Application of General Shear Theory to the Study of Formation Mechanism of the Metamorphic Core Complex:A Case Study of Xiaoqinling in Central China

The kinematic vorticity number and strain of the mylonitic zone related to the detachment fault increase from ESE to WNW along the moving direction of the upper plate of the Xiaoqinling metamorphic core complex (XMCC) and the geometry of quartz c-axis fabrics changes progressively from crossed girdles to single girdles in the same direction. Therefore, pure shear is dominant in the ESE part of the XMCC while simple shear becomes increasingly important towards WNW. However, the shear type does not change with the strain across the shear zone, thus the variation of shear type is of significance in indicating the formation mechanism. The granitic plutons within the XMCC came from the deep source and their emplacement was an active and forceful upwelling prior to the detachment faulting. The PTt path demonstrates that magmatism is an important cause for the formation of the XMCC. The formation mechanism of the XMCC is supposed to be active plutonism and passive detachment. Crustal thickening and magmatic do     

南海的右行陆缘裂解成因

南海成果是西太平洋边缘海动力学研究的重要部分,也关系到特提期,环太平洋两大超级会聚带的相互作用,是国内外地学界长期研究的热点问题。西太平洋边缘海内带,尤其是日本海和南海在形成时代,海盆形态和海底地貌,海底扩张的多轴,多阶段,由东向西扩展特征,岩石圈地幔的地球化学异常等方面具有共同特征,可能在成因上也相似,南海的海盆的楔形的楔形形状,海底扩张及陆架盆地的断陷的由北向南发展和自东向西推进的特征,地壳伸展减薄和海底扩张程度的由东向西减弱都可用尖端向西的“剪刀模型”来描述,即南海的张开是近南北向右行剪切力作用下东亚陆缘发生裂解的结果。南海张开的同时在海盆内及其西缘印支半岛上发育大量近南北向右行走滑断裂,表明当时存在区域性的近南北向右行剪切应力,而在其东缘现在看不到大型近南北向右行走滑断裂,可能是在中中新世以后受从赤道附近近滑移北上并沿马尼拉海沟仰冲的菲律宾群岛所破坏的结果。晚中生代以来,在西太平洋构造域,特提斯构造域西段（印度）及东段（澳大利亚）先后发生了朝欧亚大陆的,不同方向和速度的会聚。在这三大作用的复合和竞争的动力学背景下,东亚陆缘发生了有地幔参加传动的“超级剪切”,其应力场经历了左行压扭体制和右行张扭体制交替的阶段性变化,正是在特提斯构造域西段的会聚起主导作用的阶段,东亚陆缘在右行张扭应力场作用下发生裂解,形成了南海和其他内带边缘海。     

Structural Styles of Fronts of Thrust-Detachment Faults in Petroleum-bearing Areas of Western China

The front of a thrust-detachment fault may have various styles such as decoupling, fold, forethrust and backthrust ones because of differences in magnitude, direction and time of the forces exerted on the fault and the inhomogeneity of rock mechanical properties. They have different characteristics and are usually associated with gravity structure, inverse structure and diapir structure. These structures exist together in the same thrust-detachment fault and can influence, compensate for and convert into each other. They provide important grounds not only for the study of the dynamic state, propagation mode, evolutionary process and formation mechanism but also for the analysis of the petroleum generation, migration, accumulation and preservation and arrangement of drill holes in foreland basins.     

Occurrences of Excess ^40Ar in Hydrothermal Tourmaline： Interpretations from ^40 Ar-^39Ar Dating Results by Stepwise Heating

The occurrences of excess ^40Ar within a hydrothermal tourmaline is discussed in term of the analysis data of syngenetic muscovite and tourmaline from the Lushui hydrothermal tin-tungsten deposit in western Yunnan, China, using the ^40Ar-^39Ar stepwise heating technique. About 80% excess ^40 Ar was released in the last step when the tourmaline was fused, corresponding to a release of only -3% ^39 Ar （K）, which indicates that most excess ^40 Ar was held in the mineral lattice rather than in the channels parallel to the Z-axis. This suggests that the excess ^40 Ar was incorporated during crystallization and not diffused into the tourmaline during the post-crystallization history.     

泾河流域生态系统服务消耗及变化认知分析：基于农户问卷调查和参与式社区评估

本文以黄土高原泾河流域上游固原市为例,采用农户问卷调查和参与式社区评估方法,研究农户对生态系统服务认知及消费,并对两种方法认知结果进行比较分析。研究发现,农户问卷调查方法农户认知到食物供给、净化空气、净化环境、水土保持、供给洁净水、减少自然灾害、提高收入、薪柴供给、景观愉悦、牧草供给和防风固沙11项生态系统服务,农户日常对生态系统服务的占有和消耗及生态系统服务对农户的重要性程度影响农户对生态系统服务的认知;参与式社区评估（PRA）方法农户可以充分进行信息交流与讨论,与农户问卷调查法相比对生物多样性服务有了认知。研究区生态系统服务发生很大变化,食物供给和薪柴供给服务明显减弱,收入增加;受生态系统服务变化及收入水平的影响,农户食物和能源消费存在明显时空差异,总体而言,农户食物消费总量下降,大部分农户薪柴消费数量减少,农户对蔬菜、肉类、煤炭、天然气等的消费量增加。     

白垩纪四足动物足印的生物地层学、生物年代学与遗迹相

从全球范围来看,白垩纪四足动物的足印多数是非鸟恐龙与鸟类留下的痕迹;少量足印来自翼龙、鳄鱼、龟、哺乳动物和其他四足动物。白垩纪的足迹化石以东亚(尤其是中国和朝鲜)和北美西部的最为人所知。南美(主要是阿根廷和巴西)也有一定数量广泛分布的足迹化石,欧洲、非洲与澳大利亚的白垩纪足迹组合则鲜为人知。以白垩纪四足动物的足印记录为基础,我们对两个全球足印生物年代重新进行了检查。早白垩世生物年代以蜥脚类与鸟脚类的足迹为特征。晚白垩世生物年代中的蜥脚类足迹较少,但是鸭嘴龙、暴龙和角龙的足迹增多了。另外,白垩纪足印化石的记录中记载了许多重要的生物地层学信息,如北美白垩纪中期蜥脚类恐龙的消失,以及白垩纪末恐龙的绝灭。越来越多来自东亚的白垩纪足印记录使我们对更精细的地方性白垩纪足印生物年代学有了初步印象。因此,以地方性四足恐龙(包括鸟类)遗迹属的地层分布为基础,可以识别出三个或四个足印生物年代。种类丰富并具有地方性特色的东亚的白垩纪鸟类动物的遗迹群,可能指示白垩纪时东亚存在着一个独特而繁盛的鸟类动物群。以足印化石为基础的这一假说有待进一步的验证。     

陆内克拉通盆地层序地层构型及其控制因素

通过总结我国鄂尔多斯盆地和澳大利亚Surat basin这两个典型的陆内克拉通盆地的层序充填序列,认为该类盆地具有典型的层序地层充填模式:(1)典型的正粒序岩性组合特征;(2)基准面旋回为上升半旋回为主的不对称旋回,具有长期持续水进、短期水退旋回特征;(3)层序主要以LST为主,发育相互切割叠置的复合砂体,为最有利储层;TST和HST相对不发育,发育孤立状的单砂体,为中-差储层.陆内克拉通盆地层序地层及其控制的砂体具有溯源退积的时空展布模式,该模式主要受到盆地边缘构造、沉积物供给、湖平面变化、古地形、盆地充填和气候等因素的单独或综合控制.     

SHORT COMMUNICATION PLS FITS CLOSER THAN PCR

PLS1 regression is generally viewed as lying in between PCR and OLS regression.Proof is given thatthe coefficient of determination,R~2,for a PLS multivariate calibration model is at least as high as thatfor a PCR model with the same number of components.It appears that PLS can be linked to acorrelation-weighted polynomial regression of a constant response on the eigenvalues of the covariancematrix of the predictor variables.     

中国中西部中—新生代前陆类盆地及其含油气性——兼论准噶尔盆地内部结构单元划分

前陆及前陆盆地的概念历来有多种定义,这些概念应用于中国中西部时有混乱,建议采用“复活前陆盆地”一词。前陆盆地内部结构单元包括活动翼、前渊(或称深坳陷)、稳定前陆斜坡和前隆,这四部分有成因联系,研究中应纳入一个前陆系统进行分析。以国外和中国中西部的多个盆地实例阐述了正确认识和鉴定前陆盆地的内部结构、前渊迁移、空间上沉积楔形态及含油气性等重要特征是对前陆盆地含油气评价和选区评价的重要前提。提出当今准噶尔盆地的地质构造格局是一个由活动翼(天山山前)、前渊(昌吉凹陷)和广大稳定前陆斜坡构成的复活前陆盆地。建议应编制两张准噶尔盆地中、新生代构造区划图。提出在盆地的油气勘探中不能唯“源控论”,勘探目标还应放在背斜以外的其它类型圈闭上。