RESEARCH PROPOSAL

MULTIDISCIPLINARY GEOLOGIC STUDY OF
CRUSTAL SHEAR AND ROTATION IN YUNNAN, CHINA

Submitted to the National Science Foundation in 1988 but not funded.

ABSTRACT

The sheared metamorphic rocks in the canyon of the Mekong River have not been studied by Chinese or western geologists due to their remoteness. In addition, the Man Wan Dam will inundate the lower Mekong River Canyon in the early 1990's. Earth Science Expeditions, a non-profit, tax exempt organization, has assembled a highly qualified team of western and Chinese geoscientists with complementary areas of expertise in order to complete a geologic study of this area during 1989. A list of participating geoscientists follows. Our intent is to evaluate the timing, nature and extent of crustal deformation in western Yunnan, and its relation to crustal deformation in surrounding regions also affected by India's collision with and penetration into Eurasia.

We plan to analyze two aspects of India's collision with and subsequent penetration into Eurasia: the possibility of an early phase of extrusion of material out of India's northward path, and widespread shear as India passed northward to the west of southwest China. The former is likely to have caused left-lateral shear on northerly or northwesterly trending high angle planes, and the latter, right-lateral shear and clockwise rotation, possibly on the same planes. In addition to evaluating and modeling regional structure in western Yunnan, we plan to make a detailed examination of shear zones in metamorphic rock units along the Mekong River to determine the sense, intensity, and age of shearing, and we plan to sample and analyze the paleomagnetism of overlying sedimentary rock to constrain the amount of rotation.

LANCANG JIANG GEOLOGICAL EXPEDITION
PARTICIPATING GEOSCIENTISTS

Ronald L. Bruhn, Professor of Geology, Department of Geology and Geophysics, University of Utah

Ralf C. Buckley, Senior Research Fellow, Centre for Resource and Environmental Studies, Australian National University

B. Clark Burchfiel, Schlumberger Professor of Geology, Department of Earth and Planetary Sciences, Massachusetts Institute of Technology

Michael P. Connelly, Expeditions Director, Earth Science Expeditions and Hydrogeologist, Westinghouse Corporation

William R. Downs, Research Associate, Northern Arizona University and Southern Methodist Univerisity

John W. Geissman, Associate Professor of Geophysics, Department of Geology, University of New Mexico

Timothy F. Lawton, Assistant Professor of Geology, New Mexico State University

Peter Molnar, Senior Research Associate, Department of Earth and Planetary Sciences, Massachusetts Institute of Technology

Leigh Royden, Associate Professor of Geology and Geophyics, Department of Earth and Planetary Sciences, Massachusetts Institute of Technology

Peter Winn, Science Director, Earth Science Expeditions and Geologist, Win-Eldrich Mines Limited

Bruhn, Buckley, Burchfiel, Downs, Molnar, and Royden have strong backgrounds in various aspects of Asian tectonics and field experience in the area of China affected by India's collision with Asia. Geissman has a strong background in paleomagnetic theory and application and has all necessary laboratory instruments for obtaining paleomagnetic data. Downs has a good comprehension of Chinese language and paleontology, Lawton has a strong background in sedimentology and stratigraphy, Connelly has a strong background in geochemistry, petrology and hydrogeology, Winn has a strong background in geomorphology and structure, and all four of them have extensive experience in river expeditioning. Two geologists from the Chinese Academy of Sciences, and two representatives from China International Sports Travel (Qu Yinhua and Ma Tie) will participate in the expedition.

SUMMARY

We plan to conduct a multidisiplinary geologic expedition in western Yunnan, China. The expedition involves travel by road to various parts of western Yunnan followed by travel by raft along a remote, roadless segment of the Mekong River(Lancang Jiang) where both highly deformed metamorphic rocks and apparently less deformed Mesozoic sedimentary rocks crop out. This area offers an excellent opportunity to study the history and geometry of deformation induced by the collision and subsequent penetration of India into Asia. Specifically, we plan to focus on the intensity, sense and age of shear in mylonitized rocks and the rotations of overlying Mesozoic sedimentary rocks. Yunnan lies east of Burma and India and southeast of the Himalaya, which overlie the northern edge of the Indian plate. Some 40 to 60 million years ago, India collided with southern Asia, and at that time the southern edge of Asia lay between 0 and 10 north latitude, roughly 2000-3000 km south of where that portion of the continent lies now. Thus, India has penetrated some 2000-3000 km into the rest of Asia (Molnar and Tapponnier, 1975). In addition to causing crustal thickening in the Himalaya, Tibet, and areas farther north, India's penetration also seems to have caused an extrusion of material eastward out of its way (Tapponnier and Molnar, 1977, Tapponnier et al., 1982). India's subsequent movement northward was accompanied by major strike-slip faulting and probably by rotation of crustal blocks in Burma and western Yunnan. See Part 1 - Background Geology.

The Mekong River weaves back and forth across the contact between metamorphic rock units and Mesozoic sedimentary strata in southwestern Yunnan. According to Chinese geologists, the metamorphic rocks are of amphibolite grade, and therefore temperatures in them have exceeded 450 C. More importantly, they are strongly sheared, with a marked subhorizontal north-south trending stretching lineation. Neither the sense of shear nor its age is known. Sedimentary rocks in contact with the metamorphic rocks are shown as Jurassic and Cretaceous shallow marine deposits on Chinese maps, but Misch (1945) and Gregory and Gregory (1922) described only Triassic red sandstones and shales in this area.

We plan to study the fabric of the mylonitized metamorphic rock in as many localities as possible in order to determine the sense of shear and the intensity of deformation. Left-lateral shearing probably occurred during a phase of eastward extrusion of southeastern Tibet. If right-lateral shearing occurred, it probably formed as India later slid northward past eastern Yunnan. Techniques for determining the age and sense of shearing have been developed and will be carried out in both the field and the laboratory. An attempt to date the age of shearing will be made using 40Ar/39Ar isotopic age determination on appropriate mineral phases. See Part 2 – Methods of Shear Zone Analysis.

An important component of our work will be paleomagnetic studies of the Mesozoic sedimentary rock and the metamorphic rock units along the Mekong. Sedimentary strata are important as they provide a reference to the paleohorizontal plane at the time of acquisition of magnetization signature. If shearing over a broad area occurred as India passed northward, large clockwise rotation of all rocks in the shear zone should have occurred. Such a rotation should be recorded by differences between declinations obtained from sedimentary strata in the shear zones and those of comparable rock units in undeformed areas of Yunnan. Mesozoic paleomagnetic pole positions for rocks east of the area of deformation in Yunnan in the Southern China tectonic block are relatively well known (Opdyke et al., 1986). See Part 3 - Crustal Block Rotations.

In summary, we plan to examine in detail the deformation and rotation of material along the Mekong River valley to characterize the age, style, intensity, distribution, and sense of shearing in the crust induced by the collision and penetration of India into Eurasia. We hope to constrain the extent and the timing of extrusion of parts of Indo-China from an initially more northwesterly position, and we hope to place bounds on the amount and distribution of shearing of western Yunnan due to India sliding northward past Yunnan. We realize that by focusing on a small area, we cannot answer all questions and place definite limits on these processes, but we believe that a detailed study of one key area is a better approach than a superficial examination of a large area. The stretch of Mekong that we plan to visit appears to offer a wide range of possible approaches to studying this deformation. Our work in Yunnan is fundamental to understanding areas of complex deformation in northern Yunnan, western Sichuan, Tibet, and Qinghai. We hope to continue our collaborative research program in these areas, concentrating on areas where our collective expertise can be used to maximize the results of our research.

PART I - BACKGROUND GEOLOGY

The collision and subsequent penetration of India northward into Eurasia has led to widespread deformation across central and eastern Asia. While India is underthrusting beneath the Himalaya at roughly 15 mm/yr (Lyon-Caen and Molnar, 1985), parts of the Tibetan Plateau and the area further north are being extruded eastward out of India's path (e.g. Molnar and Tapponnier, 1975, 1977). This extrusion is reflected most clearly by the prevalence of roughly east-trending left-lateral strike-slip faults emanating from Tibet and slicing the areas east and northeast of it (Tapponnier and Molnar, 1977, 1979). See Figure 1. Rates of slip on many of these faults are rapid: Altyn Tagh fault - 20 mm/yr (Molnar et al., 1987), Kunlun faults - 18 +/- 7 mm/yr (Kidd and Molnar, 1988), Haiyuan (Gansu) fault - 8 +/- 2 mm/yr (Burchfiel et al., 1988, Zhang Peizhen et al., 1988), and Xianshuihe (Kangting) fault 15 +/- 5 mm/yr (Allen et al., 1988). Moreover, large earthquakes have occurred in areas between these faults and some are associated with large components of left-lateral slip on roughly east trending planes (e.g. Allen et al., 1988), and fault plane solutions of earthquakes attest to dispersed deformation of this type (Molnar and Lyon-Caen, 1988).

Figure 1. Indo-Eurasian tectonic features. Modified from Molnar and Tapponier, 1977b.


The active tectonics of Yunnan reveal a very different pattern. The major feature is the northwest trending right-lateral Red River fault in southcentral Yunnan (Figure 2), along which slip at a few mm/yr occurs (Allen et aI, 1984). This fault dies out in a system of grabens in western Yunnan (Figure 1), but right-lateral faulting may continue to the northwest from the northern end of the grabens. The geology of this area is not well known, yet knowledge of the tectonics of this region is one of the keys to understanding the geological evolution of southeast Asia.

Figure 2. Tectonic sketch of pull-apart area in northwest Yunnan. Legend: 1 - Quaternary basins, 2 - late Tertiary basins, 3 - uplifted area. Modified from Deng et al. 1986.

Farther west, right-lateral slip on the steeply dipping, northerly trending Sagaing fault in Burma (Curray et al., 1978, Le Dain et al., 1984, Mitchell, 1981) allows the Indo-Burman ranges to slide northward past eastern Burma and Yunnan. It follows that all of western Yunnan and eastern Burma probably are undergoing right~lateral shear on northerly trending planes as India slides northward past this area.

When India collided with the old southern margin of Asia, some 50 Ma, the Indo-Burman Ranges probably trended west-northwest, parallel to the southern margin of Asia. They presently have a northerly trend, and hence almost surely have been rotated nearly 90 degrees with respect to the rest of Eurasia, since Asia has moved little with respect to north pole since the collision began. Whether the area east of the Indo-Burman Ranges has rotated a comparable amount is not known.

Motivated by patterns of deformation observed in laboratory studies, Tapponnier et al. (1982, 1986) hypothesized that in the early stages of the collision, much of Indo-China was extruded eastward out of India's path, in much the same way as extrusion currently occurs farther north. They suggested that major left-lateral shear zones would have existed where right-lateral slip presently occurs on the Red River fault (Figures 1 and 2). They correlated this phase of extrusion with the opening of the South China Sea in Oligocene time, and if correct, the left-lateral shear would have occurred well before the right-lateral shear due to the northward movement of India to the west of Indo-China. The Cenozoic, or post collision history of Yunnan is likely to be complex, with right-lateral shear superimposed on left-lateral shear, and with or without rotation. The eastward extent of the deformation associated with the collision and penetration of India into Eurasia is not well constrained, and the amount of deformation is an open question. A corollary effect of the collision and subsequent penetration of India into Eurasia is the intermixing of flora and fauna from two continents previously isolated by a large ocean. Apparently, this process has been uneven, as flora and fauna from Eurasia have invaded India to a much greater extent than vice versa. Some unknown barrier has operated during the Cenozoic to cause this phenomenon. Reconnaissance stratigraphic and paleontological studies of fossil bearing Cenozoic sediments in basins that developed during deformation of western Yunnan will be initiated during this expedition.

Subtropical areas that are undergoing high rates of crustal deformation, such as western Yunnan, are also characterized by relatively rapid changes in drainage. Rapid uplift of northwestern Yunnan appears to be causing stream capture of Mekong River tributaries by the Salween River drainage system. In addition, drainage appears to be controlled by active fault systems. This is particularly true of the Red River and the Salween River and their tributaries, but is less apparent with respect to the Mekong. This phenomenon will be investigated during our expedition. See Figures 3 and 4.

Figure 3. Location of the 1989 proposed study area (dashed rectangle).1990 proposed study area will be the Big Bend Section of the Yangtze River immediately to the north of the 1989 study area.

Figure 4. Landsat photo of the Mekong and Yangbi rivers in western Yunnan, China showing faults near the rivers.

PART II - METHODS OF SHEAR ZONE ANALYSIS

Shearing of the crust can manifest itself in several ways. At sufficiently high temperatures and pressures shearing may be accommodated by broadly distributed ductile deformation during regional metamorphism, or alternatively, by movement along discrete zones of concentrated, ductile deformation between blocks that have undergone little, if any, internal deformation. Contemporaneous deformation in the overlying brittle part of the crust, where temperatures are lower, may occur by brittle faulting. Populations of shear zones frequently have a complex, three dimensional geometry because they must accommodate translation and rotation of intervening crustal blocks in addition to components of crustal shortening or extension.

Estimating the amount of displacement across shear zones can be very difficult, because they may vary in width from a few centimeters to ten's of kilometers, and the intensity of shearing can be variable. Nevertheless, the intensity of the structural fabric within a shear zone and the spatial continuity of the zone, or system of shear zones, can give at least a qualitative impression of their regional importance. Furthermore, shear deformation generates various types of structural features used to determine the direction of shearing within the zone. These structures vary in dimension from map-scale to microscopic features, so that exposures of all dimensions may prove useful in making inferences about the tectonics of the region.

The techniques of analysis are now standard methods in structural geology and will be carried out both in the field and the laboratory. Methods for determining the sense of shear in mylonites have been summarized by Cobbald, et al (1987). We will be alert for evidence of multiple phases of deformation within the shear zones, and for relative ages of shear zones of different orientation and sense of shear. For example, the mylonite in the shear zones may have undergone several periods of shearing, with younger brittle deformation superimposed on older, ductile fabrics. Also, conjugate shear zones of opposing shear sense are common in strike-slip belts and care must be taken to separate this type of regional structure, which is often associated with rotating crustal blocks, from that where shear zones of different orientation and slip formed sequentially under different tectonic regimes and did not overlap in time. We have experience in analyzing rock fabrics to determine separate phases of deformation with different senses of shear.

We plan two approaches to determining the age of deformation. First, we must examine the contact of the sedimentary rock with the shear zones in the underlying, regional metamorphic basement rock. If the contact is depositional, then the shearing must be older than the age of the sedimentary rock (Mesozoic) and therefore older than the collision of India and Asia. Alternatively, the shear zones may pass upward into the overlying sedimentary rock as brittle fault zones, indicating that the shearing is younger than the sedimentary rocks and may be related to the collision. Another possibility is that the contact between the sedimentary rock and underlying metamorphic rock that hosts the shear zones may everywhere be a fault. If that fault truncates the underlying shear zones, then the sedimentary and metamorphic rocks may have originated far from one another, and were then subsequently juxtaposed by faulting in Mesozoic or Cenozoic time. In this case, the age of shear zones in the metamorphic rocks must be older than the sedimentary rocks, but the younger, faulted contact between the sedimentary and metamorphic rocks may be related to India's collision with Eurasia. The alternative possibility is that the faulted contact reflects decoupling of the sedimentary rocks from the underlying metamorphic rocks during the rotation of crustal blocks. In this case, some of the shear zones will continue upward into the sedimentary cover, unlike the previous situation where shear zones would be truncated at the contact. There are reports that young Quaternary fault scarps occur along major strike-slip fault zones in this region (Deng Qidong, et al., 1986, personal communication from Deng to P. Molnar, 1987). The Nanding River fault, for example, may cut across the Mekong River in the region of our proposed trip (Figures 1, 2 and 4). We must determine if these scarps occur along faults that either parallel or truncate the older mylonitic shear zones. In the first case, reactivation or continued activation of the shear zones is indicated, and it will be important to determine whether the sense of shear in the older, mylonitic rocks is the same or different from that occurring presently. If the young faults truncate the shear zones, then the shear zones probably represent an older episode of deformation with a relative age to be determined as described above.

The second and more quantitative approach to determining the age of shearing is to date the age of cooling of syntectonic minerals using 40Ar/39Ar isotopic age determination on appropriate mineral phases. Pb-U, K-Ar or Rb/Sr dating may also be applied to determine the age of metamorphism and possibly the age of the protoliths. Petrologic, petrographic and fluid inclusion work will be conducted to determine which dating techniques will be appropriate. In addition, the microscopic work will be used to provide data on microstructures and rock fabrics which yield information on the PIT conditions of deformation. If the appropriate metamorphic mineral assemblages are present in the rocks, microprobe analysis can provide data that allows calculation of the pressure and temperature of metamorphism and shearing. Paleontological dating of the sedimentary cover may be possible, or if appropriate volcanic rocks are located in the sedimentary strata we will also attempt to date them using radiometric methods.

PART III - CRUSTAL BLOCK ROTATIONS

Blocks of crust may rotate passively during deformation if they overlie a broad region of distributed ductile shearing, or if they are bounded by a network of discrete shear zones. The sense of rotation provides direct evidence of the sense of shearing. For example, pure strike-slip deformation will cause rotation of the crustal blocks about vertical axes. The sense of "spin" will be different for right-lateral versus left-lateral shearing. Tilting of the blocks about horizontal axes may reflect components of crustal extension or compression superimposed on the components of shear. The rate of rotation and tilt is determined by the geometry of the shear zone network, the degree of mechanical coupling between the brittle crustal blocks and underlying regions of ductile flow, and the regional rates of deformation within the orogenic belt. Paleomagnetism is perhaps the most reliable method for determining large-scale rotations of crustal blocks. Numerous studies show that rotations of several of ten's of degrees may occur, particularly in regions of regional, strike-slip faulting. Sometimes the crust is broken into a complex mosaic of blocks, with individual blocks ranging in dimension from a few tens of kilometers (e.g. Hudson and Geissman, 1987; Nelson and Jones, 1987; Ron et al., 1984), to hundred's of kilometers (e.g. Luyendyk et al., 1985; Walcott, 1984), and even lithospheric fragments of 1000 km size (e.g. Beck, 1976). The abundant Mesozoic sedimentary strate of Yunnan are likely to contain geologically stable and datable magnetizations which will be appropriate for inferring amounts of true crustal rotation.

To use paleomagnetism effectively to assess absolute and/or relative amounts of rotation, one must know the orientation of the magnetization would had there had been no rotation. This requires measurements of the position of the geomagnetic pole from rocks of the same age and from the same large block or plate where no rotation has occurred. We are fortunate that Opdyke et al (1986) have measured magnetizations of Triassic rocks from four widely spaced localities in southern China, all of which are east of the deformed area of western Yunnan. In addition, Lin (1984) reported paleomagnetic measurements from middle to upper Jurassic rocks and lower Cretaceous rocks of South China. Thus, we are optimistic that paleomagnetic measurements of Mesozoic rocks from western Yunnan can yield estimates of rotation. The laboratory of one of our principal investigators, J. Geissman, has all of the equipment required to complete the paleomagnetic research.

Even the metamorphic rock units offer some potential for paleomagnetic study. If the thermochronology of these rocks can be determined using 40Ar/39Ar incremental step heating methods, then possible coherent magnetizations in these rocks can be assigned a specific age of remanent magnetization acquisition. If coherent paleomagnetic data representing a significant time interval can be obtained, we may be able to determine the sense and rate of rotation during metamorphism and/or shearing.

REFERENCES
(as of 1988)

Allen, C. R., Gillespie, A. R., Han Yuan, Sieh, K. E., Zhang Buchun and Zhu Chengnan. 1984. Red River and associated faults, Yunnan Province, China: Quaternary geology, slip rates, and seismic hazard. Geological Society of America Bulletin, 95:686-700.

Allen, C. R., Luo Zhuoli, Qian Hong, Wen Xueze, Zhou Huawei and Huang Weishi. 1988. Field study of a highly active fault zone: the Xianshuihe fault of southwestern China. In preparation. Beck, M. E. 1976. Discordant paleomagnetic pole positions as evidence of regional shear in the western cordillera of North America. American Journal of Science, 276:674-684.

Burchfiel, B. C., Zhang Peizhen, Wang Yipeng, Zhang Weiqi, Jiao Decheng, Song Fangmin, Deng Qidong, Molnar, P. and Royden, L. 1988. Geology of the Haiyuan Fault Zone, Ningxia-Hui Autonomous Region, China and its Relation to the Evolution of the Northeastern Margin of the Tibetan Plateau. Geological Society of America Bulletin, submitted 1988.

Cobbold, P., et al. 1987. Shear Criterion in Rocks. Jour. Struct. Geol. Special issue, 9: 521-778. Curray, J. R., Moore, D. G., Lawyer, L. A., Emmel, F. J., Raitt, R. W., Henry, M. and Kieckhefer, R., 1978. Tectonics of the Andaman Sea and Burma. In ed. by J. S. Watkins, L. Montadert, and P. Dickerson (eds.), Geological and Geophysical Investigations of Continental Margins Mem. Amer. Assoc. Petrol. Geol., 29:189-198.

Deng Qidong, Daning Wu, Peizhen Zhang and Shefa Chen. 1986. Structure and Deformational Character of Strike-Slip Fault Zones. Pageoph, 124, No. 1/2.

Gregory, J. W. and Gregory, C. J. 1922. The Geology and Physical Geography of Chinese Tibet, and its Relations to the Mountain System of South-Eastern Asia, from Observations made during the Percy-Sladen Expedition, 1922. Philosophical Transactions of the Royal Society of London, Sere B, v. 213.

Hudson, M. R. and Geissman, J. W. 1987. Late Cenozoic strike-slip faulting and crustal block rotations, Dixie Valley area, Central Basin and Range Province. Geology, 15:638-642.

Kidd, W. S. F. and Molnar, P. 1988. Quaternary and active faulting observed on the Academia Sinica - Royal Society geotraverse of Tibet. Philosophical Transactions of the Royal Society of London, Ser. A., in press.

Le Dain, A. Y., Tapponnier, P. and Molnar, P, 1984. Active faulting and tectonics of Burma and surrounding regions. Journal of Geophysics Research, 89:453-472.

Lin, J.-L. 1984. The apparent polar wander paths for the North and South China Blocks. Unpublished Ph.D. Dissertation, Univ. of Cal. Santa Barbara.

Luyendyk, B. P., Kamerling, M. J., Terres, R. R. and Hornafius, J. S. 1985. Simple shear of southern California during Neogene time suggested by paleomagnetic declinations. Journal of Geophysics Research, 90:454-466.

Lyon-Caen, H. and Molnar, P. 1985. Gravity anomalies, flexure of the India plate, and the structure, support and evolution of the Himalaya and Ganga Basin. Tectonics, 4: 513-538. Misch, P., 1945. Remarks on the Tectonic History of Yunnan, with Special Reference to its Relations to the Type of the Young Orogenic Deformation. Bulletin of the Geological Society of China, 25:47-153.

Mitchell, A. H. G. 1981. Phanerozoic plate boundaries in mainland SE Asia, the Himalayas and Tibet. Journal of the Geological Society of London, 138:109-122.

Molnar, P., Burchfiel, B. C., Liang K'uangyi, and Zhao Ziyun. 1987. Geomorphic evidence for active faulting in the Altyn Tagh and northern Tibet and qualitative estimates of its contribution to the convergence of India and Eurasia. Geology, 15:249-253.

Molnar, P.and Lyon-Caen, H. 1988. Some simple physical aspects of the support, structureandevolution of mountain belts. In Processes in Continental Lithospheric Deformation, Geological Society of America Special Paper, 218:179-207.

Molnar, P. and Tapponnier, P. 1975. Cenozoic Tectonics of Asia: Effects of a continental collision. Science, 189: 419-426.

Molnar, P. and Tapponnier, P. 1977. Relation of the tectonics of eastern China to the India-Eurasia collision: Application of slip-line field theory to large-scale continental tectonics. Geology, 5:212-216.

Molnar, P.and Tapponnier, P. 1977b. The collision between India and Eurasia. Scientific American, 236, No.4:30-41.

Nelson, M. R. and Jones, C. H. 1987. Paleomagnetism and crustal rotations along a shear zone, Las Vegas Range, southern Nevada. Tectonics, 6: 13-23.

Opdyke, N. D., Huang, K., Xu, G.and Zhang, W. Y. 1986. Paleomagnetic results for the Triassic of the Yangtze Platform. Journal of Geophysics Research, 91: 9553-9568.

Ron, H., Freund, R., Garfunkel, Z.and Nur, A. 1984. Block rotation by strike-slip faulting: Structural and paleomagnetic evidence. Journal of Geophysics Research, 89: 6256-6270. Tapponnier, P. and Molnar, P. 1977. Active faulting and tectonics in China, Journal of Geophysics Research, 82:2905-2930.

Tapponnier, P. and Molnar, P. 1979. Active faulting and Cenozoic tectonics of the Tien Shan, Mongolia and Baykal Regions. Journal of Geophysics Research, 84:3425-3459.

Tapponnier, P., Peltzer, G., Le Dain, A. Y., Armijo, R.and Cobbold, P. 1982. Propagating extrusion tectonics in Asia: New insights from simple experiments with plasticine. Geology, 10:611-616.

Tapponnier, P., Peltzer, G.and Armijo, R. 1986. On the mechanics of the collision between India and Asia. In M. P. Coward and A. C. Ries (eds.), Collision Tectonics, Geological Society of London, p. 115-157.

Walcott, R. I. 1984. The kinematics of the plate boundary zone through New Zealand: a comparison of short- and long-term deformations. Geophyiscal Journal of the Royal Astronomical Society, 79:613~633.

Zhang Peizhen, Molnar, P., Burchfiel, B. C., Royden, L., Wang Yipeng, Deng Qidong, Song Fangmin, Zhang Weiqi and Jiao Decheng. 1988. Bounds of the Holocene slip rate of the Haiyuan fault, north-central China. Quaternary Research, in press.

Return to Will in China