检索结果-南通市图书馆

Jurassic-Cretaceous Boundary Strata of the Somanakamura Group in NE Japan and their Correlation with Coeval Terrestrial Deposits in China

引用

Acta Geologica Sinica(English Edition) 2015年第1期89卷 285-299页

作者： LI Wei WAN Xiaoqiao Atsushi MATSUOKA ZHANG Shuqin QU Haiying Tsubasa TAMURA Kohei YOSHINO State Key Laboratory of Biogeology and Environmental Geology China University of Geosciences Department of Geology Niigata University Research Center of Paleontology and Stratigraphy Jilin Univercity

Defining the Jurassic-Cretaceous boundary is a controversy in stratigraphic study of the world. It has been widely accepted that this boundary can be defined at the bottom of Berriasian in Tetbys, with the appearance of the ammonite Berriasellajacobi dating to ca. 145 Ma. However, it is difficult for the widespread terrestrial deposits in China to correlate with the international standard of marine facies. The Somanakamura Group in Japan is represented by a succession of marinecontinental transitional strata. It provides a bridge of marine and nonmarine stratigraphic correlation. The ammonite and radiolarian fossils preserved in this group suggest an age from Bajocian to early Valanginian. The J-K boundary was defined in or atop the Tomizawa formation of the group according to the ammonite data. The present authors study the fossil spores and pollen newly found from the Tomizawa and Koyamada formations. Three assemblages have been recognized. They are Assemblage 1 （Cyathidites-Classopollis） from the upper part of the Tomizawa formation, Assemblage 2 （Cyathidites-Jiaohepollis） from the lower part of the Koyamada formation, and Assemblage 3 （Cyathidites-Spheripollenites-Ephedripites） from the middle to upper part of the Koyamada formation. With the reference of ammonite evidence, the J-K boundary can be defined between Assemblage 1 and Assemblage 2. This palynological J-K boundary can be correlated with that of terrestrial sequence in China. However, local biostratigraphy imply that the continental J-K boundary in China is of 135 or 137 Ma age. It has a considerable discrepancy from the marine standard. Biogeographically, the distribution pattern of spores and pollen in southern China is in accordance with that in the Somanakamura Group, which parallels the tuchengzi formation in northeastern China. By the palynological correlation between the Somanakamura Group and the strata in southern China, and then with the sequence in northeastern China, it is suggested that th

关键词： Somanakamura Group Jurassic-Cretaceous boundary ammonites spores and pollen,Tomizawa formation Koyamada formation tuchengzi formation

来源：

维普期刊数据库

同方期刊数据库评论

在线全文

学校读者我要写书评

暂无评论

Sedimentary Petrology Characteristics and Their Implications for Provenance of Flowerpot Basin Jurassic System in Yanqing County, Beijing

引用

Journal of Geoscience and Environment Protection 2016年第6期4卷 69-79页

作者： Yaxuan Yuan Hongliang Wang School of Energy Resources China University of Geosciences Beijing China

The characteristics of sedimentary petrology are significant in determining geological provenance. By using field outcrop observation and indoor identification of thin sections, the characteristics of Jurassic system tuchengzi formation clastic rocks exposed in the Beijing Yanqing “flowerpot” basin, which include rock types, clastic composition and cement type, etc. have been analyzed systematically to identify the provenance direction and tectonic setting and nature of the provenance. Research shows that the sedimentary rocks in this area belong to analluvial fan and braided river sedimentary rock system and include mainly conglomerates, lithic sandstone, and feldspathic lithic sandstone. The main compositions of the conglomerate are dolomite and limestone. Nearly 50% to 70% of the sandstones are mainly polycrystalline quartz;10% to 15% are feldspar;and 40% to 55% are composed of debris from mainly magmatic and metamorphic rocks. A Dickinson triangular diagram indicates that the provenance type in this area is recycled orogny evolving from clastic recycled orogeny such as a collisional orogenic belt to a transitional recycled orogeny. On the basis of the geographic position and tectonic setting, three types of provenance can be identified in the Jurassic system tuchengzi formation. The far source provenances are Archean erathem basement metamorphic rocks in the northern basin and granite or adamellite that intruded rocks of the Late Jurassic epoch of the Yanshanian period in the northeast. The nearby provenance is the Mesoproterozoic erathem Changchengian system and Jixianianian system dolomite in both the east and west.

关键词： tuchengzi formation Sandstone Components Petrologic Characteristics Provenance Analysis Dickinson Triangular Diagram

来源：

维普期刊数据库评论

在线全文

维普期刊数据库

学校读者我要写书评

暂无评论

树木的向阳性特征指示华北板块的旋转（英文）

树木的向阳性特征指示华北板块的旋转（英文）

引用

中国古生物学会第十二次全国会员代表大会暨第29届学术年会

作者：蒋子堃刘本培王永栋黄敏 Tom Kapitany 田宁卢远征邓胜徽张瑞刚 Chinese Academy of Geological Sciences State Key Laboratory of Palaeobiology and Stratigraphy Nanjing Institute of Geology and PalaeontologyChinese Academy of Sciences China University of Geosciences

Trees grow towards the sunlight via a process called positive *** measured the eccentricities of living and fossil trees at the same latitudes within the North China *** dominant eccentricity of living trees was southwest at 219°± 5°.By contrast,standing in situ fossil trunks in the Mid-Late Jurassic Tiaojishan formation and the Late Jurassic tuchengzi formation had average eccentricities of 237° and 233.5°,*** the direction of phototropism from extant trees with the in situ preserved fossil stems,the eccentricity of petrified wood from the Tiaojishan formation is 13-23° more towards the southwest than that of the living ***,the eccentricity of petrified wood in the tuchengzi formation is 9.5-19.5° more southwest than extant *** offsets indicate that the North China Plate rotated clockwise from the Late Jurassic to the present *** result is almost coincident with palaeomagnetic results that we also collected,which indicate that the North China Block rotated clockwise by 26.5°± 5.5° since the Late *** 3.5° difference in the phototropism orientation between the two fossil tree localities is suggestive of continuous clockwise rotation of the North China Plate from the Middle Jurassic through the Late *** study is using tree ring eccentricity as a proxy to determine plate rotation(in general).The useful method to explain the rotation according to the tree rings in both living and fossil plants is universal,and is applied to other fields of research.

关键词： phototropism Tiaojishan formation tuchengzi formation North China Block

来源： cnki会议评论

在线全文

cnki会议

学校读者我要写书评

暂无评论

欢迎您,

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案：

请选择收藏分类：

通借通还

欢迎您,

建议与咨询 留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

时间限定

文献类型

馆藏选择

核心期刊

语言

文献类型

帮助

文字说明：

检索规则说明：

检索范例：

分类表

所选分类

限定检索结果

文献类型

馆藏范围

日期分布

学科分类号

主题

机构

作者

语言

在线全文

在线全文

在线全文

请选择保存的检索档案： 新增检索档案 确定 取消

请选择收藏分类： 新增自定义分类 确定 取消

通借通还

建议与咨询留下您的常用邮箱和电话号码，以便我们向您反馈解决方案和替代方法

请选择保存的检索档案：

请选择收藏分类：