Dec 10, 1993 - increased, and resolution is now reaching a stage at which other geological and .... Psittacosaurus fauna found in Junggar and parts of Tibet is also found in the Khorat ... [1992] compiles a complete list of poles, which includes ...... Buffetaut, H., and V. Suteethorn, Vertebrate biostratigraphy of the Mesozoic ...
JOURNAL OF GEOPHYSICAL RESEARCH, VOL. 98, NO. B12, PAGES 21,927-21,941, DECEMBER 10, 1993
The Configuration of Asia Prior to the Collision of India' CretaceousPaleomagneticConstraints YANCItEN,1VINCENTCOURTn.! OT,JEAN-PASCAL COGNI•,
JEAN BESSE, ZHENYU YANG,ANDRANDY ENKIN 2 Laboratoirede Paldomagn•tisme et Gdodynamique, Ddpartementde Gdomagn•tisme et Paldomagn•tisme (URA CNRS 729), Institutde Physiquedu Globe,Paris Palcomagneticdata from Central Asia show that 1700-!610 km of shorteningof southernAsia since Cretaceoustime have been absorbedby distributeddeformationbetweensouthernTibet and the Siberia craton.This resultis basedon a compilationof Cretaceous polesfrom the Junggar,Tarim, Tibet, Indochina, South China, North China, and Mongolia blocks,complementingthe recentcompilationof Enkin et al. (1992a).We proposea paleogeographic reconstmction of Asia in the Cretaceous, in whichthe positionof Siberiais derivedfrom the syntheticapparentpolar wanderpathof BesseandCourtillot(1991). The resulting map, which likely represents Asia as it remainedthroughoutthe Cretaceousuntil the collisionwith India began,featuresan "unbent"Tibet,with an east-west trendingAndeanmarginat tropicallatitudesanda rather continuous belt of continental redbedbasinsextendingfromSichuanto TarimthroughTibet.The mapallows oneto estimatecontinentalshortening and rotationsbetweenthe blocks,whichare attributedto the collision.
Despitelargeuncertainties, thesehave amountsand senseswhichare in all casescompatiblewith some recentkinematicmodelssuchas that of Avouac (1991).
INTRODUCTION
The period for which the largest and best quality data are available happens to be the Cretaceous, the period For the last decade,Asia hasbeenthe targetof unprecedented immediatelyprecedingthe Indian collision.The presentpaper activity by paleomagneticians.Cooperationbetween Chinese focuses on a synthesis of these data and proposes a and principally French and U.S. laboratories has led to a Cretaceous,precollisionalreconstructionof Asia. This can be remarkablegrowth of the corresponding database.The purpose used to infer the amounts and modes of deformation that have of these studies has been to describe and quantify the led to the presentgeometry.Althoughthis paper concentrates geographical and tectonic evolution of the lithospheric on blocks presently located to the west of, say, 100øE blocksthat have accretedto form the Asian mosaic(Figure 1). longitude,referencewill be made to ongoingcompanionwork As time has passed,the samplingin both spaceand time has by Yang [1992], includingnew data from Thailand [Yang and increased,and resolution is now reaching a stage at which Besse, 1993] and from the NCB [Yang et al., 1991, 1992; Ma other geological and geophysicalfield observationscan be et al., 1993] and SCB [Enkin et al., 1992b]. comparedto and incorporatedin the reconstructions proposed by paleomagneticians. GEO•ICAL BACKGROUND Enkin et al. [1992a] have proposeda critical evaluationof the availabledata and a set of palcogeographic reconstructions The detailedgeometryof the blocksthat comprisesome 10 x goingback to the Permian.Emphasiswas placedon the major 106 km2 of Chinais still debatedbut the outlinesof the main blocks, principally North and South China (NCB and SCB, blocksare now generallyagreedupon(Figure 1). The exact age respectively)in their relationshipwith Siberia. Eurasianpolar and nature of the block boundaries, which have often had a wanderwas assessed indirectlyby transferringdata from other long history and have sometimesbeen severelyaffectedas a plates or by using data from remote areas of Eurasia itself consequenceof the India-Asia collision, are not always [Besseand Courtillot, 1988, 1991]. Less emphasiswas placed established by field observations. To the southandwestof the on central Asian blocks. Yet these smaller blocks have been larger Siberia, NCB and SCB, we encounterthe following particularly strongly affected by the Paleocenecollision of seriesof blocks,going roughly from north to south. India and their mode of deformationhasbeen the subjectof an The Junggarblock (JUN) forms the southeastern triangular ongoingcontroversyfor the last decade.End-membermodels termination of the larger Kazakhstan block (KAZ), but involve crustalor lithosphericdoubling,homogeneous crustal Mesozoic or Cenozoic relative motion of the two is not or lithospheric thickening [e.g., England and Houseman, excluded. Feng et al. [1989] believe that amalgamationof 1986], inhomogeneousstrain localized along a few major Siberia, Kazakhstan, and Tarim began in the middle mountain ranges and sutures, major strike-slip faulting Carboniferous.Carboniferousto Tertiary sedimentscrop out allowingfor lateralextrusion[Peltzerand Tapponnier,1988]. along the folded foothills of Tien Shan (Figure 1). The New paleomagneticdata have been collectedand published Cretaceous rocks conformably overlie the Jurassic strata, for these blocks, particularly the Junggarblock in Xinjiang starting with fine dark red sandstoneand conglomerates Province [Chen et al., 1991], the Tarim block [Chen et al., grading upward to variegated and light green sandstones. 1992], and Tibet farther south[Chenet al., 1993]. A general Ostracods of probable Barremian age, a typical Asian presentationof thesedata has been proposedby Chen [1992]. Psitaccosaurus of probableAlbo-Aptianage,andHadrosaurs of Santonian to Maastrichtian age have been found in these Cretaceous formations [Chen, 1983; Hao et al., 1986]. The INowat D6partement desSciences dela Terre,Universit6 d'Orl6ans, lower Tertiary is composedof brick-redgypsiferousmudstones Orl6ans, France. and sandstones with thin layers of bioclasticlimestones[Peng 2NowatPacificGeoscience Center,Sidney, BritishColumbia, Canada. and Zhang, 1989] and conformablyoverliesthe Cretaceous. Copyright1993 by the AmericanGeophysicalUnion. The Tien Shanmarksthe boundarybetweenthe Tarim (TAR) and Junggarblocks. This east-westtrending mountain belt Paper number93JB02075. extendsover 2500 km in CentralAsia; it is a Paleozoicrange 0148-0227/93/93JB~02075 $05.00 that has been reactivatedduring the Cenozoic,probablyin the 21,927
21,928
•
ETAL.:CONFIGURA•ON OFASIAPRIOR TOTIlECOLLISION OFINDIA
60 ø
120 ø
EUR
I
140 ø
SIB
! I
MON 40 ø 40'
TAR
KUN
SCB
20 ø
20'
IND
Suture
o
Fault 80øE
100øE
120øE
Fig. 1. Schematic blockmapof ChinaandSoutheast Asiashowing themainsutures andfaults(KF, KarakommFault;MBT, Main BoundaryThmst).The majorblocksare AFG, Afghanistan; EUR, Europe;INC, Indochina; IND, India;JUN, Junggar, KAZ, Kazakstan; KUN, Kunlun;MON, Mongolia;NCB, NorthChinaBlock;QA, Qaidam;QI, Qiangtang;SIR, Siberia;SCB,
SouthChinaBlock;ST, ShanThai;andTAR,Tarim.Alsoindicated arethemainlocations whereCretaceous paleomagnetic
dataareavailable.Declinationis indicatedby arrows(a thinline indicates truenorth;notethatdueto theprojecuonselected, it hasbeenpreferredto tracethesethin reference linesverdeaftratherthanactuallylocallyparallel•o the meridian).Open arrowsare for areassuspected of majorlocalscaledeformation or unreliablepaleomagnetic data(seetext). Solidarrowsare thoughtto be representative of theindividualblocksat a largerscale.
middle Miocene [Moltmr and Tapponnier,1975; Tapponnier and Moltmr, 1979; Avouac et al., 1993]. Tarira is the largest basin in China. During the early Cretaceous, a series of red clastic rocks of delta facies and
successivelyaccreted onto Asia. Each one has its own, distinctive, sedimentaryand tectonic history. The Kunlun block (KUN) is coveredwith a thick sequence going from Cambrian to Triassic in age. The strong
argillaceouslimestoneof lake facies was depositedin the deformation of Permo-Triassic formations is attributed to the western part of the basin. During the late Cretaceous, upperTriassiccollisionof Kunlun with Qiangtang[Chang et transgression of the Tethys Sea led to the depositionof a al., 1986; Bourjot, 1991]. series of littoral sediments. These sediments have been Outcroppingformationsin Qiangtang(QA) includebasalts affected, with increasingintensity toward the periphery,by and Jurassiclimestones[Matte et al., 1990], unconformably late Paleozoic to Present tectonics [e.g., Molnar and overlain by red Cretaceous sandstones.These Mesozoic Tapponnier1975;Tapponnierand Moltmr, 1979;Huang et formationsare not affectedby either strongmetamorphismor al., 1980; Tian et al., 1989; P. Tapponnieret al., manuscript deformation. The Qiangtangis separatedfrom the Lhasablock by the in preparation,1992]. Farther South, theTibetan plateau extends for1.5x 106km2 Bangong-Nujiangsuturezone [e.g., Girardeau et al., 1984; with an averagealtitudeof 5000 m. It comprisesthreemajor All•gre et al., 1984;Changet al., 1986;Pan and Wang,1991; tectonicsubdivisions:the Kunlun-Qaidam,the Qiangtang(or Bourjot, 1991]. Ophiolitic melanges have yielded upper NorthTibet), andthe Lahasa (or SouthTibe0 blockswhichwere Jurassicradiolaria [Pan and Wang, 1991], compatiblewith
CItEN LrrAL.: CONFIOI/RATIONOFASIA PRIORTO TIlE COLLISIONOFINDIA
130 M.y.ages obtained by Harris et al. [1988] for
21,929
NCB and SCB [Peltzer et al., 1989]), and Three Rivers area
granodiorites anddioriticplutonsin the eastof the plateau. [Tapponnieret al., 1990]. A major, still debatedconsequence Collisionis supposed to haveoccurred in theu• Jurassic. of the collision is the southeastward extrusion of the Cretaceous formations in the Lhasa block (LH) occur as
Indochinapeninsularelative to Eurasia [e.g., Peltzer and
Albian-Apfianlimestones in the northandwestof the block Tapponnier, 1988]. and as fluvial and deltaic red sandstones with some volcanic intercalafions to the south and east. Most formations located
P•MAGNETIC
Northof theYarlung-Zangbo suturearestrongly deformed with folds sometimesoverturned.The closerthe suture,the stronger the deformation which is attributed to the collision of India
[e.g.,Jaegeret al., 1989]. The
Markam
area is sandwiched
between
the
Jinshajiangand the Bangong-Nujiang sutures(Figure 1). A thick red bed sequence of Jurassic to Cretaceous age conformablyoverliesthe Triassicsequences and is in turn disconformablyoverlainby Eocene-Oligocene red molassic depositsor Pliocenetrachytesand continentaldeposits.The Jurassic-Cretaceous red bed sequencehas both greatthickness and wide areal distributionaroundthe Markam area [Ren et al., 19801. Sundaland includes Indochina, the Sunda shelf, Peninsular
Malaysia and Sumatra,SW Borneo, part of Burma, part of Yunnansouthof the Red River fault, and,possibly,partsof $E Tibet (Figure 1). Its presentlimits aremarkedby ancientsuture zonesof possibleupper Triassicage, the Nan-Uttaraditsuture to the northwestand the SongMa sutureto the northeast;the wide rangein the ageof the associated granites(from Triassic to upper Jurassic)underlinesour poor understandingof the geologicconfigurationin the early/middleMesozoic.Tertiary activefaults,the Red River fault to the northeastandthe Wang Chao /Three Pagodasfault systemsto the southwest,mark its lateral limits. Throughoutthe Wang Chao and Three Pagodas faults zones, a N-S trendingbelt of granitesrepresentsthe probablecontinuationof the Uttaradit suturezone. Although the ages are not well constrained[Beckinsale et al., 1979; Liew and Page, 1985], thesegranitesare easilyrecogn•edand mark the limits of Indochinawith respectto the Shan-ThaiMalay block. After a major pre-upperTriassic tectonicphase known as the Indosinianorogeny,the Khorat basin was filled by a thick continental successionof molasses(mainly red beds) ranging in age from upper Triassic (Norian) to upper Cretaceous.In the region of the western Khorat basin, the Indosinian orogeny is marked by the unconformityof the Mesozoic series over a strongly folded marine limestone series of upper Permian age. The same Albo-Aptian Psittacosaurus faunafoundin Junggarandpartsof Tibet is also foundin the Khorat [Buffetautand $uteethorn,1991]. Large continentalbasinsof the sameage can alsobe found in central
COMPILATION
Furtherpalcomagneticsamplinghas beenobtainedrecently by our group,with an emphasison Cretaceoussites:(1) in the Junggarblock to the north of the Tien Shan range west of Urumqi [Chen et al., 1991], (2) in the Tarim block at its westernterminationto the west and north of Kashgar[Chen et al., 1992], (3) along a traversethroughwesternTibet, across the Qiangtangand Lhasablocks [Chen et al., 1993]. (4) in the Indochinablock on the Khoratplateau[Yangand Besse,1993; Yang, 1992], (5) in the Sichuanbasin of the SCB [Enkin et al., 1991a,b] and (6) in the Ordospart of the NSB [Ma et al., 1993]. These new data have been compiled with all those publishedearlierby our groupand by others. This compilation (available on microfiche) follows the criteria and format of that of Enkin et al. [1992a] which it complements for the blocksunderconsideration. For a pole to be selected,it must meet the following criteria: (1) the study must be based on more than 10 specimens,(2) the 95% confidence
circle about the mean must have a radius less than
15ø, (3) resultsmust be basedon completedemagnetization, (4) there must be some evidence for the absence of
remagnefizafion,(5) the formationage must be defmed at the stagelevel and (6) sufficientinformationmust be availableto assessthe quality of the pole (field and stability tests).Chen [1992] compiles a complete list of poles, which includes Carboniferous,Permian, and Jurassicpoles for Junggar, Devonian, Carboniferous, Permian, Triassic, Jurassic,Eocene,
and Neogene poles for Tarim and Carboniferous,Permian, Triassic, Jurassic, Eocene and Neogene poles for Tibet, complementingthe China pole list of Enkin et al. [1992a]. Altogether, 13, 49, and 59 poles, respectivelyare listed for each block. All resulting data are given in the appendix,
available on microfiche 1,withthoserejected marked by an asterisk.Altogether,out of 82 upper and lower Cretaceous poleslisted in the compilation,only 16 passedthe selection process (two for Junggar, one for the Fergana part of Kazakstan,five for Tarim, and eight for Tibet). They are discussed in more detail below.
Junggar block. Three poles are available for this block (Figure2a andTable 1). Two polesfrom ½henet al. [1991] for the lower and upperCretaceous westof Urumqipassfold and Yunnan and S ichuan. reversal tests and are not significanfiy different from each Although the amount, mode, and geometry of the other.A pole from Liet al. [1991] has only beenpublishedin deformationare all subjectto large uncertainties,there is a meeting abstract and cannot be properly assessed.The generalagreement thatby Cretaceous time all of theseblocks selectedpoles are shownwith their uncertaintiesin Figure 2b
had become part of Asia with essentially no major areaof oceaniccrust interveningbetweenany two of them [e.g.,
(followingthe formatusedby Enkinet al. [1992a]), together with the apparentpolar wander path (APWP) for Eurasia Besse and Courtillot, 1988; Enldn et al., 1992a]. A Cretaceous derivedby Besseand Courtillot [1991]. The Cretaceousmean map of theseblockswould thereforeprovidea view of the for Junggaris at 73.4øN,223.6øE(A95 = 4.3ø). Asian continentas it probablyremainedfrom late Jurassicto Fergana basin.Bazhetmv[1993] hassampled15 localitiesin the end of the Cretaceous. Such a reconstruction is essential the lower Cretaceoussandstones of the Ferganabasin,at the for the quantifyingand understanding of the intracontinental southernmostpart of the Kazakstan block. Seven of these deformation that occurred since the onset of collision. localitiesyield a primary magnetization.AlthoughBazhenov This collisioninducedmajor new faults within the Asian mentions the possibility that the data are not Fisherlithosphereand reactivatedolder tectonicfeatures(faults and distributed, which he attributes to indentation of the Pamir sutures).After a first contact(estimatedto be as old as 60 belt, a Fisheraveragecan be calculatedleadingto an average M.y.by Jaeger et al. [1989]), India continuedto progress northwardat some5 cm/yr [Molnar and Tapponnier,1975; Patriat and Achache, 1984]. The collision generatedthe I Appendix isavailable withentire paper onmicrofiche. Order from Himalayan range but also reactivated and/or created American Geophysical Union, 2000 Florida Avenue, N.W., intracontinentalranges farther north and northeast,such as Washington,DC 20009. DocumentB93-007; $2.50. Paymentmust the Tien Shan,Kunlun,Qinling Shan(i.e., suturebetweenthe accompanyorder.
,930
CHEN ETAL.:CONFIOURATION OFASIAPRIOR TOTHECOLLISION OFINDIA 180 ø
-i-
•
270 ø
+
+
+
+
90 ø
+
+
.i-
1•80 ø +
+
Junggar_____j, C.• I Junggar, Ch•
• 270ø• ++++-•
Fergana,Bazhenov
+
90 ø
+
• + + -t+
+
b
o
Fig.2.Equal-area projection ofCretaceous poles fromJunggar andFergana. (a)Allpoles and(b)onlyreliable ones (see text).
Thereliable (unreliable) polesaremarked bycircles (triangles). Solid(open)symbols represent lower(upper) Cretaceous
poles. Sampling sites which contribute data tothepoles areshown onthemap. Identification ofeach polestarts withanindex in brackets, corresponding totheChina pole1List (seeappendix onmicrofiche), followed bytheblock orlocation name andthe name ofthefirstauthor oftherelevant publication. Tl•ereference APWPof Eurasia [Besse andCourtiilot, 1991]isgiven in open dotsevery10Ma,except forCretaceous poles which aremarked withsoliddots(130to70m.y.)andforwhich the overallenvelope of 95%confidence intervals is shown in shaded pattern.
poleat 77.3øN,276.0øE(dp=5.4ø, din=8.6ø;Figure2 andTable indicationthat the poles are streakedalong a small circle 1). Thereis no evidencefor significantinternaldeformation of centeredon Tarim, implyingthat someof the samplingsites the basin. may have sufferedsomeamountof rotationaboutlocally resultsis notalways Tarim block. Thirteen poles of Cretaceousage are available verticalaxes.The qualityof thepublished For instance,Liet al. [1989] did perform for this block (Figure 3a and Table 1). There is some easyto assess.
CHF• ET AL.: CONFIGURATION OFASIA PRIORTO THECOLLISIONOFINDIA
21,931
TABLE 1. SelectedCretaoeousPaleomagneticData of China
Locality
Age
(øN/øE)
Pole
A95
N
Test
Reference
Code
latitude,øN longitude,øE dp/dm North China Block
40.1/11Z9 45.4/107.6 42.0/119.2 35.0/118.0 Average
Ku K1 K1 K1 K
79.6 82.9 82.9 75.8 81.3
170.1 221.7 249.5 208.7 208.3
5.8 4.9/6.4 5.7 7.5 6.9
4 3 6 10 4
R R F R
Zhenget al. [1991] Pruner [1987] Zhao et al. [1990] Ma et al. [1993]
3Z0/119.0 30.0/102.9 26.6/102.4 26.5/102.4 22.2/114.2 25.0/116.4 27.9/102.3 29.7/120.3 30.0/102.9 26.8/102.5 Average Average Average
Ku Ku Ku Ku Ku Ku K1 K1 K1 K1 Ku K1 K
76.3 72.8 78.9 81.5 78.2 67.9 77.4 77.1 74.5 69.0 77.3 74.9 76.5
172.6 241.1 186.6 220.9 171.9 186.2 196.2 227.6 229.0 204.6 195.9 213.8 203.8
F R -
Kent et al. [1987] Enkin et al. [1991b] Zhu et al. [1988]
Huang and Opdyke[1992] Chan [1991] Hu et al. [1990] Zhuetal. [1988] L/n [1984] Enkin et al. [1991b] Huang and Opdyke[1992]
41.6/83.5 38.5fi6.4 39.5fi5.0 38.5fi6.4 39.5fi5.0 Average Average Average
Ku Ku Ku K1 K1 Ku K1 K
66.2 71.0 70.8 70.4 66.3 69.4 68.5 69.1
223.3 234.0 222.6 212.1 226.6 226.4 220.0 223.8
6.1/10.3 4 R 6.8/11.6 6 F 5.4/8.9 11 RF 6.6/10.8 3 R 9.0/15.9 7 R 5.3 3 2 3.5 5
Li et al. [1988] Chen et al. [1992] Chen et al. [1992] Chen et al. [1992] Chenet al. [1992]
44.2/86.0 44.2/86.0 Average
K/T J/K K
75. 72.3 73.4
225.3 227.3 223.6
Junggar Block 6.1/8.9 9 FR 4.8fi.2 13 FR 4.3 22
Chen et al. [1991] Chen et al. [1991]
30/91 29.7/91.2
K K
71.2 68
288.4 340
7.9 10
SouthernLhasa 29.9/91.0
K
64
348
SouthernLhasa
South China Block
10.3 4.1fi.4 4.3/6.7
7.1 10.6 9.2 11.5/18.3 5.5 Z7/4.7 4.3 6.9 6.5 4.4
10 16 3
18 F 12 R 20 R 2 7 R? 23 R 7 6 4 10
Tarim Block
Tibet Block
SouthernLhasa SouthemLhasa
K
68
297
3.5/6.9
8
F
Achacheet al. [1984] Pozzi et al. [1982] Westphalet al. [1983] (same sites as above) Lin and Watts[1988]
NorthernLhasa 31/92
K
63.5
325.4
6.5
6
F
Achache et al. [1984]
WesternPlateau 33.7/80.2 Markam 29.7/98.6 Markam 29.7/98.4
K K KI
66.2 48.5 40.6
245.0 175.9 170.5
5.1 9.5 13.0
14 FR 5 12 F
Chenet al. [1993] Otofujiet al. [1990] Huanget al. [1992]
Markam
29.7/98.7
Km
58.7
173.2
11.1
10
Huanget al. [1992]
SouthernLhasa
Average
K
69.1
283.5
2.8/5.4
16
and
N + S Lhasa
Average
K
69.6
307.5
3.0/5.6 30
,
Markam
Average
K
48.6
173.5
40.5fi2.5
K
74.3
276.0
29.9/91.2
F F
5.6/9.5
8 7 6
6.0
F
F
and
27
FerganaBlock 5.4/8.6 7
, and
FR
Bazhenov[1993]
Eurasia Block
92-65 Ma 130-98 Ma 130-65Ma
76.8 75.2 76.3
199.7 207.5 202.6
2.7 4.0 2.2
19 10 29
Besseand Courtillot[1991] Besseand Courtillot [1991] Be•seand Courtillot[1991]
Locality:geographic coordinates of sampling sites;age(Ku, Km, K1, K), magnetization agegivenby authors(upper Cretaceous, middleCretaceous, lower Cretaceous, andall Cretaceous); pole (latitude,longitude),A95, (dp/dm),coordinates of paleomagnetic poleswith uncertaintyat the 95% probabilitylevel; N, numberof studies,sitesor polesfor the averages;test (R, F), field tests(reversal,fold); andcode,indexof polescorresponding to the appendixon microfiche. stepwisethermalor alternatingfield demagnetizations but did not determinecharacteristicdirectionsby vector analysis. Rather,theyuse a particularstepin the demagnetization. Data fromLi et al. [1988] andZhanget al. [1989] correspond to the
samesamplingand sites.Resultsare similar but Zhang et al. add one site with only two specimensand a rather outlier direction. We therefore retain only the data from Li et al. [1988]. Resultsfrom Uytak, close to the westernKunlun fault
21,932
CHF2q ETAL.:CONFIGURATION OFASIAPRIOR TOTIlECOLLISION OFINDIA 180 ø
-i-
Tarim, Li
+
-i-
90 ø
Tarim, Chen
.Ta.2> Tarim, Ch 270 ø
'ar,m,
\t
+ + + +•
90 ø
+ -,[... + ++ +
Tarim, Chen
o
Fig.3. Equal-area projection ofCretaceous poles fromTarira. Seecaption ofFigure 2.
[Chenet al., 1992]aretoodispersed to providea reliablepole. the Creta•ous Finally,sixpolesmeettheselection criteria(Figure3b).Chen (A95 = 3.5ø).
mean for five studies stands at 69.1øN, 223.8øE
Tibetan blocks.As could be expected,the situationis far et al. [1992]notethatthe lowerCretaceous poleof Liet al. in Tibet thanin [1988] collectednear Kucheis somewhat remotefrom the morecomplex(andthe datamorenumerous) otherpolesandpropose thatthismaybe dueto a majorfold the more stableJunggarand Tarira blocks.Thirty-onepoles structurewith plungingfold axis, partly seenon satellite areavailable,but asmanyas23 endup beingrejectedfromthe photographs. Including thispoledoesnotchange theoverall final selection(Table1). Rejectedresultsincludethoseby Zhu to hematitebearingred average verysignificantly, butwe prefernotto useit. Finally, et al. [1977, 1981] which correspond
•
ET AL.: CONFICTION
OF ASIA PRIORTO THE COLLISION OF INDIA
180
,"
+
"
ß
+ß
,'
+ O
}•;• 90 ø
270 ø
... .,. •'
'." •::7 J • '•
Pozzi, S.Lhasa
Kl.Wi. 10> Achache, N.Lh• ............... '• 0o
Fig. 4. Eq•-am
projection • Cmm•
sandstones which were demagnetizedonly by the alternating field (a0 technique,whichis knownto be inefficientin this case.The databaseis discussed in detailby Chenet al. [1993]. Note that the poles tend to be streakedalong a small circle centeredon Tibet, although some poles are quite clearly remotefrom this circle (Figure4a). This includesa groupof four poles selected from easternmostTibet, near Markam, located about 40 to 65øN, 170 to 180øE, and some poles obtainedclose to the Zangbo suture(mostly by Otofuji et al.
•les fromTi•t. •
•on
of Figure2.
[1989];seeChenet al. 1993,Figure11b])wlfichareclearly affectedby strongshearparallel to the suture.Chen et al. also discussin detailthe large amountof datafrom the Lhasaareain centraleasternTibet, particularlyon the Takenared sandstone formation (Albian-Aptian) and the andesitic Lingzizong formation (60-50 Ma). Data from Achacheet al. [1984] and Lin and Watts [1988] reveal that the block has undergone internal local deformation in the Lhasa area with relative rotations between a South Lhasa and a North Lhasa block.
21,934
CHF.•ETAL.:CONFIGURATION OFASIAPRIOR TOTHECOLLISION OFINDIA 180 ø
Eightpolesthatpassthe selectioncriteria(Figure4b) are still quitedispersed. The datafrom centralandwesternTibet yield compatiblepaleolatitudesbut imply deformationat all scales (from a few tensof kilometers(e.g., North LhasaversusSouth Lhasa) to hundredsof kilometers (e.g., LhasaversusWest Tibet)). On the other hand, the data from easternTibet near Markam [Otofujiet al., 1989, 1990;Huanget al., 1992], some of which passthe fold and reversaltests,imply both a very
large clockwiserotationwith respectto the rest and a much higher paleolatitude,implying an origin from a different
El
block. This is discussed further below. 90 ø
Pamir-Punjab.Bazhenovand Burtman[1986] havepublished Cretaceous data for the Pamir-P•jab. However,mostsamples were not demagnetizedabove400øC, and fold testsare not documented.Also means are calculatedfrom samplesrather thansites.As a consequence, theseresultscannotbe usedwith confidence.They displaya large scatterin declinationwhich is likely due to the proximityof thrustsand shearzones,as was noted above to be the case for the data of Otofufi et al. [1989] takencloseto the Zangbosuture(seeopenarrowson Figure 1).
ß
Indochinablock.¾angandBesse[1993]havesampledsome 20 localities in and around the Khorat plateau with well-
constrained upperJurassic andlowerCretaceous age.Despite a
Fig. 5. Equal-area projection of Cretaceous meanpolesfor Asian lack of fold test, due to the flat lying strata,the sediments blocks.The formatis asm Figures2 to 4. Polesfor Eurasia,NCB, SCB,
overlieupperTriassic andlowerJurassic formations for which Junggar,Tarim,WestTibet (andIndia)lie roughlyon a (dashed)great both fold and reversal tests are available. Yang and Besse
derivea meanpoleat 63.8øN,175.6øE(A95=1.7ø). DISCUSSION A remarkable feature of the Cretaceous data from the Asian
blocksis the consistency betweenupperandlower Cretaceous results(Table 1). It seemsthat in this areathe Cretaceouswas a time of little relative motion or displacementwith respectto thepole, asnotedby Chenet al. [1991] for the Junggarblock andby Chen et al. [1992] for the Tarim. The sameappearsto hold for the NCB and SCB (see Enkin et al. [1992a], updated by Yang [1992]) andfor the EurasianAPWP as a wholethis is the "hairpin loop" or standstill of Besse and Courtillot, [1991]. It is thereforepossibleto averagethe lower and upper Cretaceousresults, leading to Cretaceouspoles shown in Figure5 andlistedin Table 2. Despitestill ratherlargeuncertainties, thepolesof NCB and SCB are compatiblewith those from Eurasia, implying that within paleomagneticuncertainties,the main Chineseblocks and Siberia had come to occupy their present respective positionsby the late Jurassic[Enkin et al., 1992a; Yang, 1992]. It is found that the Cretaceouspoles for Eurasia, Junggar,Tarim, WesternTibet, andIndia whichhasbeenadded from Besseand Courtillot [1991] for completenessare roughly
aligned along a great circle that intersectscentral Asia in a NNE direction(dashedcircle on Figure 5). This meansthat, to first order, these blocks have moved towards each other in that direction
with litfie
rotation.
More precisely, going from north to south, the angular distancebetweenthe EurasianandJunggarpoles(6.2o+4.8ø) is statisticallysignificant and correspondsto 650 km_-k530 km of shorteningin a N-S direction(i.e., a paleolatitudedifference of 5.9o+4.8ø) and an insignificant counterclockwiserotation of 2.4ø:k5.8 ø of Junggarwith respectto Siberia,for a reference point at 44øN/86øE. The angulardifferencebetweenthe Junggarand Fergana polesleadsto a negligiblelatitudinaldifferenceof 0.3o+6.9ø and a significantrotationof 15.7ø+10.0 ø at a referencesite locatednear Fergana(40.5øN,72.5øE).This is consistent with the idea that thesetwo formedpartsof Kazakstanbut that the Fergana basin has undergonesignificant counterclockwise rotationrelated to right-lateralmotion on the Talasso-Fergana
circle(paleomeridian) demonstrating therelativequasi-N-S shortenings
betweentheseblocks,withlitfie rotation.PolesfromTibet,to thewestof 95øElongitude,lie on a (dotted)smallcirclecenteredon the plateau,
indicatingrotationswithoutlatitudinalchange.Polesfrom Tibet (and Indochina), to theeastof 95øElongitude, lie on a different(dotted)small circleindicatingmajorrotationsandlatitudinalshiftwith respectto the restof Tibet (seetext for furtherexplanations).
fault [Bazhenov, 1993]. Bazhenov arguesthat this motion occurredin the Neogenepossiblyas recentlyas the last 10 m.y.
The distance between the Junggar and Tarim poles (4.3ø:t:5.5 ø) is not significantat the 95% confidencelevel, but individual Tarim poles are systematicallyfarther from the Eurasian pole than the individual Junggar poles. Corresponding shorteningof 420 km_q:605 km (paleolatitude ß differenceof 3.8ø:k5.5 ø) and rotationof 2.1ø+6.3ø are obtained for a reference site at 40øN/77øE. As noted above, the Tibetan data cannot be reduced to a
singlepole. The data from westernandcentralTibet lie on a small circle implying a similar paleolatitudebut someamount of relative rotation,whereasthe data from easternTibet imply
both significantrotationsand paleolatitudedifferences.The Tarim and WesternTibet poles differ by 8.5o+6.4ø, but the paleolatitudedifferenceis not significant(5.7ø+6.2ø);thus these data would imply a (statistically insignificant) N-S shorteningof 630 km_-k680 km (i.e., a paleolatitudedifference of 5.7o+6.2ø) and a significantrelativerotationof 7.1ø+6.4ø, for a referencepointat 34øN/80øE. Paleomagnefic work southof the Yarlung-Zangbosuture, henceon the Indian plate, near Dingri has led Besseet al. [1984] and Besse[1986] to proposethat some450 km.q:500 km of intracontinental shorteningoccurredsincethe onsetof the India-Asia collision acrossthe Main Boundaryand Main CentralThrusts,southof Dingri, and that 550 kin:k650km of shorteningtookplacebetweenDingri and the Lhasablock. Becauseno other major tectonicevent occurredsincethe time of depositionand magnetizationof the sediments,it is believed that all values of shorteningand rotation deduced frompaleomagnetic datareflecttheintegralof deformation due to the collision. Shortening values are indicated on a paleogeographicreconstructionof Asia in the Cretaceous basedon thesepaleomagneticdata (Figure 8), which updates Enkin et al.'s [1992a] Figure 27.
C-'lIENET AL.: CONFIGURATIONOF ASIA PRIORTO THE COLLISION OF INDIA
21,935
Oceanic plate kinematics allow estimation of the total convergence betweenIndia andEurasiaat 2600 kin__+900 km in the last 50 m.y. [Patriat and Achache, 1984; Besse and Courtillot, 1988], i.e., roughly since the onset of the collision, although original contact may be some 10 m.y. earlier [see Jaeger et al., 1989]. We note that the individual (block to block) shorteningsobtained from paleomagnetic data, calculatedneax 80øE longitude,axe 650 km (between Siberia and lunggax,mostly in the Altai), 420 km (between lunggax and Taxim, mostly in the Tien Shah), 630 km (betweenTaxim and Tibet, mostly in the Kunlun and Altyn Tagh), and 1000 km in the Himalayas.This addsup to 2700 km, in very good agreement with the ocean kinematic predictions.However, the uncertaintyon this figure is not computable in a straightforward fashion: total shortening calculatedfrom the EurasianandWesternTibet polesmounts to an angulardifferenceof 16.4ø:1:5.5 ø (i.e., 17005:610km in a N-S direction),but as far as shorteningacrossthe Himalayasis concerned,the Indian pole at 60 m.y.[Be$$e and Courtillot, 1991] is not independentfrom the Eurasianone, sincethe two axe synthetic poles combining paleomagnetic data from severalplates and oceankinematicmodelsfor severaloceans, and the uncertaintyis not easilyderived.Note that shortening beteweenEurasiaand Central Tibet was estimatedby Achache et al. [1984] to be 1900•850 km, based on their Lhasa block
poles and a pole for Eurasia determinedby Achache et al. [1983]. Individual shorteningvaluescan be comparedto geological
estimatesbasedon field work or topographicand geographical data that constraincrustalstructure.This comparisonis based on the work of Avouac [1991]. Assumingan initial thickness of 30 km for the crust in the Altai and SayanTuva, with a presentaveragealtitudeof 2000 m, a width of 700 km, and a crustalthicknessof 50 km [Patton, 1980] would imply some 300km of crustal shortening. This is most likely underestimatedbecause(1) initial crustal thicknesscould have
been thinner(someauthors,for instance,Feng et al. [1989], arguefor an oceaniccrust),(2) a largefractionof materialhas certainlybeen removedby erosion,as evidencedby Tertiary and Quaternarysedimentsin the basin, and (3) displacement on NW trending dextral strike slip faults in the Altai was neglected.Therefore, shorteningbasedon this reasoningis likely to have exceeded400 km, to be comparedwith the paleomagnetic value of 650•30 kin. Chen et al. [1991] and Avouac et al. [1993] have discussed the compatibilityof tectonicandpaleomagnetic datarelatedto shortening in the Tien Shah. Reconsideration of earlier paleomagnetic data from the Taxim (the Kuchepole discussed above)by Chen et al. [1992] has led to somerevisions.The estimatedshorteningproposedby Avouac et al. for the Tien Shan (at the longitudeof Kashgar)is 180 km. Again, this assumes constant crustal volume and is likely an underestimate.
Another
estimate
can be derived
from
a
kinematicmodel of active deformationin Asia proposedby Avouac[1991] andAvouacet al. [1993] (seeFigure6). Avouac and Tapponnier [1993] have selecteda systemof four rigid rotatingblocks (India, Tibet, T a rim and Junggar,which they assumeto be connectedto Siberia for lack of quantitativedata in the Altai). Constraintsare the NUVEL-1 angulaxvelocity describingthe movementof India with respectto Eurasiaand the positionof the Tarira versus.lunggaxrotationpole. Input data axeestimatedratesof shorteningacrossthe Tien Shanand Himalayasand slip ratesalongthe Altyn Tagh and Karakorum faults. Inversion yields the amounts and sensesof motion shown in Figure 6. Comparisonwith finite deformationand age determinationssuggestthat the currentkinematicshave remainedaboutthe samesince about 15 m.y. (i.e., less than one third of the time since the onset of the collision).
Although the rigid block hypothesiscannothold for such a
21,936
C-'liENETAL.: CONFIOURATION OFASIAPRIORTOTI• COLLISIONOFINDIA 80øE
Tibet/Siberia!
•
O•=.86ø/Ma \
100øE
i
t
Tibet/Tarim
.................
60=1.48ø/Ma •x• .........................
KAZAK •xx NG HTAN\\•k•_a4L © --r.-:.. -:•%DZU ..•.•.• ARIA
....... %--.... .....
x.-":.... ':':'::':' .:.:.••/T; r•m •.;•b•r i5 ,,,&,
'-- ...:.:.:.:..
/
•/e "'•/ /'//,,;40ON
40øN
ß !
TARIM + •
-,.-•',•- 2..-
(/ ORDOS /
!
•
•.
"::•:.:.•,:..::'-::::::i.:,:.:.'.':"'.:,:.:.;.:.;::::!:..:...' • '" •,•
T I I11I= T \
Iyr '
30øN
. • ,•.
4-
xI
•smm-. /yr
•
•..•
•
' ß'•
• x --
-••, .
-
..::i:ii:i::"/
..::i•!•i•:' / ..'..•..•....'•iiiii!:•?,i t/ S0 UTH
•.
:"::::.--":....-".....:• :.....:•:i!i::!i•ii:/ •/
30ON
!
:'::'"""::::'i:i x
Normal faults
•.•i
Thrust fault
•:.."•
INDIA '
18mr /yr
Strike-slip faults
-:-
/k : \
I .\
\/ ••
->15mmlyr
'"'
Active folds
• 500km I
Zones of)ression active 80DE
100øE
Fig. 6. Kinematicmodelof deformation in TibetandCentralAsia.Strike-slipfaultingandblockrotationin eastemTibet transform northward compression of Indi• intosoutheastward extrusion of SouthChina.Dashed linesaretheboundaries of deforming eastemTibet.Eulerpolesdescribing themotionof TibetandTarimwithrespect to Siberiaandof Tibetwithrespect to Tarimarealsoshown.Themodelis thought to applybackto 15m.y. [fromAvouac,1991;Avouacet al., 1993].
long time and geometricaladjustmentsmusthave taken representsmotion over the last 15 m.y. leads to another place,firstordervaluescanbe obtained fromFigure6 (rates estimate of shortening of 315 km. Convergencein the multipliedby 15 m.y.). For JunggarversusTarim motion Himalayasover the sametime intervalis 270 kin. acrossthe Tien Shan, this would imply some 200 km of
Altogether,localizedstrain in a few well-identifiedranges
shortening and10ø of rotation.Theseareon thelow andhigh accountsfor 1200 lcm of intracontinentalshorteningbetween sides,respectively, comparedto the palcomagnetic estimates, India and Siberiasince 15 m.y. This is 1500 km lessthan the but with the same senses.
The Tibetan data demonstrate internal deformation at scales
total palcomagneticestimateof convergencesincethe onset of the collision (and 500 km less than the minimum value at
ranging from1 to 1000km [Chenet al., 1993],correspondingthe 95% confidencelevel). This missing amount is either to superimposed blockrotations andoroclinal bending. Figure related to further internal deformation of the blocks since 15 5 shows the well-known rotation between the southern and
m.y., or morelikely to tectoniceventsprior to 15 Ma. Avouac [1991] arguesthat most of the deformationin the Kunlun, Altyn Tagh, and Ticn Shanoccurredsince 20 m.y. Therefore previous deformationmight have occurredeither within the
northern partsof theLhasablock[e.g.,Achache et al., 1984], amounting to 17.7ø+8.2 ø. Palcolatitudes betweencentralTibet (North Lhasa)and westernTibet (Domar) are similar (the differenceis an unsignificant1.0ø:1:5.8ø), but the declination difference is large,reaching 28.50+8.0 ø. Thisis thesameorder of magnitudeas the azimuthaldifferencebetweenthe eastern
continental subduction,for instance, in the Himalayas or Tarim, andpossiblythroughlateralexumsionof oneor several
and western terminationsof the Bangong-NujiangJurassic suturezone(about25ø).This may be consistent with the fact
blocks. The data from Markam
that both the suture and the southernEurasianmargin were
blocks themselves, between the blocks as oceanic or
stand at odds from the rest of Tibet.
Concurringresultsfrom distinctstudies[Huang et al., 1992; roughlylinearprior to collisionandthat theywerethenbent Otofuji et al., 1990] and a positive fold test leave no doubt (see the similaroroclinalbendingproposedby Klootwijk et that a characteristic prefolding magnetization has been recovered. There is no reason to suspect the age of the al. [ 1985]for thesuturebetweenthe LhasablockandIndia). Bourjotand Avouac[1990] estimatethat shortening across formations,which has been establishedby correlationwith the Kunlun amountedto 1{)0-t:15km. But a more significant South Yunnan stratigraphy.Although, as can be feared in partcouldhavebeenabsorbed alongtheleft lateralAltynTagh other cases, particularly with red beds, a prefolding alwaysremainsa possibility[e.g.,Achache fault. Offsetsby 500 and up to 700 km are advocatedby remagnetization is indeeda true Tapponrder et al. [1986]andPeltzerandTapponnier [1988], et al., 1984], we believethat the magnetization primaryone, implyingthat the Markamareawas implyinga N-S component of convergence between200 and Cretaceous, not a part of the Tibetan blocks, or at least was in a very 300 km. This is to be comparedto the unfortunatelyilldefined)palcomagnetic estimateof 570-t:680kin. Using the different relative position with respect to them prior to collision. model of Avouac [1991] under the assumption that it
CttENETAL.: CONFIGURATION OFASIAPRIORTO THECOLLISIONOFIND•
Recent resultsfrom Indochina [Yang and Besse, 1993] indicate that as is the case for Markam, this block stood
significantlynorthof Tibet ratherthan southas is the caseat present and that it has been rotated clockwise in very significantamountssincecollisiontime. We have plottedon Figure 7 inclinationand declination
more
than
1000
km
21,937
to the North
without
much
rotation
(exceptin the Lhasaarea).Indochinaand Markam have been rotated respectivelysome 15ø and 35ø clockwise,Indochina beingpushedsome1000 km southwith respectto Eurasiaand China and more than 2000 km with respectto central Asian blocks.
In Figure8 we proposea paleogeographic reconstruction of Asia in the Cretaceous.Each block has beenplacedin latitude the samesitesif thesehad been rigidly attachedto Eurasia,as and orientationin agreementwith the paleomagneticdata of a functionof presentlongitude(whichis not toodifferentfrom Table 2 and adjusted,well within the 95% uncertainties,to a plot as a functionof Cretaceous paleolongitude, in relative ensure closest packing. Mongolia, NCB, and SCB are terms).This plot (to be comparedwith the paleodeclination supposedto have been essentiallyassembledin their present map of Figure 1 and the reconstruction of Figure 8) clearly configuration,althoughsomeconvergencein the Qinling and outlinesthat with referenceto the easternmost part of Asia minor extrusionof SCB after the collision are likely (but both (NCB, SCB) which itself is compatible with Eurasian well below paleomagneticuncertainty).Indochinamust then (Siberian)values,Tibet, Tarim and Junggarhave beenpushed have lied immediately to the west of the SCB. We have "anomalies", defined as the differences between observed Cretaceousvalues and thosethat would have been expectedat
10
North China
Indochina
Markam
South China
-10 Fergana
Junggar
-2o
Tibet (Lhasa)
'/0
80
90
100
110
120
Longitude (øE)
4O
•
20 North China
Tarira
•
Junggar
•
Indochina
0 South China
•
-20
-
c• -40
•
W. Tibet
Fergana
b
Tibet (Lhasa) I
70
80
90
100
110
120
Longitude (øE) Fig.7. (a) Latitude anomalies (differences between theCretaceous paleolatitudes andthosepredicted at thesamelocations by theEurasian poles)andCo)declination anomalies (differences between Cretaceous paleodeclinations andthosepredicted at thesamelocations by theEurasian poles)for themainAsianblocksdiscussed in thispaper,shown asa function of theaverage longitudes of sampling sitesontheseblocks: (1) thestability of NCBandSCBrelativeto Eurasia, (2) thenorthward movement, withoutsignificant rotation, of Junggar andTarim,andwithdifferential rotation of western andcentralTibetandFergana, and (3). the southward movementof IndochinaandMarkam(easternTibet) withlargeclockwiserotations.
21,938
CttEN ET AL.: CONFIGURATIONOF ASIA PRIORTO THE COLLISIONOF INDIA
650=530km
1700=610km
420=600km
Asia+Himalayas ~ 2700km 630=680km
Himalayas 1000km
Fig. 8: SchematicCretaceous palcogeographic reconstruction of Asiawith indications of crustalshoretingbetweenthe blocks. Cretaceous basinsfilled with continentalsediments thatprovidedmanyof the palcomagnetic dataare shownin darkershaded pattern.Themainpaleornagnetic sampling locations areshownasblackdots(seeFigureI for blocknames).
assumed between collision
in this reconstruction that Markam was nested Indochina and the SCB. The first effect of the must therefore have been the southeastward
Kunlun blocks,will furtherconstrainthe part of continental shorteningnorth of Tibet that must be attributedto extrusion.
In conclusion,despitestill rather large uncertainties, Cretaceouspaleomagneticdata of Asian blocks are now
extrusion of Indochina, with the Markam area squeezed between some of the major NNW trending strike slip faults that congregatein the Three Riversarea. The reconstruction outlinesa broadWNW-ESE trendingzone of crustaldeformationbetweenthe Mongolia and North China blocks to the north and Junggar, Tarim, Qaidam, and Indochinato the south.This broad zone comprisesto the east the thick sedimentsthat have subsequently been deformedand extrudedto yield the presentSongpan-Ganze triangle.We have
is noteworthythat the agreementwith meanpalcomagnetic valuesappearsto be betterthan couldbe expectedfrom the calculated uncertainties. It remainsto be understood why these
assumed that Markam
uncertaintiesmight be overestimated.
was one of several slivers that have been
severedfrom this zone.The westernpart of the zonemusthave beendeformedto yield the Sayan-Tuva-Altairanges. The Tibetanblockshavebeenunbentin Figure8 andrestored to their original tropicallatitudes,with Tarim and the Qaidam on one hand and Junggaron the other hand placed farther north. Stippling underlines areas of continental crust that have been destroyed(for instance,by continentalsubduction), shortened,or displaced. Of course, shortening within the blocks (assumedto be rigid) has not been taken into account (if for only one reason, because this allows better identification of the blocks in the reconstruction)and is in fact includedin the stippledareas. The reconstructionemphasizesthe rather simple, E-W trendingshapeof the southernmarginof the Eurasiaplate near 10øN latitude. It also restores a fairly continuousseries of continentalbasins largely filled by red sandstonesfrom the Sichuanbasin, throughMarkam, to the Khorat plateau and
sufficientto restorea picturethat is almosteverywherein qualitativeandevenquantitativeagreementwith the amountof shorteningand rotationpredictedby the tectonicmodelsof extrusion [e.g., Tapponnier et al., 1986] and deformation withinTibet andTarim [Arrnijoet al., 1986;Avouac,1991].It
Noteaddedinprooff.We referthereaderto therecentpaperby Huang and Opdyke [1993] on rotationsin southeastern Asia
whichalso summarizes availableCretaceous palcomagnetic data from East Asia and overlapswith and to some extent complements thepresentpaper,whichit quotesin preprintas reference51 (with a misprintrepeatingreference50). Acknowledgments. We are particularlygratefulto J.P. Avouacfor
numerous discussions, for comments ona firstdraftof thispaper,and for makinga paperavailablepriorto publication. We alsothankP. Tapponnier, M. Mattauer,M. Bazhenov, R. Coe,andN. Opdykefor comnentsand/orfor makingpapersavailablepriorto publication andP. Molnar,M. McWilliams,andG. Schubert forthoughtful reviews.Thisis
IPGP contribution 1268 and CNRS-INSU-DBT
REFERENCES
then the Tibetan series, to western Tarira. One of the most
striking features is the present offset of the Khorat with respectto the Sichuanbasin, which it used to form a natural continuation.
The Shan Thai block is not yet properly constrainedby palcomagnetismand its exact ancient location, to the east of the Tibetan blocks or possibly between the Qaidam and
contribution 616
(dynamiqueglobale).
Achache, J., V. Courtillot, and J. Besse, Palcomagnetic constraints on the Late Cretaceous
and Cenozoic
tectonics
of southerneasternAsia, Earth Planet. Sci. Lett., 63, 123136, 1983.
Achache,J., V. Courtillot and Y.X. Zhou, Paleogeographic and
tectonic
evolution
of
South
Tibet
since
Middle
CHEN ET AL.: CONFIGURATIONOF ASIA PRIORTO THE COLLISION OF INDIA
21,939
continental sediments along the Northern Tien Shah Cretaceoustime: New palcomagnetic data and synthesis, J. (China) and heterogeneousstrain in Central Asia, J. Geophys.Res.,98, 10,331-10,339, 1984. All[gre, C.J., et al., Structureand evolutionof the HimalayaGeophys.Res., 96, 4065-4082, 1991. Chen, Y., J-P Cogn6 and V. Courtillot, New Cretaceouspoles Tibet orogenicbelt, Nature, 307, 17-22, 1984. from the Tarira basin, Northwestern China, Earth Planet. Armijo, R., P. Tapponnier, J.L. Mercier and T. Han, Sci. Lett., 114, 17-38, 1992. Quaternaryextensionin southernTibet: Field observation and tectonic implication, J. Geophys.Res., 91, 13,803- Chen, Y., J.-P. Cogn6,V. Courtillot, P. Tapponnierand X. Y. 13,872, 1986. Zhu, Cretaceouspalcomagneticresultsfrom westernTibet and tectonic implications, J. Geophys.Res., in press, Avouac, J.P., Applications des m6thodes de morphologic 1993. quantitative • la n6otectonique:Mod[le cin6matiquedes d6formations actives en Asie Centrale, Ph.D. thesis, 156 England, P., and G. Houseman, Finite strain calculation of continental deformation, 2, Comparisonwith the Indiapp., Univ. de Paris VH, 1991. Asia collision zone, J. Geophys.Res., 91, 3664-3676, Avouac.,J.P., and P. Tapponnier,Kinematicmodel of Active 1986. deformationin Central Asia, Geophy.R. Lett., 20, 895898, 1993. Enkin, R.J., Formation et d6formafionde l'Asie depuisla fin de l'•re primaire,Ph.D. thesis,333pp., Univ. de Paris VII, Avouac, J.P., P. Tapponnier,M. Bai, G. Wang and H. You, 1990. Active faulting and folding in the northern Tien Shan (Xinjiang, China), J. Geophys. Res.,98, 6755-6804, Enkin, R.J., Y. Chen, V. Courtillot, J. Besse, L. Xing, Z. 1993. Zhang, Z. Zhuang, and J. Zhang, A Cretaceouspole from SouthChina, and the Mesozoichairpin mm of the Eurasian Bazhenov, M., Cretaceouspalcomagnetismof the Fergana apparentpole wander path, J. Geophys.Res.,96, 4007basin and adjacentranges:Tectonic implications,Earth 4027, 1991 a. Planet. Sci. Lett., in press, 1993. Bazhenov, M.L., and V.S. Buttman, Tectonics and Enkin, R., V. Courtillot, L. Xing, Z. Zhang, and J. Zhuang, palcomagnetism of structural arcs of the Pamir-Punjab The stationaryCretaceouspalaeomagneficpole of Sichuan syntaxis,J. Geodyn.,5, 383-396, 1986. (South China Block), Tectonics,10, 547-559, 1991b. Beckinsale, R., S. Suensilpong, S. Nakapadungrat and J. Enkin, R., Z.Y. Yang, Y. Chen, and V. Courtillot, Walsh, Geochronology and geochemistry of granite Palcomagneticconstraintson the geodynamichistory of magmatism in Thailand in relation to a plate tectonic China from the Permianto the Present,J. Geophys.Res., model, J. Geol. Soc. London, 136, 529-540, 1979.
Besse, J., Cin6matique des plaques et d6rive des p61es magn6tiques: Evolution de la T6thys, collisions continentaleset couplage noyau-manteau,Ph.D. thesis, 380 pp., Univ. de ParisVII, 1986. Besse, J. and V. Courtillot, Palcogeographicmaps of the continentsbordering the Indian Ocean since the Early Jurassic,J. Geophys.Res.,93, 11,791-11,808, 1988. Besse,J., and V. Courtillot, Revised and syntheticapparent polar wander paths of the African, Eurasian, North American and Indian plates, and true polar wander since 200 Ma, J. Geophys.Res., 96, 4029-4050, 1991. Besse, J., V. Courtillot, J.P. Pozzi, M. Westphal and Y.X. Zhou, Palcomagneticestimatesof crustalshorteningin the Himalayan thrustsand Zangbo suture,Nature, 587, 621626, 1984.
Boutjot, L., Relation entre structurelithosph6riqueprofonde et d6formationde surfaceau Tibet, Ph.D. thesis,288 pp., Univ. de Paris VH, 1991.
97, 13,953-13,989,
1992a.
Enkin, R., V. Courtillot, H. Leloup, Z. Yang, L. Xing, J. Zhang and Z. Zhuang, The palcomagneticrecord of uppermostPermian, lower Triassic rocks from the South China Block, Geophys. Res. Lett.,19, 2147-2150, 1992b.
Fang,D., G. Jin, H. Chen,Y. Gou, Z. Wang, S. Ying andX. Tan, Discussion on palcomagnetism and tectonic evolution of Tarim plate (China), paper presentedet the 4th National Conferenceon Palcomagnetism,Chinese Acad. of Sci., Hangzhou,China, 1989. Feng, Y., R.G. Coleman, G. Tilton, and X. Xiao, Tectonic evolution of the west JunggarRegion, Xinjiang, China, Tectonics, 8, 729-752, 1989.
Girardeau,J., J. Marcoux,C. All•gre, J. Bassoullet,Y. Tang, X. Xiao, Y. Zao and X. Wang, Tectonicenvironmentand geodynamicsignificanceof the Neo-CimmericanDangqiao ophiolite, Bangong-Nujiangsuture zone, Tibet, Nature, 307, 27-31, 1984.
Bourjot, L., and J.P. Avouac, Cenozoic crustal shortening Hao, Y., D. Su, J. Xu, P. Li, Y. Li, N. Wang,H. Qi, S. Guang, accrossthe Kunlun, paper presentedat ColloqueKunlunH. Hu, X. Li, W. Yang,L. Ye, Z. Shou,andQ. Zhang,The Karakorum 90, CNRS-Chinese Acad. of Sci., Paris, 1990. Cretaceous System of China, pp. 301, Geological Buffetaut,H., and V. Suteethorn,Vertebratebiostratigraphy of PublishingHouse, Beijing, 1986. the Mesozoic Khorat Group of Thailand, Terra, 3, 332, Harris, N. R. Xu, C. Lewis, C. Hawkesworth,and Y Zhang, 1991. Isotope geochemistry of the 1985 Tibet Geotraverse, Lhasa to Golmud, Philos. Trans. R. Soc. London, Set. A, Chart,L.S., Palcomagnetism of Late Jurassic-Early Cretaceous 327, 263-285, 1988. granites in Hong Kong and tectonic history of South China, J. Geophys.Res., 96, 327-335, 1991. Hu, L., P. Li, and X. Ma, A magnetostratigraphic studyof Chang C.F., et al., Preliminary conclusionsof the Royal Cretaceous red bedsfrom Shanghan,westernFujian, China Society and Academia Sinica 1985 geotraverseof Tibet, (in Chinese),Geol. Fujian, 1, 33-42, 1990. Nature, 323, 501-507, 1986. Huang, J., J. Ren, C. Jiang, Z. Zhang, and D. Qin, The Chen, P., A survey of the non-marineCretaceousin China, GeotectonicEvolution of China, 124 pp., SciencePress, Cretaceous Res., 4, 123-143, 1983. Beijing 1980. Chen, Y., Evolution tectoniquele long d'une transversale Huang,K., and N. Opdyke,Palcomagnetism of Cretaceousto entre Inde et Sib6rie: Apports de nouvelles donn6es lower Tertiary rocksfrom Southwestern Sichuan:A revisit, pa16omagn6tiques cr6tac6esdu Tibet, du Tarim et de la Earth Planet. Sci. Lett., 112, 29-40, 1992. Dzungarie, Ph.D. thesis, 306 pp., Univ. de Paris VH, Huang, K., and N. Opdyke, Palcomagneticresults from 1992.
Chen, Y., J.-P. Cogn6, V. Courtillot, J.P. Avouac, P. Tapponnier,E. Buffetaut,G.Q. Wang, M.X. Bai, H.Z. You, M. Li, and C. S. Wei, Palcomagnetic study of Mesozoic
Cretaceous
and Jurassic rocks of South and Southwest
Yunnan: Evidence for large clockwise rotations in the Indochina and Shah-Thai-Malay terranes,Earth Planet. Sci. Lett., 117, 507-524, 1993.
21,940
CHENET AL.: CONFIGURATION OFASIA PRIORTO THE COLLISIONOF•IDIA
strike-slip faults and basins during the India-Asia Huang,K., N. Opdyke,J. Li, andX. Peng,Palcomagnetism of collision: An experimentalapproach,J. Geophys.Res., Cretaceousrocks from Qiangtangterrane of Tibet, J. 93, 15,085-15,117, 1988. Geophys.Res.,97, 1789-1799, 1992. Jaeger, J.J., V. Courtillot, and P. Tapponnier, Peltzer,G., P. Tapponnier,and R. Armijo, Magnitudeof Late Quaternaryleft-lateral displacementalong the north edge Paleontological view of the agesof the DeccanTraps,the of Tibet, Science, 246, 1285-1289, 1989. Cretaceous/Tertiary boundary, and the India-Asia collision, Geology, 17, 316-319, 1989. Peng,X., andG. Zhang,Tectonicfeaturesof the Junggarbasin and their relationship with oil and gas distribution, in Kent, D. V. Xu, K. Huang, W. Zhang, and N. Opdyke, ChineseSedimentaryBasins edited by X.Zhu, pp.17-31, Palcomagnetism of Upper Cretaceousrocks from South China, Earth Planet. Sci. Lett., 139, 133-143, 1987.
Elsevier, New York, 1989.
K1ookwijk, C., P. Conaghan, and McA. Powell, The Pozzi, J.P., M. Westphal, Y.X. Zhou, L.S. Xing, and X.Y. Chen,The positionof the Lhasablock (southTibet) during Himalayan Arc' large-scale continental subduction, Late Cretaceoustime: New palcomagneticresults,Nature, oroclinalbendingand back-arcspreading,Earth Planet. 297, 319-321, 1982.
Sci. Lett., 75, 167-183, 1985.
and palcogeography of Mongolia Li, Y.A., Q. Li, Y. L. Liu, Z.K. Zhang and X. Ji, Study on Pruner,P., Palcomagnetism in the Cretaceous, Permian, and Carboniferouspalcomagnetismof Tarim craton since late Paleozoic, Preliminary data, Tectonophysics,139, 155-167, 1987. Xinjiang Geol., 7, (3), 1-77, 1989. Li, Y.A., Y.P. Li, R. Sharps,M. McWilliams,Q. Li, andW. Ren, J., C. Jiang,Z. Zhang, and D. Qin, The Geotectonic Evolutionof China (in Chinese),124 pp., SciencePress, Zhang,Mesozoicpalcomagnetic resultsfrom the Junggar Beijing, 1980. block, Xinjiang province,northwestChina, Eos Trans.
Tapponnier,P., andP. Molnar, Active faultingandCenozoic
AGU, 72, 1292, 1991.
Li, Y.P., Z.K. Zhang,M. McWilliams,R. Sharps,Y.J. Zhai, Y.A Li, Q. Li, and A. Cox, Mesozoicpalcomagnetic results of the Tarha craton: Tertiary relative motion between China and Siberia?,Geophys.Res. Lett., 15, 217-220,
tectonicsof the Tien Shan,Mongolia and Baykal regions, J. Geophys.Res.,84, 3425-3459, 1979. Tapponnier,P., G. PeltzerandR. Armijo, On the mechanics of the collision betweenIndia and Asia, Geol. Soc. Spec. Publ. London, 19, 115-157, 1986.
1988.
Liew, T.C., andR. W. Page,U-Pb zircondatingof granitoid Tapponnier,P., R. Lacassin,P.H. Leloup, U. Sch'arer,D.L. plutonsfrom westcoastprovinceof Peninsular Malaysia, Zhong, H.W. Wu, X.H. Liu S.C. Ji, L.S. Zhang, and J. Geol. Soc. London, 142, 515-526, 1985. J.Y.Zhong,The Ailao Shan/RedRiver metamorphicbelt: Tertiary left-lateral shear between Indochina and South Lin, J., The apparentpolar wanderpathsfor the North and China, Nature, 343, 431-437, 1990. South China blocks, Ph.D. thesis, 248pp., Univ. of Calif., Santa Barbara, 1984. Tian, Z.Y., G.L. Chai and Y.Z. Kang, Tectonicevolutionof Lin, J.L. and D.R. Watts, Palcomagneticresults from the the Tarira basin,in Chinese SedimeraaryBasinseditedby Tibetan Plateau, Philos. Trans. R. Soc. London, Set.A, X.Zhu, pp.33-43, Elsevier,New York, 1989. 327, 239-262, 1988. Westphal, M., J.P. Pozzi, Y.X. Zhou, L.S. Xing, and X.Y. Ma, X., Z. Yang, L. Xing, X. Ren, S. Xu and J. Zhang,An Chen,Palcomagnetic data aboutSouthernTibet (Xizang), early Cretaceous pole from the Ordosbasinandnew view I, The Creta•ous formationsof the I.,hasablock,Geophys. for eastern Chinese late Mesozoic palcomagneticdata, J. R. Astron. Soc., 73, 507-521, 1983. Geophys.J. Ira., in press,1993. Yang, Z., Contraintes pa16omagnttiques sur l'histoire Matte, P., L. Boutjot, P. Tapponnier,Y. Pan and Y. Wang, g6odynamique de l'Asie du Sud-Est:Les apportsde l'ttude Tectonics of Western Tibet between the Tarha craton and pa16omagnttique du Mtsozo•quedes blocs de Chine du the Karakorumfault, Colloque Kunlun-Karakorum90, Nord, Chine du Sud et Indochine, Ph.D. thesis,264pp., Paris, 42-43, 1990.
Univ. de Paris VIL 1992.
Molnar, P., and P. Tapponnier, Tectonics of Asia: Yang, Z., and J. Besse,Palcomagneticstudyof Permianand Consequences and implicationsof a continentalcollision, Mesozoic sedimentsfrom northernThailand supportsthe Science, 189, 419-426, 1975.
extrusion model for Indochina, Earth Planet. Sci. Lett.,
I17, 525-552, 1993. Otofuji,Y., S. Funahara,J. Matsuo,F. Murata,T. Nishiyama, X. Zheng, and K. Yaskawa, Palcomagneticstudy of Yang, Z., X. Ma, J. Besse,V. Courtillot,L. Xing, S. Xu, and
western Tibet: Deformation of a narrow zone along the
J. Zhang, Palcomagneticresultsfrom Triassic sectionsin
IndusZangbosuturebetweenIndia andAsia,Earth Planet.
the Ordos, North China, Earth Planet. Sci. Lett., 104, 258277, 1991.
Sci. Lett., 92, 307-316, 1989.
Otofuji,Y., Y. Inoue,S. Funahara,F. Murata,andX. Zheng, Yang, Z., V. Courtillot,J. Besse,X. Ma, L. Xing, S. Xu, and Palcomagnetic studyof easternTibet- Deformationof the J. Zhang, Jurassic palcomagnetic constraints on the Three Rivers region,Geophys.J. Ira., 103, 85-94, 1990. collisionof the North and SouthChina blocks,Geophys. Res. Lett., 19, 577-580, 1992. Otofuji,Y., J. Kadoi, S. Funahara,F. Murata,andX. Zheng, Palcomagneticstudy of the EoceneQuxu pluton of the Zhang, Z., Y.A. Li, Q. Li, Y. Zhai, Y.P. Li, M. McWilliams, Gangdisc belt: Crustal deformation along the IndusA. Cox, and R. Sharps, Jurassic and Cretaceous Zangbo suturezone in southernTibet, Earth Planet Sci. palcomagnetismof the Tarim block (in Chinese with Lea., 107, 369-379, 1991.
Pan, Y.S., and Y. Wang, Geological structure of the Karakorum and westernKunlun mountains,ChineseJ. of Arid Land Res., 4, 7-16, 1991. Patriat, P., and J. Achache, India-Eurasia
collision
English abstract),SeismoL.Geol., II, 10-16, 1989. Zhao, X., R. Coe, Y. Zhou, H. Wu, and J. Wang, New palcomagneticresultsfrom northernChina: collisionand suturingwith Siberia and Kazakhstan,Tectonics,181, 4381, 1990.
chronologyhas haplicationsfor crustalshorteningand Zheng, Z., M. Kono, H. Tsunakawa,G. Kimura, Q. Wei, X. Zhu and T. Hao, The apparentpolar wanderpath for the drivingmechanism of plates,Nature,311, 615-621,1984. North China Block since the Jurassic,Geophys.J. lnt., Patton,H., Crust and uppermantle structureof the Eurasian 104, 29-40, 1991. continentfrom the phasecelocity and the Q of surface Zhu, X.Y., C. Liu, S.J. Ye, and J.L. Lin, Remanence of red waves,Rev. Geophys.,18, 605-625, 1980. bedsfromLinzhou,Xizangandthenorthwardmovement of Peltzer,G., and P. Tapponnier,Formationand evolutionof
CttENET AL.: CONFIGURATION OFASIAPRIORTO THECOLLISIONOFINDIA
the Indian plate (in Chinesewith English abstract),Sci. Geol. Sin., I, 44-51, 1977.
21,941
J. Besse,J.-P. Cogn6, V. Courtillot, and Z. Yang, Laboratoirede Pa16omagn6tisme et G6odynamique, D6partement de G6omagn6tisme et Pa16omagn6tisme (URA CNRS 729), Institutde Physiquedu Glove, 4
Zhu, Z., T. Hao, and H. Zhao, Palcomagnetic studyon the tectonicmotionof Pan-Xi block and adjacentarea during Place Jussieu,75252 Paris Cedex 05, France. Yin Zhi-Yanshanperiod(in Chinese),Acta Geophys.Sin., Y. Chen, D6partementdesSciencesde la Terre, Universit6d'Or16ans, 31, 420-431,
1988.
B. P. 6759, 45067 Orl6ans Cedex 2, France.
R. Enkin, Pacific GeoscienceCenter, 9860 West SaanichRoad, P.O. Zhu, Z.W., X.Y. Zhu, and Y.M. Zhang, Palcomagnetic Box 6000, Sidney,B.C., CanadaV8L 4B2. observation in Xizang and continental drift, Acta. Geophys. Sin., 24, 40-49, 1981. Zhuang,Z., D. Tiaa, X. Ma, X. Ren, X. Jiangand S. Xu, A palcomagneticstudyalong the Yaan-TianquanCretaceous(ReceivedDecember7, 1992; Eogenesectionin SichuanBasin (in Chinese), Geophys. revisedJuly 19, 1993; acceptedJuly 26, 1993.) Geochem. Explor., 12, 224-228, 1988.
