The Higo metamorphic complex in Kyushu, Japan as the fragment of Permo–Triassic metamorphic complexes in East Asia

The Higo terrane in west-central Kyushu Island, southwest Japan consists from north to south of the Manotani, Higo and Ryuhozan metamorphic complexes, which are intruded by the Higo plutonic complex (Miyanohara tonalite and Shiraishino granodiorite).The Higo and Manotani metamorphic complexes indicate an imbricate crustal section in which a sequence of metamorphic rocks with increasing metamorphic grade from high (northern part) to low (southern part) structural levels is exposed. The metamorphic rocks in these complexes can be divided into five metamorphic zones (zone A to zone E) from top to base (i.e., from north to south) on the basis of mineral parageneses of pelitic rocks. Greenschist-facies mineral assemblages in zone A (the Manotani metamorphic complex) give way to amphibolite-facies assemblages in zones B, C and D, which in turn are replaced by granulite-facies assemblages in zone E of the Higo metamorphic complex. The highest-grade part of the complex (zone E) indicates peak P–T conditions of ca. 720 MPa and ca. 870 °C. In addition highly aluminous Spr-bearing granulites and related high-temperature metamorphic rocks occur as blocks in peridotite intrusions and show UHT-metamorphic conditions of ca. 900 MPa and ca. 950 °C. The prograde and retrograde P–T evolution paths of the Higo and Manotani metamorphic complexes are estimated using reaction textures, mineral inclusion analyses and mineral chemistries, especially in zones A and D, which show a clockwise P–T path from Lws-including Pmp–Act field to Act–Chl–Epi field in zone A and St–Ky field to And field through Sil field in zone D.The Higo metamorphic complex has been traditionally considered to be the western-end of the Ryoke metamorphic belt in the Japanese Islands or part of the Kurosegawa–Paleo Ryoke terrane in south-west Japan. However, recent detailed studies including Permo–Triassic age (ca. 250 Ma) determinations from this complex indicate a close relationship with the high-grade metamorphic terranes in eastern-most Asia (e.g., north Dabie terrane) with similar metamorphic and igneous characteristics, protolith assembly, and metamorphic and igneous ages. The north Dabie high-grade terrane as a collisional metamorphic zone between the North China and the South China cratons could be extended to the N-NE along the transcurrent fault (Tan-Lu Fault) as the Sulu belt in Shandong Peninsula and the Imjingang belt in Korean Peninsula. The Higo and Manotani metamorphic complexes as well as the Hida–Oki terrane in Japan would also have belonged to this type of collisional terrane and then experienced a top-to-the-south displacement with forming a regional nappe structure before the intrusion of younger Shiraishino granodiorite (ca. 120 Ma).     

新疆西天山那拉提构造带变质核部杂岩地质构造特征

新疆西天山那拉提构造带变质核部杂岩分布于新疆巩留县那拉提山山脊北侧，整体沿那位提南缘构造带北侧呈近东西向展布，为一套由高级变质表壳岩、灰色片麻岩组成的早前寒武系高级片麻岩系，历经多期不同构造体制变形变质改造与再造，形成多相片麻岩系，并呈长垣状变质核部杂岩隆升，构成那拉提造山带的核部构造物质组成。     

Relation of Isotope Geochemical Steep Zones with Geophysical Fields and Tectonics in the Junction Area of the Cathaysian, Yangtze and Indochina Plates

Through lead isotope geochemical mapping in the Yunnan-Guizhou area geochemical steep zones (GSZ) have been established, which clearly reveal the junction relationship of the Cathaysian, Yangtze and Indo-China plates. GSZ are closey related to gravity Mono gradient zones and lithospheric thickness. The GSZ between the Yangtze and Cathaysian plates is consistent with the Shizong-Mile tectonic belt, where island arc basalts are well developed. The Yangtze-Indo-China GSZ is parallel to the Jingdong-Mojiang volcanic belt in rift-island arc environments. The evidence of geology, geophysics and geochemistry all indicates that Cathaysia was subducted towards the Yangtze plate and that the Yangtze plate was underthrust beneath the Indo-China, which took place from the Early Carboniferous to the Early Triassic.     

Study on Unified Inter-Spherical Acting of Continental Collision of Tibet Plateau

STUDY ON UNIFIED INTER-SPHERICAL ACTING OF CONTINENTAL COLLISION OF TIBET PLATEAU     

柴北缘锡铁山地区滩间山群构造变形分析

初步构造变形分析表明 ,柴北缘锡铁山地区的早古生代变质火山岩系 -滩间山群在加里东期碰撞造山过程中经历了两期构造变形 :第一期为垂直造山带的挤压缩短变形 ,形成一系列紧闭褶皱、区域片理和大型韧性剪切带 ;第二期为平行造山带的挤压缩短变形 ,形成区域透入性共轭破劈理或膝折带。这两期变形是柴北缘加里东期碰撞造山带的斜向碰撞造山过程中不同阶段变形特征的体现。这种构造型式可能对于认识斜向碰撞造山带的构造动力学的转换过程具有重要意义。     

船艏正撞刚性墙力—撞深关系的简化公式研究

面向工程应用,基于船艏正撞刚性墙的有限元碰撞计算,提出了撞击力—船艏撞深关系的基本简化公式,以应用于船撞桥的质量-弹簧体系简化动力分析模型的有限元计算。使用LS-DYNA软件,通过3000~50000 DWT（dead weight tonnage,载重吨）范围内4艘典型船舶的有限元碰撞分析,得到了船舶在1.0~5.0 m/s冲击速度范围内,与刚性墙面正撞的撞击力—撞深样本曲线。根据对样本曲线的观察,提出了一种基本的撞击力—撞深关系的简化数学公式,并统计得到了公式中各参数的表达式。船桥碰撞实际工况的有限元计算对比表明,提出的简化公式可以满足船桥碰撞简化动力分析的需要。     

湘东地区板杉铺加里东期埃达克质花岗闪长岩的成因及地质意义

湘东地区板杉铺加里东期岩体是一套具埃达克岩性质的花岗闪长岩。该岩石具有高的SiO2(~70%)和Al2O3(~16.5%)、中等高的Na2O/K2O比值(普遍大于1.0,可达1.4)和低但可变的Mg质指数(Mg#= 37-59)。相对高的Sr(均值: 520 ppm)和Ba(1052~1502 ppm)以及低的Y(<12 ppm)和Yb(<1 ppm)丰度,导致该岩石具有低的Rb/Sr(0.17~0.42)、高的Sr/Y(34~64)比值,以及LREE强烈富集[(La/Yb)N= 27 ~ 71]而铕弱负异常(Eu/Eu*= 0.76 ~ 0.91)的稀土配分模式。因此,板杉铺岩体源区岩可能为石榴角闪岩或石榴角闪岩-角闪榴辉岩过渡相。但低Nd和高Sr同位素组成[?Nd(t)= -6.7 ~ -8.4],(87Sr/86Sr)i= 0.7078 ~ 0.7140]说明它们并不来源于俯冲的玄武质洋壳或亏损地幔;而高放射性成因Pb[(206Pb/204Pb)i=18.22~18.78]、高微量元素比值(如Ba/La=~15-28、Th/Ce=0.29-0.36)暗示深海沉积物及再循环的陆源沉积物可能已卷入这些岩石的成因。结合区域地质、地层和构造事件,我们认为,早古生代可能的陆-弧-陆碰撞是导致研究区埃达克质花岗闪长岩产生的重要机制,而源于先前富集地幔的玄武质岩浆底侵则诱导了加厚的中酸性弧下地壳岩石部分熔融。部分熔融产生的岩浆可能经同化混染和分离结晶作用过程最终形成了板杉铺埃达克质花岗闪长岩。华南埃达克质花岗闪长岩的厘定不仅揭示早古生代时期华南地区经历了地壳增生事件,对正确理解华南、特别是扬子板块东南缘Au-Sb-W-Cu等多金属成矿作用还具有重要的意义。     

竖向荷载作用下挤扩支盘桩的试验研究及设计分析

结合实际工程,通过挤扩支盘桩的静载荷试验和桩身轴力测试试验,深入地分析了竖向荷载作用下挤扩支盘桩的荷载传递机理和变形特性,同时,给出了挤扩支盘桩的单桩承载力计算公式。结果表明,挤扩支盘桩在加荷后期支盘承担50 %以上荷载,且支盘阻力体现端承力的性质;挤扩支盘桩与普通直桩相比,单桩承载力可提高60 %～100 %。