Zhou, T. M. (2000). Early Permian fusulinid-bearing strata and fusulinid zones at Xiamidi, Mejiang, Yunnan. 古生物学报 - Acta Palaeontologica Sinica. 39(4): 521-532.

335252

Zhou, T. M.

2000

39(4): 521-532

Publication

Available for editors   [request]

This paper describes the fusulinids collected from Changmo Formation in the Xiamidi section. This section is stuated at about 1 km west of the Xiamidi village in Mejian county, Yunnan. The Xiamidi section consists of continuous marine sediments, including grey to dark grey bioclastic limestone, thin or medium bedded micritic bioclastic limestone and contain various fossils such as fusulinids, foraminifers, corals and algae. In this section, the stratigraphic succession from the Changmo Formation to Maokou Formation is continuous and extensively exposed in simple structures. The total thickness of Changmo Formation is about 76.69 m.\;The fusulinids are very abundant, with illustrations for 29 species assigned to 7 genera, including 4 new species.\;According to the stratigraphic distribution of the fusulinids in the Changmo Formation, two zones have been recognized (in descending order):\; 2. Chalaroschwagerina vulgaris Chalaroschwa gerina pseudovulgaris Zone; \; 1. Eoparafusulina gracilis Eoparafusulina mej iangensis Zone. DESCRIPTION OF NEW SPECIES Eoparafusulina nagatoformis sp. nov. (Pl.?, figs.20, 21)\;Shell large, fusiform, median portion slightly vaulted, polar ends bluntly pointed. Mature specimens having 7—712 volutions about 6.42 —7.81 mm in length and 1.82—2.21 mm in width. Form ratio about 3.53—3.55:1. The inner volution ellipsoidal and tightly coiled; outer volution loosely expanded, spirotheca thin, composed of a tectum and a keriotheca. Septa fluted in the lateral slopes to poles, median portion plane or weak, septal folds low and hemispherieal. Chomata low, massively developed in the inner volutions. Axtal fillings well defined, occurring almost in the inner whorls. Proloculus small, spherical, about 0.14—0.19 mm in outside diameter.\;Remarks This new species closely resembles Nagatoella in the character of juvenarium, by this character it can be distinguished from other species. Eoparafusulina simaoensis sp. nov. (Pl.?, figs.22, 28;Pl.?,figs.14,15)\;Test large, elongately fusiform with vaulted median portion, polar ends bluntly pointed. The holotype containing 8 volutions about 10.08 mm long and 2.28 mm wide, with a form ratio of about 4.40:1. Spirotheca composed of a tectum and fine alveolar keriotheca. Inner volution thickly fusiform and tightly coiled. Axial fillings developed: outer volutions gradually expanded. Septa fluted in the lateral slopes to poles, median portion weak, septal folds low and hemispherical. Chomata low massive, developed in the inner 6 whorls, the outer 2 volutions not seen. Tunnel low, wide. Proloculus small, spherical about 0.15 mm in outside diameter.\;Remarks This new species is similar to Eoparafusulina nagatoformis sp. nov., but differs from the latter in having larger shell and form ratio, and shell elongate fusiform with vaulted median portion. Eoparafusulina mejiangensis sp. nov. (Pl.?, figs.9—13)\;Shell large, elongate fusiform, one side of the median portions vaulted and the opposite side slightly depressed. The holotype possessing 8 volutions about 8.60 mm in length and 2.70 mm in width, giving a form ratio about 3.17:1. All volutions tightly coiled. Spirotheca thin, composed of a tectum and finely alveolar keriotheca. Septa rather strongly and very regularly fluted only for the lower part throughout the length of the shell, septal folds nearly rounded, about half as high as the respective chambers. Chomata very small, only developed in the inner volutions. Tunnel low and narrow. Proloculus spherical and small, about 0.19—0.23 mm in outside diameter.\;Remarks This new species can be readily distinguished from Eoparafusulina laohutaiensis Sun by its smaller form ratio, larger proloculus and larger size of the shell. Eoparafusulina yunnanensis sp. nov. (Pl.?, figs.16—20)\;Shell, large, cylindrical, one side of the median vaulted and the other side slightly depressed, polar extremilies sharply pointed. The holotype having 8 volutions attaining 9.32 mm long and 2.48 mm wide.

Foraminifera

RIS (EndNote, Reference Manager, ProCite, RefWorks)
BibTex (BibDesk, LaTeX)

[Back to search]