台湾国姓地区中新世海相菱铁矿结核成因——来自草莓状黄铁矿粒径和硫同位素的证据

自生菱铁矿很好地记录了其形成时的地质信息及海洋中的生物地球化学过程,是示踪成岩作用带和氧化还原环境变化的绝佳载体。台湾国姓地区中新世猴洞坑组海相泥页岩中发育有大量自生菱铁矿结核,是次氧化带的产物。为进一步确认该菱铁矿形成时所处沉积环境的氧化还原状态和生物地球化学过程。本文对该区菱铁矿中保存完好的草莓状黄铁矿开展了粒径和硫同位素研究。结果显示,草莓状黄铁矿的粒径变化较大,平均粒径为9.23～11.55μm,最大粒径大于20μm,显示氧化-弱氧化的沉积环境特征;黄铁矿的δ³⁴S为-28.5‰～+3.1‰,平均值为-11.7‰,相较于海水(+21‰)富集轻的硫同位素,表明黄铁矿形成于相对开放的浅表层沉积物。黄铁矿的粒径分布规律和硫同位素特征均指示台湾国姓地区中新世海相菱铁矿形成于浅层弱氧化的次氧化带内。     

火山侵蚀和塌陷——以侵入体为中心的矿床叠生的成因

叠生作用是早期深部斑岩型矿化与晚期浅部贵金属和贱金属低温热液型矿化并置和叠覆的过程，叠生作用被认为是由于火山机制在洪积条件下受到迅速侵蚀或扇形（及不太可能的在皮火山口）塌陷引起的火山古地表同热液剥蚀造成的，在热液系统１Ｍａ的时间间隔内，古地表可下降１ｋｍ，使所含各类矿床至少在７ｋｍ的垂向范围内密集，由同矿化侵入作用造成的火山膨胀可以引发扇形塌陷，而火山机构的水热活动减弱使塌陷更容易。扇形塌陷引起大     

皖南和皖北城市地质调查比较——以黄山市、淮北市为例

以黄山市和淮北市为例,对皖南和皖北城市自然地理、社会经济、地质背景、主要城市地质问题、城市地质调查内容进行比较,认为黄山市和淮北市是安徽省南部和北部城市的典型代表,其城市地质调查主要目的、方法手段相同,侧重点应当根据城市地质背景特征和发展需要有所不同,对今后皖南和皖北地区其他城市开展此项工作具有借鉴意义.     

生油岩测井评价的理论和实践——以南阳、泌阳凹陷为例

本文根据生油岩的矿物组成、有机质的分布形式及泥岩的基本压实特征,建立了生油岩的测井响应方程,并用实际资料分析了生油岩在测井曲线上的特征。据此,我们采用图版法、I_x指数法和多元回归法、利用泥质砂岩的韦-史方程,提出了重迭、双孔隙度法对生油岩进行了评价,同时,提出了用碳/氧比测井计算有机碳的公式,并对双检2井取心井段的生油岩做了试算,结果令人满意。     

沉积岩钾、氩分布与天然气氩同位素——以渤海湾、四川和鄂尔多斯盆地为例

本文对渤海湾盆地、四川盆地和鄂尔多斯盆地等天然气产区41个不同深度、不同时代和不同岩性的油气源岩和储集岩利用K-Ar年龄测定法进行K、Ar分析、表面年龄测定和粘土矿物分析,探讨了沉积岩中钾、氩的时代和区域分布特征及泥质岩钾含量与粘土矿物中伊利石含量的关系,并对泥质岩和碳酸盐岩的钾氩分布进行对比研究,指出了沉积岩钾丰度的时代演化旋回及其特点.并讨论了岩石中的钾氩来源及赋存状态以及天然气中氩的来源及其进入气藏的运移机理.     

长江中下游湖泊沉积物铅污染记录——以洪湖、固城湖和太湖为例

2002～2005年在长江中下游的洪湖、固城湖和太湖分别采集了沉积物柱样钻孔,测定了总有机碳（TOC）和金属元素包括Pb,Al,Fe,Ti等,并采用210Pb和137Cs进行了近代沉积物定年。研究结果表明,洪湖钻孔平均沉积速率为0.15cm/a,固城湖平均沉积速率在0.067cm/a,太湖平均沉积速率为0.35～0.41cm/a。根据湖泊沉积物中铅元素与参考元素（Al,Fe和Ti）浓度和TOC的相关关系建立了回归方程,线性关系极显著（p<0.001）。根据回归方程获取了钻孔中铅的背景值变化,研究表明近代沉积物中金属铅不仅仅来源于自然的作用,而人类活动导致铅的累积发生时间都在20世纪70年代,从一个侧面也说明利用沉积物铅含量变化进行断代存在可能性。对太湖钻孔而言,其污染程度要高于洪湖和固城湖。研究结果表明近30年来洪湖和固城湖人为造成湖泊沉积物铅累积量在不断增加,其沉积物铅污染有进一步加重的趋势,应受到科学家和管理部门的关注。     

RAGA和PPCE在崩塌、滑坡、泥石流灾害评价中的应用——以重庆市北碚区为例

基于RAGA的PPCE方法解决了多维空间数据到一维投影的过程.本论文以重庆市北碚区地质灾害数据为基础,用该方法对区域地质灾害评价和区划做初探,得出如下结论:危岩体主要分布在溪家河组和上沙溪庙组砂岩区.滑坡和泥石流主要分布在泥岩层分布区;嘉陵江回水区和侵蚀岸分布灾害体较堆积岸多.高危险等级地质灾害主要分布在嘉陵江沿岸有支流汇入地区;高等级地质灾害主要分布在嘉陵江侵蚀沿岸及峡口附近;向斜的轴部距河较远地区灾害等级较低.RAGE和PPCE方法运用到河谷地质灾害评价中,能准确反映地质灾害危险等级,为河谷地质灾害研究提供了新的思路和方法;用GIS方法从点数据到面的研究有一定创新.     

基于GIS和AHP的灰色评估法在工程建设适宜性评价中的应用——以黄山市中心城区为例

随着城市现代化进程的加快,工程建设活动日趋频繁.在城市规划、工程建设前进行地质条件分析、适宜性评价是十分必要的.工程建设适宜性受多种因素影响,各因素间相互关联但影响程度不同.文章以黄山市中心城区为实例,从地质环境条件角度出发,介绍基于地理信息系统（GIS）和层次分析法（AHP）的灰色评估法在实际评价工作中的具体应用.该方法首先选取与工程建设适宜性密切相关的影响因素作为评价因子,在对评价单因子定性评价的基础上,用AHP确定各评价单因子的权重,最后用灰色评估法对工程建设适宜性进行综合评估.该应用效果较好,可在同类评价中推广.     

Pb、Zn、Cd和Cr等元素的生物有效性研究——以胶州湾水生系统为例

本文首先利用同站位多介质同采的资料分析研究了各环境介质中的不同痕量金属对生物富集的贡献,提出孔隙水中Pb、Zn、Cd、Cr对生物体中同名组分富集的贡献较大;进而采用PHREEQC软件模拟了孔隙水中Pb、Zn、Cd、Cr四种元素的组分存在形态,结果表明:PbCO3、Zn2 、CdCl2、Cr(OH)3分别为孔隙水中Pb、Zn、Cd、Cr的优势态,但其生物有效形态依次为PbSO4、ZnOHCl、CdCl 、Cr(OH)2 。最后作者提出生物对其所处环境介质中痕量金属的富集并不取决于痕量金属的总量或其相应的优势态浓度的多寡,而是取决于痕量金属的生物有效态的浓度大小。     

1995-2005年：中国当代玉雕创作的黄金时期——以台湾回流玉器为线索

当代玉雕的发展经历了两个高峰期：20世纪80年代以及21世纪初直至当下。但整个市场环境的高峰并不一定就能完全和创作高峰划等号。当代玉雕创作的黄金时期,既不属于20世纪80年代的阵营,也不完全重合21世纪初直至当下的范畴,而是在1995-2005年这样一个时间段。这种论断的裁定并非空穴来风,最先因为2012年尚善堂一批台湾回流玉器的出现而得到了印证,这批玉器制作完工的时间是1997-2005年。在随后进一步对台湾回流玉器进行梳理的过程中,2007年一次上海玉展中的台湾玉器作为“回流玉器”的样本浮出水面,将时间范围扩大到了1995-2007年。对比发现,两批作品在材料、工艺、艺术性等各方面都具有相似的特点,并且具有相当高的艺术水准,乃至于现在也无法超越。基于此,回顾当代玉雕发展历程的诸多细节,甚至将其置于更加广阔的文化背景、社会环境中去探究,最终发现把当代玉雕创作的黄金时期划归在1995-2005年这一时间段是合乎情理的。最为重要的是,它的确以其不可复制的典范性持续影响着之后的创作,意义非凡。     

Large earthquake-triggered landslides and mountain belt erosion: The Tsaoling case,Taiwan

The 1999 Chi-Chi earthquake triggered the catastrophic Tsaoling landslide in central Taiwan. We mapped the landslide area and estimated the landslide volume, using high-resolution digital elevation model from airborne LiDAR (Light Detection and Ranging), satellite images, aerial photographs and topographic maps. The comparison between cut and fill volumes, about 0.126 and 0.150 km³, respectively, suggests a volume increase of 19% due to decompaction during landsliding. In April 2002, the cut and fill volumes were about 0.137 and 0.116 km³, respectively. These estimates suggest that 2.5 years after the event, the volume of landslide debris removed by river erosion was nearly 0.045 km³. Such a large value highlights the importance of landslide processes for erosion and long-term denudation in the Taiwan mountain belt. To cite this article: R.-F. Chen et al., C. R. Geoscience 337 (2005).     

闽、台、海峡地区地震活动整体性的时空强度韵律初探

闽、台及海峡三区域发生的较大强度的地震,在时间上具有成丛性系列的特征,在空间上具有一定顺序的迁移性。其所呈现出的不同形态的时、空、强韵律,其原因可能是“多应力集中源”效应所引起的。     

Estimation of subsidence using GPS measurements,and related hazard: the Pingtung Plain,southwestern Taiwan

Four years of GPS measurements were done since 1996 in southwestern Taiwan in order to investigate crustal deformation and land subsidence. The network of 48 stations revealed the velocity field in the Pingtung Plain. Horizontal velocities range from 31 to 54 mm?yr^?1 towards azimuths 247° to 273°. They show clear anti-clockwise deviation in the coastal area, consistent with tectonic transtension related to lateral escape at the transition collision–subduction. The deformation resembles a particle flow towards a free boundary, and is not a rigid rotation. Vertical velocities range from +13 to $?25\text{mm}{\text{yr}}^{\mathrm{?1}}$. Twenty stations show fast subsidence in the coastal area, with rates averaging $?16\text{mm}/\text{yr}$. The comparison with Holocene subsidence suggests that about 75% of the present-day subsidence result from decreasing groundwater level induced by over-pumping, adding significant short-term component to the natural risk resulting from long-term tectonic subsidence. To cite this article: C.-S. Hou et al., C. R. Geoscience 337 (2005).     

The knowledge rules of debris flow event: A case study for investigation Chen Yu Lan River, Taiwan

Debris flow, one of the most active hydrological processes, brings about a great loss of life and properties in the Chen Yu Lan River area, Nan-Tou County, Taiwan. The goal of this study is to manage and monitor the debris flows in a vast area. Thus, the strategy is to collect hydraulical and in-situ data easily and quickly through our spatial information system. Then, a novel Data Mining technique will be developed to find a rule-based knowledge system of debris flow. The entire study can be divided into two parts. In the first part, using spatial information the debris flow image is extracted from the outbreak area. The system provides precise positional information pertaining to the debris flow events. Attributes such as effective watershed area, Normalized Difference Vegetation Index (NDVI), and slope are automatically obtained from the system. In the second part of this study, K-mean theory is used to classify the observed hydraulical and in-situ data into different categories. Then, the ‘Effective Rough Set’ method is successfully used to analyze the factors influencing the debris flow phenomenon and delivers rational knowledge rules. The contribution of this study is presented that NDVI, slope and effective watershed area are the major factors influencing debris flow in the study area. The knowledge rules can provide better understanding on the elevation of high potential debris catchments.     

The effect of typhoon induced rainfall on settling fluxes of particles and organic carbon in Yuanyang Lake, subtropical Taiwan

A sediment-trap monitoring program measured the fluxes of settling particles and organic carbon in Yuanyang Lake, northern Taiwan, from July 2004 to July 2006 and assessed their relations to the amounts of normal monthly and typhoon-event precipitation. The flux of settling particles varied from 0.7 mg cm^?2 month^?1 to 14.7 mg cm^?2 month^?1, and the monthly precipitation ranged from 56 mm to 1218 mm during the survey period. The contributions from typhoon-event precipitation to monthly rainfall amounts were generally larger than 70%. Higher inputs of both particulate and organic carbon into the lake were found during typhoon seasons. Of the annual settling particle loading of 14.9 tons year^?1 to the lake floor, 69% occurred during the typhoon months, and 62% of the annual organic carbon loading of 2.3 tons year^?1 happened during the typhoon months. These results show the importance of typhoon events on the fluxes of settling particles and organic carbon and their delivery to lakes.     

Late Holocene coseismic uplift on the Hua-tung coast, eastern Taiwan: Evidence from mass mortality of intertidal organisms

The evidence of coseismic uplift on the dynamic, wave-dominated Hua-tung coast fringing the active Coastal Range (eastern Taiwan) has been equivocal, due to complex controls by wave and terrestrial sediment over morphological and ecological systems of the coast. This study, by applying radiocarbon dating methods, demonstrates coseismic-uplift nature of the coast by finding synchronously killed intertidal organisms (mostly boring shell Jouannetia sp.) stranded at different sites of the coast with distinct physiographic characters. Based on these data, together with evidence from wave-cut notch sequences, two coseismic-uplift systems are recognized. One centers around the northern-middle part of the coast and yields events with uplift amounts of maximal 3–6 m and an average recurrence interval of at least several hundred years. The most recent activity of this system, influencing at least 70 km of coast, occurred at ~ 0.9 ka. The earthquake generating this event also triggered extensive landslides/debris flows in the region. Another system, exemplified by the uplift associated with the 2003 Cheng-kung earthquake, centers on the southern part of the coast and yields uplift of likely < 1 m every < 0.2 ky. Two pre-historic events of this system are identified as occurring at ~ 0.7 ka and ~ 1.1 ka. These two coseismic-uplift systems are consistent in position with two anticlinal structures defined by long-term uplift of the coast. However, the areas subjected to maximal coseismic uplift are located off where the climaxes of long-term uplift occur, implying that the latter areas have been uplifted mainly by aseismic and/or relatively frequent/small-magnitude coseismic motion.     

Electrical structures of the source area of the 1999 Chi-Chi, Taiwan, earthquake: Spatial correlation between crustal conductors and aftershocks

Wide-band magnetotelluric (MT) data were collected on an east–west profile, approximately perpendicular to the local strike of the Chelungpu thrust, through the hypocentral area of the Chi-Chi earthquake for imaging the seismogenic structure. MT data were then inverted for two-dimensional resistivity models plus best-fitting static shift parameters using a nonlinear conjugate gradient algorithm that minimizes the sum of the normalized data misfits and the smoothness of the model. As shown in the inverted 2D resistivity models presented in this paper, an electrical conductor beside the hypocenter of the Chi-Chi earthquake indicates that deep-crustal fluids may participate in the rupture process of the Chi-Chi earthquake. A striking spatial correlation between the crustal conductor and occurrence of aftershocks beneath the Chelungpu fault suggests a postseismic pore pressure adjustment ongoing after the mainshock. Additionally, the hypocenter exhibits an electrical resistive zone, consistent very well with a predicted compact zone from a crustal deformation and transient fluid flow modeling.     

From continental margin extension to collision orogen: structural development and tectonic rotation of the Hengchun peninsula, southern Taiwan

As a result of oblique collision, the Taiwan orogen propagates southward. The Hengchun peninsula in the southern tip of the Taiwan Central Range, preserving the youngest, the least deformed and the most complete accretionary prism sequences, allows therefore better understanding of the tectonic evolution of Taiwan orogen. On the Hengchun peninsula, four main stages of paleostress can be recognized by the analysis of brittle tectonics. After recording the first two stages of paleostress, rocks of the Hengchun peninsula (the Hengchun block) have undergone both tilting and counterclockwise rotation of about 90°. The structural boundaries of this rotated Hengchun block are: the Kenting Mélange zone in the southwest, the Fongkang Fault in the north, and a submarine backthrust in the east. The angle of this rotation is principally calculated by the paleomagnetic analysis data and a physical model experiment. Through a systematic back-tilting and back-rotating restoration, the original orientations of the four paleostress stages of Hengchun peninsula are recognized. They are, from the ancient to the recent, a NW–SE extension, a combination of NW–SE transtension and NE–SW transpression, a NE–SW compression, and finally a combination of NE–SW transtension and NW–SE transpression. This result can be explained by a phenomenon of stress axes permutation, instead of a complex polyphase tectonism. This stress axes permutation is caused by the horizontal compression increase accompanying the propagation of the accretionary prism. Combining the tectonic and paleomagnetic data with paleocurrent and stratigraphic data enables us to reconstruct the tectonic evolution of the Hengchun peninsula. This reconstruction corresponds to the deformation history of a continental margin basin, from its opening to its intense deformation in the accretionary prism.     

Identification of the origin of salinization in groundwater using multivariate statistical analysis and geochemical modeling: a case study of Kaohsiung,Southwest Taiwan

The study of brine aquifers in southern Taiwan is highly complicated by hybrid geochemical reactions, which obscure important geochemical information. Using multivariate analysis on major and minor ion compositions normalized by Cl⁻ content, chemical constituents were combined into two principal components representing brine mixing and mineral precipitation. Comparing to multivariate analysis on the original data, this procedure reveals more geochemical information. It demonstrates that the brine groundwater of the region is primarily composed of highly evaporated seawater. The evaporation ratio is >70%; a point at which calcite, dolomite and gypsum precipitate. Oxygen and hydrogen isotopic compositions confirm this inference; and further, geochemical modeling quantitatively determined the evaporation ratio to be about 85%. Natural boron contamination is a consequence of brine groundwater. Two evolutionary trends in the plotting of the Cl/B ratio versus Cl⁻ can be identified: (1) Cl/B ratio decreases with boron being released from clay minerals when brine aquifers are flushed with freshwater; and (2) Cl/B ratio increases when seawater of a high Cl/B ratio infiltrates coastal aquifers.     

南海台西南区碳酸盐岩矿物学和稳定同位素组成特征——天然气水合物存在的主要证据之一

南海台西南区是中国南海中天然气水合物赋存的最有利场所。研究表明,该区的碳酸盐岩主要以结壳、烟囱的形式出现,结壳的裂隙或孔洞中常常充填有淡黄-白色的文石晶体。碳酸盐岩中自生碳酸盐矿物主要为文石、高镁方解石,少量白云石、铁白云石和菱铁矿。扫描电子显微镜(SEM)分析表明,文石主要呈针状、长柱状、放射束状,高镁方解石呈颗粒状。碳酸盐岩的碳同位素δ13C值主要在-56·878‰~-32·829‰PDB之间,大多数小于-40‰PDB,显示了生物甲烷成因碳源的特征;氧同位素δ18O值在2·1875‰~5·045‰PDB之间,主要在4‰PDB以上,这种较重的氧同位素比值表明,天然气水合物分解产生的富18O水体可能是碳酸盐岩沉淀的流体源。矿物学和碳氧稳定同位素研究表明,南海台西南区的碳酸盐岩为细菌性甲烷成因碳酸盐岩,可能与天然气水合物有关,显示了该区水合物存在的可能性很大。