Separate Blocks Research Articles

Substantiation of rational design parameters of a crusher with two movable jaws

Purpose. Design engineering of the mechanism of a two-jaw crusher with a compound motion of the jaws, which ensures a change in the angle of gripping of pieces of material within a very small range. Methodology. In the work, a theoretical study on the fourth-class lever mechanism, as the basis of a two-jaw crusher, was performed using the Mathcad 15 software. The study was performed on a vector representation of the links of the hinged mechanism. The development and analysis of constructive solutions were performed using the Autocad software product, which reduces the risk of errors and increases the quality of the design process. Findings. The paper theoretically determines the rational geometric parameters of the two-jaw crusher with the optimal value of the nip angle, whose crushing chamber is formed by the closed loop circuit of the flat fourth-class lever mechanism and proposes a new constructive solution of the mechanism for adjusting the crusher opening with two movable jaws and the bottom mounting of eccentric nodes. The developed device in the form of separate blocks is made with the possibility of their simple assembly and disassembly, which ensures the rate and quality of replacing lining plates or surfacing restoration of the worn working surface of the jaws. The relative movement of the jaws ensures the crushing of pieces of material with the required crushing coefficient. The geometric parameters were obtained by the method of kinematic synthesis. The geometric parameters of the crushing chamber of the two-jaw crusher were determined theoretically; the dependence was obtained of the change in the nip angle on the height of the movable jaw over a period of movement and the change in the compression stroke, which ensures the force interaction of the working surface of the jaws with the material. Originality. It is proved that the quadrilateral closed circuit of the fourth-class lever mechanism can be used as a crushing chamber of a two-jaw crusher. Two links of a closed circuit operate as jaws which break pieces of material. At the same time, the nip angle can vary within fairly narrow limits, ensuring the optimality of the crushing process. It was established that the considered option of the fourth-class six-link mechanism geometry has only two folds. An algorithm is presented for searching for assemblies with the purpose of identifying those that are closely adjacent. Practical value. The results of the conducted research provide the theoretical background and the algorithm for determining the optimal parameters of a two-jaw crusher which can be used at the stage of designing similar crushers. The developed design solution for adjusting the crusher opening expands the scope of application of double-jaw crushers. The obtained dependences of the change in the angle of inclination and the working surface of the jaw over a period make it possible to develop a rational mode of crushing the material

End-to-end underwater acoustic source separation model based on EDBG-GALR

In practical work scenarios, it is common for multiple vessels to be present in close proximity within the same water area. In such cases, the acoustic signals emitted by these vessels often overlap, causing interference and reducing the accuracy of vessel identification. This paper proposes an improved GALR end-to-end underwater acoustic source separation algorithm, with ECA-DE (Efficient Channel Attention-Deep Encoder) and Bi-GRU (Bidirectional Gated Recurrent Unit), which consists of an encoder, separation blocks, and a decoder (EDBG-GALR). Addressing the issue of GALR encoder’s limited expressiveness due to its single-layer one-dimensional convolutional layer, we introduce a new deep encoder, ECA-DE, to enhance the encoder’s capability to process temporal signals and improve the efficiency of the separator’s input. Additionally, we integrate Bi-GRU into the GALR separation block’s local modeling module to enhance the local modeling ability of sequence features, thereby reducing the model’s computational and parameter requirements. Experimental results demonstrate that the proposed EDBG-GALR method can effectively separate mixed multi-target signals into multiple single-target signals, achieving a maximum scale-invariant signal-to-noise ratio (SI-SNR) improvement of 3.32 dB and a signal distortion ratio (SDR) improvement of 3.38 dB over baseline methods. These results highlight the practical applicability of EDBG-GALR in complex underwater environments.

Contrastive adaptation effects along a voice-nonvoice continuum.

Adaptation to the environment is a universal property of perception across all sensory modalities. It can enhance the salience of new events in an ongoing background and helps maintain perceptual constancy in the face of variable sensory input. Several contrastive adaptation effects have been identified using sounds within the categories of human voice and musical instruments. The present study investigated whether such contrast effects can occur between voice and nonvoice stimulus categories. A 10-step continuum between "voice" (/a/, /o/, or /u/ vowels) and "instrument" (bassoon, horn, or viola) sounds was generated for each of the nine possible pairs. In each trial, an adaptor, either a voice or instrument, was played four times and was followed by a target from along the appropriate continuum. When trials with voice and instrumental adaptors were grouped into separate blocks, strong contrastive adaptation effects were observed, with the target more likely to be identified as a voice following instrumental adaptors and vice versa (Experiment 1). The effects were not observed for visual image adaptors (Experiment 2). The effects were somewhat larger when the adaptors and the target were presented to the same than to different ears, but significant adaptation was observed in both conditions, suggesting contributions of central mechanisms, following binaural integration (Experiment 3). The effect accumulated when the same type of adaptor was presented consecutively and persisted following the end of the adaptors (Experiment 4). The discovery of voice-nonvoice contrastive pairs opens the possibility of studying perceptual or neuronal voice selectivity while keeping acoustic features constant. (PsycInfo Database Record (c) 2024 APA, all rights reserved).

Implementation of a low-cost current perturbation-based improved PO MPPT approach using Arduino board for photovoltaic systems

In photovoltaic (PV) systems, the conversion of solar energy into electrical energy by the PV module is influenced by various factors, including sunlight intensity and temperature. To achieve optimal performance, it is crucial to accurately track the maximum power point (MPP) of the PV module. Among the numerous MPP tracking (MPPT) techniques that have been developed, the perturbation and observation (PO) method has gained significant attention due to its simplicity and reliability. However, the fixed perturbation step size used in the traditional PO algorithm can result in poor tracking capability, excessive ripple, and drift, leading to high power loss and low tracking efficiency. To address these limitations, this paper proposes an improved version of the PO strategy that introduces an adaptable step-magnitude mechanism, utilizing current perturbation instead of the voltage perturbation typically employed in the classical PO method. This enhanced indirect PO approach maintains low complexity and can be easily implemented on a cost-effective Arduino Uno board. A streamlined C++ code integrates the improved PO MPPT strategy with a Proportional Integral Derivative (PID) controller, eliminating the need for separate PID blocks and further reducing system complexity. To evaluate the effectiveness of the proposed technique, comparative analyses are conducted against the traditional PO algorithm, particle swarm optimization (PSO), fuzzy logic control (FLC), and a recently introduced approach, the zone voltage (ZV) method. Simulation results using Proteus software demonstrate that the improved PO approach outperforms the other techniques in various aspects, including achieving the highest static and dynamic tracking efficiencies of 99.38% and 99.88%, respectively, negligible power loss and fluctuations, the fastest convergence speed, and the shortest tracking time of 0.19 seconds.

Different peripheral nerve blocks for patients undergoing total knee arthroplasty: a network meta-analysis of randomized controlled trials.

To comprehensively compare the effect of different peripheral nerve blocks for patients undergoing total knee arthroplasty (TKA). PubMed, Embase, Cochrane Library, and Web of Science were comprehensively searched. The outcomes included postoperative pain, postoperative function, adverse events, oral morphine equivalent (OME), and perioperative indicators. Network plots, forest plots, league tables and rank probabilities were drawn for all outcomes. Totally 30 studies were included. For postoperative pain, continuous adductor canal block (cACB) + genicular nerve block (GNB) was most likely to be the most effective block regarding rest pain score at 24h; cACB + GNB was most likely to result in the lowest rest pain score at 48h; patients undergoing cACB + infiltration between the popliteal artery and the capsule of the knee (IPACK) + GNB was most likely to have the lowest motion pain score at 24h; patients undergoing cACB + GNB was most likely to have the lowest motion pain score at 48h. For postoperative function, patients undergoing cACB + IPACK + GNB had the highest likelihood to exhibit the shortest time in Timed Up and Go test (TUG); cACB + tibial nerve block (TNB) was most likely to be the most effective block in terms of range of motion (ROM); cACB + IPACK was most likely to be the optimal block concerning the ambulation distance. cACB combined with IPACK/GNB may be the most favorable block after TKA, continuous blocks may be better than single-shot blocks, and combined blocks may be better than separate blocks.

Longitudinal multimodal monitoring of transplanted islet β-cells

PurposeMonitoring β-cell mass and function would provide a better understanding of diabetes, setting the stage for truly individualized therapies. We applied a combined PET/MRI protocol to monitor engrafted islets mass and function without pre-labeling of isolated cells. A PET tracer binding to GLP-1R quantifies β-cell mass, while Mn-CA characterizes β-cell function. Both parameters were assessed in transplanted and native β-cells in vivo and validated with autoradiography and mass spectrometry imaging. MethodsIslets were collected and transplanted into the calves of C3H-mice. Accumulation of [64Cu]Ex4 and Mn-CA was examined with a PET/MRI at 1 h post-injection between 1 and 4 weeks after the transplantation. A separate blocking study with diazoxide targeted the functionality of the transplanted islets. As validation, ex vivo autoradiography and LA-ICP-MS imaging were performed after the last imaging session. ResultsPET/MRI monitored the engraftment of transplanted islets and visualized an increasing uptake of the PET tracer and Mn-CA. The Mn-CA accumulated at a higher islet-to-background ratio in the calf of mice than in the pancreas due to the high retention of Mn-CA in the exocrine pancreas. In vivo imaging data correlated well with autoradiography and LA-ICP-MS imaging, validating the in vivo approaches. ConclusionFor the quantification of β-cell function, Mn-based contrast mechanisms between native and transplanted islets differ and require further studies for optimal biological readout. However, non-invasive PET/MRI nonetheless provides the tools to investigate the relationship between β-cell mass and function in pancreatic islets.

Information accumulation on the item versus source test of source monitoring: Insights from diffusion modeling.

Source monitoring involves attributing previous experiences (e.g., studied words as items) to their origins (e.g., screen positions as sources). The present study aimed toward a better understanding of temporal aspects of item and source processing. Participants made source decisions for recognized items either in succession (i.e., the standard format) or in separate test blocks providing independent measures of item and source decision speed. Comparable speeds of item and source decision across the test formats would suggest a full separation between item and source processing, whereas different speeds would imply their (partial) temporal overlap. To test these alternatives, we used the drift rate parameter of the diffusion model (Ratcliff, Psychological Review, 85, 59-108, 1978). We examined whether the drift rates, together with the other parameters, assessed separately for the item and source decision varied as a function of the test format. Threshold separation and nondecision time differed between the test formats, but item and source decision speeds represented by drift rates did not change significantly. Thus, despite facilitation on the source decision when the item decision was immediately followed by a test for source memory than when item and source were tested in separate blocks, findings did not suggest that source information already begins accumulating in the item test in the standard format. We discuss the temporal sequence of item and source processing in light of different assumptions about the contribution of familiarity and recollection.

Central tendency and serial dependence in vestibular path integration.

Path integration, the process of updating one's position using successive self-motion signals, has previously been studied using visual distance reproduction tasks in which optic flow patterns provide information about traveled distance. These studies have reported that reproduced distances show two types of systematic biases: central tendency and serial dependence. In the present study, we investigated whether these biases are also present in vestibular path integration. Participants were seated on a linear motion platform and performed a distance reproduction task in total darkness. The platform first passively moved the participant a pre-defined stimulus distance which they then actively reproduced by steering the platform back the same distance. Stimulus distances were sampled from short- and long-distance probability distributions and presented in either a randomized order or in separate blocks to study the effect of presentation context. Similar to the effects observed in visual path integration, we found that reproduced distances showed an overall positive central tendency effect as well as a positive, attractive serial dependence effect. Furthermore, reproduction behavior was affected by presentation context. These results were mostly consistent with predictions of a Bayesian Kalman-filter model, originally proposed for visual path integration.

Influence of feedback transparency on motor imagery neurofeedback performance: the contribution of agency

Objective.Neurofeedback (NF) is a cognitive training procedure based on real-time feedback (FB) of a participant's brain activity that they must learn to self-regulate. A classical visual FB delivered in a NF task is a filling gauge reflecting a measure of brain activity. This abstract visual FB is not transparently linked-from the subject's perspective-to the task performed (e.g., motor imagery (MI)). This may decrease the sense of agency, that is, the participants' reported control over FB. Here, we assessed the influence of FB transparency on NF performance and the role of agency in this relationship.Approach.Participants performed a NF task using MI to regulate brain activity measured using electroencephalography. In separate blocks, participants experienced three different conditions designed to vary transparency: FB was presented as either (1) a swinging pendulum, (2) a clenching virtual hand, (3) a clenching virtual hand combined with a motor illusion induced by tendon vibration. We measured self-reported agency and user experience after each NF block.Main results. We found that FB transparency influences NF performance. Transparent visual FB provided by the virtual hand resulted in significantly better NF performance than the abstract FB of the pendulum. Surprisingly, adding a motor illusion to the virtual hand significantly decreased performance relative to the virtual hand alone. When introduced in incremental linear mixed effect models, self-reported agency was significantly associated with NF performance and it captured the variance related to the effect of FB transparency on NF performance.Significance. Our results highlight the relevance of transparent FB in relation to the sense of agency. This is likely an important consideration in designing FB to improve NF performance and learning outcomes.

DWTN: deep wavelet transform network for lightweight single image deraining

On rainy days the uncertainty of the shape and distribution of rain streaks can cause the images captured by RGB image-based measurement tools to be blurred and distorted. Thanks to the wavelet transform ability to provide spatial and frequency domain information about an image and its multidirectional and multiscale nature, it is widely used in traditional image enhancement methods. In image deraining the distribution of rain streaks is not only related to spatial domain features but is also closely related to frequency domain spatial features. However, deep learning-based rain removal models mainly rely on the spatial features of the image, and RGB data can hardly distinguish rain marks from image details, which leads to the loss of crucial image information during rain removal. We have developed a lightweight single-image rain removal model called the deep wavelet transform network (DWTN) to address this limitation. This method separates image details from rain images and can more effectively remove rain marks. The proposed DWTN has three significant contributions. First, DWTN uses the feature components after the wavelet transform as the input to the model and assigns a separate frequency-aware enhancement block (FAEB) to each element. These blocks focus on specific frequency features that benefit the rain removal task. Second, we introduce a frequency feature fusion block (FFFB) that fuses different wavelet components to reduce noise and enhance the image background through a channel attention mechanism while attenuating rain streaks. Finally, we design a spatial feature enhancement block (SFEB), which uses a spatial attention mechanism to calibrate the spatial position of features to improve the rain removal performance. We evaluate the performance of DWTN using PSNR and SSIM on four synthetic datasets and NIQE and BRISQUE on two real datasets. The results of the evaluation of the six datasets and at least four performance metrics show that the proposed DWTN is superior to existing methods.

Cortically Disparate Visual Features Evoke Content-Independent Load Signals during Storage in Working Memory.

It is well established that holding information in working memory (WM) elicits sustained stimulus-specific patterns of neural activity. Nevertheless, here we provide evidence for a distinct class of neural activity that tracks the number of individuated items in working memory, independent of the type of visual features stored. We present two EEG studies of young adults of both sexes that provide robust evidence for a signal tracking the number of individuated representations in working memory, regardless of the specific feature values stored. In Study 1, subjects maintained either colors or orientations across separate blocks in a single session. We found near-perfect generalization of the load signal between these two conditions, despite being able to simultaneously decode which feature had been voluntarily stored. In Study 2, participants attended to two features with very distinct cortical representations: color and motion coherence. We again found evidence for a neural load signal that robustly generalized across these distinct visual features, even though cortically disparate regions process color and motion coherence. Moreover, representational similarity analysis provided converging evidence for a content-independent load signal, while simultaneously showing that unique variance in EEG activity tracked the specific features that were stored. We posit that this load signal reflects a content-independent "pointer" operation that binds objects to the current context while parallel but distinct neural signals represent the features that are stored for each item in memory.

Global and local feature extraction based on convolutional neural network residual learning for MR image denoising.

Given the different noise distribution information of global and local magnetic resonance (MR) images, this study aims to extend the current work on convolutional neural networks that preserve global structure and local details in MR image denoising tasks. This study proposed a parallel and serial network for denoising 3D MR images, called 3D-PSNet. We use the residual depthwise separable convolution block to learn the local information of the feature map, reduce the network parameters, and thus improve the training speed and parameter efficiency. In addition, we consider the feature extraction of the global image and utilize residual dilated convolution to process the feature map to expand the receptive field of the network and avoid the loss of global information. Finally, we combine both of them to form a parallel network. What's more, we integrate reinforced residual convolution blocks with dense connections to form serial network branches, which can remove redundant information and refine features to further obtain accurate noise information. The peak signal-to-noise ratio, structural similarity index measure, and root mean square error metrics of 3D-PSNet are as high as 47.79%, 99.81%, and 0.40%, respectively, achieving competitive denoising effect on three public datasets. The ablation experiments demonstrated the effectiveness of all the designed modules regarding all the evaluated metrics in both datasets. The proposed 3D-PSNet takes advantage of multi-scale receptive fields, local feature extraction and residual dense connections to more effectively restore the global structure and local fine features in MR images, and is expected to help doctors quickly and accurately diagnose patients' conditions.

EfficientUNetViT: Efficient Breast Tumor Segmentation Utilizing UNet Architecture and Pretrained Vision Transformer.

This study introduces a sophisticated neural network structure for segmenting breast tumors. It achieves this by combining a pretrained Vision Transformer (ViT) model with a UNet framework. The UNet architecture, commonly employed for biomedical image segmentation, is further enhanced with depthwise separable convolutional blocks to decrease computational complexity and parameter count, resulting in better efficiency and less overfitting. The ViT, renowned for its robust feature extraction capabilities utilizing self-attention processes, efficiently captures the overall context within images, surpassing the performance of conventional convolutional networks. By using a pretrained ViT as the encoder in our UNet model, we take advantage of its extensive feature representations acquired from extensive datasets, resulting in a major enhancement in the model's ability to generalize and train efficiently. The suggested model has exceptional performance in segmenting breast cancers from medical images, highlighting the advantages of integrating transformer-based encoders with efficient UNet topologies. This hybrid methodology emphasizes the capabilities of transformers in the field of medical image processing and establishes a new standard for accuracy and efficiency in activities related to tumor segmentation.

Functional interactions underlying visuospatial orthographic processes in Chinese reading.

As a logographic writing system, Chinese reading involves the processing of visuospatial orthographic (ORT) properties. However, this aspect has received relatively less attention in neuroimaging research, which has tended to emphasize phonological (PHO) and semantic (SEM) aspects in processing Chinese characters. Here, we compared the functional correlates supporting all these three processes in a functional MRI single-character reading study, in which 35 native Chinese adults were asked to make ORT, PHO, and SEM judgments in separate task-specific activation blocks. Our findings revealed increased involvement of the right hemisphere in processing Chinese visuospatial orthography, particularly evident in the right ventral occipito-temporal cortex (vOTC). Additionally, time course analysis revealed that the left superior parietal gyrus (SPG) was initially involved in SEM processing but contributed to the visuospatial processing of words in a later time window. Finally, ORT processing demonstrated stronger recruitment of left vOTC-SPG-middle frontal gyrus (MFG) functional connectivity compared to SEM processing. This functional coupling correlated with reduced regional engagement of the left vOTC and MFG, highlighting that visuospatial ORT processes in reading Chinese rely on functional interactions among key regions rather than local regional processes. In conclusion, these findings underscore visuospatial ORT processes as a distinctive feature of reading logographic characters.

Effect of hearing aids on the externalization of everyday sounds.

This study examined the influence of stimulus properties on sound externalization when listening with hearing aids. Normally hearing listeners were presented with broadband "tokens" (environmental sounds and speech) from loudspeakers, and rated externalization using a continuous scale. In separate blocks, they listened unaided or while wearing behind-the-ear hearing aids with closed domes and low gain (linear or compressive). There was a significant influence of token on ratings, even for unaided listening, and the effect of hearing aids depended on token. An acoustic analysis indicated that hearing aids were more likely to disrupt externalization for peakier sounds with a low-frequency emphasis.

Color and brightness at work: Shedding some light on mind wandering.

Occupational hazards are partly caused by the physical factors of the work environment, among which are ambient color and brightness, which can interfere with cognitive performance. Especially in modern work environments, performance relies heavily on cognitive functions such as attention, and an important factor in disrupting sustained attention is mind wandering (MW). This study aimed to investigate the effects of white and blue colors with two brightness levels on sustained attention and brain electrophysiology. A total of 20 participants were exposed to 4 different conditions (white and blue as color and 300 and 800lx as the brightness level) in separate blocks in a virtual reality environment in which a continuous performance test (CPT) was performed. The high brightness blue condition induced significant changes in sustained attention. MW network analysis showed a significant decrease in delta frequency band in the blue color condition with high brightness and beta decrease in the blue color condition with low brightness, whereas the activity of MW network increased when exposed to the white color condition. High-brightness blue light resulted in better sustained attention and decreased activity of MW-related neural regions. It is thus recommended that these results be taken into consideration in the interior design of educational settings and cars among other environments that require a high level and maintenance of cognitive functions, especially sustained attention.

Modifications of some physical properties of nanostructured indium doped Co3O4 thin films

Using the chemical spray pyrolysis (CSP) technique, nanostructured undoped and Co3O4:In thin films are deposited. The effect of indium doping content in Cobalt ranged from 1% to 3% on optical, structural, and topographical properties of Co3O4 nanostructured thin films. No new peaks belonging to the In phase were seen, according to X-ray diffraction research, which revealed that pure and Co3O4: In thin films are polycrystalline in and cubic phase with (111), (311), (400), and (511) preferable orientation for all filmsThe Scherrer formula computation of average crystallite size shows that the size of Nano crystallites grows when doping is enhanced. AFM micrographs demonstrated how the surface shape of the films was discovered to be influenced by the inclusion of indium in the Co3O4 location.SEM images of Undoped Co3O4 and Co3O4:In films (CSP technique), showing separate semi-spherical blocks (120-200 nm) of nanoparticles (<30 nm). Band gap values for pure and doped were 2.52 to 2.38 eV. Resistance increases with increases Indium-doping, indicating more charge carriers and potential surface roughness influence. Sensitivity decreases with higher Indium concentrations, attributing to enhanced crystallinity and nano-crystalline size.

Modifications of some physical properties of nanostructured indium doped Co3O4 thin films

Using the chemical spray pyrolysis (CSP) technique, nanostructured undoped and Co3O4:In thin films are deposited. The effect of indium doping content in Cobalt ranged from 1% to 3% on optical, structural, and topographical properties of Co3O4 nanostructured thin films. No new peaks belonging to the In phase were seen, according to X-ray diffraction research, which revealed that pure and Co3O4: In thin films are polycrystalline in and cubic phase with (111), (311), (400), and (511) preferable orientation for all filmsThe Scherrer formula computation of average crystallite size shows that the size of Nano crystallites grows when doping is enhanced. AFM micrographs demonstrated how the surface shape of the films was discovered to be influenced by the inclusion of indium in the Co3O4 location.SEM images of Undoped Co3O4 and Co3O4:In films (CSP technique), showing separate semi-spherical blocks (120-200 nm) of nanoparticles (<30 nm). Band gap values for pure and doped were 2.52 to 2.38 eV. Resistance increases with increases Indium-doping, indicating more charge carriers and potential surface roughness influence. Sensitivity decreases with higher Indium concentrations, attributing to enhanced crystallinity and nano-crystalline size.

Determining the mechanism for generating cavitation pressure fluctuations in throttle devices at high-head throttling of liquid

The object of this study is the process of generating cavitation pressure fluctuations behind the throttle device at high-head throttling of liquid. This paper addressed the problem of calculating the amplitude of cavitation pressure fluctuations at high-pressure liquid throttling. It was established that cavitation pressure fluctuations are a consequence of collisions of discrete masses of a transiting liquid jet in the region of pressure recovery. The range of cavitation pressure fluctuations reaches the pressure values at the inlet to the throttle device. The frequency band of cavitation pressure fluctuations is in the range from 1.5 to 20 kHz and higher. At high-head throttling of the liquid, caverns attached to the surface of the throttle channel, moving caverns and small bubbles in the transit flow are formed. Moving caverns compress the transit flow and divide it into separate fluid blocks. In the region of pressure restoration, the moving caverns are slammed shut and discrete fluid blocks collide. This causes high-frequency pressure fluctuations. Special feature of the results is the possibility of estimating the range of cavitation pressure fluctuations depending on the pressure drop on the throttle device. When the back pressure on the throttle device increases, the amplitude of cavitation pressure fluctuations decreases, and the frequency band shifts to the high-frequency region. The results make it possible to calculate the range of cavitation oscillations, to predict the development of cavitation erosion of materials depending on the parameters of throttling of the working fluid. The results of the work are used to design devices for cleaning products from contamination, for determining the volume content of water in aviation fuel, for intensification of technological processes in the chemical and food industries.

Detrital zircon U-Pb-Hf isotopes of late Meso-Neoproterozoic metasedimentary rocks in the South Altyn Tagh: Implications for tectonic affinity of microcontinents in NW China

The Neoproterozoic tectonic correlation between the Central-South Altyn, Qilian, Qaidam, and East Kunlun blocks in northwestern China remains controversial, with competing models favoring separate blocks or a unified single block, and debatable paleo-positions in the Rodinia supercontinent. In this study, we present a systematic provenance study on the late Mesoproterozoic to Neoproterozoic metasedimentary rocks from the South Altyn Tagh. A mica quartz schist sample from the Bashikuergan group yielded a maximum depositional age of 1050 ± 31 Ma. Four paragneiss samples from the Altyn Complex yielded maximum depositional ages of 1106 Ma, 1065 Ma, 1054 Ma, and 870 Ma. Given that the Altyn Complex was intruded by numerous early Neoproterozoic granitoids (ca. 976–900 Ma), we propose that the sedimentary protoliths of the Altyn Complex and the Bashikuergan Group were deposited at two stages, i.e., ca. 1105–975 Ma and after 870 Ma. Provenance tracing indicates that these 1105–975 Ma sediments probably received detritus from the late Mesoproterozoic rocks of Western Australia, East Antarctica, and Central Indian Tectonic Zone in India. In contrast, the detritus of the paragneiss (deposited after 870 Ma) was likely sourced from local regions in the Altyn Tagh orogen. Combined with the comparable magmatic, sedimentary, and tectonic records, we propose that a few microcontinental fragments in northwestern China, including Central-South Altyn Tagh, Qilian, Qaidam, and East Kunlun blocks, constituted a unified block in the early Neoproterozoic and occupied a periphery position of the Rodinia supercontinent with a close paleogeographic affinity to South China and Northwest India.