首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   3篇
  免费   0篇
  2013年   3篇
排序方式: 共有3条查询结果,搜索用时 15 毫秒
1
1.
Limestone outcrops that form a north-south belt approximately 1.4 km long, 15 km east of Manilla and previously referred to as the Uralba Beds, and associated rocks, are shown to be an olistostromal component of the Wisemans Arm Formation. Elongate olistoliths up to 100 m in length are flanked by limestone conglomerate with clasts set in a volcaniclastic matrix derived from a range of volcanic rock types. Volcanic olistoliths, including a mass of ankaramitic basalt, are also present. Conodont faunas of differing ages were obtained from various outcrops. A Late Ordovician (Eastonian, Ea3) fauna of over 400 elements from some outcrops is identical to one recently documented from elsewhere in the Wisemans Arm Formation. A small Early Silurian (late Llandovery-early Wenlock) fauna from four outcrops (including two formerly thought to be Ordovician) comprises the first documented conodont fauna of this age from the New England Fold Belt.  相似文献   
2.
On the basis of representative collections made from seven measured sections in western Hubei and Hunan, four early Llanvirn and five late Llanvirn-early Caradoc trilobite biofacies are distinguished along a bathymetric gradient from shallow to deep outer shelf. The diversity and relative abundance of mesopelagic cyclopygids gradually increased southwards or seawards. According to the facies association exhibited in the region, the upper limit of living depth for different forms is inferred as follows: 1) more than 70 m (M. (Microparia)); 2) less than 100 m (M. (Quadratapyge), Pricyclopyge, Aspidaeglina); 3) at approximately 100 m (Cyclopyge); and 4) more than 100 m (Symphysops, Psilacella). Benthic forms were absent in the deep outer-shelf basin because of stagnant conditions. In shallower sites of the outer shelf, genera of nileids in the carbonate facies and raphiophorids in the clastic facies were relatively abundant, but some endemic forms, such as the asaphid Birmanites and remopleuridid Hexacopyge, became dominant during the late Llanvirn-early Caradoc. Rorringtoniids are mainly associated with deeper outer-shelf facies. Panderia is common in an early Llanvirn nileid fauna at Yichongqiao, Cili area, and may well indicate development of shelf carbonate buildups. A transgressive event is suggested by the sudden appearance of rich Cyclopyge in the early Caradoc at Jiuxi, Changde.  相似文献   
3.
An assemblage of well-preserved Devonian trilobites is described from limestones in Satun Province, southern Thailand. The biogeographic implications are briefly discussed. The fauna, which is of Early Devonian age, probably Emsian, includes Decoroproetus, Cornuproetus, Platyscutellum and two species of Reedops, one of which is new. No similar fauna has been described before from the Shan-Thai block. The fauna is a typical Hercynian assemblage with close specific comparisons with Turkey, Morocco and Bohemia.  相似文献   
1
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号