苏北地区奥陶系牙形刺及其色变指标

ORDOVICIAN CONODONTS FROM NORTHERN JIANGSU AND INDICES OF THEIR COLOUR ALTERATION

本文记叙了苏北地区10个井孔的奥陶系牙形刺34属63种(包括2新种,2新亚种,1亲缘种,1比较种,11未定种),分属8个牙形刺带或组合(自下而上)。下奥陶统:1.Glyptoconus qua-draplicatus-Teridontus nakamurai组合带,2.Serratognathus diversus带,3.Baltoniodustriangularis带,4.Baltoniodus navis带,5.Eoplacognathus folicaceus-Periodon aculeatus组合带;中奥陶统:6.Scabbardella similaris带,7.Hamarodus europaeus带;上奥陶统:8.Spathognathodus dolboricus-Belodina hongzeensis-Pseudobeldina dispansa组合带。本区牙形刺色变指标普遍好于苏南,CAI值一般为2级至3级,为成熟期或高成熟期。

The conodonts described in this paper were collected from 10 boreholes ofthe Ordovician in northern Jiangsu, comprising 34 genera and 63 species (includ-ing 2 new species and 2 subspecies), with 8 conodont zones (or assemblagezones) recognized in descending order as follows: Upper Ordovician: 8. Spathognathodus dolboricus-Belodina hongzeensis-Pseudobelodina dispansa Assemblage Zone; Middle Ordovician. 7. Hamarodus europaeus Zone; 6. Scabbardella similaris Zone; Lower Ordovician. 5. Eoplacognathus foliaceus-Periodon aculeatus Zone; 4. Baltoniodus naris Zone; 3. Baltoniodus triangularis Zone; 2. Serratognathus diversus Zone; and 1. Scolopodus quadraplicatus-Teridontus nakamurai Zone. In addition, these conodonts display the indices of their colour alterationranging from 2 to 3, and their organic metamorphism in mature stage or highlymature stage. In these aspects they are better than those of southern Jiangsu.