The Chinese Tien Shan range is a Palaeozoic orogenic belt which contai
ns two collision zones. The older, southern collision accreted a north
-facing passive continental margin on the north side of the Tarim Bloc
k to an active continental margin on the south side of an elongate con
tinental tract, the Central Tien Shan. Collision occurred along the Qi
nbulak-Qawabulak Fault (Southern Tien Shan suture). The time of the co
llision is poorly constrained, but was probably in in the Late Devonia
n-Early Carboniferous. We propose this age because of a major disconfo
rmity at this time along the north side of the Tarim Block, and becaus
e the Youshugou ophiolite is imbricated with Middle Devonian sediments
. A younger, probably Late Carboniferous-Early Permian collision along
the North Tien Shan Fault (Northern Tien Shan suture) accreted the no
rthern side of the Central Tien Shan to an island arc which lay to its
north, the North Tien Shan arc. This collision is bracketed by the Mi
ddle Carboniferous termination of arc magmatism and the appearance of
Late Carboniferous or Early Permian clastics in a foreland basin devel
oped over the extinct arc. Thrust sheets generated by the collision ar
e proposed as the tectonic load responsible for the subsidence of this
basin. Post-collisional, but Palaeozoic, dextral shear occurred along
the northern suture zone, this was accompanied by the intrusion of ba
sic and acidic magmas in the Central Tien Shan. Late Palaeozoic basic
igneous rocks from all three lithospheric blocks represented in the Ti
en Shan possess chemical characteristics associated with generation in
supra-subduction zone environments, even though many post-date one or
both collisions. Rocks from each block also possess distinctive trace
element chemistries, which supports the three-fold structural divisio
n of the orogenic belt. It is unclear whether the chemical differences
represent different source characteristics, or are due to different e
pisodes of magmatism being juxtaposed by later dextral strike-slip fau
lt motions. Because the southern collision zone in the Tien Shan is th
e older of the two, the Tarim Block sensu stricto collided not with th
e Eurasian landmass, but with a continental block which was itself sep
arated from Eurasia by at least one ocean. The destruction of this oce
an in Late Carboniferous-Early Permian times represented the final eli
mination of all oceanic basins from this part of central Asia.