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1.
浙东南下白垩统火山岩极为发育,岩石组合与浙江中部永康群差异甚大,称之为馆头组和朝川组似不合适。文成县峃口镇龙潭山(又称龙井山)剖面具代表性,拟以此部面为基础建立梅坪组和龙潭山组,合称文成群。与永康群对比,梅坪组大体相当馆头组,龙潭山组与朝川组和方岩组对比。 相似文献
2.
系统的探讨了区内白垩纪地层的划分与沉积相特征,深入研究了陆相地层的层序发育特征。指出,无论冲积扇、河流、三角洲或湖泊沉积的陆相地层层序均受地层基准面控制。地层基准面穿越旋回控制着陆相环境重大层序分布。根据不同时间间隔的基准面穿越旋回序次,将陆相层序划分为盆地充填层序、构造层序、层序、亚层序及小层序五个级别。每个层序根据基准面波动可划分为基准面上升沉积体系域和基准面下降沉积体系域,并可根据亚层序组的叠置特征进一步细分。根据上述陆相地层层序划分原理,作者将研究区白垩纪陆相地层划分为三个构造层序,并初步将葛村组划分为五个、浦口组四个、赤山组三个和泰州组三个沉积层序。 相似文献
3.
A juvenile lizard specimen with well-preserved skin impressions from the Upper Jurassic/Lower Cretaceous of Daohugou, Inner Mongolia, China 总被引:1,自引:0,他引:1
Lizards are now relatively well known from the Yixian Formation of northeastern China. In this study, we describe a juvenile
lizard from a fossil horizon at Daohugou, Inner Mongolia. These beds predate the Yixian Formation, and are probably Late Jurassic
or earliest Cretaceous in age. The new specimen thus documents the first lizard material from the Daohugou locality and is
the earliest lizard skeleton from China. Comparisons with developmental stages of modern lizards suggest the Daohugou lizard
is a hatchling. Although tiny, the specimen is notable in preserving exquisite skin impressions showing the variation in scalation
across the body, the shape and position of the cloacal outlet, and details of the manus and pes. These are the earliest recorded
lepidosaurian skin traces. In its general proportions and the possession of paired frontals, the small Daohugou lizard resembles
both the Yixian taxon Yabeinosaurus tenuis and the questionable Jeholacerta formosa, but it differs from the latter in scalation and, based on other characters, may be distinct from both. 相似文献
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5.
浙江墩头盆地横山组孢粉化石的发现及其地层意义 总被引:1,自引:0,他引:1
浙江墩头盆地红色岩层中上部首获丰富的以Cassopllis为主(58.39—62.54%)伴有Exesipollenites(15.21—15.84%),Hsuisporites(0.56—0.62%),Cicatricosisporites(0—0.31%)等孢粉化石。该孢粉组合特征既与国内外晚侏罗世孢粉组合面貌差别较大,又与早白垩世中晚期孢粉组合面貌存在明显差异,显示了早白垩世早期孢粉组合的色彩。笔者认为这套红色岩层应归早白垩世早期横山组为宜。 相似文献
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7.
The first definitive carcharodontosaurid (Dinosauria: Theropoda) from Asia and the delayed ascent of tyrannosaurids 总被引:2,自引:0,他引:2
Stephen L. Brusatte Roger B. J. Benson Daniel J. Chure Xing Xu Corwin Sullivan David W. E. Hone 《Die Naturwissenschaften》2009,96(9):1051-1058
Little is known about the evolution of large-bodied theropod dinosaurs during the Early to mid Cretaceous in Asia. Prior to
this time, Asia was home to an endemic fauna of basal tetanurans, whereas terminal Cretaceous ecosystems were dominated by
tyrannosaurids, but the intervening 60 million years left a sparse fossil record. Here, we redescribe the enigmatic large-bodied
Chilantaisaurus maortuensis from the Turonian of Inner Mongolia, China. We refer this species to a new genus, Shaochilong, and analyze its systematic affinities. Although Shaochilong has previously been allied with several disparate theropod groups (Megalosauridae, Allosauridae, Tyrannosauroidea, Maniraptora),
we find strong support for a derived carcharodontosaurid placement. As such, Shaochilong is the first unequivocal Asian member of Carcharodontosauridae, which was once thought to be restricted to Gondwana. The
discovery of an Asian carcharodontosaurid indicates that this clade was cosmopolitan in the Early to mid Cretaceous and that
Asian large-bodied theropod faunas were no longer endemic at this time. It may also suggest that the ascent of tyrannosaurids
into the large-bodied dinosaurian predator niche was a late event that occurred towards the end of the Cretaceous, between
the Turonian and the Campanian.
Electronic supplementary material The online version of this article (doi:) contains supplementary material, which is available to authorized users. 相似文献
8.
K. J. Edworthy D. A. Stott W. B. Wilkinson 《Journal of the American Water Resources Association》1978,14(3):554-575
ABSTRACT: Large-scale groundwater abstraction from the Cretaceous Chalk/Lower Tertiary Basal Sands aquifer system of the London Basin in the last 150 years has developed storage of more than 1000 Mm3. Limited operational recharge was undertaken in the 1950's encouraging further detailed study of the wider possibilities. Following a comprehensive hydrogeological reappraisal, an economic and engineering study and pilot-scale experiments, the Lea Valley has been shown to have the greatest potential for recharge. Artificial recharge into the Chalk at a rate of 9000 m3/d appears possible, through acidised 900 mm diameter boreholes. An understanding of the degree of interconnection between the Chalk and Basal Sands and of the causes of changes in quality of recharged water during storage was shown to be of particular importance to the successful operation of any recharge scheme using this system. A two-layer numerical groundwater model of the 800 km2 area and a surface/groundwater simulation model have been used to assist with the design of the 84,000 m3/d prototype scheme, and will also help in assessing its efficiency. The models will ultimately be used to manage the operation of the first stage development, now coming into use. 相似文献
9.
Theresa S. Presser 《Environmental management》1994,18(3):437-454
Hypothesized to be derived from Cretaceous marine sedimentary rocks, selenium contamination of the Kesterson National Wildlife
Refuge is traced through irrigation drainage to the source bedrock of the California Coast Ranges. This biogeochemical pathway
of selenium is defined here as the “Kesterson effect.” At the refuge ponds, this effect culminated in 1983 in a 64% rate of
deformity and death of embryos and hatchlings of wild aquatic birds. From the previous companion paper on irrigation drainage,
the Kesterson effect has been implicated in nine of 11 reconnaissance areas studied in the western United States. Deformities
have resulted in at least five of these sites. Climatic, geologic, hydrologic, and soil conditions in these reconnaissance
areas are similar to those in the area surrounding Kesterson National Wildlife Refuge in the west-central San Joaquin Valley
of California. In California, selenium, as selenate, was ultimately found weathered with sulfur from marine sources in soluble
sodium and magnesium sulfate salts, which are concentrated by evaporation on farmland soils. The Se, mobilized by irrigation
drainage, is bioaccumulated to toxic levels in refuge wetland ponds that are located mainly in hydrologically closed basins
and thus act as concentrating disposal points. The depositional environment of the ponds may be similar to that of the nutrient-rich
continental shelf edge and slope in which Cretaceous, Eocene, and Miocene sediments found to be seleniferous in the California
Coast Ranges were deposited. Bioaccumulation may be therefore a primary mechanism of selenium enrichment in ancient sediments
in addition to that of the formerly suggested Cretaceous volcanic pathway. 相似文献
10.
根据化石组合和火山岩的同位素年龄,并结合区域火山岩资料,本文厘定江苏镇江(?)山火山岩系的时代属早白垩世晚期至晚白垩世早期,而火山活动主要是在晚白垩世,进而论证了下扬子区在晚白垩世期间普遍有零星的酸性岩浆活动。 相似文献