An early Paleogene sponge fauna,Chatham Island,New Zealand     

Michelle Kelly  John S. Buckeridge 《新西兰海洋与淡水研究杂志》2013,47(4):899-914

A late Paleocene‐early Eocene (c. 60–53 Ma) poriferan fauna, comprising hexactinellids (Class Hexactinellida), astrophorids (Class Demospongiae: Family Astrophorida), and lithistids ("lithistid” Demospongiae) has been identified from the Tutuiri Greensand outcropping on the north coast of Chatham Island, New Zealand. Most of the fossils are hexactinellids, comprising extremely delicate siliceous networks embedded in friable sandstone. The sediment matrix within and around these skeletons contains numerous siliceous demosponge spicules, many of which are exceptionally well preserved. The soft friable matrix of the Tutuiri Greensand has made extraction a relatively simple process, making taxonomic identification of the material, and comparison with adjacent Recent and other New Zealand Eocene faunas possible. These sponge body fossils and spicule microfossils indicate a fauna that was once dominated by hexactinellids, lithistid, and astrophorid demosponges. A qualitative comparison of the abundance and diversity of the Tutuiri Greensand sponge fauna with the present‐day Chatham Rise sponge fauna indicates that the late Paleocene‐early Eocene fauna is as diverse as the Recent fauna, for the hexactinellid sponges and astrophorid demosponges, and much more diverse for lithistid sponges. The paleoecology of the Tutuiri Greensand has been interpreted as inner to mid shelf water depths (50–250 m) but the poriferan fauna described here is more like that of the present‐day soft sediment benthic environment of the Chatham Rise at 800–1200 m.  相似文献   

Biostratigraphy of a Paleocene–Eocene Foreland Basin boundary in southern Tibet     

Xiaoqiao Wan  Xi Wang  Luba F. Jansa 《地学前缘(英文版)》2010,1(1):69-79

This study of the Paleocene–Eocene boundary within a foreland basin of southern Tibet, which was dominated by a carbonate ramp depositional environment, documents more complex environmental conditions than can be derived from studies of the deep oceanic environment. Extinction rates for larger foraminiferal species in the Zongpu-1 Section apply to up to 46% of the larger foraminiferal taxa. The extinction rate in southern Tibet is similar to rates elsewhere in the world, but it shows that the Paleocene fauna disappeared stepwise through the Late Paleocene, with Eocene taxa appearing abruptly above the boundary. A foraminifera turnover was identified between Members 3 and 4 of the Zongpu Formation—from the Miscellanea–Daviesina assemblage to an Orbitolites–Alveolina assemblage. The Paleocene and Eocene boundary is between the SBZ 4 and SBZ 5, where it is marked by the extinction of Miscellanea miscella and the first appearance of Alveolina ellipsodalis and a large number of Orbitolites. Chemostratigraphically, the δ13C values from both the Zongpu-1 and Zongpu-2 Sections show three negative excursions in the transitional strata, one in Late Paleocene, one at the boundary, and one in the early Eocene. The second negative excursion of δ13C, which is located at the P–E boundary, coincides with larger foraminifera overturn. These faunal changes and the observed δ13C negative excursions provide new evidence on environmental changes across the Paleocene–Eocene boundary in Tibet.  相似文献   

A large collection of Presbyornis (Aves,Anseriformes, Presbyornithidae) from the late Paleocene and early Eocene of Mongolia     

Evgeny N. Kurochkin  Gareth J. Dyke 《Geological Journal》2010,45(4):375-387

We describe a large collection of fossil ‘waterfowl’ bones that are referable to the extinct clade Presbyornithidae (Anseriformes). All of these fossils were collected between 1971 and 1994 from Upper Paleocene and Lower Eocene sediments at the Tsagaan Khushuu site in the Gobi Desert of southern Mongolia. The collection includes specimens referred to a new small species within the genus Presbyornis Wetmore, 1926 as well as large numbers of bones that we place in the genus Presbyornis. On this basis of the Tsagaan Khushuu collection we suggest that several species of Presbyornis likely coexisted in this region; indeed, the presence of large numbers of middle‐sized, morphologically consistent but probably ecologically disparate species at the Tsagaan Khushuu site is consistent with the range of variation seen, for example, in taxa of extant dabbling ducks (Anatini). Although the anatomy and phylogenetic position of Presbyornithidae (in particular Presbyornis) are well known, this material from Mongolia further demonstrates the prevalence of these birds in aquatic and semi‐aquatic habitats by the earliest Paleogene. Because presbyornithids are also well documented from the late Cretaceous, their palaeoecology and morphological diversity provides a clue to selective avian survivorship across the Cretaceous‐Paleogene (K‐Pg) boundary. Copyright © 2009 John Wiley & Sons, Ltd.  相似文献   

Comparative paleofloristics of the Albian-Early Paleocene in the Anadyr-Koryak and North Alaska Subregions,part 2: The North Alaska Subregion     

A. B. Herman 《Stratigraphy and Geological Correlation》2007,15(4):373-384

The Albian-Paleocene phytostratigraphic scheme suggested in this work for the North Alaska Subregion of the North Pacific differs from the previous ones and includes three phytostratigraphic horizons of subregional extent and four plant-bearing beds. The scheme is based on distinguished successive stages in flora evolution, being substantiated by comprehensive data on the described floral (plant macrofossils) assemblages. As is established, sedimentation environments gradually changed during the Albian-Paleogene from the west of the subregion to the east so that the marine sedimentation and accumulation of sediments in general terminated in eastern areas later than western ones.  相似文献   

东海陆架盆地台北坳陷新地层单位——月桂峰组   总被引：2，自引：0，他引：2  

姜亮  李保华  钟石兰  张一勇  王建平 《地层学杂志》2003,27(3):210-211,215

在微体古生物和岩石地层学分析基础上 ,建立了东海陆架盆地台北坳陷新的地层单元——月桂峰组。月桂峰组分布于东海陆架盆地台北坳陷西带 ,由灰黑色泥岩、砂岩组成 ,上覆灵峰组、下伏石门潭组。它属古近纪古新世沉积 ,并推测可能为古新世早期。该地层相当于苏北盆地阜宁组一段。月桂峰组中微体化石特征表明月桂峰组当时沉积环境可能为淡水湖泊  相似文献   

Sur l’origine karstique et l’age plio-quaternaire des accumulations bréchiques dites ?brèches marines et paléocènes? d’Amélie-les-Bains (Pyrénées-Orientales, France)     

Joseph Canerot  Bernard Laumonier  Thierry Baudin 《Eclogae Geologicae Helvetiae》2006,99(1):49-64

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Dinoflagellate and foraminiferal biostratigraphy of the Gurpi Formation (upper Santonian–upper Maastrichtian), Zagros Mountains, Iran     

Ebrahim Ghasemi-Nejad  Mohammad Hadi Hobbi  Poul Schiler 《Cretaceous Research》2006,27(6):828-835

A rich dinoflagellate cyst assemblage has been recovered from an outcrop of the Gurpi Formation, the hydrocarbon source rock in the South Iranian Basin. Key dinoflagellates recorded in the section studied provide a means of correlation with zonation schemes for Australasia and north-west Europe. These include Eucladinium kaikourense, Nelsoniella aceras, Odontochitina spp., Cannosphaeropsis utinensis, Palaeocystodinium denticulatum and Dinogymnium spp. The assemblage points to a late Santonian–late Maastrichtian age for the Gurpi Formation. Dinoflagellate and planktonic foraminiferal evidence indicates the presence of a hiatus spanning the uppermost Maastrichtian to at least the lowermost Danian at the base of a glaucony-rich layer separating the Gurpi Formation from the overlying Pabdeh Formation. Palynofacies and lithofacies profiles suggest that the sediments were deposited in an open, relatively deep marine outer ramp environment belonging to ramp facies 8 and 9.  相似文献   

Paleogene carbon isotope excursions in the Bunkers Hill borehole: Hampshire Basin, UK     

Emma Hodgson  Stephen T. Grimes  Gregory D. Price  Meriel E.J. Fitzpatrick  Malcolm B. Hart  Melanie J. Leng 《Proceedings of the Geologists' Association. Geologists' Association》2011,122(3):460-471

This study demonstrates that the Bunkers Hill borehole, which is located within the Hampshire Basin, contains a carbon isotope excursion (CIE) in the Upnor Formation followed by a positive recovery from another CIE within the overlying Reading Formation. This study has also shown that the CIE in the Upnor Formation predates the Paleocene/Eocene Thermal Maximum (PETM), while the carbon isotope recovery at the base of the Reading Formation is most likely related to it. The positive carbon isotope trend, before a return to more negative values, seen throughout the majority of the Reading Formation can also be seen in coeval deposits in the Jubilee 404T borehole in the London Basin and in the Tienen Formation in the Doel and Kallo boreholes from the Belgium Basin. This indicates that this post-PETM carbon isotope signal may, therefore, be regional if not global in nature.  相似文献   

Inter-regional correlation of transgressions and regressions in the Cretaceous period   总被引：1，自引：0，他引：1  

T. Matsumoto 《Cretaceous Research》1980,1(4):359-373

Well investigated platforms have been selected in each continent, and the history of Cretaceous transgressions and regressions there is concisely reviewed from the available evidence. The factual records have been summarized into a diagram and the timing of the events correlated between distant as well as adjoining areas.On a global scale, major transgressions were stepwise enlarged in space and time from the Neocomian, via Aptian-Albian, to the Late Cretaceous, and the post-Cretaceous regression was very remarkable. Minor cycles of transgression-regression were not always synchronous between different areas. Some of them were, however, nearly synchronous between the areas facing the same ocean.Tectono-eustasy may have been the main cause of the phenomena of transgression-regression, but certain kinds of other tectonic movements which affected even the so-called stable platforms were also responsible for the phenomena. The combined effects of various causes may have been unusual in the Cretaceous, since it was a period of global tectonic activity. The slowing down of this activity followed by readjustments may have been the cause of the global regression at the end of the Cretaceous.  相似文献   

江陵凹陷古新世地下卤水型硼矿成因研究     

王春连  孟令阳  刘成林  余小灿  颜开  刘思晗  游超  栗克坤  滕晓华 《岩石矿物学杂志》2021,40(1):1-13

中国探明硼资源主要分布于东北和青藏等地区,矿床品位低,共伴生矿物多,开发成本高,开发利用程度低,难以满足产业发展需求。目前,在江汉盆地江陵凹陷勘探中发现卤水中B2O3浓度达3 g/L,Li、K、Br、I、Rb、Cs含量超过工业品位,综合利用价值高。本文在前人研究的基础上,对江陵凹陷新生代卤水型硼矿开展水化学、同位素地球化学及实验地球化学分析,重点研究了古气候、构造和玄武岩等对卤水成矿的影响,探究其成因机制。研究初步认为,不同的储卤层岩性具有不同的地球化学和同位素特征,玄武岩有强烈的蚀变,说明地下流体对火成岩发生了交代作用,玄武岩的水-岩反应是富硼卤水矿的重要物质来源;一定盐度的流体有利于硼离子的活化,高盐度流体是硼成矿元素主要的迁移载体,表生环境下干热的古气候使含矿水体蒸发浓缩是富硼卤水富集成矿的重要形成机制。  相似文献