Early Triassic Volcanic Rocks in the Western Yarlung Zangbo Suture Zone:Implications for the Opening of the Neo-Tethys Ocean

In this study,zircon U-Pb dating of volcanic rocks from the Zhongba ophiolite of the Yarlung Zangbo Suture Zone(YZSZ)in southern Xizang(Tibet)yielded an age of 247±3 Ma.According to whole rock geochemical and Sr-NdPb isotopic data,the Early Triassic samples could be divided into two groups:Group 1 with P-MORB affinity,showing initial^(87)Sr/^(86)Sr ratios of 0.70253–0.70602,ε_(Nd)(t)values of 4.2–5.3,(^(206)Pb/^(204)Pb)_(t)ratios of 16.353–18.222,(^(207)Pb/^(204)Pb)_(t)ratios of 15.454–15.564,and(^(208)Pb/^(204)Pb)_(t)ratios of 35.665–38.136;Group 2 with OIB affinity,showing initial^(87)Sr/^(86)Sr ratios of 0.70249–0.70513,ε_(Nd)(t)values of 4.4–4.9,(^(206)Pb/^(204)Pb)_(t)ratios of 17.140–18.328,(^(207)Pb/^(204)Pb)_(t)ratios of 15.491–15.575,and(^(208)Pb/^(204)Pb)_(t)ratios of 36.051–38.247.Group 2 rocks formed by partial melting of the mantle source enriched by a former plume,and assimilated continental crustal material during melt ascension.The formation of Group 1 rocks corresponds to the mixing of OIB melts,with the same components as Group 2 and N-MORBs.The Zhongba Early Triassic rocks belong to the continental margin type ophiolite and formed in the continental–oceanic transition zone during the initial opening of the Neo-Tethys in southern Xizang(Tibet).

Double-nylon purse-string suture in closing postoperative wounds following endoscopic resection of large(≥3 cm)gastric submucosal tumors

BACKGROUND Endoscopic full-thickness resection(EFTR)of gastric submucosal tumors(SMTs)is safe and effective;however,postoperative wound management is equally important.Literature on suturing following EFTR for large(≥3 cm)SMTs is scarce and limited.AIM To evaluate the efficacy and clinical value of double-nylon purse-string suture in closing postoperative wounds following EFTR of large(≥3 cm)SMTs.METHODS We retrospectively analyzed the data of 85 patients with gastric SMTs in the fundus of the stomach or in the lesser curvature of the gastric body whose wounds were treated with double-nylon purse-string sutures after successful tumor resection at the Endoscopy Center of Renmin Hospital of Wuhan University.The operative,postoperative,and follow-up conditions of the patients were evaluated.RESULTS All tumors were completely resected using EFTR.36(42.35%)patients had tumors located in the fundus of the stomach,and 49(57.65%)had tumors located in the body of the stomach.All patients underwent suturing with double-nylon sutures after EFTR without laparoscopic assistance or further surgical treatment.Postoperative fever and stomach pain were reported in 13(15.29%)and 14(16.47%)patients,respectively.No serious adverse events occurred during the intraoperative or postoperative periods.A postoperative review of all patients revealed no residual or recurrent lesions.CONCLUSION Double-nylon purse-string sutures can be used to successfully close wounds that cannot be completely closed with a single nylon suture,especially for large(≥3 cm)EFTR wounds in SMTs.

Transcriptomic and cellular decoding of scaffolds-induced suture mesenchyme regeneration

Precise orchestration of cell fate determination underlies the success of scaffold-based skeletal regeneration.Despite extensive studies on mineralized parenchymal tissue rebuilding,regenerating and maintaining undifferentiated mesenchyme within calvarial bone remain very challenging with limited advances yet.Current knowledge has evidenced the indispensability of rebuilding suture mesenchymal stem cell niches to avoid severe brain or even systematic damage.But to date,the absence of promising therapeutic biomaterials/scaffolds remains.The reason lies in the shortage of fundamental knowledge and methodological evidence to understand the cellular fate regulations of scaffolds.To address these issues,in this study,we systematically investigated the cellular fate determinations and transcriptomic mechanisms by distinct types of commonly used calvarial scaffolds.Our data elucidated the natural processes without scaffold transplantation and demonstrated how different scaffolds altered in vivo cellular responses.A feasible scaffold,polylactic acid electrospinning membrane(PLA),was next identified to precisely control mesenchymal ingrowth and self-renewal to rebuild non-osteogenic suture-like tissue at the defect center,meanwhile supporting proper osteointegration with defect bony edges.Especially,transcriptome analysis and cellular mechanisms underlying the well-orchestrated cell fate determination of PLA were deciphered.This study for the first time cellularly decoded the fate regulations of scaffolds in suture-bony composite defect healing,offering clinicians potential choices for regenerating such complicated injuries.

Outcomes of a non-randomised audit of single pigtail suture stents in urolithiasis management of Asian patients in Singapore

Objective:Double-J(DJ)ureteric stents are commonly placed perioperatively for semirigid or flexible ureteroscopic renal surgery.It is believed that lesser stent material within the bladder mitigates stent-related symptoms.This study aimed to evaluate the J-Fil ureteral stent,a single pigtail suture stent compared with conventional DJ stent in relation to stent symptoms in an Asian population undergoing ureterorenal intervention.Methods:Based on internal audit committee recommendation approval,the records of 50 patients retrieved,available data of 41 patients who were prospectively enrolled into two groups(Group 1[J-Fil stent group],n=21 and Group 2[DJ stent group],n=20)between August 2020 to January 2021,were analysed.Parameters compared were nature of procedure,stone location and size,ease of deployment or removal,and complications.A modified universal stent symptom questionnaire was used to assess morbidity of stent symptoms within 48 h of insertion and at removal.Results:Both groups had similar median age,distribution in male to female ratio,and stone size.The overall median universal stent symptom questionnaire score at insertion was similar for bladder pain,flank or loin pain,and quality of life between Group 1 and 2;however,at removal Group 1 fared significantly better than Group 2,especially for flank or loin pain and pain at voiding.Both groups had similar ease in insertion with no hospital readmissions.Conclusion:Our audit favoured the single pigtail suture stent in Asian ureters in mitigating stent-related issues.It showed a good safety profile with easy deployment and removal.It promises a new standard in stenting.

Single self-leading suture technique for iridodialysis repairment

Dear Editor,We described an innovative“single self-leading suture technique”for repairing iridodialysis.Instead of moving the needle forth and back,our method is easier to manipulate in the narrow surgical space between the cornea and lens,which will decrease the unnecessary complications related to iatrogenic injury.We provide an economical friendly and less time-taking method,which improves the suture accuracy.

Intermittent sliding-lock-knot suture for limbal conjunctival autograft fixation in pterygium surgery:a technique note

AIM:To report a technique used with intermittent slidinglock-knot(ISLK)fixation for limbal conjunctival autografts in pterygium surgery and compared with those of routine intermittent(RI)fixation.METHODS:Consecutive patients with primary pterygium who had undergone pterygium excision combined with limbal conjunctival autograft transplantation between March 2021 and March 2022 at our institute were retrospectively analyzed.Primary outcome measures were mean duration of surgery and suture removal,degree of conjunctival hyperemia on postoperative day 1,pain score at suture removal,postoperative symptoms at 6mo,including conjunctival hyperemia,foreign body sensation,and graft stability.RESULTS:Ninety-eight patients underwent monocular surgery and were divided into ISLK(51 eyes)and RI(47 eyes)groups according to the type of conjunctiva autograft fixation method planned.There was no significant difference in mean duration of surgery between the two groups(18.59±2.39min vs 18.15±2.20min,P=0.417);however,compared to the RI group,shorter suture removal times were observed in the ISLK group[0.58min(0.42-0.87)vs 3.00min(2.21-4.15),P<0.001].The degree of conjunctival hyperemia on postoperative day 1 was milder in the ISLK group(P<0.001).Pain scores at suture removal were lower in the ISLK group than in RI group[1(0-3)vs 2(1-4),P<0.001].Postoperative symptoms at 6mo were comparable between the groups(P=0.487),with no recurrence.CONCLUSION:ISLK is an innovative method for limbal conjunctival autograft fixation after pterygium excision.Compared to RI fixation,ISLK facilitates suture removal and reduces discomfort,with comparable surgery duration and less conjunctival hyperemia.

Arthroscopic M-shaped suture fixation for tibia avulsion fracture of posterior cruciate ligament:A modified technique and case series

BACKGROUND Tibial avulsion fractures of the posterior cruciate ligament(PCL)are challenging to treat and compromise knee stability and function.Traditional open surgery often requires extensive soft tissue dissection,which may increase the risk of morbidity.In response to these concerns,arthroscopic techniques have been evolving.The aim of this study was to introduce a modified arthroscopic tech-nique utilizing an M-shaped suture fixation method for the treatment of tibial avulsion fractures of the PCL and to evaluate its outcomes through a case series.AIM To evaluate the effects of arthroscopic M-shaped suture fixation on treating tibia avulsion fractures of the PCL.METHODS We developed a modified arthroscopic M-shaped suture fixation technique for tibia avulsion fractures of the PCL.This case series included 18 patients who underwent the procedure between January 2021 and December 2022.The patients were assessed for range of motion(ROM),Lysholm score and International knee documentation committee(IKDC)score.Postoperative complications were also recorded.RESULTS The patients were followed for a mean of 13.83±2.33 months.All patients showed radiographic union.At the final follow-up,all patients had full ROM and a negative posterior drawer test.The mean Lysholm score significantly improved from 45.28±8.92 preoperatively to 91.83±4.18 at the final follow-up(P<0.001),and the mean IKDC score improved from 41.98±6.06 preoperatively to 90.89±5.32 at the final follow-up(P<0.001).CONCLUSION The modified arthroscopic M-shaped suture fixation technique is a reliable and effective treatment for tibia avulsion fractures of the PCL,with excellent fracture healing and functional recovery.

Assessing clinical and patient reported outcomes of Sironix suture anchors in rotator cuff and Bankart repair surgeries

BACKGROUND Rotator cuff tears and Bankart lesions significantly affect shoulder function and quality of life.Arthroscopic rotator cuff repair and Bankart repair has become the standard treatment for restoring function and reducing pain.Recent advancements include new suture anchor technologies,such as the Sironix suture anchor known for its biomechanical strength and promising outcomes.However,there are limited real-world data on its effectiveness and safety,particularly in the Indian population.AIM To evaluate the effectiveness and safety of Sironix suture anchors in rotator cuff and Bankart repair surgeries.METHODS Sixty participants underwent surgery between January 2021 and December 2022,and demographic data and postoperative outcomes were collected through retrospective reviews and telephonic interviews.Validated scales,including the PENN Shoulder Score(PSS),Disabilities of the Arm,Shoulder,and Hand(DASH)score,and Single Assessment Numeric Evaluation(SANE),were utilized for assessment.RESULTS Treatment with Sironix suture anchor devices,including Ceptre Knotted UHMWPE Suture Titanium Anchor,Spyke Knotted UHMWPE Suture Peek Anchor,Stativ Knotted UHMWPE Suture Anchor,and Viplok Knotless Peek Screw Anchor with Titanium Tip,revealed no repair failures.Participants demonstrated high satisfaction and functional improvement,as evidenced by the mean Quick DASH score(32.01)and PSS(71.65)and the satisfactory SANE scores for both injured joints(74.33)and non-injured(83.67)shoulder joints.CONCLUSION The study yielded favorable outcomes for rotator cuff tear repair and Bankart repair.No repair failures were observed,supporting the safety and efficacy of these devices in shoulder injury management.

Suture Button装置修复下胫腓联合损伤的初步报告

[目的]探讨Suture Button装置治疗下胫腓联合损伤后的手术方法及临床效果。[方法]对截止于2007年9月利用Suture Button装置固定的下胫腓联合急、慢性损伤的13例病人进行连续随访观察,通过术后X线片数字化测量和标准的踝足功能评分,评估其疗效并探讨临床应用前景。[结果]除1例病人因术后短期再次创伤意外,行2次手术更换为传统螺钉内固定外,其余病人均在术后6周开始部分负重功能锻炼,术后第3个月功能平均评分达到满意,术后第6、12个月功能平均评分达到优良,X线片未发现内固定失效。[结论]Suture Button装置治疗下胫腓联合损伤具有技术简单、手术时间短、内固定器物理特性符合人体正常解剖生理、固定强度足够、无需2次手术取出等多项优势,可能成为下胫腓联合损伤新的治疗标准。

Zircon LA-ICP MS U-Pb Dating of the Longkang Andesitic Ignimbrites from Jiuzhaigou: Evidence of the Mianlue Suture Westward Extension

Genesis of metasedimentary-volcanics outcroped in Kangxian-Pipasi-Nanping （康县-琵琶寺-南坪） tectonic zone is closely related with tectonic evolution of the Mianlue （勉略） Ocean. In the west end of Kangxian-Pipasi-Nanping tectonic zone, there are hundred meters of andesitic ignimbrites and tuffites. Zircon U-Pb dating on these volcanics has great significance to the tectonic implication of the volcanic rocks. Zircons from an ignimbrite sample （JZG-L） have been collected from Yazhagou （牙扎沟） in the east end of the Tazang-Longkang （塔藏-隆康） Section for LA-ICP MS U-Pb dating. The zircons from Longkang andesitic ignimbrites are magmatic genesis with oscillatory zoning and high U （（35-750） ppm）, Th （（311-717） ppm） contents with high Th/U （0.44-1.30） ratios. The measured 206pb/238u ratios are in good analytical precision, yielding a weighted mean age of （246±3） Ma （MSWD=2.6, n=12, 2a）. Some detrital zircons have also been observed, they have maximal concordia age of （2 481±33） Ma, which indicates the existence of Precambrian material in the Jiuzhaigou （九寨沟） area. Combined with regional geology and the volcanic rocks in the studied area, the （246±3） Ma zircon U-Pb age suggests a Late Permian orogenic volcanism and provides important geochronology evidence for the Mianlue suture westward extension.

V-Locsutures与普通可吸收线在后腹腔镜肾部分切除术中应用比较

目的:比较V-Loc sutures与普通可吸收线在后腹腔镜肾癌部分切除术中的应用价值。方法:2012年5月-2013年6月,本手术组共收治了25例确诊的病理分期为T1N0M0的肾癌患者,其中12例术中肾脏创面缝合均采用V-Loc sutures,其中男9例,女3例,年龄28-68岁,平均48.2岁;肿瘤大小为0.9-4.7cm,平均2.8cm;另13例术中采用普通可吸收线缝合创面,其中男8例,女5例,年龄34-74岁,平均45.5岁;肿瘤大小为1.2-4.5cm,平均2.6cm;比较两组患者手术中的手术时间、术中出血量、肾动脉阻断时间、创面缝合时间、各组手术前后测血肌酐、胱抑素C变化,术后并发症。结果:25例手术均在后腹腔镜下顺利完成。V-Loc sutures组和普通可吸收线组手术时间、术中出血、肾动脉阻断时间、肾创面缝合时间均有差异(P<0.05);V-Loc sutures组手术前后血肌酐、胱抑素C无明显差异(P>0.05),普通可吸收线组手术前后血肌酐、胱抑素C有差异(P<0.05);V-Loc sutures组出现1例血尿,普通可吸收线组出现1例漏尿。结论:V-Loc sutures较普通可吸收线可缩短手术时间及肾创面缝合时间,减少术中出血,更好的保护小肾癌患者的肾功能。

Suture Endobutton与跖肌腱重建Lisfranc韧带的生物力学对比研究

目的通过Suture Endobutton与跖肌腱重建Lisfranc韧带的生物力学对比研究,评价两种方法对恢复Lisfranc关节稳定性的作用,为临床治疗Lisfranc损伤提供理论依据。方法选取10例成人新鲜尸体小腿标本,依次制备Lisfranc韧带完整模型、损伤模型及损伤后的Suture Endobutton或跖肌腱重建模型,并分别给予轴向或外展载荷,记录内侧楔骨（C1）～第2跖骨（M2）基底的平均位移变化。结果轴向载荷和外展载荷下,完整模型C1～M2的平均位移变化分别为（0.70±0.05）mm、（1.21±0.10）mm,损伤模型为（1.59±0.07）mm、（3.73±0.11）mm,Suture Endobutton重建模型为（0.84±0.04）mm、（1.29±0.06）mm,跖肌腱重建模型为（1.01±0.05）mm、（1.34±0.05）mm。轴向或外展载荷下,完整模型和重建模型C1～M2间位移变化明显小于损伤模型,差异具有统计学意义（P〈0.05）;重建模型的位移变化略大于完整模型,但差异无统计学意义（P〉0.05）;Suture Endobutton与跖肌腱重建模型之间位移变化相似,差异无明显统计学意义（P〉0.05）;任一模型外展载荷时的C1～M2位移变化大于轴向载荷。结论 （1）在恢复Lisfranc关节稳定性上,Suture Endobutton与跖肌腱的重建方法提供的生物力学强度相似;（2）相对于轴向载荷的位移变化,外展载荷的实验结果差异更加明显,推荐使用外展载荷进行Lisfranc关节相关力学试验。

肩关节镜下Suture Bridge双排法手术修复中型肩袖撕裂的临床效果

目的研究肩关节镜下Suture Bridge双排法手术修复中型肩袖撕裂的临床效果。方法选取2019年2月至2020年3月的150例肩袖损伤患者进行研究。按照随机数表法,分为观察组(n=79)和对照组(n=71)。对照组采用单排修复术治疗,观察组采用Suture Bridge双排法手术治疗。对比两组肩关节Constant评分、视觉模拟评分法评分(Visual Analogue Scale/Score,VAS)、美国加州大学肩关节评分系统评分(University of California at Los Angeles Shoulder Scores,UCLA)及愈合时间、康复时间及再撕裂率。结果治疗后3个月,观察组的Constant评分明显高于对照组(P<0.05);观察组治疗后3个月、治疗后1年VAS评分[(2.17±0.60、3.79±1.01)分]明显低于对照组(P<0.05);观察组UCLA评分总分、疼痛、功能、前屈角度、前屈肌力均明显高于对照组(P<0.05);愈合时间、康复时间及再撕裂率明显低于对照组(P<0.05)。结论肩关节镜下Suture Bridge双排法手术在修复中型肩袖撕裂上可取得良好的治疗效果,改善肩袖关节功能,值得推广。

SHRIMP Zircon U-Pb Dating of Gabbro and Granite from the Huashan Ophiolite,Qinling Orogenic Belt,China: Neoproterozoic Suture on the Northern Margin of the Yangtze Craton

The recently identified Huashan ophiolitic mélange was considered as the eastern part of the Mianlüe suture in the Qinling orogenic belt. SHRIMP zircon U-Pb geochronology on gabbro from the Huashan ophiolite and granite intruding basic volcanic rocks indicates crystallization ages of 947±14 Ma and 876±17 Ma respectively. These ages do not support a recently proposed Hercynian Huashan Ocean, but rather favor that a Neoproterozoic suture assemblage （ophiolite） is incorporated into the younger （Phanerozoic） Qinling orogenic belt.

Disposable circumcision suture device： clinical effect and patient satisfaction

In our experience patients undergoing circumcision are mostly concerned about pain and penile appearances. We conducted a prospective randomized trial to assess the benefits of a new disposable circumcision suture device （DCSD）. A total of 942 patients were equally divided into three groups （conventional circumcision, Shang ring and disposable suture device group）. Patients in the DCSD group were anesthetized with compound 5% lidocaine cream, the others with a 2% lidocaine penile block. Operation time, intra-operative blood loss, incision healing time, intra-operative and post-operative pain, the penile appearance and overall satisfaction degree were measured. Operation time and intra-operative blood loss were significantly lower in the Shang ring and suture device groups compared to the conventional group （P 〈 0.001）. Intra-operative pain was less in the suture device group compared With the other two groups （P 〈 0.001）; whereas post-operative pain was higher in the conventional group compared to the other two groups （P 〈 0.001）. Patients in the suture device （80.57%） and Shang ring （73,57%） groups were more satisfied with penile appearances compared with the conventional circumcision group （20.06%, P 〈 0.05）. Patients in suture device group also healed markedly faster than the conventional group （P 〈 0.01）. The overall satisfaction rate was better in the suture device group （78.66%） compared with the conventional （47.13%） and Shang ring （50.00%） groups （P 〈 0.05）. The combination of DCSD and lidocaine cream resulted in shorter operation and incision healing times, reduced intra-operative and post-operative pain and improved patient satisfaction with the cosmetic appearances.

How many sutures in the southern Central Asian Orogenic Belt:Insights from East Xinjiang-West Gansu(NW China)?

How ophiolitic mèlanges can be defined as sutures is controversial with regard to accretionary orogenesis and continental growth.The Chinese Altay,East junggar,Tianshan,and Beishan belts of the southern Central Asian Orogenic Belt（CAOB） in Northwest China,offer a special natural laboratory to resolve this puzzle.In the Chinese Altay,the Erqis unit consists of ophiolitic melanges and coherent assemblages,forming a Paleozoic accretionary complex.At least two ophiolitic melanges（Armantai,and Kelameili） in East Junggar,characterized by imbricated ophiolitic melanges,Nb-enriched basalts,adakitic rocks and volcanic rocks,belong to a Devonian-Carboniferous intra-oceanic island arc with some Paleozoic ophiolites,superimposed by Permian arc volcanism.In the Tianshan,ophiolitic melanges like Kanggurtag,North Tianshan,and South Tianshan occur as part of some Paleozoic accretionary complexes related to amalgamation of arc terranes.In the Beishan there are also several ophiolitic melanges,including the Hongshishan,Xingxingxia-Shibangjing,Hongliuhe-Xichangjing,and Liuyuan ophiolitic units.Most ophiolitic melanges in the study area are characterized by ultramafic,mafic and other components,which are juxtaposed,or even emplaced as lenses and knockers in a matrix of some coherent units.The tectonic settings of various components are different,and some adjacent units in the same melange show contrasting different tectonic settings.The formation ages of these various components are in a wide spectrum,varying from Neoproterozoic to Permian.Therefore we cannot assume that these ophiolitic melanges always form in linear sutures as a result of the closure of specific oceans.Often the ophiolitic components formed either as the substrate of intra-oceanic arcs,or were accreted as lenses or knockers in subduction-accretion complexes.Using published age and paleogeographic constraints,we propose the presence of （1） a major early Paleozoic tectonic boundary that separates the Chinese Altay-East Junggar multiple subduction systems of the southern Siberian active margin from those of the northern Tarim;and （2） a major Permian suture zone that separates the Tianshan-Beishan from the northern active margin of the Tarim Craton.These new observations and interpretations have broad implications for the architecture and crustal growth of central Asia and other ancient orogens as well.

Diamonds and Other Exotic Minerals Recovered from Peridotites of the Dangqiong Ophiolite, Western Yarlung-Zangbo Suture Zone, Tibet

Various combinations of diamond, moissanite, zircon, quartz, corundum, rutile, titanite, almandine garnet, kyanite, and andalusite have been recovered from the Dangqiong peridotites. More than 80 grains of diamond have been recovered, most of which are pale yellow to reddish-orange to colorless. The grains are all 100-200 μm in size and mostly anhedral, but with a range of morphologies including elongated, octahedral and subhedral varieties. Their identification was confirmed by a characteristic shift in the Raman spectra between 1325 cm^-1 and 1333 cm^-1, mostly at 1331.51 cm^-1 or 1326.96 cm^-1. Integration of the mineralogical, petrological and geochemical data for the Dongqiong peridotites suggests a multi-stage formation for this body and similar ophiolites in the Yarlung-Zangbo suture zone. Chromian spinel grains and perhaps small bodies of chromitite crystallized at various depths in the upper mantle, and encapsulated the UHP, highly reduced and crustal minerals. Some oceanic crustal slabs containing the chromian spinel and their inclusion were later trapped in suprasubduction zones（SSZ）, where they were modified by island arc tholeiitic and boninitic magmas, thus changing the chromian spinel compositions and depositing chromitite ores in melt channels.

Middle Jurassic-early Cretaceous radiolarian assemblages of the western Yarlung Zangbo Suture Zone: Implications for the evolution of the Neo-Tethys

Cherts in the Zhongba melange of the western Yarlung Zangbo Suture Zone(YZSZ) contain well preserved radiolarian assemblages. These radiolarian assemblages indicate that the Zhongba melange has middle Jurassic-early Cretaceous remnant, are coeval with those from the central and eastern parts of the YZSZ. Cherts from the Najiu area yield Aalenian to Aptian radiolarians, while cherts interbedded with siliceous mudstones from the Bielongjiala area yield Aptian radiolarians, indicating that terrigenousderived sediments were deposited during early Aptian. The above observations indicate that the entire YZSZ have a similar geochronological framework and thus they underwent similar geological evolution:(1) during the Jurassic, the Neo-Tethys was a wide ocean with pelagic sediments distal from continents;(2) during the Cretaceous(around 130-120 Ma), the Neo-Tethys started to subduct along the southern margin of the Lhasa block, and terrigenous-derived siliceous mudstone began deposition.

Ophiolites from the Mianlüe Suture in the Southern Qinling and Their Relationship with the Eastern Paleotethys Evolution

The Mianlue suture extends from Derni-Nanping-Pipasi-Kangxian to the Lueyang-Mianxian area, then traverses the Bashan arcuate structure eastward to the Huashan region, and finally to the Qingshuihe area of the southern Dabie Mountains. From east to west, with a length of over 1500 km, the ophiolitic melange associations are distributed discontinuously along the suture. The rock assemblages include ophiolite, island-arc and oceanic island rock series, indicating that there existed a suture zone and a vanished paleo-ocean basin. The Mianliie paleo-ocean basin experienced its main expansion and formation process during the Carboniferous-Permian and closed totally in the Triassic. It belongs to the northern branch of the eastern paleotethys, separated from the northern margin of the Yangtze block under the paleotethys mantle dynamic system.

Early Permian–Late Triassic Magmatism in the Tuotuohe Region of the Qinghai–Tibet Plateau: Constraints on the Tectonic evolution of the Western Segment of the Jinshajiang Suture

In this paper we present new zircon U-Pb ages,whole-rock major and trace element analyses,and zircon Hf isotopic data for magmatic rocks in the Tuotuohe region of the western segment of the Jinshajiang suture.Our aim is to constrain the Early Permian-Late Triassic tectonic evolution of the region.Zircons from the magmatic rocks of the Tuotuohe region are euhedralsubhedral in shape and display fine-scale oscillatory zoning as well as high Th/U ratios （0.4-4.6）,indicating a magmatic origin.The zircon U-Pb ages obtained using LA-ICP-MS are 281 ± 1 Ma,258 ± 1 Ma,244 ± 1 Ma,and 216 ± 1 Ma,which indicate magmatism in the Early Permian-Late Triassic.A diorite from Bashihubei （BSHN） has SiO2 =57.18-59.97 wt％,Al2O3=15.70-16.53 wt％,and total alkalis （Na2O ＋ K2O） =4.46-6.34 wt％,typical of calc-alkaline and metaluminous series.A gabbro from Bashibadaoban （BSBDB） belongs to the alkaline series,and is poor in SiO2 （45.46-54.03 wt％） but rich in Al2O3 （16.19-17.39 wt％） and total alkalis （Na2O ＋ K2O =5.48-6.26 wt％）.The BSHN diorite and the BSBDB gabbro both display an enrichment of LREEs and LILEs and depletion of HFSEs,and they have no obvious Eu anomaly; they have relatively low MgO contents （2.54-4.93 wt％）,Mg# values of 43 to 52,and low Cr and Ni contents （8.07-33.6 ppm and 4.41-14.2 ppm,respectively）,indicating they differentiated from primitive mantle magmas.They have low Nb/U,Ta/ U,and Ce/Pb ratios （1.3-9.6,0.2-0.8,and 0.1-18.1,respectively）,and their initial Hf isotopic ratios range from ＋9.6 to ＋16.9 （BSHN diorite） and ＋6.5 to ＋12.6 （BSBDB gabbro）,suggesting their primary magmas were derived mainly from the partial melting of a mantle wedge that had been metasomatized by subduction fluids.Taking all the new data together,we conclude that the western and eastern segment of the Jinshajiang suture regions underwent identical processes of evolution in the Early Permian-Late Triassic：oceanic crust subduction before the Early Permian,continental collision during the Early-Middle Triassic,and post-collisional extension from the Late Triassic.