Morphological and sedimentary features of sandy-muddy transitional beaches in estuaries and bays along mesotidal to macrotidal coasts

Sandy-muddy transitional beaches (SMT-Beaches), representing the transition from sandy beaches to tidal mudflats, should theoretically develop very different morphological and sedimentological characteristics in river estuaries and in semi-enclosed bays due to their contrasting dynamic sedimentary environments. Evidence, however, is rare in the scientific literature. To reveal these morphological and sedimentary differences, the sand–mud transition (SMT) boundary distribution, beach profiles, and surface and downcore sediment grain-size compositions of 27 SMT-Beaches located along mesotidal to macrotidal coasts of the western Taiwan Strait, southeastern China, were investigated. The results show that typical estuarine SMT-Beaches are mainly characterized by an ambiguous SMT, a long distance between the SMT and the coastline (31–302 m), lower SMT and inflection point altitudes (average –0.76 m and –0.04 m), and lower upper beach gradients (~0.068) with fine sand. Estuarine SMT-Beach sediments display clear interbedded mud and sand layers, implying potential SMT migrations over various timescales. By contrast, typical bay SMT-Beaches are characterized by distinct SMT, a short distance between the SMT and the coastline (11–52 m), higher SMT and inflection point altitudes (~0.24 m and ~0.35 m), and narrower upper beaches with higher gradients (~0.095) and coarse sand. Bay SMT-Beaches present relatively stable sedimentary sequences and a narrow gravel belt surrounding the inflection point and/or SMT. These morphological and sedimentary differences between the two SMT-Beach types are initially constrained by sediment supply and transport and are further affected by tide conditions and wave climate. Sediment supply and transport predominately control the sediment structures, while the tidal range strongly influences spatial variations in SMT distances. Wave climate normally drives SMT altitude variations. This study highlights the morphological and sedimentary differences in SMT-Beaches in estuaries and bays, providing important knowledge for further revealing their morphodynamic processes and potential future nourishment. © 2020 John Wiley & Sons, Ltd.     

Dynamic land use change simulation using cellular automata with spatially nonstationary transition rules

The dynamic relationships between land use change and its driving forces vary spatially and can be identified by geographically weighted regression (GWR). We present a novel cellular automata (GWR-CA) model that incorporates GWR-derived spatially varying relationships to simulate land use change. Our GWR-CA model is characterized by spatially nonstationary transition rules that fully address local interactions in land use change. More importantly, each driving factor in our GWR model contains effects that both promote and resist land use change. We applied GWR-CA to simulate rapid land use change in Suzhou City on the Yangtze River Delta from 2000 to 2015. The GWR coefficients were visualized to highlight their spatial patterns and local variation, which are closely associated with their effects on land use change. The transition rules indicate low land conversion potential in the city’s center and outer suburbs, but higher land conversion potential in the inner near suburbs along the belt expressway. Residual statistics show that GWR fits the input data better than logistic regression (LR). Compared with an LR-based CA model, GWR-CA improves overall accuracy by 4.1% and captures 5.5% more urban growth, suggesting that GWR-CA may be superior in modeling land use change. Our results demonstrate that the GWR-CA model is effective in capturing spatially varying land transition rules to produce more realistic results, and is suitable for simulating land use change and urban expansion in rapidly urbanizing regions.     

托莫尔日特金矿区韧脆性剪切带及其控矿作用

矿区位于近NW-NWW向展布的断裂带内,并严格受其控制.控矿断裂带为一条韧-脆性剪切带,其形成主要经历了早期韧性变形、晚期脆性变形及后期改造破坏3个阶段,叠加于早期韧性剪切带之上的晚期脆性破裂带,是矿脉的主要产出位置,成矿与断裂带的韧-脆性转换密切相关.矿体形成于韧-脆性剪切带的转换带附近,后期由于抬升剥蚀而出露地表.矿体分布可能具有"两层楼"式的垂直分带,上部为石英脉型金矿体,品位较高,但规模不大;下部为糜棱岩型金矿体,规模较大,但品位稍低.因此本区以后的找矿工作中应注意挖掘深部糜棱岩型金矿的潜力.     

锦屏隆里地区剪切构造变形的初步研究

在隆里地区新元古界下江群中发育有剪切变形的构造，形成脆－韧性剪切带（过渡性剪切带）。按其产状可分为切层和顺层过渡性剪切带两类，具有较典型的脆性－韧性变形的宏观和微观特征。此类变形是地壳浅层次剪切构造作用产物，显示了江南造山带外带的特征     

IMPACTS OF TWO TROPICAL CYCLONES EXPERIENCING EXTRATROPICAL TRANSITION DURING NORTHWARD PROGRESSION ON THE RAINFALL OF LIAODONG PENINSULA

Both of Typhoon Winnie (9711) and Matsa (0509) underwent an extratropical transition (ET) process when they moved northward after landfall and affected Liaodong Peninsula. However, Matsa produced half as much rainfall as Winnie, although it struck Liaodong Peninsula directly while Winnie passed through the Bohai Sea. The relations between the ET processes and the precipitation over Liaodong Peninsula are examined. The result shows that the precipitation difference between Winnie and Matsa was closely related to the interactions between the westerly systems and typhoons during their ET processes. Winnie was captured by the upper westerly trough and then coupled with it when moving to the mid-latitudes, and the positive anomaly of moist potential vorticity (MPV) was transported downward from the upper troposphere over the remnant circulation of the tropical cyclone (TC). It was favorable to the interaction between tropical warm and wet air and westerly cold air, causing convective cloud clusters to form and develop. The rain belt composed of several meso-β cloud clusters over the Liaodong Peninsula, resulting in heavy rainfall. On the other hand, Matsa did not couple with any upper trough during its ET process and the positive anomaly of MPV in the upper troposphere and its downward transfer were weak. Only one meso-β cloud cluster occurred in Matsa’s rain belt during its ET process that tended to lessen rainfall over Liaodong Peninsula.     

中国北方三流域河流—沙漠过渡带地表沉积物化学元素空间差异分析

通过对克里雅河、毛布拉格孔兑以及西拉木伦河三流域的河流-沙漠过渡带地表沉积物的7种常量氧化物以及15种微量元素进行因子分析,结果显示:三个流域之间或不同河段因子分析提取的公因子均可以概括为较稳定的铁锰矿物、较不稳定的长石类和方解石（白云石）类等硅酸盐矿物以及稳定的稀土元素和重矿物等类别;河流间因子分析结果表明,自西向东三个流域沿河地表沉积物的化学元素富集与迁移程度呈递增趋势,化学风化程度增强;流域内因子分析结果表明,自上游至下游,样点化学组成均愈变复杂,不同河段或不同河岸沉积物化学元素空间分布规律与其物源、地貌格局以及水分条件等因素有关;自河床至阶地,不同地貌单元地表沉积物化学元素呈相异的递变规律,这与在距离河道远近不同,物源、动力因素的分配不同有关。     

High-Pressure Behavior of Copper Carbonate: Data from Malachite

Abstract: In-situ high-pressure energy dispersive X-ray diffraction experiments of malachite have been performed using diamond anvil cell and synchrotron radiation. The highest recorded pressure is up to 17.4 GPa. The experimental results reveal that malachite experienced two phase transitions at 0.7 and 7.8 GPa, and the last one is reversible.     

高压下天然菱铁矿的压缩性和电子结构研究

采用同步辐射光源和金刚石对顶砧(DAC)技术,对天然菱铁矿的压缩性和电子结构进行了原位X射线衍射(XRD)和X射线吸收近边结构谱(XANES)测试研究。在室温下随着压力逐渐升高至50.2 GPa,菱铁矿保持方解石型结构不变,但是逐渐向Na Cl型结构转变;刚性[CO3]2-基团平行于ab-平面定向排列使c轴的压缩性大于a轴。菱铁矿在44.6~47.1 GPa之间发生电子由高自旋态(HS)向低自旋态(LS)的转变,表现为体积塌陷8%。HS菱铁矿的等温状态方程参数为K0=112(5)GPa和K'0=4.6(3)。首次采用XANES技术对菱铁矿中Fe2+的电子结构进行了研究,结果表明:随着压力升高至37.3 GPa,Fe2+的配位和局域对称并未发生明显变化;此后电子结构开始转变,Fe2+的3d轨道分裂能降低,电子跃迁概率增大,呈现LS特性。     

Sedimentary and drainage evolution of the Condamine Valley Transition Zone (eastern Australia)

The basal succession of the Condamine Valley, which overlays the boundary between the Surat and Clarence-Moreton basins (eastern Australia), contains a clay-rich horizon ‘the Transition Zone’ that marks a pronounced unconformity between the Jurassic Walloon Coal Measures and the Quaternary Condamine Alluvium. This paper provides insights into the tectonic and drainage evolution of the Condamine Valley through integrated analysis of U–Pb ages of detrital zircon from three samples (494 concordant analyses), stable oxygen isotope analysis on eight authigenic clay samples, X-ray fluorescence of primary and trace elements, and hyperspectral mineral analysis from two drill cores (Lone Pine 17 and Daandine 164). The Transition Zone is interpreted to consist of both weathered Jurassic sediments and Cenozoic clay deposits. Two sequential cycles of erosion, deposition and pedogenesis, related to geomorphological and climatic conditions are recognised. Distinctive oxygen isotope signatures of the two weathering fronts demonstrated an initial Early Cretaceous phase (δ¹⁸O?=?11.9–15.7‰ VSMOW) associated with laterisation and possible uplift, followed by Paleogene (δ¹⁸O?=?16.4–17.3‰ VSMOW) silcretisation of reworked Jurassic sediments. Detrital zircon geochronology yielded Jurassic maximum constraints for the age of deposition of three samples that are indistinguishable within error, the oldest of which (163?±?8?Ma from the lateritic profile) corresponds to the age of the underlying Walloon Coal Measures. The two overlaying samples from a silcrete profile and granular alluvium yielded overlapping yet younger ages of 150?±?6?Ma and 156?±?9?Ma, respectively. Vitrinite reflectance used as a proxy for the thermal condition of the coal strata enabled an estimated 2–3?km of burial and subsequent (likely Early Cretaceous) uplift. Geochemical insights from the Condamine Valley correspond to broad-scale climatic and tectonic conditions, suggesting that ‘transition zone equivalents’ and corresponding groundwater dynamics may occur in similar sedimentary settings throughout eastern Australia.     

马杏垣先生开合构造思想的提出、形成及最新进展

概述了马杏垣院士的学术生平与创建开合构造史实.开合构造提出是中国地球科学"百花齐放,百家争鸣"发展的结果;是黄汲清院士、张文佑院士、马杏垣院士领导的青年团队,在国际板块构造革命的新潮中,根据板块构造登陆存在的巨大问题,结合中国地质构造的特色,依据坚实的实际资料进行深入的全新探索.3位院士领导的团队又联合起来,进行开合构造的长期研究.2002年在构造地质专业委员会支持下,成立了开合构造研究组,召开了开合构造第一次学术研讨会,总结20多年研究成果,出了专刊书集.2015年研究组聚首北京,总结开合构造研究的新成果,并吸取地球物理研究新成果,准确地阐明开合构造的定义,提升了研究方法,总结了开合构造运动和开合构造体系特征,将构造动力来源初始点建立在古登堡面的开合构造转换带上,全新解析了转换带的重要作用,站在星球角度认识开合构造.最后,强调青年研究力量的培养,是开合构造走向世界的重要途径.