摘要
1918年丁格兰(F. K. Tengenren)在湘西黔东一带调查汞矿地质时,对湘西和黔东寒武系做了初步研究。之后,田奇(璀乃)(1940)、王作宾和贾福海(1943)、刘国昌(1945)、卢衍豪(1956)、叶戈洛娃、项礼文等(1963)、湖南省地质局区测队(1964)、林焕令等(1966)、杨家騄(1978)和李善姬等(1980)相继对湘黔边境地区寒武系和三叶虫动物群进行了研究。本文研究区位于湖南省桃源县西北部瓦儿岗乡附近,前人对该区寒武系的研究工作开展较晚。1965年和1973年,湖南省地质局区测队在进行1/20万大庸幅和常德幅的区测过程中。
This paper deals with the Middle Cambrian stratigraphy and trilobite fauna near Wa'ergang in Taoyuan County, northwestern Hunan. Based on lithological charaters, the Middle Cambrian can be divided into two parts: the lower part is the Tonggutan Formation (76.25m in thickness) composed of dark grey, thick-bedded striped dense limestone, argillaceous limestone and dolomite intercalated with grey, dark grey arenaceous, carbonaceous shale (with a layer of arenaceous, carbonaceous shale in the basal part about 4.3m in thickness); the upper part is the Fengmuping Formation (191.81m. in thickness) composed of dark grey, grey, medium-to thick-bedded argillaceous limestone, muddy limestone and crystalline limestone with dolomitic limestone lenses interbedded with dark grey arenaceous shale, dolomitic limestone and dolomite.
The Tonggutan Formation yields Protospongia sp. and hyolithids, while the Fengmuping Formation bears very abundant trilobites. The Fengmuping Formation and the lower Upper Cambrian Laochatian Formation can be divided into four trilobite zones and two subzones in descending order as follows:
Upper Cambrian
Laochatian Formation
(4) Agnostascus (Paragnostascus) sinensis Zone
ⅱ. Liostracina Subzone
ⅰ. Agnostascus (Paragnostascus) orientalis Subzone
Middle Cambrian Fengmuping Formation
(3) Lejopyge armata Zone
(2) Fuchouia chiai-Lisania tungjenensis Assemblage Zone
(1) Pseudophalacroma triangularis-Ptychagnostus atavus Assemblage Zone
The Middle Cambrian and Upper Cambrian boundary is drawn between the Lejopyge armata Zone and the Agnostascus (Paragnostascus) sinensie Zone in the present paper.
The Table Ⅲ shows the zonation and correlation of the Middle Cambrian in Taoyuan, western Zhejiang, northern Tianshan, North China, Malyi Karatau and Australia.
Family Catillicephalidae Raymond, 1938 Genus Buttsia Wilson, 1951 Waergangia subgen, nov.
Type species Buttsia (Waergangia) spect, bilis subgen, et sp. nov. From Lejopyge armata Zone, Fengmuping Formation at Wa'ergang, Taoyuan, northwestern Hunan, designated herein. Other species Buttsia globosa Lu et Lin (Peng, 1987, p. 94, pl. Ⅵ, figs. 4a, b) from Lejopyge sinensis Zone, Yangliugang Formation of Duibian, Jiangshan, western Zhejiang.
Diagnosis Glabella subglobose in shape. Fixed cheek comparatively broad, about onehalf as wide as the glabella between palpebral lobes. Lateral glabellar furrows and brim distinct. Occipital ring with a mesial tubercle and a small spine located slightly behind the tubercle. Thorax composed of 8 segments. Axis slightly broader than the pleural lobe, with a small node on each axial ring. Distal extremities of the pleurae prolonged into spines. Pygidium semicircular. Axial lobe wide and long, segmented into 3 rings and a terminal piece. Three pairs of marginal spines.
Discussion The new subgenus is closely similar to Buttsia Wilson, 1951 typified by Buttsia drebensis Wilson, but the latter differs in (1) the absence of brim and pygidial marginal spines; (2) the faint glabellar furrows; (3) the comparatively narrow fixed cheeks about 1/4 as wide as the glabella between palpebral lobes, and (4) the small palpebral lobes.
出处
《古生物学报》
CAS
CSCD
北大核心
1991年第3期360-376,427-430,共17页
Acta Palaeontologica Sinica
