西藏拉萨地区三叠系诺利阶牙形石分带及其国际对比

CONODONT ZONATIONS OF NORIAN IN LHASA AREA, XIZANG(TIBET)AND THEIR GLOBAL CORRELATION

麦龙岗剖面位于西藏拉萨地区达孜县麦龙岗村 (N2 9°5 6′0 6″ ,E91°2 7′5 5″)。麦龙岗组中共发现牙形石 7属 :Epigondolella ,Hindeodella ,Priniodella ,Xaniognathodus,Lonchodina ,Metalonchodina和Enantiognathus属。其中Epigondolella属有 9种 ,包括 1新种和 1未定种 ,它们是E .primitia ,E .spiculata ,E .cf.spiculata ,E .tozeri,E .violinformissp .nov .,E .cf.triangularisuniformis,E .postera ,E .bidentata ,E .sp .。基于本次发现的化石材料 ,对西藏林周地区麦龙岗组进行新的牙形石带划分。自下而上划分为 :?Epigondolellaprimitia ,E .spiculata ,E .tozer i,E .postera和E .bidentata等带。与毛力等 (1987)、Orchard(1983,1991,1994 )和Krystyn(1977)

Mailonggang section is located at Mailonggang village in Dagze County, Lhasa area, Tibet (N29°56′06″, E91°27′55″). There are 7 conodont genera found in Mailonggang Formation including Epigondolella,Hindeodella,Prioniodina,Xaniognathodus,Lonchodina,Metalonchodina and Enantiognathus. Epigondolella includes 9 species which are E. primitia,E. spiculata,E. cf. spiculata,E. tozeri,E. violinformis sp. nov., E. cf. triangularis uniformis,E. postera,E. bidentata , and E. sp. Based on evolution of the Epigondolella , conodont biostratigraphic division of Late Triassic Mailonggang Formation was restudied,Five conodont zones have been recognized. From bottom to top,the five new conodont zones are: ?Epigondolella primitia,E. spiculata,E. tozeri,E. postera ,and E. bidentata zones. They can also be correlated with those of Mao Li et al . (1987),Orchard(1983,1991,1994)and Krystyn(1977).