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The Eastern Himalayan Syntaxis (EHS) serves as a natural laboratory for the study of intense continental collision and lateral extrusion tectonics. By aiming at the intricate tectonic dynamics south and southeast of the EHS, we integrate seismic data from new broadband stations in central Myanmar with permanent stations in southeastern Tibet to establish a high‐resolution 3‐D shear wave velocity model through ambient noise surface wave tomography. Our imaging results reveal distinct differences in crustal seismic velocity structures between the West Burma Block, Chuan‐Dian Block, and the Shan Plateau, highlighting the extent of oblique subduction and restricted crustal extrusion. Notably, two north‐south oriented low‐velocity zones in the mid‐to‐lower crust of southeastern Tibet are mainly confined within the Chuan‐Dian Block and terminate near the Red River Fault, with limited extension into the Shan Plateau. The Eastern Himalayan Syntaxis (EHS) marks the point where the Indian and Asian plates collide most intensely in the eastern Himalayas. Geoscientists have observed significant mountain‐building activities around the EHS extending into southeastern Tibet (SE Tibet), driven by the intense collision of these continental plates. In SE Tibet, materials are squeezed sideways, a process known as lateral extrusion due to the collision of these plates. This is evident from seismic studies showing slower wave speeds in two distinct regions of the middle to lower crust. We analyzed seismic data from new stations in central Myanmar and permanent stations in SE Tibet to better understand the zone transitioning from intracontinental collision to lateral extrusion. Using a technique called ambient noise tomography, we developed a high‐resolution 3‐D model of the crust and uppermost mantle. Our findings reveal significant differences in the crust's structure between areas of subduction, extrusion, and transition, enhancing our understanding of the geodynamic processes beneath the EHS and its surrounding areas. Particularly, two slow‐speed belts related to the lateral extrusion are confined within SE Tibet, supporting a model of limited crustal extrusion. We obtain an integrated 3‐D Versus model by ambient noise tomography based on the data from both central Myanmar and southeastern TibetDistinct crustal structures in the West Burma Block, southeastern Tibet, and the Shan Plateau coincide with distinct tectonic responsesTwo north‐south low‐velocity zones in mid‐to‐lower crust end near Red River Fault, indicating restricted crustal extrusion We obtain an integrated 3‐D Versus model by ambient noise tomography based on the data from both central Myanmar and southeastern Tibet Distinct crustal structures in the West Burma Block, southeastern Tibet, and the Shan Plateau coincide with distinct tectonic responses Two north‐south low‐velocity zones in mid‐to‐lower crust end near Red River Fault, indicating restricted crustal extrusion

Ultrahigh-temperature (UHT) metamorphism is critical for understanding the most extreme thermal evolution of continental crust. However, UHT metamorphism predominantly occurred in the Precambrian and is rarely observed in the modern Earth. Here, we report the discovery of ∼25 Ma UHT granulites from the Mogok metamorphic belt (MMB) in Myanmar via a combined study of petrology and geochronology. The studied pelitic granulites well preserve a peak mineral assemblage of garnet + sillimanite + plagioclase (antiperthite) + K-feldspar + quartz + Ti-rich biotite + rutile + ilmenite. Pressure (P)-temperature (T) pseudosections and conventional geothermobarometry data only constrain the P-Tconditions of the peak stage to <12 kbar and 780–890°C. However, high Zr contents in the matrix rutile (3005–4308 ppm) and high Ti contents (up to 9.2 wt% TiO2) in the biotite demonstrate that the Mogok granulites may have experienced UHT metamorphism. The Zr-in-rutile thermometer and XGrsisopleth in the pseudosections yield peak P-Tconditions of ∼12 kbar and >900°C. In situSIMS and LA-ICP-MS U-Pb dating and trace element analyses show that both metamorphic zircon cores and rims have flat heavy rare earth element (HREE) patterns with negative Eu anomalies. The metamorphic zircon rims show the lowest HREE contents and yield 206Pb/238U ages of 24.9±0.5 and 25.4±0.6 Ma, respectively, representing the timing of UHT metamorphism. Our results indicate that the central MMB underwent ∼25 Ma UHT metamorphism, which is possibly induced by continental rifting along the thinned orogenic lithosphere. Our data, as well as reported Cenozoic UHT events, further suggest that UHT metamorphism can be produced in the modern plate tectonic regime by lithospheric extension.

Myanmar bears a high risk of destructive earthquakes, yet detailed seismicity catalogs are rare. We designed a deep‐learning‐based data processing pipeline and applied it to the data recorded by a large‐aperture (∼400 km) seismic array in central Myanmar to produce a high‐resolution earthquake catalog. We precisely located 1891 earthquakes at shallow (<50 km) depth, a 2‐fold increase compared to the traditional procedures. The new catalog reveals the Kabaw Fault seismicity disappears south of ∼22.8°N, where the deeper (20–40 km) seismicity appears west of the southern Kabaw Fault. Such seismicity contrast along the strike of the Kabaw Fault possibly implies an along‐strike change of deformation responses to the shortening process by the India plate oblique subduction. The middle segment of the Sagaing Fault is likely locked and prone to hosting large earthquakes according to the derived low b‐value. Myanmar is a highly seismically active region, yet fault geometry and activities remain poorly understood because of limited modern seismological investigations. Here, we designed a set of machine‐learning algorithms to detect small earthquakes and determine their locations precisely. The seismic data are recorded by a temporary seismic network deployed in central Myanmar. We obtained twice as many earthquakes as the previous research used the regular procedure. Our improved earthquake data set unveils seismic activity changes along the Kabaw Fault through the changes in earthquake locations, depths, and magnitude‐frequency relations. Kabaw Fault is an import boundary fault in the subduction system of the Indo‐Burma Range. This subtle change was not previously observed but means a significant alternation in deformation style along the subduction strike. Moreover, our improved data set indicates that the Sagaing Fault, the most active fault in Myanmar, is prone to generating large earthquakes in the future. This implication warns the nearby populated cities, like Mandalay, of a significant megaquake threat. We detect 1891 shallow earthquakes in Myanmar with a deep‐learning‐empowered pipeline, a 2‐fold increase against the routine procedureN‐S seismicity discrepancy is observed near the Kabaw Fault and may imply different responses to E‐W shortening by the Indian subductionLow b‐value derived from the new catalog on the middle Sagaing Fault indicates a high risk of destructive earthquakes We detect 1891 shallow earthquakes in Myanmar with a deep‐learning‐empowered pipeline, a 2‐fold increase against the routine procedure N‐S seismicity discrepancy is observed near the Kabaw Fault and may imply different responses to E‐W shortening by the Indian subduction Low b‐value derived from the new catalog on the middle Sagaing Fault indicates a high risk of destructive earthquakes

Subduction zone fluids are critical for transporting materials from subducted slabs to the mantle wedge. Jadeitites from Myanmar record fluid compositions and reactions in the forearc subduction channel. Here we present high‐precision Mg isotope data of the Myanmar jadeitites and associated rocks to understand the Mg isotope composition of subduction zone fluids at forearc depths. Two types of jadeitites (white and green) exhibit distinct Mg isotope compositions. The white jadeitites precipitated from Na‐Al‐Si‐rich fluids and have low δ26Mg values, varying from −1.55‰ to −0.92‰, whereas the green jadeitites have higher δ26Mg values (−0.91‰ to −0.74‰) due to metasomatic reactions between fluids and Cr spinel. The amphibole‐rich blackwall in the contact boundaries between jadeitites and serpentinites also exhibits low δ26Mg values (−1.17‰ to −0.72‰). Therefore, the jadeite‐forming fluids have not only high concentrations of Na‐Al‐Si but also low δ26Mg values. The low δ26Mg signature of the fluids is explained by the dissolution of Ca‐rich carbonate in subducted sediments or altered oceanic crust, which is supported by the negative correlation of δ26Mg with CaO/TiO2, CaO/Al2O3, and Sr in the white jadeitites. Given the common occurrence of Ca‐rich carbonates in the subduction channel, the Mg isotope composition of low‐Mg aqueous fluids would be significantly modified by dissolved carbonates. Metasomatism by such fluids along conduits has the potential to generate centimeter‐scale Mg isotope heterogeneity in the forearc mantle wedge. Therefore, Mg isotopes could be a powerful tracer for recycled carbonates not only in the deep mantle but also in the shallow regions of subduction zones. The Myanmar jadeitites have δ26Mg values lower than normal mantleJadeite‐forming fluids have high contents of Na‐Al‐Si and low Mg contents and δ26Mg valuesSubduction zone fluids at forearc depths may have low δ26Mg values due to carbonate dissolution

This study represents the first campaign‐style teleseismic shear wave splitting (SWS) investigation of central Myanmar, an area that is tectonically controlled by the oblique subduction of the Indian Plate underneath the Eurasian Plate. The resulting 678 well‐defined and 247 null SWS measurements obtained from recently deployed 71 broadband seismic stations show that the Indo‐Burma Ranges (IBR) possess mostly N‐S fast orientations that are parallel to the trend of the depth contours of the subducted slab. Relative to the global average of 1.0 s, extremely large splitting times with station‐averaged values ranging from 1.28 to 2.79 s and an area‐averaged value of 2.09 ± 0.55 s are observed in the IBR. In contrast, the Central Basin (CB) and the Shan Plateau (SP) are characterized by slightly larger than normal splitting times. The fast orientations observed in the CB are mostly NE‐SW in the northern part of the study area, N‐S in the central part, and NW‐SE in the southern part. The fast orientations change from nearly N‐S along the N‐S oriented Sagaing Fault, to NW‐SE in the central and eastern portions of the SP. These observations, together with SWS measurements using local S events, crustal anisotropy measurements using P‐to‐S receiver functions, and the estimated depth of the source of anisotropy using the spatial coherency of the splitting parameters, suggest the presence of a trench‐parallel sub‐slab flow system driven by slab rollback, a trench‐perpendicular corner flow, and a trench‐parallel flow possibly entering the mantle wedge through a slab window or gap. Myanmar is located at the boundary between the Indian Plate and the Eurasian Plate. Here, the Indian Plate moves northward at a rate that is faster than most other tectonic plates on Earth and subducts obliquely beneath the Eurasian Plate. This subduction not only causes a strong deformation of the Earth's surface, forming the approximately 1,250 km long, N–S trending Indo‐Burma Ranges, but also results in pervasive crustal deformation and possibly modulates the mantle flow field in the area. Mostly due to the limited coverage by broadband seismic stations until recently, crustal deformation and mantle flow beneath Myanmar were poorly understood. In this study, we used data from 71 seismic stations that we deployed in central Myanmar to analyze seismic azimuthal anisotropy, that is, the directional dependence of the velocity of seismic waves in a medium, at different depths. Based on the established relationship between seismic anisotropy and mantle flow, we proposed a model to explain the observations. Our model implies the presence of a trench‐parallel mantle flow beneath the subducted Indian Plate. Above the plate, there are two flow systems with trench‐parallel and trench‐orthogonal orientations, respectively, with spatially varying strengths. N‐S anisotropy and large XKS splitting times (∼3 s) on the Indo‐Burma Ranges are from trench parallel flow and lithospheric shorteningXKS and local S results indicate trench‐parallel flow and corner flow coexist in the mantle wedge beneath the Central BasinE‐W oriented corner flow explains the splitting measurements in the Shan Plateau N‐S anisotropy and large XKS splitting times (∼3 s) on the Indo‐Burma Ranges are from trench parallel flow and lithospheric shortening XKS and local S results indicate trench‐parallel flow and corner flow coexist in the mantle wedge beneath the Central Basin E‐W oriented corner flow explains the splitting measurements in the Shan Plateau

Fluid infiltration into metacarbonates is a key mechanism to induce orogenic decarbonation, which influences the global carbon cycle and long‐term climate evolution. Little is known regarding the fluid pathways during episodic infiltration events and how flow patterns control time‐integrated CO2outflux. We investigate the “vein‐like” polycrystalline mineral reaction zones (PMRZs) in dolomite marbles (Mogok metamorphic belt, Myanmar), which are formed by metasomatism via the infiltration of Si–Al–K–Ti–Zr‐bearing fluids. The petrographic textures and mineral U–Pb chronology reveal three episodes of fluid influx in a single PMRZ: (1) the initial episode (Stage‐I) transformed most dolomite into Mg‐rich silicates/oxides and calcite at ∼35–36 Ma indicated by baddeleyite cores; (2) baddeleyite rims gave ages of ∼23–24 Ma, representing a subsequent infiltration episode (Stage‐II) that modified Stage‐I minerals via a dissolution–precipitation mechanism; (3) the final episode (Stage‐III) is recorded by zircon replacing baddeleyite, which yielded ages of ∼17 Ma. Stage‐III fluid has a higher SiO2activity and XCO2[CO2/(CO2+ H2O)] than Stage‐I/Stage‐II fluids. Thermodynamic and mass‐balance analyses indicate that Stage‐I infiltration causes >62–67% loss of CO2by both dolomite‐consuming reactions and calcite dissolution, whereas the latter two infiltration episodes induce <12–18% loss of CO2via calcite dissolution. Our results provide compelling evidence that repeated episodes of infiltration (each separated in time by 7–13 Ma) occurred along a single channel in marbles. The initial infiltration episode may create high‐permeability regions, offering favorable channels for later‐stage fluids that transfer obviously less CO2than the initial metasomatism. This considerably complicates a quantitative assessment of CO2liberation from metacarbonates during orogenesis. Gem‐bearing reaction zones in Mogok marbles record three episodes of fluid infiltration each separated in time by 7–13 MaInitial fluid infiltration drives dolomite‐consuming reactions and produces high‐permeability zones that channelize later fluid transportEffect of multiple fluid infiltration episodes on metamorphic CO2release from marbles in orogenic belts is assessed Gem‐bearing reaction zones in Mogok marbles record three episodes of fluid infiltration each separated in time by 7–13 Ma Initial fluid infiltration drives dolomite‐consuming reactions and produces high‐permeability zones that channelize later fluid transport Effect of multiple fluid infiltration episodes on metamorphic CO2release from marbles in orogenic belts is assessed

The tropical Asian regions are particularly prone to catastrophic droughts due to high temperature and evaporation and their sensitivity to variable oceanic‐atmospheric circulation. The extent to which future global warming may intensify droughts in this populous region is a matter of utmost concern. Palaeoclimatic data can help inform scientists learn more about the temporal patterns and drivers of monsoon change over geological timescales. In this paper, we present a new 8,200 year biomarker record preserved in the annually laminated sediments of Maar Lake Twintaung, Myanmar. The δ13C27‐35sedimentary record is mainly derived from leaf wax lipids in the lake catchment, which is presently dominated by C3vegetation in the modern lake catchment. The δ13C27‐35is mainly regulated by plant physiological and biochemical responses to drought stress and, as such, can be used as a proxy of past changes in moisture. The δ13C27–35record reveals distinct decadal‐to‐centennial‐scale droughts superimposed on a trend of gradually decreasing summer monsoon intensity from the mid‐Holocene to late Holocene. Within the limits of the dating uncertainties, these decadal‐to‐centennial‐scale droughts are found to be well correlated with the southward shift of the Intertropical Convergence Zone. It highlights thepimportance of the Intertropical Convergence Zone shift (tropical monsoon trough) in regulating monsoon rainfall in the region. In addition, most of the droughts are likely to be linked with active volcanism and solar minima and suggest a coupled process between external drivers and internal climate dynamics. Leaf wax n‐alkanes record in varved sediment of Maar lake Twintaung, MyanmarThe result indicates distinct decadal‐to‐centennial‐scale droughts over the past 8.2 kaThe drought cycles link with the ITCZ shift, solar and volcanic eruption

Myanmar, one of the most active tectonic regions in the world, endures the risk of destructive earthquakes. Based on seismic data recorded at the recently deployed dense array of the China‐Myanmar Geophysical Survey in the Myanmar Orogen (CMGSMO), we detect 854 and locate 599 shallow earthquakes with high precision and determine the focal mechanisms of 40 earthquakes. We identify two NW‐SE trending fault zones accommodating dextral strike‐slip earthquakes beneath the Central Basin, indicating potential seismic risk in the region. We also recognize a nearly N‐S trending seismic zone in the overlying Indo‐Burma Ranges (IBR) crust near the Kabaw Fault (KBF). The earthquakes within this seismic zone mostly show thrusting focal mechanisms. Our results suggest that strike‐slip deformation dominates to the east of the KBF, while shortening is mainly confined to the west of the KBF in Central Myanmar. Myanmar in Southeast Asia suffers from disasters resulting from destructive earthquakes. However, the present knowledge on their causative faults is limited due to the deployment of few seismic observation stations in Myanmar. We deployed a seismic observation network containing 71 stations for 1.5 years and tried to identify unknown causative faults and their characteristics by studying the small earthquakes there. Our results suggest that larger areas than previously expected in Myanmar may encounter significant seismic hazards. More attention to mitigating hazards should be paid to the Central Basin and western mountain areas, where densely populated cities are located. We detect 854 shallow earthquakes and analyze the focal mechanisms of 40 events based on the data set from a new seismic array in MyanmarWe identify two fault zones in the Central Basin that may accommodate surplus strike‐slip deformations not taken up by the Sagaing FaultWe observe a lower‐crustal seismic zone west of the Kabaw Fault, which is controlled by eastward subduction of the Indian Plate