Peak Age Research Articles

Epidemiological analysis of the patients with psoriasis in Asian countries and region using the same clinical case cards between 2020 and 2022.

Although many epidemiological surveys for patients with psoriasis have been reported based on individual countries or facilities, there has been no study encompassing the major countries or the region in Asia. The Asian Society for Psoriasis (ASP) has been conducting an epidemiological study across various Asian countries and regions to elucidate the and compare the epidemiology of psoriasis. A total of 1948 cases were analyzed, with 938 cases from Japan, 530 cases from China, 325 cases from Korea, 141 cases from Chinese Taipei, and 14 cases from Thailand, all of which were enrolled between 2020 and 2022. In the Asian region total, the male-female ratio was 1.87:1 and the peak age at disease onset was 20-29 years. The proportion of psoriasis vulgaris (PsV), psoriatic arthritis (PsA), and pustular psoriasis (PP) was 80.1%, 17.7%, and 2.2%, respectively, and PsA was more commonly associated with nail symptoms than psoriasis vulgaris (PsV). Of the patients, 13% had a familial history of psoriasis and the most frequently affected family member was the father. Regarding treatment, 78.3% of the patients received topical medications, 9.0% underwent phototherapy, 34.0% received oral medications, and 36.1% were treated with biological agents. This study provided valuable information on the epidemiology and treatment of psoriasis using the registry data collected with the common reporting form in the same period in major Asian countries and regions. Male predominance is a distinctive feature of psoriasis in Asia. This epidemiological data registry in the ASP will continue afterwards.

Tailoring precipitate distribution in 2024 aluminum alloy for improving strength and corrosion resistance

For the traditional peak-aged (PA) AA2024 alloy, the formation of large S-phase precipitates within the grains, wide precipitate-free zones (PFZs) near the grain boundaries (GBs), and continuous distribution of grain boundary precipitates (GBPs) can be observed. As a result, the PA alloy exhibits relatively high strength but poor corrosion resistance. However, with the application of cyclic plasticity treatment, high-density 1–2 nm clusters form within the matrix, and no PFZs form near GBs. In this study, this treatment yields the optimal balance between strength–elongation characteristics and corrosion resistance. By combining cyclic plasticity and ageing heat treatment with different heating rates, the nanoscale clusters play a crucial role as heterogeneous nucleation sites, resulting in the formation of finer and higher number density of S precipitates within the matrix. Additionally, the presence of these clusters reduces the formation of GBPs and minimizes the width of PFZs. Consequently, compared to the traditional PA sample, this approach achieves a significantly higher yield strength (increased by 46 %) and ultimate tensile strength (increased by 18 %), along with superior corrosion resistance. Although the influence of ageing heat treatment with different rates on mechanical properties is not significant, it notably affects the formation of GBPs and corrosion resistance. Specifically, a slower heating rate leads to an increase in the spacing between adjacent GBPs, resulting in improved corrosion resistance. In summary, cyclic strengthening, as a novel method for alloy strengthening, when combined with ageing heat treatment, modulates the distribution of S precipitates within the matrix and GBs. This optimization maximizes the effects of precipitation strengthening and breaks the inverse relationship between strength and corrosion resistance.

U–Pb detrital zircon ages from late Eocene to early Oligocene Pinghu formation of the East China Sea Shelf Basin: Inferences on synergistic effects between East Asia offshore sedimentation and major rivers supply

Our understanding of the late Eocene to early Oligocene provenance evolution of the East China Sea Shelf Basin has been limited, which hampers our study of the synergistic effects between East Asia offshore sedimentation and major rivers. To address this, we compared newly acquired detrital zircon chronological data from the East China Sea with published detrital U–Pb ages of major rivers in East Asia. Through this analysis, we have been able to reconstruct the provenance changes of sediments in the East China Sea during this crucial period. We have identified two large-scale and three small-scale denudation surfaces that developed in the Pinghu and lower Huagang Formations. These surfaces indicate that sediments were also derived from underlying strata and bedrock, particularly in the lower Pinghu and lower Huagang Formations. The newly acquired detrital zircon U–Pb age range was found to be roughly similar, ranging from 36.2 ± 0.7 to 2954.0 ± 30.3 Ma. The age peaks of the lower Pinghu Formation were more consistent, while the middle, upper Pinghu Formation, and lower Huagang Formation exhibited multiple age peaks. Comparing the compiled zircon U–Pb age peaks of the Chuanjiang segment of the upper Yangtze River with those of the East China Sea Shelf Basin, we found relative similarity. Additionally, the younger zircon grains with ages <500 Ma in the east Cathaysia catchment showed similarities with the East China Sea Shelf Basin. In terms of provenance contribution, the sediments of the lower Pinghu Formation were predominantly provided by the adjacent uplifts in the east Cathaysia catchment, with the Chuanjiang segment also playing a significant role. From the middle Pinghu Formation onwards, the provenance from the Chuanjiang segment became dominant, accounting for over 90 % of the sediments. However, this influence was limited to the northern part of the study area. This suggests a substantial increase in the Yangtze River catchment during this period, potentially related to the complete connection of the modern Yangtze River.

Trends of hospitalisation among new admission inpatients with oesophagogastric variceal bleeding in cirrhosis from 2014 to 2019 in the Affiliated Hospital of Southwest Medical University: a single-centre time-series analysis

ObjectivesThis study aimed to assess the internal law and time trend of hospitalisation for oesophagogastric variceal bleeding (EGVB) in cirrhosis and develop an effective model to predict the trend of...

Survival rate of cervical cancer: a five year review at a Major Teaching Hospital in Ghana, West Africa.

Cervical cancer (CC) is one of the leading causes of cancer-related deaths among females in Ghana. Despite the magnitude of the public health challenge posed by CC in Ghana, survival data as well as reported incidence and mortality rates are primarily based on studies conducted in the capital city of the country. Even though age at diagnosis is known to affect the overall survival of CC patients, the role of this factor in the prognosis of CC patients in Ghana has not been sufficiently explored. The aim of this study was to determine the 5-year survival rate of Ghanaian woman treated for CC at a large tertiary healthcare facility in Ghana. This research was a single-institution-based quantitative retrospective cohort study conducted among patients with histopathologically confirmed CC. Clinical and socio-demographic data were retrieved from patients' medical records. Data analysis was done using the Statistical Package for the Social Sciences software version 23. Kaplan Meier curves were used to present the survival rates and median survival time. The peak age at diagnosis was between 45 and 80 years with the modal age group of patients between 75 and 80 years. The mean age at diagnosis was 63.3 ± 15.7 years ranging from 27 to 104 years. The overall survival rates at 1, 3 and 5 years were 76.5%, 51.5% and 32.4%, respectively. The median survival time was 65.8 months. Age < 50 years was associated with higher survival estimates than age >50 years. The 5-year overall survival rate of CC patients reported in this study (32.4%) is relatively low compared with countries in the developed world but like previous reports at other healthcare facilities in Ghana as well as in other underdeveloped countries.

Effect of heat treatment on microstructural characteristics and mechanical properties of hypereutectic B390 aluminium alloys modified by phosphorus and bismuth

This study investigated the effects of solution treatment and aging processes on microstructural characteristics and mechanical properties of hypereutectic B390 Al-Si Alloy modified by phosphorus (P) and bismuth (Bi). The morphology evolution of primary Si, eutectic Si, intermetallic compounds, and secondary dendrite arm spacing (SDAS) of both initial and modified alloys were investigated in as-cast and heat-treated conditions. It was found that the combination of 0.1 wt%P and 0.5 wt%Bi in B390 alloy resulted in a remarkable modification and refinement of primary Si, eutectic Si, and SDAS compared to initial specimens in the as-cast condition. After heat treating, the fine lamellar eutectic Si and intermetallic compounds underwent a higher degree of fragmentation and coarsening, appearing as small round particles, leading to a more pronounced formation of a supersaturated solid solution. Additionally, the peak aging time of the B390-P-Bi alloy was only 7 h, 2 h less than the initial specimen. After T6 treatment and addition of both 0.1 wt%P and 0.5 wt%Bi, the B390-P-Bi alloy exhibited a smaller rounded Mg3Bi2 phase at peak aging with a 62.07% size reduction compared to the B390-Bi alloy. The results show that adding P with Bi enhanced hardness, ultimate tensile strength (UTS) and elongation because of refinement of the SDAS, primary Si and eutectic Si. These refinements played a crucial role in increasing tensile strength by more effective strengthening through precipitation and grain size reduction. The B390-P-Bi alloy is a promising choice for applications requiring a balance between strength and ductility.

Microstructures and cryogenic mechanical properties of spray deposited 2195 Al–Cu–Li alloy with different heat treatments

In this study, 2195 Al–Cu–Li alloys with a remarkable layered structure were fabricated through spray deposition, hot extrusion, and three distinct heat treatment processes (namely, solid solution treatment (ST), artificial peak-aging (PA), and artificial over-aging (OA)). The samples subjected to varying heat treatments are revealed to exhibit an exceptional combination of strength and ductility at 77 K, in contrast to their counterparts at 298 K. Specially, the mechanical properties of the PA samples are enhanced to various degrees with decreasing temperature from 298 K to 77 K. It is found that the synergistic effects of dense dislocations and uniform T1 precipitates, as well as their extensive interactions, are responsible for the exceptional strain hardening capacity at cryogenic temperature. Particularly, multiple slip systems and the temperature-dependent relative slip distance are beneficial for the formation of dense dislocations and thus for enhancing ductility at 77 K. Furthermore, the observation of rare and small microcracks, along with intergranular delamination at 77 K, suggests that layered structures impede the plastic instability of the alloy and improve its ductility. These findings provide valuable insights into the deformation behaviors of high-strength aluminum alloys for cryogenic applications.

Polyphase Exhumation of the East Kunlun Orogenic Belt: Evidence from Modern River Detrital Zircon and Apatite Fission Track Dating

Abstract The East Kunlun Orogenic Belt (E-KOB) stands out as one of the most prominent basin-mountain geomorphic features in the northern interior of the Tibetan Plateau. It records a series of accretion-collision events from the Mesozoic to the Cenozoic. In particular, with the uplifting of the Tibetan Plateau, the E-KOB experienced intracontinental deformation and exhumation in the Cenozoic. Clarifying the exhumation history of the E-KOB is crucial to define the growth time and mechanism of the Tibetan Plateau. In this study, we apply detrital zircon fission-track (ZFT) and apatite fission-track (AFT) analyses on modern river sands in order to constrain the regional exhumation history of the eastern E-KOB. Four peak ages have been identified and interpreted as results of rapid exhumation correlated with intracontinental deformation. Two older peak ages at 144.7–141.0 and 114.6–82.1 Ma are in good accordance with the collision time of the north-south Lhasa-Qiangtang Block along the Bangong-Nujiang suture zone and the subsequent progressive deformation stage toward the north. Peak age at 60.9–45.3 Ma is coeval with the initial timing of the India-Asia collision. The youngest peak age at 25.1–18.3 Ma matches well with the extensive outward and upward growth of the Tibetan Plateau during the Oligocene to Miocene time. The Cretaceous and early Cenozoic rapid exhumations suggest that the E-KOB has been involved in the intracontinental deformation induced by collisions of the Lhasa-Qiangtang and India-Asia from the south. It implies that the northern Tibetan Plateau likely has been elevated or was a structural high before the Eocene. In addition, some of our detrital samples show a younger ZFT peak age than the AFT peak age. We attributed this data bias to the contribution of hydrodynamic sorting and/or lithological difference. The combination of ZFT and AFT dating has advantages in eliminating interfering age signals in detrital thermochronology.

Risk of gastric adenoma and adenocarcinoma in patients with familial adenomatous polyposis in Japan: a nationwide multicenter study

BackgroundPatients with familial adenomatous polyposis (FAP) have an increased risk of developing gastric neoplasms. However, the clinical course of FAP with these gastric lesions has not yet been fully clarified. The present study aimed to clarify the changes in the incidence risk of developing gastric adenoma or gastric cancer during the lifespan of patients with FAP.MethodsFour hundred forty-three patients with data regarding gastric adenoma and gastric cancer retrospectively registered in a nationwide Japanese multicenter study were enrolled. The cumulative incidences and hazard rates (HRs) of gastric neoplasms were evaluated.ResultsThe cumulative incidence rates in 50-year-old patients with FAP were 22.8% for gastric adenoma and 7.6% for gastric cancer, respectively. No significant association was found between gastric neoplasms and the colonic phenotype. The peak age for the HR of gastric adenoma was 65 years, with the highest HR (0.043). Regarding the incidence of gastric cancer, the HR increased moderately up to the age of 40 years, but the increase accelerated from the age of 50 years (HR = 0.0067).ConclusionCareful surveillance of the upper gastrointestinal tract in elderly patients with FAP, such as shortening the interval of follow-up according to age, may be helpful for early diagnosis of gastric cancer.

Epidemiologic investigation of pediatric distal humerus fractures: An American insurance claims database study.

Distal humerus elbow fractures are one of the most common traumatic fractures seen in pediatric patients and present as three main types: Supracondylar (SC), lateral condyle (LC), and medial epicondyle (ME) fractures. To evaluate the epidemiology of pediatric distal humerus fractures (SC, LC, and ME) from an American insurance claims database. A retrospective review was performed on patients 17 years and younger with the ICD 9 and 10 codes for SC, LC and ME fractures based on the IBM Truven MarketScan® Commercial and IBM Truven MarketScan Medicare Supplemental databases. Patients from 2015 to 2020 were queried for treatments, patient age, sex, length of hospitalization, and comorbidities. A total of 1133 SC, 154 LC, and 124 ME fractures were identified. SC fractures had the highest percentage of operation at 83%, followed by LC (78%) and ME fractures (41%). Male patients were, on average, older than female patients for both SC and ME fractures. In the insurance claims databases used, SC fractures were the most reported, followed by LC fractures, and finally ME fractures. Age was identified to be a factor for how a pediatric distal humerus fractures, with patients with SC and LC fractures being younger than those with ME fractures. The peak age per injury per sex was similar to reported historic central tendencies, despite reported trends for younger physiologic development.

Benign Phyllodes Tumor with Extensive Cystic Squamous Metaplasia, Clinically Presenting as Malignant Phyllodes

Abstract Phyllodes tumor are very rare fibroepithelial lesions which comprises 0.3%–1% of all primary breast tumors with peak age around 40–50 years. Phyllodes tumor are classified ino three types: Benign, borderline and malignant tumors. Metaplastic change is very rare in these tumors and can involve both epithelial or stromal components. Stromal metaplastic changes include cartilage, bony or fatty change. Epithelial metaplastic changes include apocrine or squamous change. About 10% of phyllodes tumor show squamous metaplasia. We report a case of 47-year-old patient presenting with large lump in right breast measuring 16 cm × 15 cm × 11 cm, occupying all four quadrants. Clinically, it appeared as malignant phyllodes. But, microscopically, it was benign phyllodes tumor having extensive cystic squamous metaplasia.

Disease Trends in Children and Adolescents in Japan: A Retrospective Observational Study Using the Nationwide Claims Data for 2012-2016.

This study aimed to clarify diseases that occur more frequently by age and identify the peaks and trends of each disease from infancy to adolescence for early detection and treatment. This retrospective observational study was conducted using Japan's National Database of Health Insurance Claims Specific Health Checkups from January 2012 to December 2016. Using peak ages and trends in the number of patients, we grouped diseases by the International Classification of Diseases chapters. Although diseases that peaked during infancy were the most common (10 disease chapters), other diseases peaked at school-going age and adolescence. Diseases in four chapters peaked during adolescence and continued to increase toward the age of 18. These four chapters included mental, behavioral, and neurodevelopmental disorders; diseases of the nervous system; the genitourinary system; and pregnancy, childbirth, and the puerperium. Childhood-onset diseases can affect long-term health and healthcare needs, and timely screening and guidance based on disease trends can provide an effective intervention. To establish a child healthcare system that provides preventive support for children and adolescents' physical, psychological, and social health, further research is needed to comprehensively understand the issues per age and developmental stage.

Laser powder bed fusion of crack-free 6061Al alloy using nano-sized TiO2 modified powders

Growth of coarse columnar grains during solidification easily leads to hot cracking during laser powder bed fusion (LPBF) of Al alloys. This work offers an alternative route to inhibit the formation of coarse columnar grains during LPBF process. The crack-free 6061Al alloy with a refined microstructure was obtained using nano-sized TiO2 modified feedstock powders. After HIPPing, a nearly defect-free sample was obtained with a fracture elongation of 19.5 ± 0.14%. After artificially peak ageing treatment, the TiO2 modified 6061Al alloy fabricated by LPBF exhibits a tensile strength of 336.1 ± 3.5 MPa and the fracture elongation is still 8.1 ± 0.92%. It is believed that the approaches used in this work are also effective for other LPBF fabrication of low-printability Al alloys.

Heavy mineral indicators of ridge subduction beneath the Bainaimiao arc in the southeastern Central Asian Orogenic Belt

As one of the major subduction-accretionary systems in the southeastern Central Asian Orogenic Belt, the Bainaimiao arc presents a valuable opportunity for investigating the subduction–accretion process of accretionary orogens. It is located adjacent to the northern margin of the North China Craton and developed arc-related deposits during the Silurian–Devonian period. In this paper, we employed heavy mineral geochemistry and U–Pb ages of zircon and rutile, to determine the provenance of the Silurian–Devonian deposits and reconstruct the paleogeography of the source area. The stratigraphic units involved include the Xuniwusu Formation of Early Silurian and the Xibiehe Formation of Early Devonian.Both the Xuniwusu and Xibiehe formations exhibit heavy mineral assemblages dominated by zircons and tourmalines. Nevertheless, the Xibiehe Formation contains Cr-spinels and garnets which are absent in the Xuniwusu Formation. Geochemical analyses of the detrital Cr-spinels exhibit characteristics of a supra-subduction zone ophiolite. The garnets originated from middle- to high-grade metamorphic rocks, as well as mafic and felsic rocks. The tourmalines in both formations primarily indicate a metasedimentary rock source, with a small percentage of Li-poor granitoid species in the Xuniwusu Formation. The U–Pb age spectra of both detrital zircon and rutile in the Xuniwusu Formation show multiple peaks. The age spectra consist of Precambrian ages, indicative of a recycled origin, as well as Paleozoic ages, suggesting a magmatic origin. In contrast, the U–Pb age spectra of zircon and rutile in the Xibiehe Formation display a unimodal age peak at ca. 455 and 490 Ma, respectively. These differences suggest a provenance shift from the Xuniwusu to Xibiehe formations. The Xuniwusu Formation was sourced from the Bainaimiao arc itself, whereas the Xibiehe Formation has a mixed origin of the Bainaimiao arc and Ondor Sum accretionary complex. The provenance change correlates with the unconformity between the two formations, suggesting a forearc uplift event. In combination with the previous research on the Tulinkai ophiolite, it can be inferred that the forearc uplift was triggered by ridge subduction of the Paleo-Asian Ocean plate at ca. 450–430 Ma. This research provided a new perspective on the ridge subduction of the oceanic slab in fossil orogens.

Structural patterns and ages of Permian-Triassic multistage strike-slip faulting in the Chifeng area, southeastern Inner Mongolia, China: Implications for the final closure of the Paleo-Asian Ocean

The closure of the Paleo-Asian Ocean (PAO) to the north of the North China Craton (NCC) holds significance in comprehending the Phanerozoic continental evolution of East Asia. However, the timing of the final closure of the PAO, tectono-magmatic records of this process in the northern margin of the NCC, and related geodynamics remain to be resolved. Here we undertaken detailed macro- and micro-structural investigations on the E-W-striking and NNE-striking fault system in the Chifeng area, northern edge of the NCC. Combined with new zircon U-Pb and muscovite 40Ar/39Ar dating, we delineated three phases of strike-slip faulting in the research region during the Permian-Triassic, including WNW-ESE-striking and NE-SW-striking ductile sinistral shearing at ∼ 270–258 Ma and 258–246 Ma, respectively, and subsequent ∼ E-W-oriented ductile–brittle dextral shearing at ∼ 230–209 Ma. Based on analysis of paleotectonic stress fields, we propose that the first two-stage deformation shared a regional unified N-NNE contractional setting, while the late ∼ E-W-striking dextral shearing reflected a distinct regional NNW-SSE shortening event. The regional magmatism reveals three age peaks of ∼ 270 Ma, ∼250 Ma and ∼ 230 Ma, corresponding well to the above three-phase deformation. Further, zircon Hf isotopic data imply that the composition of juvenile material in regional deep-seated crust gradually increased from Permian to Triassic. The N-NNE contraction may be controlled by the eastward scissor-like final closure of the PAO during the Middle Permian-Early Triassic. The middle-late Late Triassic NNW-SSE contraction is likely influenced by the remote effect of the low-angle southward subduction of the Mongol-Okhotsk oceanic plate.

Effect of heat treatment on microstructure and mechanical property of roll-bonded 1060/7N01/1060 laminates

1060/7N01/1060 laminated composites with reliable bonding interfaces were successfully fabricated via single-pass hot rolling at 475 °C. The effects of layer thickness ratios on microstructure and mechanical property of synthesized laminates were studied using scanning electron microscope, transmission electron microscope and electron backscattered diffraction technique accompanied with hardness and tensile testing. Moreover, microstructure and mechanical property of DCR (direct cold rolling) and ACR (solution annealing and peak ageing plus cold rolling) samples were also explored. The results show that layer thickness ratios have little effect on microstructure of each layer in hot-rolled sheets, and their mechanical properties are consistent with theoretical predictions based on the rule of mixture. In comparison, extra heat treatment has no obvious effect on grain size of pure aluminium layers. However, smaller strip-like grains along with dispersed, finer precipitates are formed in 7N01 layer of ACR samples, leading to stronger grain refinement strengthening, precipitation strengthening and dislocation strengthening.

Sedimentological Evidence for Pre‐Early Permian Continental Subduction in the Dabie Orogen, Central‐East China

AbstractHow to constrain the onset of continental subduction and prograde metamorphism in an orogen remains a fundamental question. The widespread Triassic ultrahigh‐pressure (UHP) metamorphic rocks in the Dabie orogen in central‐east China are generally attributed to continental subduction. The earliest Triassic peripheral basins (the Huangshi, Yueshan and Nanjing basins) around the Dabie orogen represent an ideal archive to reconstruct the early evolution of the orogen. Here we present a multidisciplinary provenance study on these Triassic strata, including framework petrography and heavy mineral analyses combined with U‐Pb age and trace‐element analyses of detrital zircon, rutile and apatite. The abundant metapelitic lithics and muscovite grains, a heavy mineral population dominated by metamorphic apatite, and a significant Permian (270–290 Ma) age peak from U‐Pb age spectra of detrital zircon, rutile and apatite imply an Early Permian medium‐high grade metamorphic source in the uppermost structural levels of the Dabie orogen. Our provenance data indicate that the onset of northward continental subduction of the South China Block commenced no later than the Early Permian (c. 290 Ma). This event is clearly earlier and distinct from the more widespread Triassic UHP metamorphism of the Dabie orogen, suggesting that continental subduction and mountain‐basin interaction were protracted processes (&gt;55 Myr, c. 290–235 Ma). When combined with other geological evidence, our results show that the prolonged continental subduction is not always preceded by subduction of oceanic crust.

Pattern of Childhood malignant tumours in Umuahia South East Nigeria

Introduction: Cancers in children should be incorporated as one of the childhood killer diseases in developing countries.&#x0D; Aim: The aim of this study is to evaluate the demographic and pathologic characteristics of childhood tumours in Umuahia. South East Nigeria&#x0D; Methodology: The Operative records, histology request and report forms were studied and the clinico-pathologic information were retrieved and analysed using SPSS version 20.0&#x0D; Results: A total of 50 cases of malignant diseases of children were clinically diagnosed and histologically confirmed. The mean age of the patients were 8 years with age range of 1 to 17 years. The male to female ratio was 1:1. The peak age of incidence falls in the 1-5 age groups which accounted for 40%. Wilm’s tumour was the commonest 25, Rhabdomyosarcoma 10 cases, Neuroblastoma 5cases, Oesteosarcoma 5cases, Teratomas 5 cases.&#x0D; Conclusion: childhood cancer is increasing in our environment. However, late presentation, ignorance, poverty leads to poor outcome.

Mesozoic evolution of large-scale drainage systems in the Indochina Block: evidence from palaeomagnetic and U–Pb geochronological constraints

The collage of the Indochina Block to the Eurasian continent during the Mesozoic resulted in major changes in source-to-sink systems of East Asia, whilst the sedimentation in the Khorat–Simao Basin of the Indochina Block transited from marine to continental environments. Previous studies uncovered the existence of transcontinental river systems in the East Asia mainland during the Cretaceous to Early Cenozoic, although there have been few studies on pre-Cretaceous drainage systems. To determine the impact on the evolution of palaeo-drainage systems triggered by tectonic movement of the Indochina Block, we performed palaeomagnetic and U–Pb geochronologic analyses on the Late Triassic to Early Cretaceous sedimentary rocks in the Simao Basin. Palaeomagnetic data indicate stable Jurassic tectonic environments between the Indochina and Songpan–Ganzi–South China blocks, following their Late Triassic collision. Based on detrital zircon U–Pb dating, the Late Triassic age spectra consist mainly of Phanerozoic components, while the Jurassic to Cretaceous age spectra display more Precambrian age peaks. The contribution of potential provenance to the Simao Basin changed during the Early Cretaceous, suggesting several sedimentary provenance transitions. Also, we believe that large continental-scale drainage systems flowing through the North Qiangtang, Sichuan, Simao and Khorat Basins were sourced from the Songpan–Ganzi Block since the end of the Late Jurassic. Supplementary material: The findings of a quantitative statistical study (Fig. S1; Table S5), the location of the Late Triassic to Early Cretaceous samples from the Simao Basin (Table S1), palaeomagnetic poles for Eurasia, South China, Indochina, North Qiangtang and Tarim (Table S2), the result of quantitative analysis for the Late Triassic and Middle Jurassic sedimentary rocks from the Simao and Sichuan basins (Table S3), and results of zircon U–Pb dating (Table S4) are available at https://doi.org/10.6084/m9.figshare.c.6862918 Thematic collection: This article is part of the Mesozoic and Cenozoic tectonics, landscape and climate change collection available at: https://www.lyellcollection.org/topic/collections/mesozoic-and-cenozoic-tectonics-landscape-and-climate-change

The effect of parent rocks on river sediment composition and implication for regional tectono-magmatic events: a case from two tributaries of the Songhua River, NE China

Abstract Modern fluvial sediments provide important information about source-to-sink process and regional tectono-magmatic events in the source area, but many factors, e.g., chemical weathering, sedimentary cycles and source-rock types, can interfere with the establishment of the source-sink system. The Lalin River (LR) and the Jilin Songhua River (JSR) are two important tributaries of the Songhua River in the Songnen Plain in NE China. They have similar flow direction, topography and identical climate backgrounds, but have notably different parent-rock types in the headwater, which provides an opportunity to explore the influencing factors of river sediment composition. To this end, the point bar sediments in the two rivers were sampled for an analysis of geochemistry (including element and Sr-Nd isotopic ratios), heavy mineral and detrital zircon U-Pb dating. The results are indicative of the fact that the two rivers have the similar geochemical composition (e.g., elements and Sr isotopes) as well as chemical weathering (CIA = 51.41–57.60, CIW = 59.68–66.11, PIA = 51.95–60.23, WIP = 56.00–65.47, Rb/Sr = 0.38–0.42) and recycling (SiO2/Al2O3 = 5.79 and 5.03, ICV = 1.0 and 1.2, CIA/WIP = 0.81–1.03) characteristics, showing a major control of climate on the low-level weathering and recycling of the river sediments. However, there are significant differences in the detrital zircon U-Pb age (a significant Mesozoic age peak for the LR but an additional Precambrian peak for the JSR), Nd isotope ratio (−6.2812–8.5830 and −8.1149–10.2411 for the LR and the JSR, respectively) and to a certain extent heavy mineral composition (e.g., for the &lt; 63 μm fraction, a dominance of hornblende and magnetite in the LR, but haematite-limonite in the JSR) in the two river sediments, indicating that source rocks largely control the composition of the river sediments. Some of the major tectono-magmatic events (e.g., crustal growth and cratonisation of the North China Craton, closure of the Paleo-Asian Ocean, subduction and rollback of the Paleo-Pacific plate) occurring in the eastern Songnen Plain are well documented in the JSR sediments but not in the LR, the difference of which is largely regulated by the source rocks in the source area.