Dunhua-Mishan Fault Research Articles

Fault-scale crustal structure across the Dunhua-Mishan fault (Tanlu northern segment) constrained from teleseismic P-wave receiver functions

The Dunhua-Mishan fault, located in the northern segment of the Tanlu fault zone, experienced multiple tectonic processes associated with the effects of the Pacific Plate subduction and the Indo-Asia collision. The high-resolution fault-scale structure is critical for understanding the fault evolution and potential fault damage. However, the well-defined deep structure of the Dunhua-Mishan fault is still unclear due to the lack of the dense seismic array. In this study, we construct a high-resolution P-wave receiver function imaging based on linear dense seismic array across the fault. Our results reveal the strong Moho depth variation across the Dunhua-Mishan fault zone. The slightly higher Vp/Vs ratio values within the fault zone indicate the presence of a small amount of mafic crust composition. Interestingly, the significant double positive Ps converted phases are observed within the fault zone, which may represent double Moho discontinuities. The double Moho structure may be related to multiple significant tectonic activities in the Tanlu northern segment. These newly observed structures provide new seismic constraints on the formation and evolution of the Tanlu fault zone and probably reflect that the lithospheric structure of the Dunhua-Mishan fault has been modified by a series of tectonic processes.

The boundary between the North China Craton and the Central Asian Orogenic Belt in NE China: Seismic evidence from receiver function imaging

• 38 broadband seismic stations (profile NCISP-10, 400-km-long) were deployed across the North China Craton (NCC) and the Central Asian Orogenic Belt (CAOB) in Northeast China. • Receiver function CCP images reveal a southward thrust nappe structure at the boundary of the NCC and the CAOB. • Yilan-Yitong fault (YYF) cuts through the Moho and has a vertical offset of 2–3 km indicating that it represents an ultra-crust normal fault. This study imaged the crustal structure and tectonic state of the interacting North China Craton (NCC) and Central Asian Orogenic Belt (CAOB) using receiver function imaging. The seismic profile derived from the NCISP-10 broadband seismic array spanning a northeasterly area of the NCC and a southeasterly area of the CAOB. The profile shows a flat Moho with localized anomalies but generally resting at an average depth of 32 km. The average Vp/Vs ratio was about 1.75 but the crust around the Songliao Basin exhibits a relatively high Vp/Vs ratio and a shallow Moho. An obvious velocity discontinuity appears within the crust beneath the Songliao Basin as evidenced by theoretical model tests which managed effects from multiple waves generated by sedimentary layers in the basin. This discontinuity inclines gently and is interpreted to represent the deep extension of the Chifeng-Kaiyuan fault (CKF), which itself serves as the surface boundary between the NCC and CAOB. The NCC feature appears to the south of this boundary, while a nappe structure formed during subduction-collision and composed primarily of a subduction-accretionary complex lies to the north. The Tanlu Fault consists of two branches in the study area, the Yilan-Yitong fault (YYF) and the Dunhua-Mishan fault (DMF). The YYF cuts through the Moho and has a vertical offset of 2–3 km indicating that it represents a crustal-scale normal fault. The DMF gives no obvious indication of vertical offset in the images but may be mainly characterized by sinistral strike slip movement.

Early Cretaceous provenance-depositional systems and volcano-sedimentary responses to strike-slip faulting in southern Jilin and eastern Liaoning provinces, NE China: a case study of the Tonghua Basin

ABSTRACT Understanding how the sedimentary responses adapt to the structural styles of fault basins in the strike-slip fault systems is one of the key goals of basin analysis. Variability of volcanic and epiclastic provenance-depositional systems and tectonic controls of the Lower Cretaceous Hengtongshan Formation in the Tonghua Basin are crucial to determine the evolution of the fault basins and wrench tectonics in southern Jilin and eastern Liaoning provinces (SJELP), NE China. Study of volcanism-induced sedimentation, composition plot, and depositional systems elucidates the sequence stratigraphy and volcano-sedimentary responses to wrench tectonics based on cores, outcrop sections, and seismic profiles of the Tonghua Basin. Two types of provenance-depositional systems (volcanic and epiclastic) were reconstituted using eight lithofacies and seven lithofacies associations. Of the lithofacies, six pyroclastic lithofacies and two epiclastic lithofacies were identified based on compositions, textures, and sedimentary structures. The presence of these lithofacies in different vertical successions was described as different lithofacies associations to interpret depositional processes and sedimentary environments. Depositional-system maps of the three sequences in the Hengtongshan Formation and analysis of structural framework indicate that volcanism and sedimentation were controlled by wrench faulting. Statistical analysis of rock compositions reveals that the deposition of the Hengtongshan Formation shows mixed contribution from both the volcanic and granitic fragments. Triangular compositional plots of detrital composition suggest a diverse provenance by straddling the litho-feldspatho-quartzose (lFQ), feldspatho-litho-quartzose (fLQ), feldspatho-quartzo-lithic (fQL), and quartzo-feldspatho-lithic (qFL) fields, indicating that the sources were derived from uplifted basement blocks and volcanic eruptions in a rift basin related to strike-slip faulting. The Tonghua Basin developed as a wrench-fault basin on the east side of Dunhua–Mishan Fault systems (DMF). This model for the Tonghua Basin can be used to understand the Liuhe Basin in the DMF and other Early Cretaceous basins in adjacent areas.

Study on the crustal velocity structure of the Dunhua-Mishan fault based on the dense seismic array by ambient noise tomography

The Dunhua-Mishan fault is a component of the Tanlu fault zone, and it is also a major regional fault structure in Liaoning area. The study area is located in Fushun area of the Dunhua-Mishan fault. In order to study the crustal velocity structure in this region, we used 60 sets of three-component short-period seismographs and lay out two temporary profiles in Fushun, Liaoning from Nov. 3 to 25, 2019. Each temporary profiles is about 12km long that is composed of 30 seismometers, which nearly vertically cross the Dunhua-Mishan fault where the survey lines are 6km apart. The installation stations spacing distance from 200 to 400m use the external GPS time service to record frequency range of 0.2 to 150Hz in the instrument. The crustal structure characteristics of the fault zone are studied by ambient noise cross-correlation method. In order to efficiently extract high and low frequency surface wave dispersion signals at the same time, we adopt the Extended Range Phase Shift (ERPS) method. Finally, we use ERPS method to process the collected data and invert the S-wave velocity structure. We initially obtained the S-wave velocity structure of the upper crust below 5 km in the area, which matches well with the local geological data. The S-wave velocity structure has significant lateral inhomogeneity of the Dunhua-Mishan fault in Fushun area. The S-wave velocity is obviously lower on the Dunhua-Mishan fault, while with the existence of ancient mixed granite the velocity on both sides of the fault is obviously higher.

Upper Mesozoic stratigraphy of Sikhote-Alin (Russian Far East) and northeastern China: Non-marine and marine correlations. Part 2: Barremian–Albian

The present paper is the second article in a series of publications dedicated to the upper Mesozoic stratigraphy of Sikhote-Alin (Russian Far East) and northeastern China. The Barremian–Albian stratigraphy of Sikhote-Alin and northeastern China is reviewed and a correlation scheme between these regions is proposed. Barremian–Albian rocks in Sikhote-Alin are mainly represented by marine deposits. Non-marine deposits occur in the south of Sikhote-Alin in the Partizansk and Razdolny basins. In northeastern China, in contrast, the Barremian–Albian rocks are mainly non-marine often intercalated with volcanic rocks. Non-marine deposits alternating with marine ones occur in northeastern Heilongjiang near the border with Russia. They fill a system of sedimentary basins restricted to the Dunhua-Mishan Fault Zone and linked in the east with the Alchan Basin of Sikhote-Alin. The deposits of these basins, represented by the Jixi, Longzhaogou, Dajiashan and Huashan groups, and the Assikaevka and Alchan formations, are of high importance for non-marine and marine correlation because they contain non-marine fauna and flora assemblages together with marine molluscs. The range of the Jixi and Longzhaogou groups is clarified based on the correlation with the Assikaevka Formation containing marine index fossils and is considered here as Barremian (possibly extending to Hauterivian)–middle Albian. The Jixi Group yielding elements of the Jehol Biota corresponds to the Jehol Group, and, therefore, the range of the Jehol Group is also considered as Barremian–middle Albian.

Coal-bearing strata sequence stratigraphy of Paleogene Meihe Formation, Meihe Basin, NE China

The Meihe Basin is an important Paleogene coal-bearing basin located in the Dunhua-Mishan Fault Zone, northeastern China. Based on a comprehensive study of well logs, seismic profiles, cores and rock geochemical properties, the coal distribution, paleoenvironment evolution within a sequence stratigraphic framework and the accumulation model to explain how coal seams developed in small fault basin were discussed in detail. Three-third-order sequences were identified in the Paleogene Meihe Formation of Meihe Basin and the two coal-bearing sequences are the Lower Coal-bearing Member of Sequence I and the Upper Coal-bearing Member of Sequence III. All three types of system tracts are developed in both sequences, i.e., the lowstand systems tract (LST), the transgressive systems tract (TST), and the highstand systems tract (HST). In LST of Sequence I, fan delta plain marsh is the main coal accumulating environment where coal seams are thin, discontinuous and therefore uneconomic for mining, and it is the same with all coal seams developed in Sequence III. While in TST and HST of Sequence I, lake swamp is the main sedimentary environment where coal seams are thick, continuous, widely distributed, and thus economically attractive for mining. In the study area, the nice thick economical coal seams are usually developed in an ideal stable depositional environment where organic matter accommodation space grows at a balanced rate with peat, in other words, free of sediment input or channel migration. The key findings of this study could provide guidance for the exploration of coal seams in the Meihe Basin and other similar basins.

Petrography and Geochemistry of Cenozoic Sandstones in the Dunhua Basin, Northeast China: Implications for Provenance, Source Weathering, and Tectonic Setting

Petrographic, mineralogical, and geochemical analyses were conducted on Cenozoic sandstones from the Dunhua Basin, which located in Dunhua-mishan fault zone of northeast China, to investigate the provenance of the sediments, as well as the weathering intensity and tectonic setting of the source region. Petrographic data indicate that average quartz-feldspar-lithic (Q-F-L) proportions in the sandstones are Q = 68%, F = 16%, and L = 16%, the lithic fraction mainly contains volcanic clasts. The chemical index of alteration (CIA) varies from 59 to 69 (average 63), while the index of chemical variability (ICV) ranges from 0.68 to 0.91 (average 0.77), and the average Th/U ratio is 3.2. Chondrite-normalized REE distributions show LREEs enriched relative to HREEs, and a prominent negative Eu anomaly. These data indicating that the sandstones are compositionally immature and a weak degree of weathering in the source region. The petrographic and mineralogical characteristics, combine with Zr/Sc–Th/Sc, Hf–La/Th and Co/Th–La/Sc discrimination diagrams reveal that these sandstones are derived from the surrounding felsic volcanic and intrusive rocks of Late Triassic-Early Jurassic, which exposed to the southeast or northwest of the basin. Multidimensional tectonic discrimination diagrams, including geochemical data and Dickinson triangular charts, indicate that the sandstones were derived from recycled orogenic in an active continental margin setting.

Crustal Deformation of Northeastern China Following the 2011 Mw 9.0 Tohoku, Japan Earthquake Estimated from GPS Observations: Strain Heterogeneity and Seismicity

Using global positioning system (GPS) observations of northeastern China and the southeast of the Russian Far East over the period 2012–2017, we derived an ITRF2014-referenced velocity field by fitting GPS time series with a functional model incorporating yearly and semiannual signals, linear trends, and offsets. We subsequently rotated the velocity field into a Eurasia-fixed velocity field and analyzed its spatial characteristics. Taking an improved multiscale spherical wavelet algorithm, we computed strain rate tensors and analyzed their spatial distribution at multiple scales. The derived Eurasia-referenced velocity field shows that northeastern China generally moved southeastward. Extensional deformation was identified at the Yilan–Yitong Fault (YYF) and the Dunhua–Mishan Fault (DMF), with negligible strike–slip rates. The principal strain rates were characterized by NE–SW compression and NW–SE extension. The dilation rates show compressional deformation in the southern segment of the YYF, northern end of the Nenjiang Fault (NJF), and southeast of the Russian Far East. We also investigated the impact of the 2011 Tohoku Mw 9.0 earthquake on the crustal deformation of northeastern China, generated by its post-seismic viscoelastic relaxation. The velocities generated by the post-seismic viscoelastic relaxation of the giant earthquake are generally orientated southeast, with magnitudes inversely proportional with the epicentral distances. The principal strain rates caused by the viscoelastic relaxation were also characterized by NW–SE stretching and NE–SW compression. The dilation rates show that compressional deformation appeared in the southern segment of the DMF and the YYF and southeast of the Russian Far East. Significant maximum shear rates were identified around the southern borderland between northeastern China and the southeast of the Russian Far East. Finally, we compared the multiple strain rates and the seismicity of northeastern China after the 2011 Tohoku earthquake. Our finding shows that the ML ≥ 4.0 earthquakes were mostly concentrated around the zones of high areal strain rates and shear rates at scales of 4 and 5, in particular, at the DMF and YYF fault zones.

Tectonic affinity of the Khanka Massif in the easternmost Central Asian Orogenic Belt: evidence from detrital zircon geochronology of Permian sedimentary rocks

ABSTRACTThe tectonic affiliation of the Khanka Massif, in the easternmost section of the Central Asian Orogenic Belt (CAOB), is still a matter of debate. Here, we provide new constraints on the provenance and timing of deposition of Permian strata in the western margin of the Khanka Massif. The results, which include U–Pb dating of detrital zircon grains using laser ablation–inductively coupled plasma–mass spectrometry (LA-ICP-MS), provide evidence regarding the tectonic position of the Khanka Massif and its role in the late Palaeozoic evolution of the eastern CAOB. Detrital zircon grains from a sublitharenite (Pingyangzhen Formation), a litharenite (Liangzichuan Formation), and a metamorphic siltstone (Qinglongcun Group) yielded multiple age populations ranging from Neoproterozoic (~914 Ma) to Permian (~272 Ma). Combined with age constraints from overlying/late-stage igneous rocks and other magmatism of the Khanka Massif, we conclude that the dated strata were deposited during the early–middle Permian and were sourced from the Khanka Massif. A comparison between the detrital zircon age populations and the history of magmatic activity in the neighbouring areas suggests that the Khanka Massif was tectonically linked to the Songnen–Zhangguangcai Range Massif. Based on tectonic discrimination diagrams, we conclude that the western margin of the Khanka Massif was positioned in a convergent-boundary basin during the early–middle Permian. Strike-slip faulting along the Dunhua–Mishan Fault, in response to ridge subduction of the Paleo-Asian Ocean Plate, resulted in a north-eastward movement of the Khanka Massif. The occurrence of Precambrian detrital zircon grains (with ages of 1900–1700 and 900–700 Ma) implies the presence of an ancient basement within the Khanka Massif.

A study of the deep electrical structure of the northern segment of the Tan-Lu fault zone, NE China

We studied a magnetotelluric transect from Tongliao, Inner Mongolia, to Baishan, Jilin, that crosses the northern segment of the Tan-Lu fault zone. Based on the profiling data, we calculated and analyzed the two-dimensional (2D) deviation degree and the tectonic strike, inverted the data using the 2D nonlinear conjugate gradient inversion method, and obtained an electrical structure model of the crust and upper mantle along the transect. Our analysis reveals that the western portion of the transect is within and at the margin of a typical sedimentary basin, and a high-conductivity layer is present in the lower crust. In comparison, the eastern portion of the transect is in the Jihei fold zone and has a relatively stable electrical structure, but its resistivity is one to two orders of magnitude higher than that of the western portion. A distinct electrical anomaly exists between the western and eastern sides. The Yilan-Yitong Fault of the northern segment of the Tan-Lu fault zone dips to the northwest, has strike-slip characteristics, extends to a depth of 40–50 km, and induces upwelling of upper mantle materials. The Dunhua-Mishan Fault of the northern segment of the Tan-Lu fault zone has a clear electrical gradient, and similar to the Yilan-Yitong Fault, it also dips to the northwest. However, the Dunhua-Mishan Fault is mostly fractured, extends to a depth of approximately 20 km and is slightly smaller than the Yilan-Yitong Fault. The inferred distribution of deep resistivity values indicates that the lithosphere is generally thinner at the center of the transect and thicker at the edges: the lithosphere is approximately 150 km thick on the western end, thins eastward to approximately 60 km thick near the Tan-Lu fault zone and then gradually thickens eastward to 100 km thick.

Location and sinistral displacement of the eastern Liaoyuan Accretionary Belt along the Tan–Lu Fault Zone, NE China

The NE- to NNE-striking, continental-scale Tan–Lu Fault Zone (TLFZ) in NE China is subdivided into the ∼900 km long Yilan–Yitong Fault (YYF) in the west and the ∼1000 km long Dunhua–Mishan Fault (DMF) in the east. Both faults record sinistral displacement during the earliest Cretaceous, leading to an obvious offset of the boundary between the Liaoyuan Accretionary Belt (LAB) and the North China Craton (NCC). Previous studies have demonstrated that the LAB in the south of the eastern Central Asian Orogenic Belt (CAOB) extends eastwards into an area between the YYF and the DMF. The boundaries between the LAB and NCC indicate a 35 km sinistral displacement upon the YYF. However, it remains unclear whether the LAB extends to the east of the DMF, and the amount of sinistral displacement on the DMF is poorly constrained. Here we present lithological observations and U–Pb and Hf isotopic data from zircon to constrain the age and position of the LAB to the east of the DMF. The data indicate an eastward extension of the LAB across the DMF, suggesting the continuous presence of the LAB east of the TLFZ in NE China. The U–Pb ages, εHf(t) values, and two-stage model ages of zircons from the study area constrain the boundary between the LAB and NCC to an extension of the NE-dipping Chifeng–Kaiyuan Fault to the east of the DMF. The geological boundaries on both sides of the DMF indicate a 170 km sinistral displacement along the fault. Thus, the TLFZ has a total sinistral displacement of 205 km in NE China. The eastern branch of the TLFZ records significantly more movement due to its proximity to the Pacific Ocean, where subduction of oceanic crust might have caused sinistral faulting along the TLFZ.

Mesozoic strike-slip movement of the Dunhua–Mishan Fault Zone in NE China: A response to oceanic plate subduction

The NE-striking Dunhua–Mishan Fault Zone (DMFZ) is one of two branches of the continental-scale sinistral Tan–Lu Fault Zone in NE China. The field data presented here indicate that the ca. 1000km long DMFZ records two phases of sinistral faulting. The structures produced by these two phases of faulting include NE–SW-striking ductile shear belts and brittle faults, respectively. Mylonite-hosted microstructures and quartz c-axis fabrics suggest deformation temperatures of 450°C–500°C for the ductile shear belts. Combining new zircon U–Pb dates for 14 igneous rock samples analyzed during this study with the geology of this region indicates these shear belts formed during the earliest Early Cretaceous. This phase of sinistral displacement represents the initial formation of the DMFZ in response to the northward propagation of the Tan–Lu Fault Zone into NE China. A phase of Early Cretaceous rifting was followed by a second phase of sinistral faulting at 102–96Ma, as evidenced by our new U–Pb ages for associated igneous rocks. Combining our new data with the results of previous research indicates that the DFMZ records a four-stage Cretaceous evolutionary history, where initial sinistral faulting at the beginning of the Early Cretaceous gave way to rifting during the rest of the Early Cretaceous. This was followed by a second phase of sinistral faulting at the beginning of the Late Cretaceous and a second phase of local rifting during the rest of the Late Cretaceous. The Cretaceous evolution of the DMFZ records the synchronous tectonic evolution of the NE China continent bordering the Pacific Ocean. Two phases of regional N–S compression generated the two phases of sinistral faulting within the DMFZ, whereas two-stage regional extension generated the two phases of rifting. The two compressive events were the result of the rapid low-angle subduction of the Izanagi and Pacific plates, whereas the two-stage extension was caused by the roll-back of these respective plates. The final closure of the Mongol–Okhotsk Ocean at the beginning of the Early Cretaceous intensified the synchronous compression in NE China, causing the northward propagation of the Tan–Lu Fault Zone.

Diverse Sedimentary Conditions During Deposition Of Coal And Oil Shale From The Meihe Basin (Eocene, Ne China)

The Meihe Basin in northeastern China is a normal-fault-controlled basin filled with Eocene nonmarine deposits, the sediments assigned to the Meihe Formation. Sediment grain-sizes, core study, well-log analysis and micropetrographic study combined with sedimentary facies analysis indicate that the main sedimentary facies of the Meihe Basin represent fan-delta, lake, and turbidite deposits. Thick coal seams that are mainly distributed in the eastern part of the studied area were deposited in the swamp facies of the Lower Coal-Bearing Member. Oil shale was mainly deposited in the deep lake represented by the Mudstone Member, and is mainly distributed in the southern part of the studied area. In the Lower Coal-Bearing Member, organic-rich sediments are characterized by TOC content between 0.6 wt.% and 43.1 wt.%and contain Type II and III kerogen. The thick coal seams are the result of high landplant productivity and good preservation conditions. Thin coal seams in the fan-delta plain resulted from the migration and erosion of the fan-delta channel. In the shallow lake and fan-delta front, limited productivity coupled with dilution by inorganic matter resulted in lower organic-matter content in theMudstoneMember. Oil shale and mudstone rich in organic matter were deposited in a deep lake with an average TOC content of 3.4 wt.%. The origin of the organic matter was mainly algae and aquatic plants mixed with land plants. The improved preservation conditions and high bioproductivity in this environment resulted in three oil-shale layers in the lower part of this sedimentary succession. Three coal-bearing and oil-shale-bearing fault basins lie adjacent to the Dunhua-Mishan Fault zone, among which the Fushun Basin is located in the southwest, the Meihe Basin is in themiddle, and theHuadian Basin is in the southeast. From the Fushun Basin to the Huadian Basin, the oil shale and coal seams have distinct sedimentation characters laterally. Vertically in each basin, the organic-matter sources all have the same variation trend from land plants to land plants mixed with algae to algae then to algae mixed with land plants, and the TOC content also shows a similar trend from high to medium-high then to low in each basin.

Geochronology and geochemistry of early Paleozoic intrusive rocks from the Khanka Massif of the Russian Far East

The Russian Far East and Northeast (NE) China are located in the eastern part of the Central Asian Orogenic Belt (CAOB), which consists of a series of micro‐continental massifs including the Erguna, Xing'an, Songnen–Zhangguangcai Range, Bureya, Jiamusi, and Khanka massifs. The Khanka Massif is located in the easternmost part of the CAOB, mainly cropping out in the territory of Russia, with a small segment in NE China. To the north and west of the Khanka Massif are the Jiamusi and Songnen–Zhangguangcai Range massifs, respectively. The boundary between these massifs is marked by the Dunhua–Mishan Fault. To the south lies the North China Craton, and to the east is the Sikhote–Alin Orogenic Belt separated by the Arsenyev Fault.However, the early Paleozoic evolution and tectonic attributes of the Khanka Massif are debated. These conflicting ideas result from the lack of systematic research on early Paleozoic igneous rocks from the Russian part of the Khanka Massif.It is generally accepted that the CAOB represents the largest known Phanerozoic accretionary orogenic belt. However, questions remain concerning the nature of the deep crust beneath the Khanka Massif, and whether Precambrian crust exists within the massif itself.In this paper, we report new zircon U–Pb ages, Hf isotopic data, and major‐ and trace‐element compositions of the early Paleozoic intrusive rocks from the Khanka Massif of the Russian Far East, with the aim of elucidating the early Paleozoic evolution and the tectonic attributes of the Khanka Massif, as well as the nature of the underlying deep crust.New U–Pb zircon data indicate that early Paleozoic magmatism within the Khanka Massif can be subdivided into at least four stages: ∼502 Ma, ∼492 Ma, 462–445 Ma, and ∼430 Ma.The ∼502 Ma pyroxene diorites show negative Eu anomalies, and the ∼492 Ma syenogranites, intruding the ∼502 Ma diorites, show positive Eu anomalies. These observations indicate that the primary parental magmas of these rocks were derived from different origins.The 462–445 Ma magmatism is made up of syenogranites and tonalites. The ∼445 Ma Na‐rich tonalites contain low REE concentrations, and are enriched in Eu and Sr. These observations, together with the positive εHf(t) values, indicate that they were derived from magmas generated by partial melting of cumulate gabbros.The ∼430 Ma I‐type granodiorites and monzogranites from the northern Khanka Massif, and the A‐type monzogranites from the central Khanka Massif display zircon εHf(t) values ranging from −5.4 to +5.8. This suggests that they formed from magmas generated by partial melting of heterogeneous lower crustal material.Zircon Hf isotopic data reveal the existence of Precambrian crustal material within the Khanka Massif. The geochemistry of the Middle Cambrian intrusive rocks is indicative of formation in an extensional setting, while Late Cambrian–middle Silurian magmatism was generated in an active continental margin setting associated with the subduction of a paleo‐oceanic plate beneath the Khanka Massif. Regional comparisons of the magmatic events indicate that the Khanka Massif has a tectonic affinity to the Songnen–Zhangguangcai Range Massif rather than the Jiamusi Massif.

Structural characteristics of the Yilan–Yitong and Dunhua–Mishan faults as northern extensions of the Tancheng–Lujiang Fault Zone: New deep seismic reflection results

The Tancheng–Lujiang Fault Zone (TLFZ) can be subdivided into three segments that exhibit sharp contrasts in their deep structures. A deep seismic reflection profile (length ~600km) across the north part of the TLFZ, which provides new constraints on the structural styles of the northern TLFZ, was recently completed by the Chinese Sinoprobe Project. Here, the TLFZ branches into the Yilan–Yitong Fault (YYF) to the west and the Dunhua–Mishan Fault (DMF) to the east. The YYF developed as an internal fault in the Songnen–Zhangguangcai massif, while the DMF serves as the tectonic boundary between the Nadanhada terrane and the Khanka massif. Both faults developed large-scale flower structures, with that of the YYF being negative and that of the DMF being positive with reverse faults. The Moho in the profile is at a depth of 25–39km and is offset by the faults. The north part of the TLFZ extends into the upper mantle as thin shear zones with the reflectors truncated in the middle/lower crust. This feature differs from most crustal-scale strike-slip faults that distribute over a discrete shear zone in the lower crust, such as the San Andreas Fault.

The deformation and tectonic evolution of the Huahui Basin, northeast China, during the Cretaceous–Early Cenozoic

The Cretaceous Huahui basin lies along the Dunhua–Mishan fault (Dun–Mi fault), which is one of the northern branches of Tan–Lu fault in northeastern China. The study of the formation and the tectonic movements that took place in the basin can provide very important information for deciphering the tectonic evolution of northeastern China during Cretaceous–Early Cenozoic. The field analysis of fault-slip data collected from different units in the basin, demonstrates changes in the paleo-stress state that reveals a three-stage tectonic movement during the Cretaceous–Early Cenozoic. The earliest tectonic movement was NW–SE extension, which was responsible for the formation of the basin and sedimentary infilling during the Early Cretaceous. Dating of the andesite in the fill indicates it began during about 119.17±0.80Ma. The extensional structures formed in the Latest Early Cretaceous imply that this tectonic movement lasted until the beginning of the Late Cretaceous. The second stage began during the Late Cretaceous when the tectonic stress state changed and was dominated by NW–SE compression and NE–SW extension, which caused the inversion of the extensional basin. This compression folded the Early Cretaceous deposits and reactivated pre-existing faults and uplifted pre-existing granite in the basin. The strata and the unconformity in the basin shows that this compressive phase probably took place during the Late Cretaceous and ended in the Early Paleogene by a compressional regime with NE–SW compression and NW–SE extension that constitutes the third stage. The tectonic stress fields documented in the Huahui basin provide insight into the influences of plate tectonics on the crustal evolution of northeastern China during the Cretaceous to Early Cenozoic. These results show that the development of Huahui basin was controlled by the northwestward subduction of the paleo-Pacific plate during the Cretaceous, and later by the far-field effects of India–Asia collision in the Paleogene.

The Khanka Block, NE China, and its significance for the evolution of the Central Asian Orogenic Belt and continental accretion

Abstract Sensitive high-resolution ion microprobe and inductively coupled plasma mass spectrometry U–Pb dating of zircons from granitoids and paragneiss in the Chinese segment of the Khanka Block reveals that granite magmatism occurred at 518±7 Ma and was followed shortly after by high-grade metamorphism at c . 500 Ma (timing ranging from 491±4 Ma in medium-grained granitoid, through 499±10 Ma in porphyritic granite, to 501±8 Ma in paragneiss). Such a scenario has previously been established on similar lithologies in the Jiamusi Block to the west, with identical ages. This suggests that the Khanka and Jiamusi blocks form part of a single terrane and that the Dunhua–Mishan Fault, which was previously considered to separate two unique terranes, cannot be a terrane boundary fault. Previous suggestions of a link between the Khanka Block and the Hida Block in Japan are not supported following a comparison of the new zircon data with published ages for the Japanese terranes. A granitoid with an age of 112±1 Ma in the Khanka Block probably records the effect of Pacific plate subduction, as such ages are common further south in the extreme eastern part of the North China Craton, where they have been related to post-collisional extension and lithospheric thinning in the Jiaodong Peninsula. The presence of such young granitoids, and the previous dating of blueschist-facies metamorphism as late Early Jurassic in the Heilongjiang Complex of the Jiamusi Block, supports the view that the current location of the Jiamusi–Khanka terrane is a product of circum-Pacific accretion rather than it being a microcontinental block that was trapped by the northward collision of the North China Craton with Siberia as part of the assembly of the main Central Asian Orogenic Belt.

Study on Crustal Structures of Changbaishan-Jingpohu Volcanic Area using Receiver Functions

We have obtained 34 receiver functions from 71 teleseismic waveforms recorded by 34 stations that were installed in Changbaishan-Jingpohu volcanic area. Through inversing receiver function of 34 seismic stations, we obtain S wave velocity structures beneath the stations. The results revealed that the Moho depth is about 32-33km along Shenyang-Dunhua direction and becomes deeper toward its west side. In Changchun area, the Moho thickness reaches about 36km and under the crater of Changbaishan-Tianchi volcano, the depth of Moho reaches about 38km while beneath Jingpohu volcanic area, Moho depth is about 39km. Overall, the crustal thickness of studied area is thick in north and thin in south. We found an anomalous layer with obvious low Swave velocity beneath Changbaishan-Tianchi crater at about 10km depth. Beneath Jingpohu volcanic area there is also possibly a low S-wave velocity anomalous body at about 30km depth. The results show that the S-wave velocity gradients at Moho are obviously different between near crater and far apart from the crater. S-wave velocity gradient of Moho near crater is clearly smaller than that in area without volcano, which suggests that Moho structures beneath volcano are different from general Moho structures in other areas. The crust thickness on the two sides along Shenyang-Dunhua direction has a comparatively great changes and its location is almost the same as Dunhua-Mishan fault at near surface. Therefore, Dunhua-Mishan fault is a very important geological structure zone in the studied area.