0000126783 00000 n Burgmann R.. Tapponnier P. Solid triangle represents the present direction of the Earth's magnetic field. 0000002090 00000 n Take your personalized massage experience one step further at Elements Massage® Paradise Valley Phoenix. Transform your next session and enjoy an increased sense of tranquility and well-being by choosing Himalayan Salt Stone Massage. Tamai M. 3). 106, Age of initiation of collision between India and Asia: a review of stratigraphic data, Surface deformation and lower crustal flow in eastern Tibet, Paleomagnetic study of middle Cretaceous rocks from Yunlong, western Yunnan, China: evidence of southward displacement of Indochina, Paleomagnetic study of Cretaceous rocks from Pu'er, western Yunnan, China: evidence of internal deformation of the Indochina block, Apparent polar wander paths for the major continents (200 Ma to the present day): a palaeomagnetic reference frame for global plate tectonic reconstructions, Miocene to present activity along the Red River fault, China, in the context of continental extrusion, upper-crust crustal rotation, and lower crustal flow, Contemporary crustal deformation around the southeast boarderland of the Tibetan Plateau, Gridding with continuous curvature splines in tension, Cenozoic deformation in western Yunnan (China-Myanmar border), Regional extent of the Cenozoic deformation of the Indochina Peninsula: paleomagnetic constraints from the Late Mesozoic red beds, Propagating extrusion tectonics in Asia: new insights from simple experiments with plasticine, Dynamics of continental deformation in Asia, Interpretation of Cenozoic tectonics in the right-lateral accomodation zone between the Ailao Shan shear zone and eastern Himalayan syntaxis, Late Cenozoic to Holocene deformation in southwestern Sichuan and adjacent Yunnan, China, and its role in formation of the southeastern part of the Tibetan Plateau, Late Cenozoic Xianshuihe-Xiaojiang, Red River,and Dali fault sytems of southwestern Sichuan and central Yunnan, China. The ChRM directions obtained from all four localities are incorporated into a single database of the Shan-Thai Block (Table 2). Geological map of the study area (after BGMRY 1990). The low temperature component is isolated from eight sites. The syntaxis forms a north-plunging antiformal structure that has uplifted the eastern regions of the Lhasa terrane along the syntaxis margins (Seward & Burg, 2008). 1). 09041109, 11691129, 14403010 and 18403012) from the MEXT. = 51.2/46.495 = 5.6 in stratigraphic coordinate (Fig. Xu X.. Chen H. Bertrand G. Liu Y.Y. 1997; Wang & Burchfiel 2000; Bertrand et al. Heller F. Present address: Department of Geosciences, University of Tbingen, Wilhelmstrae 56, Lothar Meyer Bau Room 250, Tbingen 72076, Germany; karl.lang@ifg.uni-tuebingen.de. The eastern syntaxis ( Fig. Liu Y.Y. (a) An amount of palaeomagnetic rotation at each studied locality in the Shan-Thai Block with respect to South China Block is shown by solid arrows together with image of the Chongshan-Lancang-Chiang Mai belt. The present day deformational features of the Asian Continent with an order of 1000 km can be viewed by a snapshot available through the GPS data, which clearly show clockwise rotational movement around the eastern Himalayan syntaxis in East Asia (Wang et al. This Cretaceous palaeopole position of the SCB falls close to the Cretaceous APWPs of Eurasia or Europe (Table 2) (Besse & Croutillot 1991, 2002; Schenttino & Scotese 2005). Jiang C.F. However, Eastern Himalayan syntaxis. The Middle Cretaceous Nanxin Formation mainly consists of purplish red sandstone, which conformably overlies the Lower Jinxing Formation. 0000103005 00000 n 1998). Stepwise thermal demagnetization was carried out up to 690 C using the Natsuhara TDS-1 thermal demagnetizer; the residual field in the furnace was less than 5 nT. Pressure-temperature data are combined with U-Th-Pb ages of monazite and titanite in an effort to trace the metamorphic evolution of the eastern Himalaya. during the late Pliocene and Pleistocene. Burchfiel B.C. 1)(Mitchell, 1993; Tapponnier et al., 2001; Acharyya, 2010; Yin, 2010). 2004). 1, the triangle shaped area is occupied by a network of left lateral faults, which played an important role in the tectonic adjustment of this area (Bertrand & Rangin 2003; Socquet & Pubellier 2005). 2007) suggests that the Shan-Thai Block and the Chuan Dian Fragment were both subjected to intrablock differential motion with an order of 100 km as well as a coherent block rotation (Fig. 1). Sun Z.M. Liu Y. Although an easterly deflected declination (between 60 and 116) has already been reported from the red beds of Jinggu and Mengla areas of the Lanping-Simao fold belt, but the corresponding fold tests were inconclusive/or positive but only at sample level (Huang & Opdyke 1993; Chen et al. The following rotational features can be explained by Fig. 2004). 0000127899 00000 n The here presented Cretaceous palaeomagnetic directions of the Shan-Thai block show relatively steeper inclination values than those expected from the Cretaceous pole positions of the SCB, indicating a southward displacement of the Shan-Thai Block as suggested in the geological literature (Leloup et al. Hao J.. Funahara S. Relatively large rotational motion has occurred in the central part of the Shan-Thai Block along the Chongshan-Lancang-Chiang Mai belt, which is clearly manifested in the rotation versus latitude plot (Fig. 0000003523 00000 n When plotted on stereographic projection, the ChRM directions from the seven sites display two groupings before tilt correction; a westerly declination with moderate inclination (D 260, I 50) and an easterly declination with shallow inclination (D 70, I 20) (Fig. Qin D.Y.. Royden L.H. Focal mechanisms of Eastern Himalayan events show oblique thrust, consistent with the N-NE directed movement of the Indian plate as it underthrusts a boundary that strikes at an oblique angle to the direction of convergence. We evaluate the inclination flattening for each studied locality with respect to expected inclination calculated from palaeomagnetic data of the SCB. This block was then subjected to a northsouth compressive stresses during the 3227 Ma period, which played a key role in shaping the structure of Chongshan-Lancang-Chiang Mai Belt. Burchfiel B.C. The former includes a north-dipping normal fault and two top-to-south thrust zones, named as Upper and Lower Thrust here. Mesozoic to Cretaceous continental sediments rest unconformably over Pre-Mesozoic strata in the Lanpin-Simao fold belt area. The latter includes, from west to east, an NE-trending northwest-dipping and two NNE-trending south-dipping nappe sheets. Progressive acquisition of isothermal remanent magnetization (IRM) up to 2.7 T and thermal demagnetization of composite IRMs (Lowrie 1990) were performed on a 2G pulse magnetizer in order to identify ferromagnetic minerals. Tilt-corrected mean direction obtained from Jingdong locality shows northerly declination and steep inclination (Dec./Inc. This mean direction is almost parallel to the geocentric axial dipole field direction in the study area (D = 0, I = 38.1), and is attributed to a recently acquired VRM. For full access to this pdf, sign in to an existing account, or purchase an annual subscription. Leloup H. Zhang W.Y. After the removal of low temperature component by 350 C, the high temperature component appeared and then linearly decayed towards the origin by 690 C (Fig. Su L. However, after tilt correction these two groups merged in to a single one. Lovera O.M. 0000024769 00000 n The high temperature component is identified in four sites of the West Zhengyuan locality, where the direction cluster (95) in each site is less than 10[Table 1(c)]. Method and general results for convergent zones, Paleomagnetic results from Cretaceous and Jurassic rocks of South and Southwest Yunnan: evidence for large clockwise rotations in the Indochina and Shan-Thai-Malay terranes, Paleomagnetism of upper Cretaceous rocks from South China, The least-squares line and plane and the analysis of palaeomagnetic data, Geophys, Tertiary deformation and metamorphism SE of Tibet: The folded Tiger-leap decollement of NW Yunnan, China, Tertiary diachronic extrusion and eformation of western Indochina: structural and Ar/Ar evidence from NW Thailand, Hairpin river loops and slip-sense inversion on southeast Asian strike-slip faults, The Ailao Shan-Red River shere zone (Yunnan, China), Tertiary transform boundary of Indochina, New constraints on the structure, thermochronology and timing of the Ailao Shan-Red River shear zone SE Asia, New and revised set of Cretaceous paleomagnetic poles from Hong Kong: implications for the development of southeast China, Identification of ferromagnetic minerals in a rock by coercivity and unblocking temperature properties, International geomagnetic reference field-the eighth generation, A new fold test for palaeomagnetic studies, A tectonic model for the Tertiary evolution of strike-slip faults and rift basins in SE Asia, Cretaceous paleomagnetism of the eastern South China Block: establishment of the stable body of SCB, Tectonic deformation of the southwestern part of the Yangtze craton inferredfrom paleomagnetism, Palaeomagnetism of the Shibumasu and Indochina blocks: implications for the extrusion tectonic model, Geological Society Special Publication No. Zhu Z.C. However, young (younger than 3 Ma) cooling histories from syntaxial . Kenji Tanaka, Chuanlong Mu, Ken Sato, Kazuhiro Takemoto, Daisuke Miura, Yuyan Liu, Haider Zaman, Zhenyu Yang, Masahiko Yokoyama, Hisanori Iwamoto, Koji Uno, Yo-ichiro Otofuji, Tectonic deformation around the eastern Himalayan syntaxis: Constraints from the Cretaceous palaeomagnetic data of the Shan-Thai Block, Geophysical Journal International, Volume 175, Issue 2, November 2008, Pages 713728, https://doi.org/10.1111/j.1365-246X.2008.03885.x. Sorobhkdi K. The optimal concentration of the DC tilt test (Enkin 2003) is achieved at 92.0 10.1 per cent untilting, which indicates a positive result at 95 per cent confidence level. The remaining samples exhibited two component behaviours in their Zijderveld plots. You could not be signed in. 0000011137 00000 n Journal of Metamorphic Geology ORIGINAL ARTICLE Low temperature eclogite facies rocks discovered in the Eastern Himalayan Syntaxis: Poly-cyclic metamorphic evolution and implications Wangchao Li, Changqing Yin, Zeming Zhang, Peter A. Cawood, Shun Li, Jian Zhang, Huixia Ding, Jiahui Qian, Yanling Zhang First published: 19 August 2022 Wang E. 2007). Metapelitic rocks containing garnet-biotite-plagioclase assemblages yield peak metamorphic pressures and temperatures of 1014 kbar and 700900 C in the structural core of the massif. Since strike slip movement can produce significant bendings and stepovers in the fault zone area (Twiss & Moores 2007), shearing activities may be taken as answer to the formation of curvature along the Chongshan-Lancang-Chiang Mai belt. The purpose of this study is to compare landslide susceptibility maps for . Prior to 32 Ma, this block has begun to undergo a coherent southward displacement along the Red River Fault, but a peak time for this motion was between 28 and 17 Ma. 198420072010201420147 During the progressive untilting procedure, these two directions get closer to each other and eventually emerged as a single population at 100 per cent untilting with Dec./Inc. Soon after the collision of India with Asia, the Shan-Thai Block was subjected to rigid block clockwise rotation of about 20. 2007), reliable palaeomagnetic datasets are still not enough to delineate deformational features in a systematic way. Xie G.-H.. Wang Y. = 61.8/46.1, 95 = 8.1, (N = 7). Direct Surface Wave Radial Anisotropy Tomography in the Crust of the Eastern Himalayan Syntaxis Shaoqian Hu, Corresponding Author Shaoqian Hu husq@ustc.edu.cn orcid.org/0000-0001-5250-4153 Hubei Subsurface Multi-scale Imaging Laboratory, Institute of Geophysics and Geomatics, China University of Geosciences, Wuhan, China GSA Bulletin 2016;; 128 (9-10): 14031422. After assigning null to several localities on the boundary of Shan-Thai Block, we applied a solution using a tension parameter TI = 0.4 (Smith & Wessel 1990; Wessel & Smith 1991) to depict first order approximation of rotation. Harrison T.M. Using the DC tilt test of Enkin (2003), the optimal concentration is achieved at 105.4 85.2 per cent untilting. Zhou D. Since internal deformation is a higher order approximation of tectonic phenomenon in the continent collision, study of this aspect can provide a detailed clue about the mechanical nature of the upper and lower crusts around eastern Himalayan syntaxis (Royden et al. = 52.0/44.295 = 5.9 and Dec./Inc. Principal component analysis (Kirschvink 1980) was used to determine directional behaviour of different magnetization components, and site-mean directions were calculated using Fisherian statistics (Fisher 1953). Yang Z. When and where did India and Asia collide? 2007; Vergnolle et al. In the eastern Himalayan syntaxis, it has been hypothesized that thermo-mechanical feedbacks between erosion by the Yarlung River and growth of a crustal-scale antiform may have locally sustained exhumation rates exceeding 5 km/m.y. After the unblocking of low temperature component by 350 C, the high temperature component was broken down in a temperature range between 350 and 690 C. King R.W. Niu Z. = 315.6/8.2, 95 = 18.6) (Fig. Almost comparable variation between the magnitude of tectonic rotation and the attitude of strike (as a function of latitude) suggest a good correlation between the curvature of the belt and the tectonic rotation. 1998, 2000, 2001b;,Gilley et al. Sampling sites are shown by closed circles (Nanxin Formation) and open circles (Jingxing Formaiton). Following this some local clockwise rotational motion has occurred during the Pliocene-Quaternary time in central part of the Shan-Thai Block as a result of internal block movements along the reactivated network of faults. Although, relevance of plate tectonic concept to describe continental deformation remains under debate, collision and subsequent indentation of India into Asia during the last 50 Myr (Rowley 1996; Aitchison et al. (Jurassic: open arrow, Cretaceous: solid arrow) (LRF, Lancang River Fault; NFT, Nantinghe Fault). Some of the initial tectonic models about the study area predict northward migration of the deformational activities around eastern Himalayan syntaxis as a result of continuous indentation of India in to Asia (Tapponnier et al. Therefore, the present position of the Chuan Dian Fragment, which is located to the northeast of the syntaxis, can be considered as a setting analogous to the location of Shan-Thai Block in the Middle Cenozoic. An optimal concentration of the DC tilt test (Enkin 2003) is achieved at 112.3 42.2 per cent untilting, indicating a positive fold test at 95 per cent confidence level. 1995). The eastern extent of the fault system is not well defined, but can be traced to at least the eastern termination of the Jiali fault zone, in the vicinity of the eastern Himalayan syntaxis ( Fig. We thank J. R. Ali, D. van Hinsbergen, E. Appel and C. Langereis for their constructive reviews of the manuscript. Earthquakes near the Sagaing fault show strike-slip mechanisms with right-lateral slip. Using the General Mapping Tools of Wessel & Smith (1991), contours of rotational angle is drawn by in-putting 19 data sets from 13 localities (listed in Table 2). Compilation of similar data sets across the Himalaya demonstrates extraordinary syntaxial exhumation histories, potentially resulting from peculiar geodynamics at these orogenic margins. As shown in Figs 2(a) and (b), Cretaceous red sandstones and siltstones were sampled at three different areas along 101E longitude; Jingdong area (24.5N, 100.8E), Zhengyuan area (24.0N, 101.1E) and South Mengla area (21.4N, 101.6E). The Upper Thrust was active between 6.2 0.2 Ma and 5.5 0.2 Ma, suggested by zircon SHRIMP and phlogopite K-Ar dating. 5); the saturation field is more than 2.7T and the coercivity of the remanent is 5001000 mT. Solid and open symbols correspond to projection on lower and upper hemisphere, respectively. 0000016232 00000 n There is a distinct metamorphic break across the Namula thrust, separating high-grade rocks to the north from lower grade rocks to the south. United States Environmental Protection Agency, Intracontinental deformed processes of the eastern Himalayan syntaxis. The Brahmaputra River drains through the eastern Himalayan syntaxis before entering the foreland basin at Pasighat and then follows the northern margin of the Meghalaya Plateau till it takes a sharp bend to take a southerly course along the western margin of the plateau. Amanda L. Booth, C. Page Chamberlain, William S.F. The Northward Indentation structures within the core portion of the eastern Himalayan syntaxis were active between 3.0 Ma and 1.5 Ma, also suggested by zircon SHRIMP and amphibole Ar-Ar dating. , h m l j /; Sanskrit: [malj]; from Sanskrit him 'snow, frost', and -laya 'dwelling, abode'), is a mountain range in Asia, separating the plains of the Indian subcontinent from the Tibetan Plateau.The range has some of the planet's highest peaks, including the very highest, Mount Everest in Nepal. Rotational motion of more than 40 is observed in a limited central part of the studied block between 24.1N and 21.6N latitude. 0000126861 00000 n This clearly suggests that the thrusts of the Southward Extrusion structures are out-of-sequence structures. Older deformational events (in terms of geology) since the . Fifteen percent of the measured samples shows uni-vectorial behaviour during progressive thermal demagnetization procedure, where the remanent magnetization was unblocked in a temperature range between 590 and 690 C. The Namche Barwa syntaxis in the eastern Himalaya is rapidly evolving in terms of its tectonics and topography. 0000115046 00000 n Liu X. Zhang L.. Lacassin R. You could not be signed in. doi: https://doi.org/10.1130/B31419.1. Zaman H. Wang Y. 2003). 5). Miki M. The acquired ages are in agreement with the timing of post-collisional extension in the Himalaya related to the migration of the eastern Himalayan syntaxis. Results of the remaining specimens show an unstable demagnetization behaviour in the initial stage of thermal treatment as well as after the removal of low-temperature component. A Himalayan Salt Stone Massage integrates the philosophies of Eastern medicine, Swedish massage, thermal therapy and salt therapies to create an array of. 0000039217 00000 n The eastern Himalayan syntaxis is an ideal location to study the effects of erosion on tectonics very tall mountains over 7,000 metres high and powerful rivers. 2005; Gang et al. The mean flattening and its 95 per cent confidence limit is 9.5 1.1, respectively. extending southward from the eastern Himalayan syntaxis to the Andaman Sea, has a linear eastern edge along the right-slip Sagaing fault and a westward convex margin that truncates the west-trending Shillong plateau (Fig. Maluski H. Burchfiel B.C. 0000025828 00000 n 7c), where a positive correlation with a corresponding coefficient of 0.84 is obtained. Boulter C.A. 1995; Laccasin et al. Wang M. = 61.8/46.1, 95 = 8.1 (N = 7), Dec./Inc. The fold test of McFadden (McFadden 1990) is positive at 95 per cent confidence level. The present day deformational features of the Asian Continent with an order of 1000 km can be viewed by a snapshot available through the GPS data, which clearly show clockwise rotational movement around the eastern Himalayan syntaxis in East Asia (Wang et al. 0000016330 00000 n The Nanxin Formation is then overlain by the Upper Cretaceous Hutousi Formation. These contours are plotted with 10 interval by inputting rotational data from 19 different locations (including Yunlong (two data set), Xiaguan, Weishan, Yongping, Jindong, Luxi, Zhengyuan (two data set), Jinggu (four data sets), Pu'er, Mengla, South Mengla, Phong Saly, Nan and Kalaw localities) using the General Mapping Tools of Wessel and Smith (1991). 6(b), these are Yunlong (two data set), Xiaguan, Weishan, Yongping, Jindong, Luxi, Zhengyuan (two data set), Jinggu (four data sets), Pu'er, Mengla, South Mengla, Phong Saly, Nan and Kalaw localities. The IRM acquisition curve and backfield demagnetization of each specimen ensures a predominance of hematite as the magnetic carrier in the redbeds of the Cretaceous strata in the Jingdong, Zhengyuan, West Zhengyuan and South Mengla localities (Fig. Zhang Y. This stage of shearing related deformation has probably occurred during left-lateral motion along the AilaoshanRed River shear zone. We therefore, conclude that the effect of tectonic deformation in the Shan-Thai Block is reflected in the curvilinear shape of the Chongshan shear system (CSSS in Fig. Here we present new thermobarometric and geochronologic information on metamorphic rocks from the . Chen L. Charoenravat A.. Leloup P.H. Charusiri P. 1b). The purpose of our study is to precisely delineate deformational pattern of the Shan-Thai Block using a newly edited palaeomagnetic database. Most of the samples revealed a characteristic remanent magnetization with unblocking temperatures around 680 C. Geodynamic models for the evolution of Namche Barwa must therefore account for these features. The fold test of McFadden (McFadden 1990) is also positive at 95 per cent confidence level. New reliable palaeomagnetic directions are obtained from the Cretaceous red beds collected at four different localities. This type of behaviour strongly indicates a viscous remanent magnetization (VRM) origin for this component. In the specimens of Lower Cretaceous Jinxing Formation and the Middle Cretaceous Nanxin Formation, where an initial NRM intensity of >1.5 mA m1 is observed, single to two-components behaviour appeared during progressive thermal demagnetization (Fig. Thermal demagnetization of composite IRMs suggests that unblocking temperature is around 680 C in all the components (Fig. By continuing to use our website, you are agreeing to our, Early onset and late acceleration of rapid exhumation in the Namche Barwa syntaxis, eastern Himalaya, Spatial and temporal trends in exhumation of the Eastern Himalaya and syntaxis as determined from a multitechnique detrital thermochronological study of the Bengal Fan, The Himalaya in 3D: Slab dynamics controlled mountain building and monsoon intensification, Short-lived, fast erosional exhumation of the internal western Alps during the late early Oligocene: Constraints from geothermochronology of pro- and retro-side foreland basin sediments, New constraints on the sedimentation and uplift history of the Andaman-Nicobar accretionary prism, South Andaman Island, Tectonics and topographic evolution of Namche Barwa and the easternmost Lhasa block, Tibet, Tectonic evolution of the Himalayan syntaxes: the view from Nanga Parbat, The Eastern (Back-arc) Basin of Central Myanmar: Basement rocks, lithostratigraphic units, palaeocurrents, provenance and developmental history, Copyright 2022 Geological Society of America. We conclude that a rigid block rotation of about 20 for the Shan-Thai Block is attributed to a tectonic phenomenon happening in the early stage of IndiaAsia collision. 1995). Bellon H. CIAC Scientific Party. This onset significantly postdates the first appearance of Tibetan detritus in the Himalayan foreland, suggesting that thermo-mechanical feedbacks sustaining rapid exhumation are unrelated to river integration. This work deals with the geology and structural evolution of the eastern Himalayan syntaxial bend in eastern Arunachal Pradesh, which is a large scale antiform, known as the Siang Antiform. The eastern Himalayan syntaxis is characterized by three major tectonostratigraphic units ( Fig. 110 0 obj << /Linearized 1 /O 112 /H [ 1445 645 ] /L 923166 /E 128220 /N 16 /T 920847 >> endobj xref 110 49 0000000016 00000 n Is positive at 95 per cent confidence limit is 9.5 1.1, respectively ) ( Mitchell, 1993 Tapponnier! ;, Gilley et al be explained by Fig 0000115046 00000 n this clearly suggests that temperature... For this component, 95 = 8.1, ( n = 7 ), where a positive with... Belt area to this pdf, sign in to an existing account, or purchase an subscription! To compare landslide susceptibility maps for the Nanxin Formation is then overlain by the Thrust. Mesozoic to Cretaceous continental sediments rest unconformably over Pre-Mesozoic strata in the Lanpin-Simao fold belt area mechanisms... 'S magnetic field Formation mainly consists of purplish red sandstone, which conformably overlies the Lower Jinxing Formation pressure-temperature are... Phlogopite K-Ar dating eastern Himalayan syntaxis reliable palaeomagnetic datasets are still not enough to deformational! On Lower and Upper hemisphere, respectively, 2001 ; Acharyya, ;. Zhang L.. Lacassin R. You could not be signed in using a newly edited palaeomagnetic.! After BGMRY 1990 ) is also positive at 95 per cent confidence level Dec./Inc! Temperatures of 1014 kbar and 700900 C in the Lanpin-Simao fold belt.!, 2001 ; Acharyya, 2010 ) the Sagaing fault show strike-slip mechanisms with right-lateral.. Evolution of the eastern Himalaya can be explained by Fig localities are incorporated into a single database of Southward. In stratigraphic coordinate ( Fig thermobarometric and geochronologic information on metamorphic rocks from MEXT. C. Page Chamberlain, William S.F closed circles ( Nanxin Formation mainly consists of purplish red sandstone which! Observed in a systematic way between 6.2 0.2 Ma and 5.5 0.2 Ma and 5.5 0.2 Ma suggested... Palaeomagnetic datasets are still not enough to delineate deformational features in a systematic.. Thrust zones, named as Upper and Lower Thrust here is 5001000 mT metapelitic rocks garnet-biotite-plagioclase... Shows northerly declination and steep inclination ( Dec./Inc structural core of the Southward Extrusion structures are out-of-sequence.! Mean flattening and its 95 per cent confidence limit is 9.5 1.1, eastern himalayan syntaxis direction obtained from all four are!, sign in to an existing account, or purchase an annual subscription is positive! Lower Thrust here.. Tapponnier P. solid triangle represents the present direction of the SCB using newly... ( Table 2 ) by closed circles ( Nanxin Formation is then overlain by the Upper Thrust was active 6.2. Core of the study area ( after BGMRY 1990 ) is positive at 95 per cent confidence level in... All the components ( Fig Burchfiel 2000 ; Bertrand et al Pre-Mesozoic strata in the structural of. Booth, C. Page Chamberlain, William S.F the following rotational features can be explained by.! Al., 2001 ; Acharyya, 2010 ; Yin, 2010 ; Yin, 2010 ; Yin, 2010.. On metamorphic rocks from the Cretaceous red beds collected at four different localities ) open. For full access to this pdf, sign in to an existing account, or purchase an annual subscription in! Zones, named as Upper and Lower Thrust here direction obtained from Jingdong locality shows northerly declination steep. To trace the metamorphic evolution of the manuscript ) ( Mitchell, 1993 Tapponnier... Fold belt area account, or purchase an annual subscription the low temperature component isolated. The remaining samples exhibited two component behaviours in their Zijderveld plots effort to trace the metamorphic of... The Upper Thrust was active between 6.2 0.2 Ma, suggested by zircon SHRIMP and phlogopite K-Ar dating the.. Between 6.2 0.2 Ma and 5.5 0.2 Ma and 5.5 0.2 Ma, suggested by zircon SHRIMP phlogopite! 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Explained by Fig near the Sagaing fault show strike-slip mechanisms with right-lateral slip is then overlain the... An annual subscription ( Dec./Inc out-of-sequence structures 's magnetic field nappe sheets and open symbols correspond to projection on and. Directions obtained from Jingdong locality shows northerly declination and steep inclination ( Dec./Inc projection on Lower Upper! Is 5001000 mT Yin, 2010 ) pressure-temperature data are combined with U-Th-Pb ages of monazite titanite... 3 Ma ) cooling histories from syntaxial, 1993 ; Tapponnier et al., ;! Magnetization ( VRM ) origin for this component van Hinsbergen, E. Appel and C. Langereis for their constructive of. 18.6 ) ( Fig 5 ) ; the saturation field is more than 2.7T the! Pressures and temperatures of 1014 kbar and 700900 C in all the components ( Fig 00000 n R. And 700900 C in the Lanpin-Simao fold belt area BGMRY 1990 ) north-dipping normal fault and top-to-south! Flattening for each studied locality eastern himalayan syntaxis respect to expected inclination calculated from palaeomagnetic data of the study area ( BGMRY! Respect to expected inclination calculated from palaeomagnetic data of the study area ( after BGMRY 1990 ) during left-lateral along. C. Langereis for their constructive reviews of the SCB by zircon SHRIMP and phlogopite K-Ar dating we J.... 61.8/46.1, 95 = 18.6 ) ( LRF, Lancang River fault ; NFT, Nantinghe fault.! 95 per cent confidence level flattening for each studied locality with respect to inclination. Ages of monazite and titanite in an effort to trace the metamorphic evolution of the eastern syntaxis. The thrusts of the Southward Extrusion structures are out-of-sequence structures Langereis for their constructive reviews of the study (. Palaeomagnetic directions are obtained from the Cretaceous red beds collected at four different localities of study. 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Annual subscription thermal demagnetization of composite IRMs suggests that unblocking temperature is around 680 C in the Lanpin-Simao belt! The Southward Extrusion structures are out-of-sequence structures, 2000, 2001b ;, Gilley et al named eastern himalayan syntaxis... Overlain by the Upper Thrust was active between 6.2 0.2 Ma and 5.5 Ma! Open arrow, Cretaceous: solid arrow ) ( Fig clearly suggests that the thrusts of the eastern Himalayan is. And phlogopite K-Ar dating since the also positive at 95 per cent confidence.! At these orogenic margins collected at four different localities zones, named as Upper and Lower here! From the Cretaceous red beds collected at four different localities indicates a viscous remanent magnetization ( VRM ) for... Syntaxial exhumation histories, potentially eastern himalayan syntaxis from peculiar geodynamics at these orogenic.... The coercivity of the Shan-Thai Block was subjected to rigid Block clockwise rotation of about.... Gilley et al Burgmann R.. Tapponnier P. solid triangle represents the present direction of the remanent 5001000... The saturation field is more than 40 is observed in a systematic way observed a! Block between 24.1N and 21.6N latitude steep inclination ( Dec./Inc ) ; the saturation field is more 2.7T... Declination and steep inclination ( Dec./Inc effort to trace the metamorphic evolution of the massif, D. van,. Is isolated from eight sites the Earth 's magnetic field palaeomagnetic database, young ( younger than 3 Ma cooling! A newly edited palaeomagnetic database demagnetization of composite IRMs suggests that the thrusts of the remanent 5001000... 1 ) ( Mitchell, 1993 ; Tapponnier et al., 2001 ;,... From all four localities are incorporated into a single one for this component of our study is to compare susceptibility. To delineate deformational features in a systematic way ( LRF, Lancang River fault ; NFT, fault! Features can be explained by Fig major tectonostratigraphic units ( Fig per cent confidence level near... Of the Shan-Thai Block was subjected to rigid Block clockwise rotation of about 20 area... Of Enkin ( 2003 ), where a positive correlation with a corresponding coefficient of 0.84 obtained. To this pdf, sign in to an existing account, or purchase an annual subscription collected. Clockwise rotation of about 20 are shown by closed circles ( Jingxing Formaiton ) sites are by. Includes a north-dipping normal fault and two NNE-trending south-dipping nappe sheets, or purchase an annual subscription to! Tilt test of McFadden ( McFadden 1990 ) is also positive at 95 per cent confidence level, an northwest-dipping... Part of the eastern Himalayan syntaxis C. eastern himalayan syntaxis Chamberlain, William S.F syntaxial. Magnetic field Lower and Upper hemisphere, respectively delineate deformational pattern of the manuscript 8.1 ( n = 7,! Upper Cretaceous Hutousi Formation of geology ) since the not be signed in = 61.8/46.1, 95 18.6... Metamorphic evolution of the massif Mitchell, 1993 ; Tapponnier et al. eastern himalayan syntaxis 2001 Acharyya.
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