安徽省黄山地区唐家坞组生物地层

安徽省南部黄山市刘村一带唐家坞组的时代以往归为晚志留世,新近在唐家坞组中采获腕足类、瓣鳃类、腹足类等多门类化石,并首次采获胞石、鹦鹉螺等化石,其中胞石Conochitina(Densichitana)dens的时代为兰多维列世末至文洛克世初期,含这些化石的层位相当于秀山动物群的层位。结合地质情况分析,唐家坞组时限主要属于早志留世。     

南海表层沉积物中钙质超微化石分布特征

为系统描述钙质超微化石在南海表层沉积中的分布特征,对遍布南海的175个样品进行了实验分析。发现不同地区钙质超微化石绝对丰度相差很大,从0—3.8×1010个.g-1不等。平面上将钙质超微化石丰度分为3个区。共鉴定出钙质超微化石21属28种,以Emiliania huxleyi、Florisphaera profunda和Gephyrocapsa oceanica为优势种,其中Florisphaera profunda占据绝对优势。南海钙质超微化石分布具有两个明显特征:一是14°N线南北两边钙质超微化石的分布存在差异;二是南海钙质超微化石丰度以南沙群岛和西沙群岛两片海域为最高,并有东北-西南走向的分布趋势。对影响钙质超微化石分布的水深、上升流与营养盐、陆源物质稀释作用、碳酸盐溶解作用等因素作了讨论,并根据钙质超微化石随水深的变化推测南海碳酸盐补偿深度应在4 000m左右。     

湖南张家界地区志留纪晚期地层新见兼论小溪组的时代

就华南板块而言,志留纪晚期(Ludlow世—Pridoli世)近岸浅海、非笔石相地层多分布在边缘海湾处,是否在扬子地台内部发育,以往尚无确凿记载。依据来自湘西北张家界—桑植地区新近发现的微体化石(主要指植物碎片),确认志留纪晚期地层在扬子地台内部确实存在。对原小溪组(又称小溪峪组)进行厘定,将它"一分为二":上部仍称小溪组,命名地在桑植瑞塔铺,发育最好的是张家界温塘剖面,岩性为黄绿色碎屑岩,富含大型虫管遗迹化石,时代为Ludlow晚期—Pridoli早期;下部称迴星哨组,归于Llandovery统Telychian阶上部。小溪组与迴星哨组之间为假整合接触,缺失Telychian末期、Wenlock世和Ludlow世早期地层。由此得出结论:在"扬子上升"后,扬子地台内部曾被志留纪晚期的海水侵漫;对其他地区迴星哨组与上覆地层的研究需要细化。     

Pendleian (early Serpukhovian) marine carbonates from SW Spain: sedimentology,biostratigraphy and depositional model

The San Antonio–La Juliana tectono‐sedimentary unit contains the only Namurian marine carbonates in the southwestern part of the Iberian Peninsula. The analysis of this unit is fundamental in understanding the sedimentary evolution and tectonic movements which operated during the Namurian in this area. Using foraminifera the succession has been assigned to two biozones (Zones 17 and 18), both occurring in the Pendleian (early Namurian). Seven stratigraphic sections have been analysed: San Antonio, Burjadillo, Lavadero de la Mina, Cornuda, Lozana, Caridad and Via Crucis. The stratigraphic succession of the San Antonio–La Juliana Unit consists of olistolites in the basal part, with common debris‐flow deposits (mainly of carbonates, with minor siliciclastic rocks), and turbidites, all of them embedded in shales. These rocks, interpeted as slope deposits, pass up into shallow‐water platform facies, with sediments characteristic of the inner platform and tidal flats. Above these rocks, terrigenous deltaic deposits occur. Thus, the stratigraphic sections show an overall shallowing‐upward trend. The isolation of some outcrops, and the duplication and absence of some parts of the stratigraphic succession are explained by tectonic movements. Overall, tectonic factors seem to be the main control rather than glacio‐eustatic or autocyclic processes, and sedimentation took place in a strike‐slip regime. Copyright © 2004 John Wiley & Sons, Ltd.     

四川盆地西部雅安地区陆相中-新生代地层划分及区域对比

四川盆地西部雅安地区中-新生代地层中发育多门类化石,以介形类生物最为丰富,综合前人资料,可划分出1个植物组合带、1个双壳组合带和6个介形类组合带。部分地层的古地磁和ESR测年数据与2000年公布的地质年代数据基本吻合,可以作为年代地层划分的辅助依据。     

New data on paleontological characteristic of the Oligocene in the Il’pinskii Peninsula, northeastern Kamchatka

Fossil diatom algae first found in the Paleogene marine succession (Alugivayam Formation) of the Il’pinskii Peninsula, northeastern Kamchatka are studied, and new data on molluscan assemblages from the same sequences are presented. Some of the diatom forms identified suggest the Oligocene age of their host deposits. This is consistent with earlier inference from benthic groups of marine organisms.     

龙门山的石炭系

四川江油马角坝、北川沙窝子是龙门山上泥盆统、下石炭统区域性主要岩石地层单位的命名地,对这两地及前龙门山北段地区的调查发现:1)前人关于马角坝地区下石炭统的层序和马角坝组主要化石群的记载有与实际不符之处,当地实际缺失杜内期至维宪早、中期地层,总长沟群的时代应属晚维宪—谢尔普霍夫期,重新厘定马角坝组含义,新指定北川桂溪沙窝子的长滩子剖面为该组的参考剖面;2)在长滩子剖面长滩子组顶部Beichuano-phyllum与Cystophrentis珊瑚化石富集层之上、马角坝组Pseudouralinia富集层之下的大套厚层白云岩层组合的中上部层位,发现Cystophrentis等化石,基于这套厚层白云岩组合的岩性特征明显、顶底接触关系清楚、区域展布广泛,建议引用前人提出的黑岩窝组,同时对黑岩窝组的岩性、岩层组合与古生物组合特征、厚度和时代归属等作了补充和修正,根据其中所含生物群认为黑岩窝组时代为晚泥盆世法门晚期;3)通过与周边地区的地层对比,探讨了龙门山石炭纪的古地理格局及环境演变,认为除前龙门山中部的桂溪—沙窝子等狭窄地区因长期地处泥盆纪海水入侵通道,地势低洼,出现了残存式的杜内期沉积外,前龙门山南、北段广大地区杜内期至维宪早、中期已大部抬升露出水面,直到维宪晚期的全球性海侵,前龙门山遂再度没于水下,出现准平原化浅滩相沉积环境,并延续至石炭纪末。     

海南岛含杜内早期腕足动物群层的发现

白沙县金波附近的 Spirifer subgrandis Rotai,Unispirifer extensus Tan,Fusella tornacensis (Koninck) ,Punctospirifer insculptus (Phillips) ,Marginatia huaqiaoensis Tan,Palaeochoristites sp.,Megachonetes sp.,Plicochonetes sp.,Schuchertella sp.,Pustula sp.,Sentisia sp.,Crurithyris sp.,Rhipidomella spp.等是海南岛首次发现的最丰富的杜内早期腕足动物群。据此 ,该地区含化石的南好组第四段确定为下石炭统岩关阶 ,似可与湖南马栏边组、黔南汤耙沟组等层位对比。以石燕贝类最繁盛、长身贝类数量少为特征的该动物群与华南其他地区同期腕足动物群存在诸多相同属种但又有明显差异。     

Data on stratotypes of the neopleistocene-holocene regional and local subdivisions in the Caspian region

Considered in the work are data characterizing stratotypes of regional and local stratigraphic subdivisions, which are distinguished in the Neopleistocene-Holocene sedimentary succession of the Caspian region. The succession is composed of sediments deposited by the Caspian transgressions and intervening continental sediments of the late Quaternary. Except for stratotypes of the Tyurkyany Horizon and Gyurgyany Formation, which are established in borehole sections, the other ones represent the well-stratified natural sections accessible for examination of their subdivisions distinguished based on biostratigraphic criteria. Mollusks of the genus Didacna Eichwald and fossil assemblages of large mammals are used to substantiate stratigraphy of marine and terrestrial deposits, respectively.     

Middle Permian radiolarians from Anmenkou, Chaohu, Northeastern Yangtze platform, China

The biostratigraphy of the Middle Permian Gufeng Formation in the northeastern Yangtze platform is examined based on radiolarians. This study is concentrated on the Anmenkou section in the Chaohu area of Anhui Province, China. The Gufeng Formation is divided into the Phosphate Nodule-bearing Mudstone Member (PNMM) and the Siliceous Rock Member (SRM) in ascending order. The former primarily consists of mudstone including abundant phosphate nodules, and the latter consists mainly of alternating beds of chert, siliceous mudstone and mudstone, with intercalations of porous chert. Ammonoids in the mudstone of the lower PNMM are Wordian. Chert, siliceous mudstone and mudstone of the SRM include abundant radiolarians with sponge spicule assemblages suggestive of the Wordian–Capitanian. Albaillellaria are predominant in the lower SRM, while Entactinaria and Spumellaria are predominant in the middle and upper SRM. These radiolarians correspond to three radiolarian assemblage zones: Pseudoalbaillella longtanensis – Pseudoalbaillella fusiformis , Follicucullus monacanthus , and Follicucullus scholasticus – Ruzhencevispongus uralicus . The assemblage of radiolarians and sponge spicule fauna suggests a depositional depth of 150–500 m. The radiolarian fauna of the Gufeng Formation is considered to be representative of the relatively shallow, tropical radiolarian fauna of the Middle Permian eastern Paleotethys.