Deformational behaviour of continental lithosphere deduced from block rotations across the North Anatolian fault zone in Turkey

Theoretical considerations of lithosphere deformation across transform plate boundaries predict an expression in terms of 3istributed deformation. The magnitude of rotation is expected to diminish away from the fault zone in a way which depends on the length of the fault, the amount of displacement, and the ductility of the lithosphere. Palaeomagnetic studies across the North Anatolian transform fault zone, which separates the Eurasian Plate and Anatolian Block in northern Turkey, show that clockwise rotations predicted from the sense of dextral motion are indeed present and have attained finite rotations of up to 270° during the 5 Ma history of Neotectonic deformation. Such rotations are, however, confined to narrow ( 10 km wide) zones between system-bounding faults and appear to have resulted from rotation in ball-bearing fashion of equidimensional blocks a few kilometres in size. Outside of this zone only anticlockwise rotations are observed; these are unrelated to deformation across the fault zone and record regional anticlockwise rotation of Turkey which is complementing clockwise rotation of Greece and accompanying Neogene opening of the Aegean Sea. The observed behaviour of continental lithosphere satisfies no plausible value of power law behaviour. We therefore conclude that relative motion across this transform boundary occurs as a discrete zone of intense deformation within a brittle layer comprising the seismogenic upper crust. This is presumed to be detached from a continuum deformation response to shearing in the lower crust and mantle beneath.     

中新生代中国及邻区板块碰撞、旋转及离散模式初探

本文在6000多个资料点的42000余数据的基础上,应用计算机成图技术,以活动论的观点对中国大陆的运动程式进行初探。根据煤和蒸发盐岩沉积范围的变迁以及火山活动的分布特点推断中生代以来,中国大陆在周边各板块的相互作用下,由北向南迁移并作顺时针旋转,从而形成当今的大地构造格局。     

西北太平洋强地震的节律性与El Nino和地球自转

本文利用100年来西北太平洋强地震资料分析发现:强震有明显的“活跃期”与“平静期”交替的现象。“强震活跃”与“E1 Nino事件”两者的同时相关系数达0.62,信度高于0.1％。“强震活跃”与地球自转减慢亦有很好的同步性。文中还对这三种重要的地球物理现象基本同步的原因进行了讨论,认为可能是叠加在太平洋地幔对流圈上的“正扰动”所同时产生的三个结果。     

Paleomagnetic study on the Early Triassic red beds from Jiaocheng, Shanxi Province--Local rotation and tectonic significance

Paleomagnetic and rock magnetic study has been conducted on the Early Triassicred beds of Liujiagou Formation from Jiaocheng, Shanxi Province. Hematite was shown as themain magnetic mineral. After eradicating an initial viscous component at room temperature to～100℃-200℃, thermal demagnetization shows that most samples contain two remanencecomponents, intermediate-temperature remanence component at 250℃-500℃ and high-tem-perature component at 500℃-680℃. The intermediate-temperature component has a negativefold test at the 95% confidence level. And the pole position of the intermediate-temperaturecomponent in geographic coordinates is correlated with the Middle Jurassic reference pole of theNorth China Block (NCB) within the 95% confidence, suggesting that it might be a remagnetiza-tion component acquired during the Yanshanian period. The high-temperature component con-tains both reversal and normal polarities with positive fold test and C-level positive reversal test atthe 95% confidence level, which suggests that this high-temperature component can be regardedas primary magnetization. Comparison of this newly obtained Early Triassic paleopole with thecoeval mean pole of the Ordos Basin suggests that a locally relative rotation may have happenedbetween the Ordos and the Jiaocheng area of Shanxi Province. This rotation may be related withtwo faults: one is Lishi big fault separating Ordos from Shanxi and the other is Jiaocheng big fault,which is situated in the southeast of sampling locality and was still in motion during the Cenozoic.     

Testing of the IERS2000 Sub-Daily Earth Rotation Parameter Model

The differences between the new International Earth Rotation Service (IERS) 2000 and the previous IERS1996 sub-daily Earth rotation parameters (ERP) models can reach 0.1 mas (0.001 arc sec) and 0.1 mas/day. The largest differences are seen for the aliasing periods of 14.2 and 360 days, which correspond to the diurnal tidal waves of O1 and (K1, P1), respectively. Precise independent polar motion (PM) rate solutions effectively doubles the sampling rate and allows for effective testing of sub-daily ERP models and other periodical effects at the diurnal and semi-diurnal frequency bands. Since November 12, 2000, when the Jet Propulsion Laboratory (JPL) Analysis Center of International GPS Service (IGS) has switched to the conventional IERS1996 sub-daily ERP model, from the older model of Herring and Dog (1994), the JPL daily PM rate solutions show no, or greatly reduced 14.2 day amplitude (O1) peaks. This confirmed that the anomalistic amplitudes at 14.2 day period seen for JPL PM solutions prior November 12, 2000 was largely due to the effects of the older sub-daily ERP model on independent PM rate solutions. As indicated by the latest IGS PM rate solutions, which were corrected for the IERS1996 and 2000 model differences, the new IERS2000 sub-daily ERP model is expected to perform equally well as the conventional IERS1996 model.     

Pattern of latest tectonic motion and its dynamics for active blocks in Sichuan-Yunnan region, China

Based on the concept of "active blocks" and spatial distribution of historical earthquakes with surface ruptures as well as major and subordinate active faults. The Sichuan-Yunnan region can be divided into four first-order blocks. They are the Markam block (I), the Sichuan-Yunnan rhombic block (II), Baoshan-Pu'er block (III), and Mizhina-Ximeng block (IV). Cut by sub-ordinate NE-trending active faults, the Sichuan-Yunnan rhombic block (II) can be further divided into two sub-blocks: the northwestern Sichuan sub-block (II1) and the middle Yunnan sub-block (II2), while the Baoshan- Pu'er block (III) can be further divided into three sub-blocks: Baoshan sub-block (III1), Jinggu sub-block (III2), and Mengla sub-block (III3). A quantitative study of offset landforms is carried out and the basic types of active faults and their long-term slip rates along the major boundaries of active blocks of different orders in the Sichuan-Yunnan region are determined, through slip vector analysis, the motion states of the active blocks are clarified and the deformation coordination on the block margins is discussed. It is suggested that the tectonic motion of the blocks in this region is a complex or superimposition of three basic types of motions: southeastward sliding, rotating on vertical axis, and uplifting. The Markam block (I), the northwestern Sichuan sub-block (II1), and middle Yunnan sub-block (II2) have a southeastward horizontal sliding rate of 1-5 mm/a, clockwise rotating angular rate of 1.4-4(/Ma, and uplifting rate of about 1 mm/a. The Baoshan-Pu'er (III) and Mizhina-Ximeng (IV) blocks have also been extensively clockwise rotated. This pattern of motion is a strain response to the collision between the Indian and Eurasian plates and the localized deformation and differential slip on the block margins associated with the northward motion of the Indian Plate. Because a set of transverse thrusts between the blocks absorbs and transforms some components of eastward or southeastward sliding motion, the eastward escape or extrusion of the Tibetan Plateau is limited as "imbricated thrusting transformation-limited extrusion model".     

地球的差异旋转

对于具有流体对流层的旋转星球 ,由于星球自转对对流的影响 ,必然会在星球对流层内部不同部分间以及星球的不同圈层间产生差异旋转 (differentialrotation) .所谓差异旋转是指旋转角速度随着深度 (星球不同圈层的旋转角速度不同 )以及纬度 (同一圈层内部不同部分间的角速度不同 )具有差异的现象 .地球是一个多圈层的旋转系统 ,主要由大气圈、水圈、岩石圈、地幔、外核以及内核组成 .大气圈和水圈具有明显的流体性质 ,并且在漫长的地质年代中 ,地幔、岩石圈和地幔之间的软流层以及外核均具有流体性质 ,而且在大气压力、热、重力和电磁力等的作用下发生了对流 .这些对流运动一旦受到地球自转的影响 ,就必然会致使地球各圈层间以及对流层内部不同部分间产生差异旋转 .几个重要现象 :基本地磁场的长期西漂、岩石圈的长期西漂、地球自转速率变化 (周日长度波动 )和固体内核各向异性对称轴的移动表明在固体地球内部各圈层—岩石圈、地幔、外核和内核间存在差异旋转 .来自地震学上的数据证明了固体内核与地幔之间存在较明显的差异旋转 ,速率可达 1.1°～ 3.0°/a.这跟其它数据如自由振荡数据以及地磁场长期西漂数据获得的结果具有很大的差异 .导致固体地球内核相对于地幔差异旋转的主要宏观机制为电磁力矩、引     

同步耦合断裂及其动力学依据

通过对地球自转速率变化推动构造运动的可能性以及地球自转角速度变化的原因和依据的讨论，提出地球自转惯性力差是决定板块相对运动趋势的主要动力学因素之一，揭示了加速期和减速期经、纬向构造之间的分布规律性，认为经、纬向构造之间的耦合关系是一种客观存在，同步耦合断裂就是由地球自转速率变化所反映的动力学状态决定的。同时，笔者对同步耦合断裂概念及耦合区构造组合的研究意义进行了探讨。     

Comparison of Two Wavelet Transform Coherence and Cross-Covariance Functions Applied on Polar Motion and Atmospheric Excitation

The wavelet transform techniques were applied to compute time-frequency spectra, coherence and cross-covariance functions between complex-valued polar motion and atmospheric excitation functions. These wavelet transform approaches are based on the classical wavelet transform with Morlet wavelet and the harmonic wavelet transform. The computed coherence and cross-covariance functions enable comparison of polar motion and atmospheric excitation functions data in the chosen frequency band. In the study we concentrate on short period oscillations with periods ranging from several to about 250 days. The time lag functions show frequency dependent time lags corresponding to maxima of the modules of cross-covariance functions between the polar motion and atmospheric excitation functions.     

Sub-Daily Earth Rotation Parameters and the International GPS Service Orbit/Clock Solution Products

Tidally induced sub-daily Earth Rotation Parameters (ERP) variations, when not properly accounted for, can cause apparent orbit and ERP rate errors, which can significantly exceed the IGS solution errors. All International GPS Service (IGS) Analysis Centers currently apply the conventional sub-daily ERP model in their transformations from ITRF (International Terrestrial Reference Frame) to ICRF (International Celestial Reference Frame), both of which are used for IGS global analyses. However, some IGS Analysis Centers did not apply the sub-daily ERP model when transforming ICRF orbit solutions to ITRF, which is used for IGS orbit/clock products. This transformation inconsistency can cause significant orbit RMS differences that could exceed the 5-cm level. Independent ERP rate solutions are sensitive even to small errors in the sub-daily ERP model, and can be used to verify the sub-daily ERP model at, or below 0.1 mas/day precision level.The Precise Point Positioning (PPP) via precise station position solutions with the IGS orbit/clock combined products, provides an ideal interface to access the IGS realization of ITRF. PPP also yields precise station clock and tropospheric zenith delays (TZD) solutions, all at the sub-cm precision level. However, when using IGS orbit/clock products it is important that the same convention be used with respect to sub-daily ERP. Otherwise, the solutions of station navigation positions, station clocks and TZD's will be affected by significant errors that could exceed the 1-cm level.