Vol. 19 No. 3 CHINESE JOURNAL OF GEOCHEMISTRY 2000 Paleozoic Accretionary Terranes in Northern Tianshan, NW China" SHU LIANGSHU (í ` M ) 1) , CHEN YUNTANG ( ) 1) , LU HUAFU (t Z ) 1' , CHARVET JACQUES2) , LAURENT-CHARVET SEBASTIE 2) AND YIN DONGHAO (Eli S á)1) 1) (Department of Earth Sciences and State Key Lab of Metallization, Nanjing University, Nanjing 210093, China) 2) (Department des Sciences de la Terre, Universite d ' Orleans, 45067 Orleans Ceder 2, France) Abstract : During the Paleozoic, the Northern Tianshan region of China in Central Asia consists of 7 allochthonous terranes which were situated in the ancient Sino-Mongolian Ocean as vol- canic arcs and splitted continental fragments. The tectonic framework was similar to that of Southwest Pacific today. In the Late Paleozoic, these terranes started mutual amalgamation to cause strong thrusting. At the end of Carboniferous, the Sino-Mongolian ocean including sever- al inter-terrane small sea basins closed and these terranes accreted on the margins of the Siberian and Tarim continents. The 6 ophiolitic zones among the terranes recorded this collision event. Key words : Paleozoic ; accretion ; terrane ; Northern Tianshan Introduction The Northern Tianshan in Xinjiang, China, named also the Kazakhstan plate (Li Chunyu et al. , 1982 ; Sengor et al. , 1993) , was an organic belt consisting of many terranes including conti- nental fragments (Coleman, 1989) (Fig . 1) that formed during the Late Paleozoic . Six ophiolitic melange zones are distributed in this area; their tectonic implications pertaining to tectonic frame- work are of long-standing controversy. Many geologists have noted that collision tectonics didn' t take place among the continental blocks; in general, displacement distance of thrusting is not so large, as to exceed 100 km. Recent results suggest that a Late Paleozoic accretionary event of terrane took place in the Northern Tianshan . This process was called a soft collision event distinguished from one between two large continents. During the Early and Late Paleozoic, several continental crustal fragments and volcanic arcs as well as sea mounts scattered in the Sino-Mongolian ocean between the Tarim and Siberian continental plates (Ma Ruishi et al. , 1990 ; Lu Huafu et al. , 1996) . The continen- tal fragments include the Yili, Junggar and Turpan-Hami (Tu-Ha in short) blocks; the volcanic arcs include the Bogda, the Harlik and the Eastern Junggar. The Western Junggar (Darbut) ter- rane is like a sea mount . The tectonic framework during the Late Paleozoic was similar to the modern Southwest Pacific separating various islands and crustal blocks. In, this paper we shall describe the compositional features of terranes, the geochemical fea- tures of ophiolite in the Karamaili-Almantai suture zone and volcanic rocks in the Bogda arc, ana- lyze kinematics of terrane boundaries, and finally discuss the evolutionary model of the Northern Tianshan belt . ISSN 1000-9426 * Project supported by the National Natural Science Foundation of China (Grant Nos. 49772151 and 49832040) and University of Orleans, France.
Transcript
Vol. 19 No. 3 CHINESE JOURNAL OF GEOCHEMISTRY 2000
Paleozoic Accretionary Terranes in NorthernTianshan, NW China"
SHU LIANGSHU (í M ) 1) , CHEN YUNTANG ( ) 1) , LU HUAFU (t Z )1' ,
CHARVET JACQUES2) , LAURENT-CHARVET SEBASTIE 2) AND YIN DONGHAO (Eli S á)1)1) (Department of Earth Sciences and State Key Lab of Metallization, Nanjing University, Nanjing 210093, China)
2) (Department des Sciences de la Terre, Universite d ' Orleans, 45067 Orleans Ceder 2, France)
Abstract : During the Paleozoic, the Northern Tianshan region of China in Central Asia consists
of 7 allochthonous terranes which were situated in the ancient Sino-Mongolian Ocean as vol-
canic arcs and splitted continental fragments. The tectonic framework was similar to that of
Southwest Pacific today. In the Late Paleozoic, these terranes started mutual amalgamation to
cause strong thrusting. At the end of Carboniferous, the Sino-Mongolian ocean including sever-
al inter-terrane small sea basins closed and these terranes accreted on the margins of the Siberian
and Tarim continents. The 6 ophiolitic zones among the terranes recorded this collision event.
The Northern Tianshan in Xinjiang, China, named also the Kazakhstan plate (Li Chunyu etal. , 1982 ; Sengor et al. , 1993) , was an organic belt consisting of many terranes including conti-nental fragments (Coleman, 1989) (Fig . 1) that formed during the Late Paleozoic . Six ophioliticmelange zones are distributed in this area; their tectonic implications pertaining to tectonic frame-work are of long-standing controversy. Many geologists have noted that collision tectonics didn' ttake place among the continental blocks; in general, displacement distance of thrusting is not solarge, as to exceed 100 km.
Recent results suggest that a Late Paleozoic accretionary event of terrane took place in theNorthern Tianshan . This process was called a soft collision event distinguished from one betweentwo large continents. During the Early and Late Paleozoic, several continental crustal fragmentsand volcanic arcs as well as sea mounts scattered in the Sino-Mongolian ocean between the Tarimand Siberian continental plates (Ma Ruishi et al. , 1990 ; Lu Huafu et al. , 1996) . The continen-tal fragments include the Yili, Junggar and Turpan-Hami (Tu-Ha in short) blocks; the volcanicarcs include the Bogda, the Harlik and the Eastern Junggar. The Western Junggar (Darbut) ter-rane is like a sea mount . The tectonic framework during the Late Paleozoic was similar to themodern Southwest Pacific separating various islands and crustal blocks.
In, this paper we shall describe the compositional features of terranes, the geochemical fea-tures of ophiolite in the Karamaili-Almantai suture zone and volcanic rocks in the Bogda arc, ana-lyze kinematics of terrane boundaries, and finally discuss the evolutionary model of the NorthernTianshan belt .
ISSN 1000-9426
* Project supported by the National Natural Science Foundation of China (Grant Nos. 49772151 and 49832040) and University of
Ma aa 92°:; . {mei; ^^^^}^^ f{}: r :: titi; :}:: f' 'r sti?•.• v.
194CHINESE JOURNAL OF GEOCHEMISTRY Vol.19
Fig. 1. Sketch tectonic map of the Northern Tianshan.
Geological and Compositional Features of Terranes
Compositional features
Seven Paleozoic terranes have been found in the Northern Tianshan region, NW China.Large faults border each of the terranes . Each terrane has its distinct geologic history. Ophioliticzones occur among these terranes. From petrotectonic assemblages and fossil groups, three typesof terrane were distinguished : (1) continental fragment type (Yili, Junggar, Tu-Ha) , (2) seamount type (Western Junggar or Darbut) , and (3) volcanic arc type ( Eastern Junggar, Bogda,
and calc-alkaline volcanic rocks that are unconformably overlain by Permian red molasses with arift-type continental basalt-rhyolite series. Of them, the Yili block has a core of Proterozoic meta-morphic basement surrounded by Early-Middle Carboniferous calc-alkaline volcanic rocks on itssouthern and northern sides. While the oldest rocks outcropping in the Junggar Basin are Siluriansandy-pelitic slates and phyllites, the oldest rocks occurring in the Tu-Ha Basin are Devonian sedi-mentary rocks. Geophysically, both Junggar and Tu-Ha blocks display distinctly gravitational andmagnetic anomalies at depth, which was interpreted as evidence of pre-Cambrian basements(Deng Zhenqiu et al. , 1992) . Lower Permian rocks in the Junggar and Tu-Ha basins belong toterrestrial molasses and basalt-rhyolite assemblages.
No. 3 CHINESE JOURNAL OF GEOCHEMISTRY 195
The Bogda terrane is characterized by abundant gabbro, diabase and pillow lava, with minorgranitic rock. Geochemical features display two tectonic settings : A-type igneous series took placeduring Cl and the calc-alkaline volcanic assemblages occurred during C.
The Harlik terrane is marked by intermedial-acid volcanic rocks and . large numbers of graniticbatholiths. These volcanic rocks were developed on an Early Paleozoic basement composed oflimestone and muddy-sandy flysch-containing Gondwana-type Ordovician sinoceras and Siluriangraptolite fossils (Ma Ruishi et al . , 1994) .
The Eastern Junggar terrane was a Middle-Devonian-Carboniferous calc-alkaline volcanic arcconsisting of basalt, andesite, rhyolite and pyroclastic rocks.
The Western Junggar ( Darbut ) terrane is composed of Devonian-Carboniferous . metamor -
phosed ultramafic rocks, peridotite-gabbro-diabase cumulate, deep-water turbidite, red-colorchert and pillow basalt, like a Late Paleozoic seamount.
The Junggar, Tu-Ha and Bogda terranes belong to suspect ones, their original locations arenot clear due to the lack of Early Paleozoic strata at the surface.
The Eastern Junggar terrane shows obviously an affinity of the Siberian continent marked bySiberian-type bearing- Isotelus Ordovician mudstones and Tuvaella-bearing Upper Silurian strata inthe Karamaili area (Su Yangzhen, 1981; XBGMR, 1992 ; Zhou Zhiyi and Dean, 1996) .
The Yili and Harlik terranes display an affinity of the Gondwana old land, marked by Agnos-tus-bearing Cambrian-Ordovician limestone, Sinoceras-bearing Ordovician mudstone and Siluriangraptolite shale (XBGMR, 1992) . Rocks and strata of the above-mentioned terranes are shown inFig. 2.
Ophiolitic zones among the terranes
Six ophiolitic zones are distributed among these terranes. (1) The Karamaili-Yiwu ophioliticzone along the SW-margin of the Eastern Junggar terrane represents a Late Paleozoic suture zonebetween the Tarim and Siberian plates (Windley et al. , 1990) . (2) The Almantai-Zaysan ophi-olitic zone at the margins of the Junggar Basin was perhaps a western extension of the Karamailizone, indicating a suture zone lying between the Junggar terrane and the Siberian plate, its cur-rent situation is the result of a late NE-trending dextral strike-slip faulting (Xu Weixin, 1992).(3) The Darbut ophiolitic zone along the SE-margin of the Western Junggar terrane consists of ul-tramaf ic-maf ic rocks, red chert, pillow lava, tuff blocks emplaced structurally in the spilite, ker-atophyre, flysches, limestones and siltstone-shale from Devonian to Carboniferous . The Darbutzone represents the amalgamating of the Darbut seamount toward the Junggar continental blockduring the Late Paleozoic . (4) The Bayingou ophiolitic zone, which was emplaced structurally inthe Middle Devonian or Lower Carboniferous as melanges along the northern margin of the Bogdaterrane, represents the amalgamating of this volcanic arc toward the Junggar continental terraneduring the Late Paleozoic . (5) The Kuosiaoba ophiolitic melanges in western Balikun indicate asmall oceanic basin once developed between the Bogda and the Harlik arc terranes . (6) TheMishigou-Weiya ophiolitic zone represents a suture zone between the Yili or Tu-Ha continentalterrane and the Early Paleozoic Central Tianshan island arc.
Geochemical Features of Karamaili Ophiolite and Bogda Volcanic Rocks
Geochemistry of the Karamaili ophiolite
Ophiolites in the Karamaili-Yiwu ( Fig . 3) , Almantai, Darbut, Bayingou, Kuosiaoba and
on a passiveand limestone depositedcontinental margin
Fig. 2. Stratigraphic columns for the seven terranes . WJG . Western Junggar; JG. Jung-
gar; TU-HA. Turpan-Hami; EJG . Eastern Junggar.
Mishigou-Weiya zones are fragments of ancient oceanic crust and have very similar lithological andgeochemical features. These ophiolites are composed of metamorphic chromite-bearing peridotite,
orthopyroxene-clinopyroxene olivinite, ultramaf ic-maf ic cumulate, rodingite, pillow basalt, chert
and limestone. Except the Mishigou-Weiya ophiolite that is situated in the Early Paleozoic strata,they were emplaced in the Devonian or Carboniferous strata as melanges.
Nine samples collected from the Karamaili and Almantai ophiolitic zones were used for analy-sis of the tectonic settings . Major element compositions indicate that peridotite rocks are of theAlpine-type ultramafic rocks. The REE abundance ( Table 1) of metamorphic peridotite is verylow, totaling 0.672 X 10 - 6 ; however, that of gabbro and diabase in the cumulate is 4 — 6 times
No. 3 CHINESE JOURNAL OF GEOCHEMISTRY 197
and of pillow basalt is 10 - 20 times as high as that of the chondrite . The E REEs are (1.908 -2.097) x 10 - 6 for peridotites in the cumulate, (4.907 - 13.086) X 10 - 6 for gabbro, 9.351 X
10 - 6 for diabase and (28.04 - 47.649) X 10 - 6 for basalt . The REE distribution patterns (Fig .. 4)display that the peridotite rocks are obviously depleted, exhibiting normal Eu anomalies, and thepillow lava and basalts have even to weakly LREE-enriched patterns.
Table 1. REE composition of the Late Paleozoic ophiolite in the Northern Tianshan ( X 10 - 6)
Number 1 3 5 7 9 2 '4 6 8
Location Karamaili Almantai
Rock Metamorphic
Peridotite Gabbro Basalt Pillow
Peridotite Gabbro Diabase Basaltperidotite basalt
La 0.092 0.142 1.943 2.18 5.688 0.191 0.353 0.474 3.21
Ce 0.193 0.331 4.468 6.732 13.464 0.416 0.832 1.597 8.691
Lu 0.009 0.021 0.071 0.213 0.35 0.015 0.051 0.086 0.23
Total 0.672 2.097 13.086 28.04 47.649 1.908 4.907 9.351 34.044
1. Analyst: Lin Liping, 1998, Lab of Geochemistry, Department of Earth Sciences, Nanjing University. 2. Normal-
ized (n) to chondrites for rare earth elements after Sun and McDonough, 1989.
Geochemistry of volcanic rocks inthe Bogda arc N . 11 S
The 18 samples from the Qiketai isection (Fig. 5) in the Bogda Carbonifer- .41 ' A` n "7i%9ous volcanic arc were analyzed for major 300 m
elements and rare earth elements ( Tables
2 and 3 ) . Results suggest that this arc ®2 3 ®4 0 5 L1 6 EI 7
can be divided into two parts : Cl and CZ . Fig. 3 . Geological section of the Karamaili ophiolite. 1. RedThe Lower Carboniferous is in contact chert; 2 . limestone; 3 . tuff ; 4 . basalt; 5 . diabase; 6 . gabbrowith the Upper Carboniferous by a fault. or rodingite; 7. ultramafic rock.
Basalt and basic tuff are predominant inCl . The REE compositions show the
geochemical characteristics of alkali basalts and the REE distribution . curves are intermediate be-tween the Hawaiian alkaline basalt and the oceanic island basalt (Fig . 6) .
The Bogda arc is composed mainly of C( Fig . 6) and belongs to the calc-alkaline to weakly
alkaline type, showing a different tectonic setting from that of Cl . The samples fall in the fieldsof basalt, andesite, dacite and rhyolite, respectively. In the Bogda, syn-tectonic granitoid is veryscarce . Compared with the typical REE curves of basalts all over the world, the REE distribution
patterns of local basalts suggest that the tectonic setting of C2 was - a calc-alkaline volcanic islandarc.
Along the southern margin of the Bogda, some diabase dikes, dated at 307 ± 3 Ma on zircon
by the U-Pb method ( the authors, 1998) , intruded into basalt and tuff strata, they could be
198 CHINESE JOURNAL OF GEOCHEMISTRY Vol.19
residual magmatic rocks of the volcanic arc typeduring its terminative period.
The Harlik terrane is characterized by widelyspread S- type granites and calc alkaline basic- inter-mediate-acid volcanic rocks; the basic rocks arepoorly developed. Pyroclastic rocks account for morethan 60 % of the total. A high content of K20 indi-cates a high maturation degree of the : continentalcrust. This volcanic arc is developed on the basis ofthe continental crust.
Kinematic Features of lèrrane Boundaries
Rock/Chondrite
20
910 S
75
3 ^5
2 4
1 3
0.5 2
All the seven terranes are bounded by regional- 1scale fault zones. Along the boundaries of the ter-ranes, thrust or strike-slip ductile structures are de-veloped well (Xiao Xuchang et al. , 1990 ; ZhangChi et al. , 1990 ; Tang Yueqing et al. , 1995 ; Shu La Ce Nd Sm Eu Gd Th Dr Ho Er Yb Lu
Liangshu et al. , 1997, 1999 ) ( Fig. 1) . Theabove-mentioned six ophiolitic melange zones were Fig. 4 . REE distribution patterns in ophiolites from the
subjected to distinct ductile deformation, stretching Karamaili -Yiwu and Almantai zones. 1 , 3, 5, 7 and 9:
lineation, shearing foliation and various non co-axial Karamaili ; 2, 4, 6 and 8 : Almantai . 1. Metamorphic
shearing fabrics developed widely. Kinematics of the pendotite; 2 - 3. peridotite; 4 - 5. gabbro; 6. dia-base ; 7 - 8 . basalt ; 9 . pillow basalt.
terrane boundaries has been studied in detail, thegeological-field sections, more than 30 in number, and oriented thin sections, more than 500 in number,were observed. From these investigations, some preliminary recognition for kinematic features of terraneboundaries• has been obtained.
Table 2 . Major element composition of the Carboniferous volcanic rocks in the Bogda Mount (wt%)
Number Rock SiOO TiO2 Al203 Fe2O3 FeO MnO MgO CaO Na20 K20 P205 IL Total SI AR
1. Analyst : Lin Uping, 1999, Lab. of Geochemistry, parnentofEarthSdeiics, Nanjing University. 2. Normalized (n) to chondrites fa rare earth dements af-
ter Sun and McDonough (1989) : La 0.237, Ce 0.612, Pr-, Nd 0.467, Sm 0.153, Eu 0.058, Gd 0.206, Tb 0.037, Dy 0.254, Ho 0.057, Er 0.166, Tm
0.026, Yb 0.17, Lu 0.025, Y . Elements Pr and Y after Irrmann, V. G. (1970) : Pr 0.12, Y 1.96. 3. Analytical erears involved in ICP OES analyses are of
0.5 X 10 - 6 for oocioentrations< 10 X 10 - 6 and 5 % for c trations > 10 X 10 - 6 . 4. Eu/Eu [Eu/(Sm+ Gd) /2]„.
(1) Ductile deformation took place only in the pre-Permian rocks, but never in the rocks
and strata from Permian to Cenozoic where brittle faulting, cleavage and terrace-type thrusting-
folding are well developed.
(2) The Karamaili-Yiwu suture zone was subjected to two phases of ductile deformation : an
early stage of northward thrust-shearing (poorly developed) and a late stage of southward thrust-
shearing deformation.(3) The Almantai and Irtysh zones are obviously characteristic of sinistral ductile strike-slip
deformation, and the Darbut zone was characterized by normal dextral strike-slip shearing.Thrusting structures are scarcely reserved in these three zones owing to predominantly sub-vertical
foliation and sub-horizontal lineation in the deformed rocks.
200 CHINESE JOURNAL OF GEOCHEMISTRY Vol.19
011-201.1-2
Q11 GaoquandabanYangblak Q15 j
N 1 021 -2 018 0 4 010Q9
als
I Q21-1 Q 19 ^ Q17 1 Q12 ` Q8 Q7-2 Qs Q5
Q25 Q23i C IQ201^ t I Q16 - ' ^ ^ Q4 Q2
1 Q24 1 022 I ; , . + ' , , I Jianquanzi
So: 210 L 35 So:350 L 70So. 170 70
1 So: 150 70 ' • f `^ C2F: 200 30 So. 170 L 60So: 3051.50
0 5 10 kmI
Conglomerate • • Sandstone (] Slate M Siliceous rock E]Limestone Orff 0 Wcanic []Basalt CJAndesite tjhyoIitebreccia
Fig. 5. The Qiketai geological section across the Bogda Mount in northeastern Turpan.
(4) The Bayingou zone has recorded a ductile thrust shearing event from south to north, sev-eral klippes of ophiolite providing strong evidence for their vergencing north toward. Ductilestrike-slip structures are seldom observed.
(5) A series of thrust imbrications in the Kuosiaoba zone between the Bogda and the Harlikarc terranes represent a northward brittle deformation at higher structural level.
(6) The Mishigou -Weiya suture zone between the Yili or Tu-Ha terrane and the CentralTianshan arc is a large-scale dextral strike-slip ductile-slip zone at the recent surface. Some earlystructures showing signs of thrusting from south to north have been found in several places (ShuLiangshu et al. , 1999) .
(7) The Kumux area in the southern Tianshan region has reserved a series of syn-tectonicasymmetric folds, displaying a kinematic trend from southwest to northeast on the XZ plane, fol-
lowed by a sinistral strike-slip ductile deformation; the northeastward kinematic trend is in con-flict with the Allen's recognition of a southwestward trend (Allen et al. , 1992) .
Tectonic Evolution
The tectonic framework during the Paleozoic of Xinjiang, China, was similar to that of the
Mesozoic-Cenozoic Southwest Pacific. During the Early Paleozoic, the ancient Sino-Mongolian o-cean subducted south toward under the Tarim continent along the northern margin of the central
Tianshan basement, forming the Ordovician-Silurian central Tianshan calc-alkaline volcanic arcand the Silurian-Middle Devonian southern Tianshan back-arc basin. At that time, the WesternJunggar sea mount, the Yili block with Gondwana affinity, and the Junggar and Tu-Ha continen-tal 'blocks, were scattered in the Sino-Mongolian ocean as terranes.
At least from Middle Devonian, the Sino-Mongolian ocean began to subduct, back to back,north toward under the Siberian continent and south toward under the Tu-Ha, Yili and Junggarblocks. Late Paleozoic volcanic lava, pyroclastics, pyroclastic sedimentary rocks and turbiditeswere cumulated widely in the Bogda, Harlik, Eastern Junggar island arcs and interarc basins andon the Tu-Ha and Yili basements.
At the end of Carboniferous, subduction ceased (Windley et al. , 1990 ; Xiao Xuchang et
RocklChondrite
0-2, -9, -13: basalt from Lower Carboniferous
100 Hawaiian alkaline basalt; OI8: oceanic
island basalt (Condie,1989)
50 H^e40
30
20 `°--bom
1s ~0-9
10ál3
5 i i 1MLa Ce Nd Sm Eu Gd Th Dy Ho Er Tm Yb Lu
Rockl'Chondrite
100 \ 0-13,48: basalt, 0-19, -27, andesite
(Upper Carboniferous)
50 \40
0-27
Q-191 ,
10re r^^ G-18
:-•5 -----!—.-1 0-13La Ce Nd Sm Eu Gd Th Dy Ho Er Tm Yb Lu
RocldChondrite
100 • 0-14, -15, C-46, -51: rhyoiite
80(Upper Carboniferous)
50 °ire
40 e C-513020 ía-14
150-15
10
5 I I 1 1 1 1 1 I 9 1 1 15•
La Ce Nd _ Sm Eu Gd Th Dy Ho Er Tm Yb * Lu
No. 3 CHINESE JOURNAL OF GEOCHEMISTRY
al. , 1990) , interarc basins or back-arc basinswere closed (Ma Ruishi et al. , 1990) , causingstrong compression-collision of island arcs andsmall oceanic basins . The terranes began to a-malgamate each other while intervening seasclosed . At the end of Carboniferous, they ac-creted on the margins of the Siberian or of theTarim, followed by ophiolitic melanging, fold-ing-thrusting, ductile shearing and formation offoreland basins . There existed two forms ofmalgamation or collision : (1) the face-to-facemalgamation, producing thrust imbrication;and (2) oblique malgamation, causing thrustingplus strike-slip shearing. The ophiolitic blockswere emplaced during collision along suturezones .
The closure of the Sino-Mongolian oceanhad produced a large ophiolitic zone along Kara-maili-Almantai-Zaysan, and the closure of inter-terrane, small oceanic basins led to the forma-tion of other several ophiolitic zones . Thrusts,strike-slip, ductile deformation and S-type gran-ites developed during and after the collision.
The Lower Permian molasses were under-lain unconformably by these terranes, indicatingthe ending of a collision-uplifting process. Thenorthern Tianshan orogenic belt has erected inthe Central Asia since the Permian . The wholeTianshan belt was strongly eroded during theMesozoic, and then was strongly reformedstructurally, re-uplifted and dislocated geo-graphically due to the Mesozoic-Cenozoic Hi-malaya event (Tapponnier et al . , 1986) .
201
Fig. 6 . REE distribution patterns of volcanic rocks
from the Bogda terrane (upper: basalt from Lower Car-
Acknowledgements: The supports of the Na- boniferous; middle: basalt and andesite; lower: rhyolite
tional Natural Science Foundation of China from Upper Carboniferous) .
(Nos. 49772151, 49832040) , the Bureau ofState 305 Project and the "Conseil Regional du Centre" of France, through a grant, and facilitiesprovided by the "Laboratoire de Géologie Structurale" of Orléans University, France, are grate-
fully acknowledged. Special thanks are due to Academician Guo Lingzhi, Profs. Shi Yangshen,Ma Ruishi, Gao Jun and Profs. Ma Yinjun, Wu Naiwen, Xu Xin, Wang Jinliang, Xie Deshun,Jiang Yuanda working in the Bureau of State 305 Project for their valuable suggestions during ge-ological field work.
202 CHINESE JOURNAL OF GEOCHEMISTRY Vol.19
References
Coleman Robert, G. , 1989, Continental growth of Northwest China: Tectonics, v. . 8, n. 3, p. 621- 635.
Deng Zhenqiu, Wang Tieguan, and Xie Deshun, 1992, The features of geophysical fields in Xinjiang. Geology, v.
10, n. 3, p. 233 - 243 (in Chinese with English abstract) .
Li Chunyu, Wang Quan, Liu Xueya, and Tang Yaoqing, 1982, Explanatory notes to the tectonic map of Asia:
Beijing, Cartographic Publ. House, 49 p.
Liou, J. G. , S. Maruyama, Wang, X. M. , and S. Graham, 1990, Precambrian blueschist terranes of the world:
Tectonophysics, v.181, p.97-ill.
Lu Huafti, Jia Dong, Cai Dongshen,' and Chen Churning, 1996, Plate tectonic evolution of the Tarim and West
Tianshan, in Tong Xiaoguang et al. , eds . , New advances in the study of petroleum geology of Tarim basin:
Beijing, Science Press, p. 235 - 245 (in Chinese with English abstract) .
Ma Ruishi, Ye Shanfu, and Wang Ciyin, 1990, The plate framework and crustal evolution in the eastern Tian-
shan: Geoscience of Xinjiang, v. 2, p. 21- 36 (in Chinese with English abstract) .
Sengor, A. M. C. , B. A. Natal' in, and B. Burtman, 1993, Evolution of the Altai tectonic collage and Paleozoic
crustal growth in Eurasia: Nature, v. 364, p. 299 - 307;Shu Liangshu, Ma Ruishi, Guo Lingzhi, and Sun Jiaqi, 1997, Study of a large scale thrust tectonics in the eastern
Tianshan belt : Scientia Geologica Sinica, v. 32, n. 3, p. 337 - 350 (in Chinese with English abstract) .
Shu Liangshu. , Charvet Jacques, Guo Lingzhi, Lu Huafu, and Laurent-Charvet Sebastien, 1999, A large-scale
Palaeozoic dextral ductile strike-slip zone: the Aqqikkudug-Weiya zone along the northern margin of the Central
Tianshan belt, Xinjiang, NW China: Acta Geol. Sinica, v. 73, n. 2, p.148 - 162.Su Yangzheng, 1981, On the geological and geographical distribution of Tuvaella with reference to its habitat: Acta
Palaeontologica Sinica, v. 20, n, 6, p. 567 - 575 (in Chinese with English abstract) .
Sun, S. S. and W. F. McDonough, 1989, Chemical and isotopic systematics of oceanic basalts: implications for
mantle composition and processes, in A. D. Saunders and M. J . Norry, eds. , Magmatism in the Ocean Basins:
