Mixed Sequence Research Articles

Controls on carbonate-siliciclastic relationships in quaternary deposits of the Midyan coast of the Gulf of Aqaba, Saudi Arabia

Quaternary deposits of the Midyan coast of Saudi Arabia include coral-bearing limestones interbedded with sheet-flow siliciclastic sands and gravels, interpreted as braid-delta fan deposits. The limestones and their contained faunas provide evidence of periodic local stabilization of gravel surfaces and effective starvation of siliciclastic supply. Some indicate growth and deposition in waters a metre or so deep whereas others were substantially deeper. An additional group reflects initial deposition in shallow waters with resedimentation downslope by storm or other ‘delta-front’ processes. The surfaces of the fans provided morphological and environmental analogues to fore- and back-reef situations in which corals, calcareous coralline algae, molluscs, and echinoderms flourished, but in this area did not form independent reefs. The dominant controls on the changes from siliciclastic- to carbonate-dominated deposition were not transitional, and primarily related to channel and fan-lobe migration rather than tectonic or eustatic sea level changes. Similar variations in the distribution of siliciclastic sediments may control carbonate occurrence in other mixed sequences.

Study on the mixing process improvement for hot recycled asphalt mixture

Existing studies have shown that the mixing process of hot recycled asphalt mixture has a considerable effect on its performance. The conventional mixing process applied widely in pavement industry, mixed the RAP and virgin aggregate first. Then asphalt binder was added for the second mixing. This conventional mixing process, however, ignored the asphalt-adsorbing capacity of different aggregates, may resulting in the heterogeneity of recycled asphalt mixture after mixing. Adjusting the mixing sequence of RAP, virgin asphalt binders and aggregate is confirmed as an effective way to solve the above-mentioned issue. However, the change in the demand for virgin asphalt binders for each mixing step, which is raised from aggregate gradation and different RAP content, is not taken into consideration in this improved method. In view of this weakness, this study proposed an improved mixing technique for hot recycled asphalt mixture, which comprehensively considered the mixing sequence of materials and determined the amount of asphalt binders added for different RAP content based on the specific surface area of aggregates. And the prediction formula for the amount of virgin asphalt added each step is further proposed from the perspective of aggregate specific surface area. Several laboratory experiments were conducted to verify the feasibility of this improved technique. The results indicated that, the improved mixing technique could contribute to enhancing the water stability, low temperature cracking resistance and fatigue performance of hot recycled asphalt mixtures. And the higher the content of the RAP used in recycled mixture, the stronger the improvement of the improved mixing process.

Pharmacogenetics of CYP2A6, CYP2B6, and UGT2B7 in the Context of HIV Treatments in African Populations.

This study focuses on identifying variations in selected CYP genes related to treatment responses in patients with HIV in African populations by investigating variant characteristics and effects in African cohorts. Cytochrome P450 (CYP) 2A6, 2B6, and Uridine 5'-diphospho-glucuronosyltransferase (UGT) 2B7 allele frequencies were studied using public-domain datasets obtained from the 1000 Genomes Phase 3 project, the African Genome Variation Project (AGVP), and the South African Human Genome Programme (SAHGP). Variant annotations were performed using self-identified ethnicities to conduct allele frequency analysis in a population-stratification-sensitive manner. The NCBI DB-SNP database was used to identify documented variants and standard frequencies, and the E! Ensembl Variant Effect Predictor tool was used to perform the prediction of possible deleterious variants. A total of 4468 variants were identified across 3676 individuals following pre-filtering. Seventy-one variants were identified at an allelic frequency (1% or more in at least one population), which were predicted to be linked to existing disease associations and, in some cases, linked to drug metabolisms. This list was further studied to identify 23 alleles with disease considerations found at significantly different frequencies in one or more populations. This study describes allele frequencies observed in African populations at significantly different frequencies relative to at least one other reference population and identifies a subset of variants of clinical interest. Despite the inclusion of mixed sequence coverage datasets, the variants identified pose notable avenues for future inquiries. A subset of variants of clinical interest with statistically significant inter-population frequency differences was identified for further inspection, which provides evidence of an African population-specific variant frequency profile. This study highlights the need for additional research and African genetics data given the presence of this unique frequency profile to better facilitate the genetic pre-screening of patients as a standard of practice in HIV care, particularly on the African continent where HIV is highly prevalent.

A Mixing Sequence Optimization Method for Focused Compressed Sampling Based on Modulated Wideband Converter

In modulated wideband converter (MWC), all signals are aliased and sampled indiscriminately, which reduces the reconstruction accuracy of target signal. The focused compressed sampling uses optimized mixing sequence to increase the mixing gain of the target signal. To establish the sequence library with selective characteristics, this brief analyzes the signal components aliased into baseband, then proposes a sequence optimization method based on the greedy algorithm. Simulation and experiments show that the optimized sequence possesses a high gain for a desired frequency band signal. In the three-carrier signal test, as the approximate desired signal power ratio (DSR) is raised to 0.99 in baseband, the normalized mean square error (NMSE) of the reconstructed desired signal is improved by nearly 10 dB compared to using pseudorandom sequences.

Burial stylolites enhance karst dissolution and control cave geometry in heterolithic carbonates, Salitre Formation, Brazil

Understanding the karstification process in fractured carbonates is a key factor in developing and exploiting fractured and karstified reservoirs. This study documents the relationship among the 2D geometry, stratigraphy and petrophysical properties of a cave system developed in a Neoproterozoic mixed carbonate-siliciclastic sequence. We applied a multidisciplinary and multiscale approach that combined structural geological surveys, cave imaging by Laser Detecting and Ranging (LiDAR), linear scanlines, stratigraphic logs, uniaxial compressive strength (UCS), mercury-intrusion porosimetry, and 2D image analysis. We found that bedding-parallel stylolites in dolomitic limestone consist of mm-to cm-thick high-porosity zones (up to 20% measured via 2D image analysis). They acted as fluid conduits that enhanced bedding-parallel dissolution. Field and thin section analyses showed that beds with close spacing and thicker stylolites are more karstified and dissolved than beds showing greater spacing or completely devoid of stylolites, indicating that stylolitic zones act as flow pathways in low porosity-permeability carbonates. Primary porosity, pore size distribution, density and capillary pressure of host rocks have no direct relationship with karstification intensity. We conclude that clusters of burial stylolites may control the hypogenic cave geometry. These findings have direct implications for subsurface permeability prediction in karstified carbonate reservoirs.

A local limit theorem for a number of multiple recurrences generated by some mixing processes with applications to Young towers

We prove a local central limit theorem for “nonconventional” sums generated by some classes of sufficiently fast mixing sequences.

A NEGATIVE BINOMIAL AUTOREGRESSION WITH A LINEAR CONDITIONAL VARIANCE-TO-MEAN FUNCTION

A general integer-valued time-series model with a conditional variance proportional to the conditional mean is proposed. Specifically, the conditional distribution is a Poisson mixture with a dependent mixing sequence, which results in a negative binomial distribution with a linear conditional variance-to-mean relationship. In addition, the conditional mean is specified as a general parametric function of past observations. We first propose stationarity, ergodicity, and finite moment conditions for the model. Furthermore, the parameters are estimated using the Poisson quasi-maximum likelihood estimate, whose asymptotic properties are studied under weak conditions. Illustrations of the proposed methodology on simulated and actual time series of counts are given.

Short PolyA RNA Homopolymers Undergo Mg2+-Mediated Kinetically Arrested Condensation.

RNA-RNA interactions have increasingly been recognized for their potential to shape the mesoscale properties of biomolecular condensates, influencing morphology, organization, and material state through networking interactions. While most studies have focused on networking via Watson-Crick base pairing interactions, previous work has suggested a potential for noncanonical RNA-RNA interactions to also give rise to condensation and alter overall material state. Here, we test the phase separation of short polyA RNA (polyrA) homopolymers. We discover and characterize the potential for short polyrA sequences to form RNA condensates at lower Mg2+ concentrations than previously observed, which appear as internally arrested droplets with slow polyrA diffusion despite continued fusion. Our work also reveals a negative cooperativity effect between the effects of Mg2+ and Na+ on polyrA condensation. Finally, we observe that polyrA sequences can act as promoters of phase separation in mixed sequences. These results demonstrate the potential for noncanonical interactions to act as networking stickers, leading to specific condensation properties inherent to polyrA composition and structure, with implications for the fundamental physical chemistry of the system and function of polyA RNA in biology.

An almost sure invariance principle for some classes of non-stationary mixing sequences

In this note we (in particular) prove an almost sure invariance principle (ASIP) for non-stationary and uniformly bounded sequences of random variables which are exponentially fast ϕ-mixing. The obtained rate is of order o(Vn14+δ) for an arbitrary δ>0, where Vn is the variance of the underlying partial sums Sn. For certain classes of inhomogeneous Markov chains we also prove a vector-valued ASIP with similar rates.

Sequence Stratigraphy of Miocene Mixed Carbonate-Siliciclastic in Fold and Thrust Belt System, Banggai Basin

This study was specifically analyzed in the southern part of the Banggai Basin, precisely in the TKA Field. In the Tertiary, regional stratigraphy reveals, the Banggai Sula microplate comprises carbonate shelf and siliciclastic sequence. Several previous studies had been concluding, the tertiary limestone was deposited during the Early Eocene to Middle Miocene. Carbonate formations which has been known by Tomori and Minahaki Formation. Meanwhile, their siliciclastic dominated is Matindok Formation and Celebes Mollase. These sequences formed a distinct stratigraphic style in the geophysical well log and seismic data. Four cycles are distinguished, the lower part of Tomori Formation at the outer shelf and directly overlying by the upper part of inner shelf Tomori Formation. it was superimposed by siliciclastic sediments that have been deposited in the outer litoral during regressive phase. Whereas during rising sea level or highstand, the litoral system migrated to basinward wherein Minahaki Formation was deposited. Sequence stratigraphy provides a reliable methodology for correlate both carbonate and siliciclastic successions. It was analyzed based on 4 wells, 2D, and 3D seismic data which has been available. Sequence stratigraphy analysis using T-R sequence concept by Embry and Johanessen. Trasngressive and regressive phases were obviously determined by lithofacies, coral colony and foram that were recorded on biostratigraphic analyses. In this study, cyclic sea-level change will be recognized as system tract record of mixed carbonate-siliciclastic sequence.

Bidirectional hybridisation and introgression between introduced European brown hare, Lepus europaeus and the endemic Irish hare, L. timidus hibernicus

Introduced non-native species can threaten native species through interspecific hybridisation and genetic introgression. We assessed the prevalence of hybridisation and introgression between introduced European brown hare, Lepus europaeus, and the endemic Irish hare, L. timidus hibernicus. Roadkill hares (n = 56) were sequenced for a 379bp section of the mitochondrial DNA D-loop and a 474bp segment of the nuclear transferrin (Tf) gene. A species-specific indel in the transferrin gene was present in L.t. hibernicus and absent in L. europaeus. Excluding three hares from which molecular data could not be recovered, 28 hares (53%) were native L.t. hibernicus, 7 (13%) were non-native L. europaeus and 18 (34%) were hybrids; of which 5 (28%) were first generation (F1) involving bidirectional crosses with mismatched nuclear and mtDNA (3 ♂ europaeus x ♀ hibernicus and 2 ♂ hibernicus x ♀ europaeus). Mixed nuclear transferrin sequences suggested 13 (72%) of hybrids were at least 2nd generation (F2) with 9 (69%) possessing L.t. hibernicus and 4 (31%) L. europaeus mtDNA (the latter indicative of hybrid backcrossing with the non-native). The prevalence of hybridisation at similar mountain-brown hare contact zones throughout Europe is notably lower (4–16%) and typically unidirectional (♂ europaeus x ♀ timidus). A high prevalence of bidirectional hybridisation and introgression (in association with projected climate change) may favour the introduced species over the native. Genetic surveillance and population monitoring are needed to further explore the potential conservation implications of European brown hare in Ireland.

Reservoir heterogeneity of an Eocene mixed siliciclastic-carbonate succession, northern Pannonian Basin

The quality of any reservoir is strongly controlled by diagenetic processes, especially of those that are comprised of mixed siliciclastic-carbonate sequences. An Eocene mixed siliciclastic-carbonate sequence forms reservoirs with diverse reservoir quality in the Hungarian Palaeogene Basin, which is found within the Pannonian Basin. Late Eocene transgression established extensive shallow-marine depositional environments strongly controlling the early diagenetic processes. Drill cores and cuttings were selected from several boreholes, representing a wide range of lithofacies to reveal the cause for reservoir heterogeneity. Petrographic, stable isotope and fluid inclusion analyses were performed to identify the diagenetic processes that controlled the porosity evolution of the reservoir, The early diagenetic calcite neomorphism caused lateral homogeneity, whereas the early meteoric water incursion enhanced reservoir properties via the development of dissolution pores, which in turn resulted in vertical reservoir heterogeneity. The deterioration of porosity started in the eogenetic realm by kaolinite formation and continued during mesodiagenesis as burial calcite, quartz, dolomite and minor illite cement precipitated in remaining pore spaces. Petrographic evidence, such as kaolinite transformation into dickite and fluid inclusion homogenisation temperatures highlight the role of temperature increase with burial, the effect of changing fluid chemistry during the evolution of the basin is documented by the chemical zonation of dolomite, the variation in salinities of the fluids enclosed fluid inclusions, as well as recurrent and prolonged periods of cementation with calcite, quartz and dolomite. Mesogenetic processes were accompanied by hydrocarbon emplacement and the formation of late-stage pyrite. The propagation and cementation of faults first contributed to increase and later to reduce fluid flow, respectively. These steps collectively resulted in a heterogeneous reservoir, characteristic of the Eocene sequence in the Hungarian Palaeogene Basin.

Facies distribution along salt walls: The Upper Cretaceous mixed siliciclastic-carbonate deposits of the Cotiella minibasins (Southern Pyrenees, Spain)

To assess the influence of growing salt structures on facies distribution, stratal pattern, and thickness trends, this paper provides the tectonostratigraphic framework of the outstandingly exposed Cotiella minibasins (South-Central Pyrenees, Spain). Based on detailed analysis of field cross-sections, our results showcase the syn-halokinetic upper Coniacian-lower Santonian Cotiella minibasins infill (1.5–3 km thick) records four shallow-marine depositional sequences, made of mixed siliciclastic-carbonate stratigraphic sequences. This infill is subdivided in three tectonostratigraphic units, identified by using large and small-scale halokinetic structures (i.e. wedges, megaflaps) and variations in facies associations, thicknesses, stratal patterns from the salt wall flanks to the central part of the minibasins. The first unit records the onset of salt movement with overlying laterally continuous sheet-like sedimentary layers and progressive facies transitions over distances of kms. The influence of halokinesis on sedimentation patterns was minor, and only impacted thickness trends and depocenters localization. The second unit records salt evacuation at the surface with the presence of salt-wall derived detritus, the rapid downbuilding and a increase of sand-rich facies proportions. The stratal pattern is characterized by sheet like layers, laterally discontinuous over distances of 300–600 m downdip to the salt wall. Topographically elevated salt walls likely amplified tidal currents, implying sand-rich facies accumulation along the salt wall margin. The halokinesis influence on sedimentation, thickness trends and depocenter localization was significant. The third unit records the end of the salt evacuation stage, marking a brutal decrease of sand-rich facies, likely controlled by regional controls such as eustacy and tectonics. The influence of halokinesis on sedimentation patterns, thickness trends, large-scale geometries and depocenter localization was significant. Our work indicates that distinguishing these large-scale tectonostratigraphic units and their characteristics is of prime importance to understand the archetypal facies distribution, thickness and stratal patterns along salt structures margins.

Investigating the role of PA6/GO interactions on the morphological, rheological, and mechanical properties of PA6/ABS/GO nanocomposites

ABSTRACT This study is dedicated to investigate the rheological, mechanical, and morphological properties of polyamide 6/poly (acrylonitrile butadiene styrene) (PA6/ABS) blends in the presence of graphene oxide nanoplates (GO). In this regard, scanning electron microscopy analysis, rheological assessments, and mechanical tests were performed. PA6/ABS (65 wt%, 35 wt%) blends were prepared by melt mixing method in the presence of 0.25 wt%, 0.5 wt%, and 1 wt% GO nanoparticles. Also, to study the effect of mixing protocol on these properties, the mixing sequences varied for the blends containing 0.5 wt% GO. The rheological, mechanical, and morphological analyses demonstrated the formation of significant interaction between PA6 and GO for polymer blends having 0.25 wt% GO. On the other hand, the decrease in the elasticity for the 0.5 wt% GO incorporated polymer blend was attributed to the lubricating role of GO in PA6 as a consequence of weak interactions between PA6 and GO. ABS/GO pre-mixed blend showed good interfacial adhesion between PA6 and ABS as a result of kinetic influence of GO for interfacial localization in PA6/ABS polymer blends. Furthermore, PA6/GO pre-mixing protocol demonstrated the highest elasticity for PA6/ABS blend due to the PA6/GO adhesion reinforcement.

Hajek–Renyi-type inequality for (alpha , beta )-mixing sequences and its application to change-point model

In this paper, we investigate the Hajek–Renyi-type inequalities for (alpha ,beta )-mixing sequences. As an important application of the results, we further study the CUSUM-type estimator of mean change-point models for (alpha , beta )-mixing sequences. We establish the convergence rate of weak consistency for the CUSUM estimator. Moreover, we also present some simulation studies and a real data example to support the theoretical results.

The impact of zirconium-89 solution formulation on the efficiency of [89 Zr]Zr-deferoxamine synthesis.

In recent years, clinical imaging with 89 Zr-based radiopharmaceuticals has been gaining significant importance in nuclear medicine. This article provides the results of a comparative study of methods for obtaining 89 Zr solutions using ZR, Chelex-100, and TBP resins in the form of [89 Zr]Zr-oxalate, [89 Zr]Zr-chloride, and [89 Zr]Zr-citrate in terms of purification and labeling efficiency. All evaluated methods allowed us to obtain 89 Zr with high yield (>90% in 1 ml). The chemical form of 89 Zr has a significant influence on the radiolabeling efficiency of the deferoxamine (DFO) chelator and its derivatives. Compared with [89 Zr]Zr-oxalate, the application of [89 Zr]Zr-chloride and [89 Zr]Zr-citrate solutions leads to a higher efficacy of [89 Zr]Zr-DFO complex formation. It should be noted that the sequence of mixing of the reagents during the radiolabeling reaction and the residual concentration of oxalic acid appeared to be crucial in the case of [89 Zr]Zr-chloride. According to the experimental data, radiolabeling of DFO and its derivatives is preferable to use more stable chemical forms of 89 Zr, such as [89 Zr]Zr-citrate. The concept will be applied in the further studies involving antibody-based bioconjugates.

Migration behavior of reclaimed asphalt pavement mastic during hot mixing

The production of hot central plant recycling asphalt mixture (RHMA) is more complex and uncertain than conventional hot mix asphalt. An adequate blend of virgin and aged asphalt is essential to recovering the performance of aged asphalt in reclaimed asphalt pavement (RAP). Therefore, the amount of aged asphalt migrating from the RAP into the recycled material system determines the level of blending and the durability of RHMA. To reveal the influencing factors of migration rate, we used fine aggregates in RAP as tracers to measure the RAP mastic concentration in the blended mastic. The considered factors included mixing time, asphalt-aggregate ratio, rejuvenator content, mixing sequence, RAP pseudo ratio, and RAP agglomeration rate. Then, the migration behavior of aged mastic was investigated from the viewpoints of the temperature field and microscopic features using the infrared thermogram and CT scan techniques, respectively. In addition, FTIR, GPC, and AFM were used to study the influence of migration of RAP mastic on the composition of blended asphalt. Finally, the effect of RAP mastic migration on moisture stability of RHMA was investigated using moisture induced sensitivity test, freeze-thaw indirect tensile test, and water immersion rutting test. The results show that the migration rate of RAP mastic during hot mix can be improved by reducing RAP content, raising the preheating temperature of RAP, extending the mixing time, increasing the asphalt content, and using dry mixing method, whereas the amount of regenerator has no significant effect. The temperature is the essential factor affecting the migration level. The RAP mastic migration is highly synchronized with RAP aggregate movement under forced mixing. Furthermore, increasing the migration level of RAP mastic can significantly increase the proportion of aged asphalt in blended asphalt. At last, the higher RAP mastic migration can prevent void development in RHMA under freezing-thawing and hydrothermal washing, thereby improving the moisture stability of RHMA and alleviate peeling aggregates and mastic. This study contributes to current knowledge by explaining the essence of RAP mastic migration during hot mixing, the results should be interested by road contractors, producer of RHMA, and academic society.

H-Bond Templated Oligomer Synthesis Using a Covalent Primer.

Template-directed synthesis of nucleic acids in the polymerase chain reaction is based on the use of a primer, which is elongated in the replication process. The attachment of a high affinity primer to the end of a template chain has been implemented for templating the synthesis of triazole oligomers. A covalent ester base-pair was used to attach a primer to a mixed sequence template. The resulting primed template has phenol recognition units on the template, which can form noncovalent base-pairs with phosphine oxide monomers via H-bonding, and an alkyne group on the primer, which can react with the azide group on a phosphine oxide monomer. Competition reactions between azides bearing phosphine oxide and phenol recognition groups were used to demonstrate a substantial template effect, due to H-bonding interactions between the phenols on the template and phosphine oxides on the azide. The largest rate acceleration was observed when a phosphine oxide 2-mer was used, because this compound binds to the template with a higher affinity than compounds that can only make one H-bond. The 31P NMR spectrum of the product duplex shows that the H-bonds responsible for the template effect are present in the product, and this result indicates that the covalent ester base-pairs and noncovalent H-bonded base-pairs developed here are geometrically compatible. Following the templated reaction, it is possible to regenerate the template and liberate the copy strand by hydrolysis of the ester base-pair used to attach the primer, thus completing a formal replication cycle.

Sensitivity-Enhanced Multidimensional Solid-State NMR Spectroscopy by Optimal-Control-Based Transverse Mixing Sequences.

Recently, proton-detected magic-angle spinning (MAS) solid-state nuclear magnetic resonance (NMR) spectroscopy has become an attractive tool to study the structure and dynamics of insoluble proteins at atomic resolution. The sensitivity of the employed multidimensional experiments can be systematically improved when both transversal components of the magnetization are transferred simultaneously after an evolution period. The method of preservation of equivalent pathways has been explored in solution-state NMR; however, it does not find widespread application due to relaxation issues connected with increased molecular size. We present here for the first time heteronuclear transverse mixing sequences for correlation experiments at moderate and fast MAS frequencies. Optimal control allows to boost the signal-to-noise ratio (SNR) beyond the expected factor of for each indirect dimension. In addition to the carbon-detected sensitivity-enhanced 2D NCA experiment, we present a novel proton-detected, doubly sensitivity-enhanced 3D hCANH pulse sequence for which we observe a 3-fold improvement in SNR compared to the conventional experimental implementation. The sensitivity gain turned out to be essential to unambiguously characterize a minor fibril polymorph of a human lambda-III immunoglobulin light chain protein that escaped detection so far.

Sedimentary evolution and sea-level fluctuation of a Paleo-Tethyan Permian carbonate-dominated succession from central China

The Paleo-Tethys experienced major geographic, tectonic, climatologic, and environmental changes during the Permian. A newly documented and complete Permian carbonate-dominated succession (>3 km) in the Xikou section, Zhen'an, Shaanxi, central China provides a unique opportunity to record its depositional environment evolution, sea-level fluctuation, and associated paleogeographic and paleoclimatic perturbation of the eastern Paleo-Tethys. Field observation and petrographic analysis document eighteen facies and indicate evolutional facies of a carbonate ramp within the Xikou section. The vertical distribution of those facies in the Xikou section indicates a fluctuated sea-level during the Permian, which reflected the global climatic changes and was associated with eastern Paleo-Tethys evolution. The relatively low sea-level accompanied by high-frequency fluctuations during the Asselian to Artinskian may be related to the expansion of glaciation (P1 and P2), while the followed significant rising at Kungurian may reflect the major deglaciation of the Late Paleozoic Ice Age (LPIA). The abrupt falling of sea-level at the end of the Capitanian was globally synchronous and may be relevant to mid-ocean ridge spreading and superimposed with global cooling (P4), which was in accord with the skeletal grain replacement of the fusulinaceans and dasyclads by small foraminifers and Gymnocodium, and was considered as a major reason for Middle Permian Extinction. The early Wuchiapingian characterized by densely mixed sequences of carbonate and siliciclastic intervals had a highly frequent fluctuating sea-level, which may be influenced by high frequent short-term climatic variations. The sea-level falling after it reached its highest stand during the middle Wuchiapingian, was suggested as a far-field response to the expansion of the Permian glaciation episode P4, or as a result of a regional tectonic transition from extension to compression relevant to the eastern Paleo-Tethys evolution. In addition, the overall rising trend of the sea-level and the thick succession in the Xikou area suggest that the South Qinling belt was primarily under an extensional setting during the Late Carboniferous to Early Triassic, in response to Tethys rifting, which may imply the subduction of Mianlue Ocean was possibly beyond the Permian.