台湾海峡新生代断裂构造及其形成演化

论述了台湾海峡新生代断裂构造基本特征，划分出海峡及两侧两大断裂系，探讨了断裂系的形成演化过程，阐明了断裂构造的形成演化与海峡裂谷演化的对应关系，并进一步探讨了海峡裂谷的演化模式。文中对ＮＷ向断裂折射平移和扇状收敛的首次发现，为弧陆碰撞引起海峡裂谷封闭的观点提供了重要佐证。     

海底地质勘查现代技术方法的应用现状及发展趋势

概述了当今海底地质勘查现代技术的应用现状及发展趋势,主要包括高精度全球定位系统。海底地形测深系统,海洋水声,声层析技术,海底取样技术,深潜器技术和海底天然气水合物资源探测技术等,特别是20世纪90年代国家“863”计划海洋领域“海洋探查与资源开发技术”主题研究,研制和开发取得的一系列高技术成果。     

The morphology and tectonics of the Mark area from Sea Beam and Sea MARC I observations (Mid-Atlantic Ridge 23° N)

High-resolution Sea Beam bathymetry and Sea MARC I side scan sonar data have been obtained in the MARK area, a 100-km-long portion of the Mid-Atlantic Ridge rift valley south of the Kane Fracture Zone. These data reveal a surprisingly complex rift valley structure that is composed of two distinct spreading cells which overlap to create a small, zero-offset transform or discordant zone. The northern spreading cell consists of a magmatically robust, active ridge segment 40–50 km in length that extends from the eastern Kane ridge-transform intersection south to about 23°12′ N. The rift valley in this area is dominated by a large constructional volcanic ridge that creates 200–500 m of relief and is associated with high-temperature hydrothermal activity. The southern spreading cell is characterized by a NNE-trending band of small (50–200 m high), conical volcanos that are built upon relatively old, fissured and sediment-covered lavas, and which in some cases are themselves fissured and faulted. This cell appears to be in a predominantly extensional phase with only small, isolated eruptions. These two spreading cells overlap in an anomalous zone between 23°05′ N and 23°17′ N that lacks a well-developed rift valley or neovolcanic zone, and may represent a slow-spreading ridge analogue to the overlapping spreading centers found at the East Pacific Rise. Despite the complexity of the MARK area, volcanic and tectonic activity appears to be confined to the 10–17 km wide rift valley floor. Block faulting along near-vertical, small-offset normal faults, accompanied by minor amounts of back-tilting (generally less than 5°), begins within a few km of the ridge axis and is largely completed by the time the crust is transported up into the rift valley walls. Features that appear to be constructional volcanic ridges formed in the median valley are preserved largely intact in the rift mountains. Mass-wasting and gullying of scarp faces, and sedimentation which buries low-relief seafloor features, are the major geological processes occurring outside of the rift valley. The morphological and structural heterogeneity within the MARK rift valley and in the flanking rift mountains documented in this study are largely the product of two spreading cells that evolve independently to the interplay between extensional tectonism and episodic variations in magma production rates.     

应力-应变过程中海底沉积物微结构变化对其声速的影响

阐述了对海底沉积物样品在应力-应变过程中进行同步声学测量的实验工具及方法,分析了采自南海45个站位的海底沉积物样品的实验数据资料,结果表明,沉积物颗粒越粗、孔隙越小、无侧限抗压强度越大,声速越高.沉积物样品在受力应变过程中,声速具有明显的随应力而变化的特征.进一步探讨了不同应变阶段沉积物的声学特征以及应力所导致沉积物微结构变化对其声速的影响过程,这一研究将在石油地质测井和海底工程基底稳定性评价等方面具有重要应用意义.     

An east–west‐trending Quaternary tunnel valley in the south‐eastern North Sea and its seismic–sedimentological interpretation

A combination of a dense reflection seismic grid and up to 50‐m‐long records from sediment cores and cone penetration tests was used to study the geometry and infill lithology of an E–W‐trending buried tunnel valley in the south‐eastern North Sea. In relation to previously known primarily N–S‐trending tunnel valleys in this area, the geometry and infill of this 38‐km‐long and up to 3‐km‐wide valley is comparable, but its E–W orientation is exceptional. The vertical cross‐section geometry may result from subglacial sediment erosion of advancing ice streams and secondary incision by large episodic meltwater discharges with high flow rates. The infill is composed of meltwater sands and reworked till remnants on the valley flanks that are overlain by late Elsterian rhythmic, laminated, lacustrine fine‐grained sediments towards the centre of the valley. A depression in the valley centre is filled with sediments most likely from the Holsteinian transgression and a subsequent post‐Holsteinian lacustrine quiet‐water setting. The exceptional axis orientation of this tunnel valley points to a regional N–S‐oriented ice front during the late Elsterian. Copyright © 2012 John Wiley & Sons, Ltd.     

Infiltration,runoff and soil loss in Andisols affected by forest fire (Canary Islands,Spain)

Depending on the severity of the fire, forest fires may modify infiltration and soil erosion processes. Rainfall simulations were used to determine the hydrological effects of fire on Andisols in a pine forest burned by a wildfire in 2007. Six burned zones with different fire severities were compared with unburned zones. Infiltration, runoff and soil loss were analysed on slopes of 10% and 30%. Forest floor and soil properties were evaluated. Unburned zones exhibited relatively low infiltration (23 and 16 mm h^?1 on 10% and 30% slope angles, respectively) and high average runoff/rainfall ratios (43% and 50% on 10% and 30% slope angles, respectively), which were associated with the extreme water repellency of the forest floor. Nonetheless, this layer seems to provide protection against raindrop impact and soil losses were found to be low (8 and 16 g m^?2 h^?1 for 10% and 30% slope angles, respectively). Soil cover, soil structure and water repellency were the main properties affected by the fire. The fire reduced forest floor and soil repellency, allowing rapid infiltration. Moreover, a significant decrease was noted in soil aggregate stabilities in the burned zones, which limited the infiltration rates. Consequently, no significant differences in infiltration and runoff were found between the burned and the unburned zones. The decrease in post‐fire soil cover and soil stability resulted in order‐of‐magnitude increases in erosion. Sediment rates were 15 and 31 g m^?2 h^?1 on the 10% and 30% slope angles, respectively, in zones affected by light fire severity. In the moderate fire severity zones, these values reached 65 and 260 g m^?2 h^?1 for the 10% and 30% slope angles, respectively. Copyright © 2012 John Wiley & Sons, Ltd.     

浸矿开采对离子型稀土基岩力学特性的影响研究

为研究原地浸矿母液对离子型稀土矿收液底板的侵蚀影响,以离子型稀土矿基岩（半/弱风化花岗岩）为研究对象,开展了室内浸矿模拟试验。对比分析了不同浸矿时间岩样的应力−应变曲线、峰值应力、峰值应变和弹性模量,获取了不同浸矿历时岩样的孔隙度和细观形貌特征,并运用盒维法对岩样的非线性裂纹特征进行了定量化描述。结果表明：浸矿侵蚀作用对离子型稀土矿底板基岩力学性质的影响主要表现在前150 d,破坏形式由贯穿破坏转变为贯穿破坏与片状剥落并存;浸矿母液侵蚀作用下,基岩力学特性呈现先大幅减小后大幅回升,其后在小范围波动现象,浸矿约60 d对基岩力学特性的影响程度最大;浸矿母液侵蚀造成基岩内小孔隙增长,导致表面出现腐蚀及孔洞现象;浸矿时间不同将造成岩石不同的微观结构变化。     

四川盆地裂陷槽研究新进展——关于裂陷槽成因机制与形成时间的探讨

最新钻井和地震资料研究表明,四川盆地裂陷槽内大部分地区缺失震旦系（埃辿卡拉系）灯影组灯四段、灯三段及灯二段上部地层,灯二段仅残留富藻层及以下地层,震旦系地层具有环状剥蚀特征;残留的灯二段岩性主要为泥粉晶白云岩、藻纹层白云岩、藻格架白云岩、雪花状构造白云岩及砂砾屑白云岩,局部层段葡萄花边构造发育,沉积相属于典型的局限台地,沉积特征与盆地内其它地区灯影组沉积特征相同,表明在震旦纪四川盆地碳酸盐台地内部并没有明显的构造分异。本文从地层、沉积特征及构造动力机制方面提出了四川盆地裂陷槽成因的解释意见,认为震旦系内部的裂陷槽形成于震旦系沉积之后,其成因可能与地幔柱拱升—地层剥蚀—地幔柱塌陷再沉降有关。     

Geomorphology of a modern carbonate slope system and associated sedimentary processes: Example of the giant Great Abaco Canyon,Bahamas

The large acoustic data set acquired during the Carambar cruises is composed of high resolution bathymetry, backscatter data and very‐high resolution seismic lines which allow for an overview of the morphology and sediment transfer processes from the shallow upper slope to the abyssal plain of a modern carbonate system: the north‐eastern slope of the Little Bahama Bank. Surficial distribution of the acoustic facies and echofacies reflects a wide variety of sedimentary processes along and across the slope. The western sector of the Little Bahama Bank is dominated by depositional processes whereas its eastern sector, which is incised in the lower slope by giant canyons, is affected by erosion and bypass processes. Datasets suggest that currents play an important role both in along‐slope sedimentary processes and in the abyssal plain. The Antilles Current appears to affect a large part of the middle and lower slopes. The absence of sizeable present‐day channel/levée complexes or lobes at the mouth of the canyon – revealed by the bathymetric map – indicates that the southward flowing Deep Western Boundary Current influences modern abyssal sediment deposition. Based on depositional processes and indicators of canyon maturity observed in facies distribution, the current study proposes that differential subsidence affects the eastern versus western part of the bank. The morphology of the Great Abaco Canyon and Little Abaco Canyon, which extend parallel to the platform, and the Little Bahama Bank slope appears to be related to the Great Abaco Fracture Zone.     

On the Anomalous Behaviour of Scalar Flux–Variance Similarity Functions Within the Canopy Sub-layer of a Dense Alpine Forest

Within the canopy sub-layer (CSL), variability in scalar sources and sinks are known to affect flux–variance (FV) similarity relationships for water vapour (q) and carbon dioxide (C) concentrations, yet large-scale processes may continue to play a significant role. High frequency time series data for temperature (T), q and C, collected within the CSL of an uneven-aged mixed coniferous forest in Lavarone, Italy, are used to investigate these processes within the context of FV similarity. This dataset suggests that MOST scaling describes the FV similarity function of T even though the observations are collected in the CSL, consistent with other studies. However, the measured FV similarity functions for q and C appear to have higher values than their temperature counterpart. Two hypotheses are proposed to explain the measured anomalous behaviour in the FV similarity functions for q and C when referenced to T. Respired CO₂ from the forest floor leads to large positive excursions in the C time series at the canopy top thereby contributing significantly to both C variance increase and C vertical flux decrease—both leading to an anomalous increase in the FV similarity function. For q, transport of dry air from the outer-layer significantly increases both the variance and the water vapour flux. However, the expected flux increase is much smaller than the variance increase so that the net effect remains an increase in the measured FV similarity function for water vapour above its T counterpart. The hypothesis here is that identifying these events in the temporal and/or in the frequency domain and filtering them from the C and q time series partially recovers a scalar flow field that appears to follow FV similarity theory scaling. Methods for identifying both types of events in the time and frequency domains and their subsequent effects on the FV similarity functions and corollary flow variables, such as the relative transport efficiencies, are also explored.