吉林省大黑山条垒中部早二叠世地层的发现及其意义     

寇晓威 《吉林地质》1994,13(1):35-41

在吉林省梨树县孟家岭一带，于前人所划属的石炭纪磐石组砂岩、板岩、灰岩中发现丰富动植物化石。经鉴定有Ｈｕｓｌｅｄｉａｃｆｇｍｎｄｉｃｏｓｌａ，Ｓｔｅｎｏｓｃｉｓｍａｓｐ．，Ｃｏｍｐｓｏｐｔｅｒｉｓｓｐ．，其中植物与我国北部和西伯利亚等地区的安格拉植物群相当；从腕足、苔藓虫等化石组合上看均为早二叠世常见分子。大黑山条垒中部的这一首次发现，对吉林省的地层划分、分区及对比具有重要意义。  相似文献   

辽河坳陷滩海月东油田新近系馆陶组底界研究   总被引：3，自引：9，他引：3  

崔向东  王仁厚  石敦久  袁清秋  马宏斌 《地质科学》2007,42(3):455-468

辽河坳陷南部滩海地区馆陶组底界的确定长期以来缺乏划分的依据,因靠近南部中央低凸起及其两侧的馆陶组巨厚块状砂砾岩层与下伏东营组之间发育一套厚50～100m不等的砂砾岩与砂泥岩的正粒序沉积,其时代归属有不同意见。本文首次在这套有争议的地层的岩心中发现了属新近纪的孢粉化石组合以及属于古近纪沙河街组和东营组中-下部的藻类再沉积化石,为本套地层归属新近纪馆陶组提供了可靠的生物化石对比依据。渤海湾盆地的新近系与下伏古近系间普遍为角度不整合接触,因风化侵蚀面起伏不平而馆陶组与下伏东营组的岩性变化可分为突变型、渐变型和“三明治”型3种。正确认识馆陶组底界对合理划分和对比油气层组有重要的勘探意义。  相似文献   

Rapid response of forested vegetation to multiple climatic oscillations during the last deglaciation in the northeastern United States     

Zicheng Yu 《Quaternary Research》2007,67(2):297-303

Isotopic and pollen results from a marl lake (White Lake) in the Mid-Atlantic region of USA indicate the coupling of climate and vegetation changes. Oxygen isotopes of calcite from this site show multiple oscillations at millennial and centennial scales, including the Younger Dryas with 3‰ negative shifts in δ¹⁸O at 12.4-11.4 ka (1 ka = 1000 cal yr BP) and three cold events of magnitude 1-2‰ shifts during the Bølling-Allerød warm period (BOA) at 14.3-12.4 ka. Pollen data from the same core show nearly synchronous, close correspondence with isotope-inferred climate shifts, indicating rapid forest response to deglacial climate oscillations in southern New England. A plateau-like BOA is similar to other records around the North Atlantic Ocean.  相似文献   

A fossil insect egg on an Early Cretaceous conifer shoot from the Wealden of Germany     

《Cretaceous Research》2015

  相似文献   

A new genus and species of Praeaulacidae (Hymenoptera: Evanioidea) from Upper Cretaceous Myanmar amber     

《Cretaceous Research》2015

A new fossil praeaulacid wasp, Habraulacus zhaoi gen. et sp. nov., is described and figured from Upper Cretaceous Myanmar amber. The new genus is established based on the following characters: mesosoma stout, metasoma elongated ellipse with the first metasomal segment very thin and tubular (like a petiole), forewing with pterostigma long and narrow, and both veins Rs+M and 1m-cu very long, forming a long cell 1mcu. Species of Praeaulacidae demonstrate a distinct evolutionary trend, which consists of miniaturization, venational reduction and enlargement of pterostigma, and reduction of number of the antennal segments from the Jurassic to Cretaceous. However, except for the miniaturization, this hardly concerns Habraulacus.  相似文献   

New genera and species of bark-gnawing beetles (Coleoptera: Trogossitidae) from the Yixian Formation (Lower Cretaceous) of Western Liaoning,China     

《Cretaceous Research》2015

Two new genera from the Lower Cretaceous Yixian Formation of Beipiao City, Liaoning Province, northeastern China are described and illustrated. Paracretocateres gen. nov. (type species P. bellus, sp. nov.) and Yixianteres gen. nov. (type species Y. beipiaoensis sp. nov.) are assigned to the subfamily Lophocaterinae based on the state of the procoxae which are not projecting, the transverse procoxal cavities, and the exposed protochantins. The new taxa broaden the diversity of this family and provide further morphological characters for phylogenetic studies of Trogossitidae. They also provide evidence that lophocaterines well-diversified prior to the trogossitines and their biologies may have been similar to extant forms.  相似文献   

Early Cretaceous spinicaudatans (“conchostracans”) from lacustrine strata of the Sidi Aïch Formation in the northern Chotts range,southern Tunisia: Taxonomy,biostratigraphy and stratigraphic implication     

《Cretaceous Research》2015

The fossil clam shrimp genus Cratostracus was first described from the Turonian–Coniacian (Upper Cretaceous) Qingshankou Formation in the Jilin and Heilongjiang provinces of China, and it has been found to range down into the Aptian Guantou Formation in Zhejiang Province of southeastern China. Recently, species tentatively attributable to it (Cratostracus? cheni) has been recorded in the well-known Jehol Biota bearing Barremian–lower Aptian (Lower Cretaceous) Yixian Formation in western Liaoning Province of northeastern China. The species described in this paper as Cratostracus? tunisiaensis sp. nov. was recovered from the Sidi Aïch Formation in the Chotts area of southern Tunisia. Although only tentatively attributed to Cratostracus, its occurrence is consistent with a Barremian (Early Cretaceous) age for the formation. This first direct dating of the Sidi Aïch Formation gives a valuable insight for the stratigraphy of the region and will make it possible to more precisely correlate the different outcrops of the Sidi Aïch Formation. Moreover, the new fossil discovery allows a reconstruction of the paralic ecosystem that characterized the study area during the Barremian.  相似文献   

Paleoenvironmental reconstruction of the coastal Monte Léon and Santa Cruz formations (Early Miocene) at Rincón del Buque,Southern Patagonia: A revisited locality     

《Journal of South American Earth Sciences》2015

Sedimentological, ichnological and paleontological analyses of the Early Miocene uppermost Monte León Formation and the lower part of the Santa Cruz Formation were carried out in Rincón del Buque (RDB), a fossiliferous locality north of Río Coyle in Santa Cruz Province, Patagonia, Argentina. This locality is of special importance because it contains the basal contact between the Monte Léon (MLF) and the Santa Cruz (SCF) formations and because it preserves a rich fossil assemblage of marine invertebrates and marine trace fossils, and terrestrial vertebrates and plants, which has not been extensively studied. A ∼90 m-thick section of the MLF and the SCF that crops out at RDB was selected for this study. Eleven facies associations (FA) are described, which are, from base to top: subtidal–intertidal deposits with Crassotrea orbignyi and bioturbation of the Skolithos-Cruziana ichnofacies (FA1); tidal creek deposits with terrestrial fossil mammals and Ophiomorpha isp. burrows (FA2); tidal flat deposits with Glossifungites ichnofacies (FA3); deposits of tidal channels (FA4) and tidal sand flats (FA5) both with and impoverish Skolithos ichnofacies associated; marsh deposits (FA6); tidal point bar deposits recording a depauperate mixture of both the Skolithos and Cruziana ichnofacies (FA7); fluvial channel deposits (FA8); fluvial point bar deposits (FA9); floodplain deposits (FA10); and pyroclastic and volcaniclastic deposits of the floodplain where terrestrial fossil mammal remains occur (FA11).The transition of the MLF–SCF at RDB reflects a changing depositional environment from the outer part of an estuary (FA1) through the central (FA2–6) to inner part of a tide-dominated estuary (FA7). Finally a fluvial system occurs with single channels of relatively low energy and low sinuosity enclosed by a broad, low-energy floodplain dominated by partially edaphized ash-fall, sheet-flood, and overbank deposits (FA8–11). Pyroclastic and volcaniclastic materials throughout the succession must have been deposited as ash-fall distal facies in a fluvial setting and also were carried by fluvial streams and redeposited in both estuarine and fluvial settings. These materials preserve most of the analyzed terrestrial fossil mammals that characterize the Santacrucian age of the RDB's succession. Episodic sedimentation under volcanic influence, high sedimentation rates and a relatively warm and seasonal climate are inferred for the MLF and SCF section.Lateral continuity of the marker horizons at RDB serve for correlation with other coastal localities such as the lower part of the coastal SCF south of Río Coyle (∼17.6–17.4 Ma) belonging to the Estancia La Costa Member of the SCF.  相似文献   

成矿古水热系统与热液铀矿床研究历史,现状与展望   总被引：3，自引：0，他引：3  

孙占学  李学礼 《地球科学进展》1996,11(6):569-574

介绍了成矿古水热系统与热液铀矿床研究的历史与现状。指出了以往研究只强调水及溶质起源，而对热源重视不够的欠缺。同时，结合热液铀 矿床的研究情况，对成矿古水热系统研究的下一步发展方向进行了展望。  相似文献   

The first record of a bryophyte in Upper Cretaceous amber from Taimyr,northern Siberia: Taimyrobryum martynoviorum gen. et sp. nov. (Bryopsida)     

《Cretaceous Research》2016

Cretaceous bryophyte fossils are known only from a few localities and only a few are known in ultrastructural fidelity. We describe a fossil moss gametophyte from Upper Cretaceous Taimyr amber and place it in the fossil genus Taimyrobryum martynoviorum gen. et sp. nov. (Bryopsida). Its unbranched, somewhat zig-zagged stems with distantly spaced, spreading, narrowly lanceolate leaves and the unbranched costa match the gross morphology of Dicranidae; however, the uniformly prosenchymatous leaf cells contradict an affiliation to this subclass. The Yantardakh in the Taimyr Peninsula is the fourth and northernmost Cretaceous amber locality yielding inclusions of bryophytes.  相似文献