西藏措勤地区地层古生物研究新进展——兼论古生物学在新一轮地质大调查中的作用          下载免费PDF全文

石和  马润则  陶晓风  胡新伟  廖崇高  刘登忠 《沉积与特提斯地质》2001,21(2):78-83

在西藏措勤地区进行的1：25万区调中,地层古生物的研究取得一些新进展,在原来被认为属上新世陆相沉积的“乌郁群”上部发现丰富的有孔虫化石,根据有孔虫化石组合,这套地层应属阿普特期至赛诺曼期的深浅海沉积;在早白垩世至晚白垩世早期的角砾凝灰岩中首次发现大量硅化木化石,表明在此期间西藏气候温暖湿润,并有大量森林被毁于频繁的火山喷发;在拉果错-川巴断层南、北两侧的下二叠统 存在不同的化石群落,其南侧为代表浅海环境的珊瑚-Ting群落,北侧为深浅海的菊石群落,由此可以看出古生物化石研究在区调中的重要作用。  相似文献   

Fourier analysis of bivalve outlines: Implications on evolution and autecology     

Joel L. Gevirtz 《Mathematical Geology》1976,8(2):151-163

Fourier analysis of shape provides a unique means of studying morphologic variation of bivalves, especially in terms of their evolution and autecology. Amplitude spectra resulting from analysis may be refined, summarized, and further evaluated by a series of statistical measures designed to extract the maximum amount of information from outline features. Root mean square error comparison of harmonics, combined with a modified analysis of variance design and Snedecor's F-test, permits identification of significant amplitudes. Intra- and interspecific variation may be expressed as variance about mean power estimates derived from significant amplitudes for each species. Variance estimates of 14 species of heterodont bivalves indicate that venerid bivalves show considerably more intraspecific shape variability than do tellinid species. In both groups, however, species characterized by more elongate shells show less intraspecific variability. Evolutionary and environmental implications of interspecific shape variance in bivalves suggest that future comprehensive examination of specimens, collected in situ, may be fruitful.  相似文献   

Numerical strain analysis using polar coordinate transformations     

V. Hirsinger 《Mathematical Geology》1976,8(2):183-202

  相似文献   

地层及古生物学研究中系统观的再认识   总被引：3，自引：0，他引：3  

杨遵仪  史晓颖 《地球科学》1993,18(1):1-10

  相似文献   

内蒙古温都尔庙地区晚古生代石炭系沉积背景:沉积岩石学、古生物学及锆石U-Pb测年证据     

吕红达  王师捷  徐仲元  董晓杰 《世界地质》2019,(2):322-338

苏尼特右旗温都尔庙地区作为内蒙古兴蒙造山带南侧晚古生代构造研究的重点区域,对其研究有助于了解区内盆地的沉积年代、物质来源和构造演化等问题。选择区内石炭系酒局子组、阿木山组进行剖面、古生物以及LA-ICP-MS U-Pb定年等系统研究。分析结果显示:两组地层锆石年龄均在440Ma±,具有岩浆锆石特征,锆石磨圆分选特征均显示盆地有快速沉积、近源沉积的特征。酒局子组为一套滨浅海--沼泽-湖相沉积,磨圆分选差,局部含煤层;阿木山组为一套滨-浅海沉积环境下以灰岩为主的碳酸盐岩沉积地层。两组地层中发现了Neuropteris pseudovata、Callipteridium sp.及Schubertella sp.、Psedoschwagerina borealis等典型的晚石炭世-早二叠世植物、筳类化石。  相似文献   

福建泉州晚第四纪盆地沉积的孢粉和微体古生物及其古环境意义     

何耀堂 《福建地质》2011,30(3):224-232

福建泉州晚第四纪沉积物中孢粉,晚更新世以气候适应范围较宽的木本植物花粉占优势,适应温暖湿润气候的蕨类植物孢子较少;早全新世二者含量相当;中全新世蕨类植物孢子增多,木本植物花粉退居第二;晚全新世蕨类植物孢子占绝对优势,木本植物花粉相对减少。草本植物花粉浓度始终不高,但随着时代更新,种类增多。区内微体古生物在晚更新世和早全...  相似文献   

A New Triassic Primitive Ichthyosaur from Yuanan, South China     

CHEN Xiaohong  P. Martin SANDER  CHENG Long  WANG Xiaofeng 《《地质学报》英文版》2013,87(3):672-677

Based on the systematic study of two fossil skeleton specimens collected from the top of the third member of the marine Lower Triassic Jialingjiang Formation of Yuanan, Hubei Province, South China, a new Early Triassic primitive ichthyosaur Chaohusaurus zhangjiawanensis sp. nov. is reported and described. The beds yielding the type material are correlated with the Neospathodus homeri-N. triangularis Conodont zone. The new taxon is most similar to Chaohusaurus geishanensis Young and Dong, 1972 in the shape and configuration of the scapula, forefin, pelvic girdle and hindfin, presacral vertebral count and well-developed caudal peak, but distinguished from the latter by its larger size, the position of the pineal foramen in the centre of the parietal, the occurrence of a larger calcaneum in hindfin and the first sacral rib with distal expansion. The new species exhibits common features of primitive ichthyosaurs such as: (1) the prefrontal has an antero-dorsal shelf projecting towards the orbit; (2) the upper temporal fenestra is small; (3) the postorbital and the squamosal meet laterally to the upper temporal fenestra; and (4) cylindrical centra. However, more derived ichthyosaur characters are seen with the frontal separated from the orbital dorsal margin by the contact of the prefrontal and postfrontal, which offer new clues to the early radiation of ichthyosaurs.  相似文献   

西藏雅鲁藏布缝合带三叠系朗杰学群沉积岩古生物、地球化学特征及其物源区和构造背景分析   总被引：2，自引：0，他引：2  

王金贵  张鑫全  魏文通  专少鹏  陈超  张振利  常立海  申宗义 《地质学报》2020,94(4):1208-1226

随着近年来对朗杰学群的解体,发现前人对于朗杰学群、涅如组、修康群及洛林岩群的研究存在混淆,研究对象是否为朗杰学群应重新审慎,同时,几者是否为同一构造背景产物仍存在较大争议。本文对朗杰学群命名地(贡嘎县姐德秀镇-朗杰学乡一带)的朗杰学群重矿物特征、地球化学特征及古生物化石进行了研究。朗杰学群砂岩主量元素和微量元素化学成分低于地壳克拉克值,SiO_2含量平均为74.14%,K_2O/Na_2O值平均为0.70,反映砂岩成熟度较低,没有经历明显的成岩后生改造;化学蚀变指数(CIA)较集中,平均为71.55,属低级-中等风化程度,指示气候和构造环境都处于相对稳定状态;古环境分析显示,100Mg/Al_2O_3值平均为7.85,CaO/Fe+CaO值平均为0.314,表明朗杰学群形成于中等盐度的深水厌氧环境,且由北向南沉积水体逐渐加深;重矿物以锆石为主,其次为金红石,分选磨圆较差,ATi指数为93.3～98.97,ZTR指数为48.01～85.75,反映朗杰学群物源区的火山岩较为丰富,且搬运距离较近;REE-La/Yb图解、Hf-La/Th图解、F_1-F_2图解、Th/Sc-Zr/Sc图解及重矿物特征均显示朗杰学群物源区主要为中酸性火山岩及长英质陆源碎屑岩,结合前人研究的古水流方向证据,并对比直孔-松多特提斯洋演化及南冈底斯中-晚三叠世岩浆岩与朗杰学群碎屑锆石峰值年龄(240Ma),确认了朗杰学群物源来自南冈底斯;构造判别图解显示朗杰学群为大陆岛弧与活动大陆边缘环境之间特定构造背景下的产物,形成环境更靠近活动大陆边缘一侧;古生物化石以凸海燕蛤(Halobia convexa Chen, 1964)为代表,显示朗杰学群形成于晚三叠世卡尼期;综合风化程度、物源区、构造背景及形成时代分析,朗杰学群的形成与雅鲁藏布特提斯洋的演化相吻合。  相似文献   

Cleaning symbiosis among New Zealand fishes     

A. M. Ayling  R. V. Grace 《新西兰海洋与淡水研究杂志》2013,47(2):205-218

These first observations of cleaning symbiosis amongst New Zealand fishes were made between June 1967 and March 1970. Five species of labrid fishes; Halichoeres sp., Coris picta (Bloch and Schneider, 1801), Coris sandageri (Hector, 1884), Pseudolabrus luculentus (Richardson, 1848) and Pseudolabrus miles (= coccineus) (Bloch and Schneider, 1801) are now known to be facultative cleaners. One is an undescribed species and two others are new records for New Zealand. Halichoeres sp. is a more active cleaner than the other four and is almost an obligate cleaner. Observed behaviour indicates that these species are typical temperate zone cleaners.  相似文献   

脊椎动物化石的野外发掘与采集     

丁今朝 《贵州地质》2005,22(1):63-65

化石的野外发掘和采集是古生物研究的基础,本文通过对各种类型脊椎动物化石挖掘过程的介绍,详细讲述了这项工作的一般步骤、技术要点、器材设备、人员组织以及注意事项。  相似文献