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the upper part varies: in some places tholeiitic compositions dominate, in others the
volcanic rocks belong to island arc series (Pospelov 1987, Pospelov & Sigachev 1989).
Based on biostratigraphic determinations (Budanov & Pashkov 1988, Leven 1981,
Ruzhentsev & Shvol’man 1981, Ruzhentsev et al. 1978, and Pospelov 1987) Burtman &
Molnar (1993) conclude a pre-Late Carboniferous ocean basin and its closure in the
Late Carboniferous. Following stratigraphic interpretations (Ratschbacher 2003, pers.
comm.; Schwab et al. in review), the base of the oceanic sequence is dominated by
mafic lavas of likely Lower Carboniferous age, whereas the Upper Carboniferous is
heterogenous. The magmatic-arc sequence is capped by limestones reaching into the
Permian and is laterally replaced by thick greywacke, which is in turn overlain by
molasse.
In summary, it is concluded that the Lower Carboniferous to ?Triassic Altyndara
metavolcanic and volcanoclastic rocks, which are exposed in the Trans-Alay mountains
of the Northern Pamirs, are part of an oceanic basin succession and a magmatic arc
complex of which lateral continuations should be identifiable.
Similar Lower to Middle Palaeozoic belts to the east might be found in the western
Kunlun, south of the Tarim basin. The western Kunlun (Fig. 3.1, 3.11-12, 3.14) is
divisible into the North Kunlun, South Kunlun and Kara-Kunlun (or Mazar terrane, part
of the Taxkorgan-Tianshuihai terrane) (e.g., Pan et al. 1992, Mattern et al. 1996, Yang et
al. 1996, Xiao et al. 2002). The basement of the North Kunlun is interpreted to document
Sinian rifting along the southern Tarim margin with ocean spreading during the later
Sinian and Lower Palaeozoic, resulting in the formation of the Proto-Tethys Ocean
(Mattern & Schneider 2000). The consumption of the Proto-Tethys is documented by
arc-type granitic rocks of Lower to Middle Palaeozoic age. The basement of the South
Kunlun consists of gneisses, amphibolites and migmatitic gneisses. Protoliths of the
migmatites south of Kudi seem to be of Proterozoic age (Mattern et al. 1996). 40 Ar/ 39 Ar
age spectra on K-feldspars of 380-350 Ma were interpreted by Matte et al. (1996) as the
minimum age for metamorphism. Zhang et al. (1992) distinguished two arc granitoid
belts in the South Kunlun, an older Palaeozoic one in the north, and a younger, Late
Palaeozoic to Mesozoic one in the south. Both, the North and South Kunlun show a pre-
Devonian stratigraphic gap which exists between the Sinian rift sequence (North
Kunlun) respectively the Proterozoic metamorphic rocks (South Kunlun) and the
unconformably overlying Upper Devonian terrestrial red molasse deposits, followed by
Permo-Carboniferous shallow marine carbonates.
The Lower to Middle Palaeozoic Wuyitake (Oytag)-Kudi-Subasi ophiolite belt (e.g., Pan
1993, Pan 1994, Deng 1995, Mattern et al. 1996, and Yang et al. 1996) is proposed as the
suture zone between the North and South Kunlun (Fig. 3.12) (Jiang et al. 1992, Pan
1994, Deng 1995, Mattern et al. 1996, Yang et al. 1996) and is here interpreted as
eastward continuation of the volcanic arc sequence of the Altyndara section.
Only very few rocks have been analysed and dated from the Oytag suture, but more
data are available from the Kudi suture. From the Oytag region, plagiogranites
intruding basic lavas of an ophiolite suite were determined geochemically; the Sm-Nd
model ages of the basic volcanic rocks are 970-690 Ma (Deng 1995) and the Sm-Nd
isochron age of dunite, pyroxene peridotite, gabbro and plagioclase in the gabbro is
651±53 Ma (Ding et al. 1996). The plagiogranites are determined as ocean ridge
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