Early Carboniferous brachiopod faunas and their biogeographical affinities from the western Kunlun Mountains, north-west China

Sixty-two brachiopod species belonging to 42 genera are systematically described for the first time from the Viséan-Serpukhovian Heshilafu Formation of the western Kunlun Mountains, North-west China. Two new genera Robertsella and Aitegounetes are proposed. New species include Rhipidomella aitegouensis, Rhipidomella radiata, Brochocarina kunlunensis, Rugosochonetes damusiensis, Robertsella tarimensis, Robertsella greenhillsensis, Aitegounetes aitegouensis, Aitegounetes burvillensis, Marginatia ruani, Latiproductus convexa, Globosoproductus xinjiangensis, Semiplanella yangi, Unispirifer heshilafuensis, and Beecheria yeerqiangensis. Six brachiopod assemblages are recognised from the Kunlun faunas. Close correlation of the Kunlun Mountains faunas with those from South China, Tienshan Mountains, Qilianshan Mountains and Tibet of China, Japan, Malaysia, Australia, central Asia, Urals, Kutznesk Basin and Moscow Basin of Russia, West Europe, and North America reinforced by some data from the associated foraminifers, fusulinids, conodonts and corals, suggests that the first three assemblages, Brochocarina kunlunensis-Orthotetes australis, Rugosochonetes hardrensis-Marginatia ruani and Buxtonia pseudoscabricula-Punctospirifer scabricostus are probably early Viséan in age, the Pugilis pugilis-Globosoproductus xinjiangensis Assemblage is of a middle Viséan age, the Semiplanella yangi-Datangia weiningensis Assemblage is late Viséan, and the Gigantoproductus edelburgensis- Striatifera striata Assemblage is Serpukhovian. Faunal correlation with the regions outside the Kunlun Mountains also reveals that the faunal affinities of the Kunlun assemblages with those of adjacent regions were variable throughout the Early Carboniferous. Generally, in sharp contrast to the extremely high generic and specific affinities between Kunlun and South China faunas in the Tournaisian, faunal links with South China apparently weakened in early Viséan. The Kunlun fauna appears to be of a mixed nature, with elements from Europe, North America, Siberia and Gondwanaland, indicating a possible intermediate position between European, American, Gondwanan as well as South Chinese faunal provinces. The middle-late Viséan faunas of Kunlun Mountains remained strongly an European aspect with limited South Chinese species, and completely lack any North American or Australian forms. Instead, the Kunlun Mountains, along with other central Asian blocks, such as the Chaidam Basin, northern Tienshan-Junggar, Uzbekistan and Kazakhstan, developed a higher degree of endemism, suggesting that the Kunlun Mountains were probably biogeographically and palaeogeographically further away from South China and closer to the central Asian blocks. The European and central Asian affinities of the Kunlun faunas became reinforced in the Serpukhovian. At the same time, the Kunlun Mountains maintained strong faunal affinities with these northwestern Chinese blocks (Qaidam and Tienshan-Junggar), and the links with South China further decreased. © 2003 E. Schweizerbart'sche Verlagsbuchhandlung.