To the problem of stage subdivision of the Lower Cambrian

It was a serious mistake when subdivision stratotypes had been disposed of in practice of constructing the General stratigraphic scale, because they cannot be substituted by the boundary stratotypes. A subdivision stratotype and respective GSSP are complementary parts characterizing any stratigraphic unit. The best candidates for stage stratotypes of the Lower Cambrian are certainly sections of the Lena-Aldan region in the Siberian platform, which have been studied in detail during many years, are well exposed, and contain abundant and diverse fossils, being insignificantly disturbed by tectonic dislocations. Nomenclature, stage and boundary stratotypes of the Siberian standard can be successfully used therefore for stratigraphic subdivision of the Lower Cambrian.     

新近纪海相生物地层事件年龄新编

介绍新近纪海相生物地层研究的新进展。2004年新的"国际地质年代表"以405ka偏心率长周期为基础来划分新近纪的主要地层界线,标志着轨道地层学时代的到来。新生代包括E1—E162偏心率长周期,底界的年龄为65.5±0.3Ma,其中新近纪有E1—E58周期,底界年龄为23.03Ma,并且根据天文调谐得出一系列新的古地磁年龄和生物事件年龄。由于这些新年龄,特别是接近新近纪底部的年龄与早期结果相差0.5Ma或更大,所以将其汇总介绍,以求与当前国际研究保持同步衔接,增强海洋新近纪高分辨率地层工作的准确性。     

Solutions in chronostratigraphy: the Paleocene/Eocene boundary debate,and Aubry vs. Hedberg on chronostratigraphic principles

In several recent papers, M.-P. Aubry et al. have argued that “Hedbergian” principles of chronostratigraphy are being violated by the International Commission on Stratigraphy (ICS) when selecting Global Stratotype Sections and Points (GSSPs) for the formal divisions of the geological time scale. The current debate over the definition of the Paleocene/Eocene (P/E) boundary has been a major focus of their arguments. Unfortunately, Aubry et al. have obscured matters by misusing the term “unit stratotype,” and by equivocally using the term “stage” for the very different concepts of “synthem” and “global chronostratigraphic stage.” The P/E boundary option most repugnant to Aubry et al. (Carbon Isotope Excursion (CIE)=P/E=Thanetian/Ypresian boundary) is perfectly compatible with H.D. Hedberg's views. In contrast, another option preferred by Aubry et al. (recognition of new ∼1 m.y. duration age/stage between Thanetian and Ypresian) is inconsistent with Hedberg's views. Additional problems with the P/E boundary arguments of Aubry et al. include the fact that a “Ypresian unit stratotype” does not exist, the fact that the base of the Ypresian synthem is not immutable, and the fact that the nannofossil Tribrachiatus digitalis is of dubious relevance to the boundary debate.As for chronostratigraphy in general, Aubry et al. have misrepresented Hedberg's views by: (1) falsely claiming that the content of a stage is what determines its boundaries; (2) misunderstanding the general concept of the boundary stratotype; (3) distorting the “base defines boundary” principle; (4) falsely claiming that traditional (pre-GSSP) chronostratigraphic boundaries cannot be changed; (5) falsely implying that traditional stage unit stratotype boundaries can be adjusted by no more than 300,000 years when defining formal age/stage boundaries with GSSPs; (6) falsely claiming that the definition of a geochronologic/chronostratigraphic boundary should precede its correlation; (7) claiming that traditional unconformable “stage” boundaries may be suitable horizons for GSSPs; (8) distorting the meaning of “arbitrariness” in regard to the definition of geochronologic/chronostratigraphic boundaries; and (9) claiming that GSSPs are inherently unstable in that they are subject to redefinition whenever a more powerful element of correlation is discovered. If taken seriously, the unit stratotype-sanctifying chronostratigraphic philosophy of Aubry et al. would require the creation of perhaps dozens of new Phanerozoic ages/stages of relatively very short duration wherever there was a significant gap between two successive historical stage unit stratotypes. For all of these reasons, the arguments of Aubry et al. have no merit.     

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.     

新近系保德阶建阶研究新进展

根据与古地磁极性年表的对比 ,山西保德冀家沟剖面含保德动物群的保德组上界年龄为 5 .30 Ma,底界年龄不超过 10 Ma,其红黏土的底界为 8Ma,显示该剖面不存在定义的保德阶 11.2 Ma的下界 ,也没有保存保德阶下部的沉积。《国际地层指南》提倡用选择下界的界线层型来确定年代地层单位 ,其上界应该由后续单位的下界来确定。冀家沟剖面显然不具备保德阶的下界 ,但甘肃临夏盆地郭泥沟剖面含三趾马动物群的红黏土之下还有发育的中中新世沉积出露 ,因此 ,后一个地点应存在保德阶的下界 ,并有保德阶最底部的化石和适合于作古地磁分析的沉积物 ,所以临夏盆地是一个有可能建立保德阶下界界线层型的有利地点     

新近系研究进展简介

新近系各阶全球层型剖面和点位( GSSP)的选定工作近年来取得了许多实质性的进展,至今上新统3个阶的GSSP已全部获得批准,中新统有3个阶获批准、2个阶有望在2 0 0 4年获得通过、1个阶的指示事件尚未确定,有待进一步的工作。除介绍新近系各个阶最新的GSSP内容外,还就中国陆相新近系建阶工作的进展和研究重点作了简要的回顾与展望,认为上新统麻则沟阶、高庄阶和中新统谢家阶有望在命名剖面定义底界的界线层型和点位,中新统保德阶、通古尔阶和山旺阶的底界有待在甘肃临夏盆地、兰州盆地和秦安地区寻找。中国陆相新近系建阶工作的开展与完成,会给中国地层学研究工作带来积极而又深远的影响。     

地磁极性年表的发展回顾

磁性地层研究是对新生代乃至中生代沉积序列定年的重要方法之一。地磁极性年表作为磁性地层定年的标准,其精度对地层学、古生物学、古气候学等领域的研究有重要影响。回顾了地磁极性年表的发展历史,并着重介绍了当前天文极性年表的发展现状。按照地磁极性年表不同时期的发展特点,可将其发展大致归纳为3个阶段:①早期阶段:20世纪60年代末,主要基于火山岩剩磁测量和K/Ar测年建立了最近约5Ma以来的地磁极性年表;②中期阶段:20世纪60年代末到90年代初,基于大量海底磁异常条带相对宽度建立了中中生代以来完整的地磁极性年表;③现今阶段:20世纪90年代以来,基于天文学和古气候学研究对极性界限的轨道调谐,正在构建高精度的天文极性年表。在天文学和古气候学发展的推动下,高精度的天文极性年表有望取代传统的CK95年表而被广泛应用并促进相关领域的发展。     

Late Cretaceous chronostratigraphy （Turonian-Maastrichtian）： SK1 core Songliao Basin, China

Non-marine ostracodes,charophytes and palynomorphs are abundant in most Cretaceous lacustrine basins of East Asia.However,their ranges are not directly integrated with marine biota that defines the Cre...     

“陆相层型”建立的认识与思考

从总结陆相侏罗-白垩纪地层界线的研究成果和工作方法,结合国际地层委员会“修订准则”和国际地层指南的规定,论述了建立“陆相层型”的紧迫性、理论和方法。我国陆相地层极为发育,但研究明显滞后于海相地层,主要问题是缺乏划分对比标准。目前以海相地层研究建立的层型尚不能应用于陆相地层,况且一些地质断代还未建立层型。陆相地层研究要先建立自己的标准。与海相地层比较,陆相地层在同位素测年、磁性地层划分和事件地层学研究方面具备建立层型的优势,同样可以找到分布广泛和利于大范围地层对比的化石门类。建立陆相层型的关键是找到沉积连续、化石丰富和暴露完全的剖面。陆相层型可以“单位层型”与“界线层型”建立并举,有条件的地质断代还是要重视建立“界线层型”。生物地层学研究一定要以恢复演化谱系或发生序列为基础,界线化石标志应该选在其“首现”层位。“陆相层型”的建立应强调多学科、多门类、多方法的综合研究。     

中国奥陶系和下志留统下部年代地层单位的划分

十多年来全球和我国奥陶系和下志留统下部年代地层研究取得很大进展 ,在前人所积累的大量成果和资料的基础上 ,结合近年来的研究 ,厘定了我国奥陶系和下志留统下部年代地层单位系统 ,建议分别以吉林浑江大阳岔 (或江西武宁或湖北宜昌黄花场 )、湖北宜昌黄花场、浙江常山黄泥塘、新疆柯坪大湾沟和湖北远安苟家垭剖面为界线层型 ,将中国奥陶系自下而上划分为 :新厂阶 (或特马豆克阶 )、道保湾阶、大湾阶、达瑞维尔阶、艾家山阶和钱塘江阶。为了客观反应我国奥陶系的特点 ,同时便于与全球年代地层单位界线对比 ,建议将上述各个阶底界的的界线依次划在 R.taojiangensis( =R.praeparabola) / H .simplex、 O.communis、 B.triangularis/ T.laevis、 U.austrodentatus、 N .gracilis和 N ankinolithus带的底部 ;中下奥陶统和中上奥陶统之间的界线分别定在道保湾阶 /大湾阶和达瑞维尔阶 /艾家山阶之间。建议下志留统最下部两个年代地层单位——龙马溪阶和大中坝阶——以湖北宜昌王家湾剖面为界线层型 ,分别以 A.ascensus和 D .triangulatus的首现为划分标志。对每一个阶的命名、含义、界线层型剖面的岩性特征、界线划分的生物标志、与全球相关年代地层单位层型和点 ( GSSP)的对比 ,以及与过去曾经建议或使用过?     

Cyclostratigraphy and astrochronology of the Tripoli diatomite formation (pre-evaporite Messinian, Sicily, Italy)

The ongoing debate about the Messinian salinity crisis in the Mediternean is fuelled in part by the lack of an adequate time control. The most accurate and, at the same time, detailed constraints are nowadays provided by the astronomical dating technique. Here we present an astronomical age model for the cyclically bedded Tripoli diatomite Formation on Sicily (pre-evaporite Messinian, Italy) based on an integrated stratigraphic study of three key-sections, Falconara, Gibliscemi and Capodarso. Characteristic sedimentary cycle patterns allow (i) the sections to be cyclostratigraphically correlated, the 'bed-to-bed' correlations being confirmed by high-resolution planktonic foraminiferal biostratigraphy, and (ii) the Tripoli cycles to be calibrated to the astronomical record. Despite minor misfits the correctness of the tuning is evident from the match between precession-obliquity interference in the astronomical target and its reflection in the sedimentary cycle record. The tuning provides absolute astronomical ages for all sedimentary cycles and planktonic foraminiferal events. The base of the Tripoli is astronomically dated at 7.005 Ma, indicating that the onset of diatomite formation is diachronous in the Mediternean since it started 300 000 years earlier on Sicily than on Gavdos, south of Crete. The top of the Tripoli, and thus the onset of the salinity crisis proper on Sicily, arrives at 5.98 Ma.     

Obliquity‐dominated glacio‐eustatic sea level change in the early Oligocene: evidence from the shallow marine siliciclastic Rupelian stratotype (Boom Formation,Belgium)

Our results prove that glacio‐eustatic sea level oscillations in the early Oligocene were dominantly obliquity controlled with additional influence of the ∼100‐ and 405‐kyr eccentricity cycles. This was derived from spectral analysis of resistivity records from an extended downhole section of the Boom Clay succession in Belgium, that reveals a prevailing obliquity control on the laterally persistent metre‐scale alternations of shallow marine silt‐ and claystones in the Rupelian historical stratotype succession. These direct measurements of sea level variations in a shallow marine setting corroborate that variations with similar frequencies in benthonic oxygen isotope records from the open ocean indeed reflect, at least partly, ice volume change. A very tentative astronomical tuning has been established for the Boom Clay succession which awaits future confirmation with the addition of more accurate age calibration points.     

Pacing of the Toarcian Oceanic Anoxic Event (Early Jurassic) from astronomical correlation of marine sections

The Early Toarcian Oceanic Anoxic Event (OAE) in the Early Jurassic Period is associated with a major negative carbon isotope excursion (CIE), mass extinction, marine transgression and global warming. The Toarcian OAE is thought to have been caused by flood basalt magmatism, and may have been a trigger for mass extinction. However, these proposed causes of the Toarcian OAE and associated biotic crisis are not adequately resolved by a precise chronology. The duration of the Toarcian OAE has been estimated to be anywhere from ~ 0.12 to ~ 0.9 Myr, most recently 0.74 to 3.26 Myr from U–Pb dating. The CIE associated with the Toarcian OAE has a similar pattern at numerous localities, and there is evidence that the marine carbon isotope variations recorded astronomical forcing signals. Here we estimate a duration of ~ 620 kyr for the main negative CIE, ~ 860 kyr for the polymorphum zone and > 1.58 Myr for the levisoni zone based on 405-kyr astronomical eccentricity tuning of the marine section at Peniche (Portugal). This 405-kyr tuned series provides a ~ 2.5 Myr continuous high-resolution chronology through the Early Toarcian. There are 6, or possibly 7 short eccentricity cycles in the main CIE interval at Peniche. To confirm this astronomically based estimate, we analyzed three other sections at Yorkshire (UK), Dotternhausen (Germany), and Valdorbia (Italy) from marine carbon isotopic series. These four stratigraphic sections from Early Jurassic western Tethys record the Toarcian OAE with ~ 6 prominent carbon isotope cycles in the CIE that span a 600 ± 100 kyr duration. The Peniche 405-kyr tuned series indicates that the pre- and post-CIE intervals experienced strong precession–eccentricity-forced climate change, whereas the CIE interval is marked by dominant obliquity forcing. These dramatic and abrupt changes in astronomical response in the carbon isotopes point to fundamental shifting in the Early Toarcian paleoclimate system that was directly linked to the global carbon cycle.     

新疆若羌县阿热力一带冰沟群沉积环境及层序地层分析

新疆若羌县阿热力一带位于东昆仑西段北坡、柴达木盆地西南缘。地层区划隶属于秦祁昆地层区、东昆仑-中秦岭地层分区,该区冰沟群分布广泛。对该区开展区域地质调查、对冰沟群的沉积环境和层序地层进行分析研究具有重要地质意义。在开展区域地质调查中,采用路线调查、剖面测量、实验测试等方法对冰沟群的岩性特征、岩石组合、地球化学特征、古生物特征以及形成时代等进行了系统研究,依据岩石组合特征将其划分为狼牙山组和丘吉东沟组。把该区冰沟群与区域上都兰县冰沟群层型剖面进行了对比,通过对比研究,认为该区的冰沟群与都兰县冰沟群层型剖面具明显可对比性。依据岩性特征、岩石组合特征、古生物特征等,对冰沟群沉积环境进行了分析,认为狼牙山组沉积环境属于潮下较深水陆棚相低能环境;丘吉东沟组属于浅海陆棚相带内缘斜坡沉积环境。并对冰沟群层序地层进行了划分,将其划分为2个Ⅲ级层序,即第一层序（B-1）和第二层序（B-2）。     

Paleogene–Neogene Boundary of Primorye,Russian Far East

Complex geological and paleobotanic analysis of sections of the boundary Oligocene–Miocene sediments of southern Primorye is conducted. The presence of a stratigraphic hiatus is identified in the transitional complexes of the Pushkino and Pavlovka depressions but not in the sections of the Rakovka depression; thus, it is suggested to use one of them (borehole no. 15) to choose the stratotype of the Paleogene–Neogene boundary. The previous conclusion on the presence of economic coal deposits of Primorye within the Paleogene part of the Tertiary complex is supported. It is suggested to use the section which is exposed by the Rakovka brown coal open pit (point 9209) as a stratotype of the upper subformation of the Pavlovka Formation.     

High-resolution integrated stratigraphy of the OAE1a and enclosing strata from core drillings in the Bedoulian stratotype (Roquefort-La Bédoule,SE France)

In 2009 two wells were drilled with 100% core recovery at Roquefort-La Bédoule (Bouches-du-Rhône, SE France), the historical Bedoulian stratotype. Here we present holostratigraphic results based on a detailed study of the cored sediments. Our work confirms that the La Bédoule area offers one of the best records for the period spanning the late Bedoulian, the anoxic event OAE1a and the Bedoulian/Gargasian (lower-upper Aptian substages) transition. New data provide a refined succession of micropaleontogical events already well correlated with ammonites from previous fieldwork and, thus, improve the cross-calibration of bioevents with high-resolution isotope stratigraphy. Methods of the quantitative micropalaeontology applied on benthic foraminifera such as tritaxias help testing their probable orbitally triggered cyclicity, which might be used to precise estimates of duration of events such as OAE1a, the Dufrenoya furcata ammonite Zone, the Globigerinelloides ferreolensis planktonic foraminiferal zone and the C7 isotopic stage.The lithologic, biotic and possibly isotopic changes seen at the level of and around bed 170 (top of “Niveau Blanc” sensu auctorum) are strong arguments to use this key-level as the boundary between the two Aptian substages (or stages in an alternative classification) and to support the proposal of La Bédoule as a potential locality for the GSSP of the Gargasian Substage (or of historical Aptian sensu stricto, in the alternative classification).     

The famennian-lower carboniferous reference section Geran-Kalasi (Nakhichevan Autonomous Region,Azerbaijan)

One of the most complete sections of the Upper Devonian-Lower Carboniferous in the Nakhichevan Autonomous Region in Azerbaijan is described bed-by-bed. The section is located on the northeastern slope of Geran-Kalasi Mountain. The section features a continuous succession of marine beds and abundant fossils, including foraminiferans, bryozoans, tabulates, rugoses, brachiopods, ostracodes, crinoids, conodonts, and algae. A few ammonoids found in the section have not yet been identified. In the process of composing the 1:25000 scale geological map, a complex brachiopod zone is for the first time accepted as a major stratigraphic unit (indicating the stratotype and an assemblage of zonal brachiopod species).     

Only four major 100-ka glaciations during the Brunhes Chron?

 Early attempts at land–sea correlations between continental glaciations and the marine δ¹⁸O record were premature without a high-resolution continental stratigraphy. Existing schemes of continental subdivision and correlation-based facies floras and facies faunas do not provide the necessary resolution. This paper reports on a new high-resolution subdivision and correlation of the Pleistocene of the British Isles. Subdivision and correlation is accomplished primarily by aminostratigraphy based on aminozones which is calibrated by other geochronological means (U-series, TL, OSL, ESR, ¹⁴C, palaeomagnetic and ³⁶Cl rock-exposure dating) for correlation with oxygen isotope stratigraphy. These data are then used to test the hypotheses of Shackleton (1987) and Raymo (1997) that only four major glaciations occurred in the Brunhes Chron: during oxygen isotope stages 16, 12, 6 and 2. Their hypotheses are confirmed except for stage 2, when at least part of the British ice sheet was at its maximum somewhat earlier during stages 4 and 3. Received: 8 June 1998 / Accepted: 27 November 1998     

古近系研究新进展

介绍国际地层委员会古近系分会在全球界线层型剖面和点位( GSSP)工作上的新进展和我国陆相古近系分阶情况。中国陆相古近系分为8个阶:上湖阶(下古新统)、池江阶(上古新统)、岭茶阶(下始新统)、卢氏阶(中始新统下部)、垣曲阶(中始新统上部)、蔡家冲阶(上始新统)、乌兰布拉格阶(下渐新统)和塔本布鲁克阶(上渐新统)。其中,白垩系-古近系界线、古新统-始新统界线和始新统-渐新统界线与国际上相应界线接近或一致。近来,在湖南衡东地区获得碳同位素负向漂移的数据,使得该剖面可与新近国际地层委员会批准的伊普里斯阶层型剖面对比,其余各个阶的界线缺少磁性地层学和同位素地层学的证据,同时也有待于国际上“金钉子”的确立     

Coniacian-Santonian Planktic Stratigraphy in central Tunisia

In this study, we describe a new stratigraphy of three exposed sections in central Tunisia, integrating Coniacian and Santonian planktic foraminifera and calcareous nannoplankton, supported by ammonite and inoceramid bioevents. In the three sections, the Coniacian/Santonian (C/S) boundary lies slightly above the lowest occurrence (LO) of the calcareous nannofossil Lucianorhabdus cayeuxii, which marks nannofossil Zone CC16 and matches well with the LO of the planktic foraminifera Dicarinella asymetrica. It also lies ∼4–7 m below the LO of the inoceramid Platyceramus cycloides and the ammonite Texanites (Texanites) sp. Comparing these marker C/S bioevents with the global stratotype section, the Olazagutia section (Spain) shows that the stratigraphic range of the bioevents are variable. This observation must be taken into consideration when making regional chronostratigraphic correlations.