二叠-三叠系界线综合研究

首次对江西信丰县铁石口二叠—三叠系界线剖面的生物地层学、岩石地层学、微量元素、碳及氧稳定同位素、粘土岩和沉积环境以及数学地质的有序最优分割计算进行了综合研究,通过分析,将铁石口剖面二叠—三叠系界线置于第26层底。界线粘土岩(第26层)的矿物组成以伊利石和高岭石为主,仅含少量蒙脱石 伊利石不规则混层矿物,这是首次发现的新类型界线粘土岩。     

贵州省盘县地区羊圈——-楚皮凹剖面中三叠统关岭组上段牙形石生物地层

选择贵州省盘县地区新民乡羊圈村附近羊圈-楚皮凹剖面中三叠统关岭组上段至杨柳井组下部地层进行牙形石生物地层再研究, 补充描述牙形石Neogondolella constricta cornuta, Neogondolella constricta longa, Neogondolella constricta balkanica, Neogondolella alpina alpina, Neogondolella cf. Neogondolella acuta, Paragondolella excelsa和Paragondolella tornaesis等物种, 丰富了该段地层牙形石多样性组成, 并重新划分牙形石带, 进行区内和区外对比。结果表明: 1) 羊圈-楚皮凹剖面关岭组上段至杨柳井组下部可划分5个牙形石带, 自下而上为Nicoraella germanica带(未见底界)、Nicoraella kockeli带、Neogondolella bifurcata带、Neogondolella constricta带和Neogondolella constricta cornuta带(未见顶界); 2) 该段地层牙形石序列区内可与贵州省青岩剖面垄头组上部(台缘斜坡)、关刀(2)剖面关刀岩楔(盆地边缘相)同名化石带对比, 区外与西特提 斯生物区菊石binodosus带、trinodosus带、reitizi带内的牙形石面貌组成相似; 3) 进一步证明该段地层时代为中三叠世安尼期Pelsonian亚期至Illyrian亚期中晚期, 但未进入拉丁期。     

Geochemical significance of the relative enrichment of pristane and the negative excursion of δ^13CPr across the Permian-Triassic Boundary at Meishan, China

Changes in the distribution of isoprenoid hydrocarbons and in δ^13Ckero or δ^13Cpr across the section from the Changxing Formation to the lower Yinkeng Formation at Meishan （the GSSP of PTB） are studied, in which a relative enrichment of pristane and a sharp shift in both δ^13Ckero and δ^13Cmole near the boundary are revealed. A possible mechanism for the abnormal accumulation of pristane near PTB is suggested： Lipids in some marine animals and their metabolites, rich in pristane, can be preserved and accumulate in some suitable depositing facies under certain special conditions, such as the catastrophic death of animals and/or developing of an anoxic water column, and thus the pristane enrichment occurs in the sediment. The occurrences of isoprenoid enrichment and high Pr/Ph ratios have been found in other typical marine anoxic sediments accompanied by mass extinction in various extent during the most important geological periods, such as Late Ordovician, end of Devonian, Early Jurassic and Late Cretaceous. These occurrences support to a certain extent the above mechanism that interprets the genesis of a high Pr/Ph ratio in some typical marine anoxic sediments. The synchronous sharp negative shifts in δ^13Cmole, δ^13Ckero and δ^13Ccarb from Beds 24 to 26 of the Meishan profile indicate that a sudden and strong variation of carbon source in the atmosphere-ocean system occurred during the quick but equable evolution from the end-Permian to Early Triassic, and the coupling between the pristane enrichment and negative shift in δ^13Ckero and δ^13CPr may well indicate the importance of the release of methane hydrates and marine anoxia in the end-Permian mass extinction.     

贵州黔东地区中-下寒武统凯里组发育特征

贵州黔东地区中－下寒武统凯里组主要由粉砂质泥岩，页岩及灰岩组成，富产三叶虫，其中台江八郎乌溜－曾家岩的凯时组含著名的中寒武世凯里生物群、早寒武世台江生物群，2001年成为国际中－下寒武统层型界线候选部，对其深入研究具有重大科学和实用意义。就我省黔东地区凯里组的岩石地层，生物地层，年代地层，沉积环境等进行研究及总结，亦确认黔东凯里组是一个十分重要的地层单位。     

Extinction pattern of reef ecosystems in latest Permian

Studies of two Permian-Triassic boundary (PTB) sections on top of a Changhsingian reef in Ziyun, Guizhou Province, southwestern China indicate that the end-Permian mass extinction of reef ecosystems occurred in two steps. The first step is the extinction of all stenotropic organisms such as calcisponges and fusulinids in the latest Permian (in the Clarkina yini conodont zone). The biota after the first extinction is simple, comprising eurytropic organisms including microgastropods, ostracods, and some small burrowing organisms, or only algal mats. At the beginning of the Early Triassic (i.e. the beginning of the Hindeodus parvus zone), the environments became anoxic, and the microgastropod dominated biota or algal mats disappeared, which constituted the second episode of the mass extinction. The biota after the second extinction comprises small spherical microproblematica, some kinds of specialized organisms tolerant of anoxic or oxygen-poor conditions. As the environments became oxygenated, the specialized biota was replaced by a microgastropod-dominated simple biota. When the environmental conditions improved further, the simple biota was replaced by a diverse biota with normal-sized ammonoids, bivalves, and gastropods, representing restoration of normal oceanic condi- tions. Comparison with PTB sections in Dolomites, Italy and Meishan, Zhejiang Province shows that non-reef ecosystems had a similar first episode of mass extinction in the latest Permian. In the case that oceanic anoxia happened, non-reef ecosystems had a second extinction episode similar to that of reef ecosystems.     

新疆北部二叠系特征及其与三叠系界线划分

目的对新疆准噶尔盆地南缘、吐哈盆地和三塘湖盆地的二叠系及其与三叠系界线的划分提供新的依据。方法在该区长期工作的基础上,参考前人地层划分成果及当地使用习惯,利用岩石地层、生物地层、火山岩同位素年龄、古地磁等方法进行综合分析,对三地区的二叠系进行了综合划分与对比。结果将新疆北部二叠系分别称下、中、上统,与中国南方及国际标准的3个统对应;中二叠统对应于瓜德鲁普统,地质时代为早二叠世(290~265 Ma),中、上二叠统界线在中二叠统塔尔郎组上部,上二叠统与三叠系界线在上二叠统锅底坑组内;中二叠统分布于准噶尔盆地中南部、吐哈盆地北部和三塘湖盆地南部。结论建议将大龙口、锅底坑、塔尔郎沟、照壁山剖面和跃进沟剖面分别作为北疆地区二叠系—三叠系标准剖面。     

贵州拉也剖面下Kellwasser事件生物地层及化学地层特征研究

为研究下Kellwasser事件的生物地层及化学地层特征, 对贵州拉也剖面进行细致的牙形石生物地层学和高分辨率化学地层学研究。结果表明, 剖面底部无机碳同位素及有机碳同位素有显著正向偏移, 样品LY-8代表的层位为下Kellwasser事件的界线。Kellwasser事件碳同位素变化的主要原因是有机碳埋藏量的增加, 可能是由初级生产力增加和缺氧环境共同造成的。     

中国东南部晚古生代—早三叠世陆缘裂陷系的形成和演化

文章从泥盆系、石炭系尤其是二叠系到下三叠统在中国东南部的展布、系统的沉积演变，联系到该阶段古特提斯洋对其影响和控制，提出了华南陆块东南部晚古生代—早三在世陆缘裂陷系发展的沉积构造模式。     

川东北元坝地区长兴期-飞仙关期碳酸盐岩台地沉积体系及演化

四川盆地东北部元坝地区二叠纪-三叠纪沉积环境主要与北部广旺海槽形成与关闭、米仓山与大巴山隆起及二叠纪峨眉山玄武岩喷发有关.通过野外露头、三维地震数据、钻井资料的综合研究,认为长兴组-飞仙关组沉积为碳酸盐台地沉积体系,可进一步划分为台地蒸发岩、局限台地、开阔台地、台地边缘生物礁滩和台地边缘斜坡5个相带.长兴期沿台地边缘发育了台地边缘礁滩;飞一段早期相对平静,沉积末期广旺海槽全部关闭;飞二段至飞三段早期主要为开阔台地沉积;飞三段晚期-飞四段演变为局限台地-台地蒸发岩相.飞二段浅滩与长兴期礁滩大致处于相同位置,未发生侧向迁移;飞三段台内浅滩的发育有明显的侧向迁移和垂向叠置的特征;从西南向东北方向,飞仙关组早期台地沉积区向陆棚沉积区迁移.     

新疆三塘湖盆地烃源岩特征

新疆三塘湖盆地主要有三套烃源岩:中生界上三叠统和中下侏罗统煤系烃源岩、古生界上二叠统湖相低熟烃源岩和古生界下二叠统和石炭系湖相成熟烃源岩.烃源岩在马朗凹陷、条湖凹陷和汉水泉凹陷均有分布,岩性主要为暗色泥岩、煤和碳质泥岩.最有利的烃源岩为马朗凹陷中有机质丰度高、类型好、油气生成量大且碳酸盐岩含量高的上二叠统芦草沟组烃源岩.     

贵州罗甸大文二叠三叠系界线剖面海平面变化及其全球对比

对华南地区贵州罗甸大文剖面早三叠世早期的凝块石进行了系统的沉积学描述,区分出斑状、层状、枝状和网状4种中型构造。凝块石所具有的沉积构造特征和岩石学统计数据表明其形成于潮下带沉积环境,其中,斑状和层状中型构造的凝块石形成于能量较低的深潮下带,而枝状和网状中型构造的凝块石形成于能量较高的浅潮下带。18个向上变浅的沉积旋回显示Hindeodus parvus带内部海平面逐渐降低;Isarcicellastaeschei带和I.isarcica带早期,海平面降到最低,之后海平面开始升高。通过与其他地区二叠–三叠系界线剖面的海平面变化情况对比发现,全球普遍存在二叠–三叠纪之交的海平面下降,而大文剖面早三叠世早期的H.parvus带、I.staeschei带和I.isarcica带的海平面变化情况在古特提斯洋范围内可以广泛对比,可能主要受到全球海平面变化的影响。     

川北曾家地区二叠纪──早三叠世地层学研究

川北曾家地区二叠纪－早三叠世的生物地层研究表明，该区二叠系有４个生物带：Ｎａｎｋｉｎｅｌａｌａｔａ－Ｐｉｓｏｌｉｎａｓｔａｆｆｅｌｉｎｏｉｄｅｓ组合带，Ｎｅｏｓｃｈｗａｇｅｒｉｎａ－Ｖｅｒｂｅｅｋｉｎａｖｅｒｂｅｅｋｉ组合带，Ｃｏｄｏｎｏｆｕｓｉｅｌａ－Ｒｅｉｃｈｅｌｉｎａｃｈａｎｇｈｓｉｎｇｅｎｓｉｓ组合带和Ｐｓｅｕｄｏｔｉｒｏｌｉｔｅｓ－Ｃｈａｏｔｉａｎｏｃｅｒａｓ组合带；下三叠统也有４个生物带：Ｃｌａｒａｉａｗａｎｇｉ－Ｏｐｈｉｃｅｒａｓ组合带，Ｃｌａｒａｉａａｕｒｉｔａ－Ｃｌａｒａｉａｓｔａｃｈｅｉ组合带，Ｅｕｍｏｒｐｈｏｔｉｓｍｕｌｔｉｆｏｒｍｉｓ－Ｅｎｔｏｌｉｕｍ组合带和Ｔｉｒｏｌｉｔｅｓ组合带。在此基础上，结合火山沉积事件、沉积物注入和分布的明显变化及陆上暴露标志等的研究，建立了该区二叠系－下三叠统层序地层格架，划分出７个层序，并分析了相应的环境演变和不同的构造背景