A data‐mining approach for assessing consistency between multiple representations in spatial databases

When different spatial databases are combined, an important issue is the identification of inconsistencies between data. Quite often, representations of the same geographical entities in databases are different and reflect different points of view. In order to fully take advantage of these differences when object instances are associated, a key issue is to determine whether the differences are normal, i.e. explained by the database specifications, or if they are due to erroneous or outdated data in one database. In this paper, we propose a knowledge‐based approach to partially automate the consistency assessment between multiple representations of data. The inconsistency detection is viewed as a knowledge‐acquisition problem, the source of knowledge being the data. The consistency assessment is carried out by applying a proposed method called MECO. This method is itself parameterized by some domain knowledge obtained from a second method called MACO. MACO supports two approaches (direct or indirect) to perform the knowledge acquisition using data‐mining techniques. In particular, a supervised learning approach is defined to automate the knowledge acquisition so as to drastically reduce the human‐domain expert's work. Thanks to this approach, the knowledge‐acquisition process is sped up and less expert‐dependent. Training examples are obtained automatically upon completion of the spatial data matching. Knowledge extraction from data following this bottom‐up approach is particularly useful, since the database specifications are generally complex, difficult to analyse, and manually encoded. Such a data‐driven process also sheds some light on the gap between textual specifications and those actually used to produce the data. The methodology is illustrated and experimentally validated by comparing geometrical representations and attribute values of different vector spatial databases. The advantages and limits of such partially automatic approaches are discussed, and some future works are suggested.     

Subsidence and thermal history of an inverted Late Jurassic‐Early Cretaceous extensional basin (Cameros,North‐central Spain) affected by very low‐ to low‐grade metamorphism

The Cameros Basin (North Spain) is a Late Jurassic‐Early Cretaceous extensional basin, which was inverted during the Cenozoic. It underwent a remarkable thermal evolution, as indicated by the record of anomalous high temperatures in its deposits. In this study, the subsidence and thermal history of the basin is reconstructed, using subsidence analysis and 2D thermal modelling. Tectonic subsidence curves provide evidence of the occurrence of two rapid subsidence phases during the syn‐extensional stage. In the first phase (Tithonian‐Early Berriasian), the largest accommodation space was formed in the central sector of the basin, whereas in the second (Early Barremian‐Early Albian), it was formed in the northern sector. These rapid subsidence phases could correspond to relevant tectonic events affecting the Iberian Plate at that time. By distinguishing between the initial and thermal subsidence and defining their relative magnitudes, Royden's (1986) method was used to estimate the heat flow at the end of the extensional stage. A maximum heat flow of 60–65 mW/m² is estimated, implying only a minor thermal disturbance associated with extension. In contrast with these data, very high vitrinite reflectance, anomalously distributed in some case with respect to the typical depth‐vitrinite reflectance relation, was measured in the central‐northern sector of the basin. Burial and thermal data are used to construct a 2D thermal basin model, to elucidate the role of the processes involved in sediment heating. Calibration of the thermal model with the vitrinite reflectance (%Ro) and fluid inclusion (FI) data indicates that in the central and northern sectors of the basin, an extra heat source, other than a typical rift, is required to explain the observed thermal anomalies. The distribution of the %Ro and FI values in these sectors suggests that the high temperatures and their distribution are related to the circulation of hot fluids. Hot fluids were attributed to the hydrothermal metamorphic events affecting the area during the early post‐extensional and inversion stages of the basin.     

Analysis of the Devonian (Frasnian) platform from Belgium: a multi‐faceted approach for basin evolution reconstruction

This study undertakes a multi‐disciplinary approach (sedimentology, carbon isotopes, magnetic susceptibility and thickness distribution) to improve understanding of a major Palaeozoic carbonate platform, the Frasnian platform of Belgium. These combined techniques are used to reconstruct the platform history, which evolved in two main steps. During the first phase, the basin was strongly influenced by faulting, producing notable thickness and facies variations, with open ocean conditions, with good water circulation and no/or limited barrier reef. The second phase of platform development was less influenced by differential subsidence, as indicated by homogeneous facies distribution. However, this platform developed under restricted waters, with low circulation which is likely related to the development of a barrier reef.     

A frequency response function change method for damage localization and quantification in a shear building under ground excitation

A frequency response function change (FRFC) method to detect damage location and extent based on the change in the frequency response functions of a shear building under the effects of ground excitation was proposed in this paper. The damage identification equation was derived from the motion equations of the system before and after the occurrence of the damage. Efforts to make the FRFC method less model‐dependent were made. Intact system matrices, which could be estimated using the measured data without the need for an analytical model, and the frequency response functions were required for the FRFC method. The effects of measurement noise and model parameter error in the FRFC method were studied numerically. The proposed FRFC method was validated by experimental studies of a six‐story steel building structure with single and multiple damage cases. Copyright © 2012 John Wiley & Sons, Ltd.     

辽西医巫闾山地区晚侏罗世花岗岩脉中热液锆石的成因与定年

辽西医巫闾山变质核杂岩经历过两阶段演化,晚侏罗世发育了围绕核部医巫闾山岩体周缘展布的长环形韧性剪切带（称为医巫闾山剪切带）,早白垩世西侧叠加了北北东走向瓦子峪伸展韧性剪切带。在医巫闾山剪切带及其变形下盘中侵入了大量的晚侏罗世花岗岩脉,其所含的锆石包括古老继承锆石、新生岩浆锆石、热液锆石等多种类型。根据锆石阴极发光图像、稀土元素配分曲线以及U、Th、Pb含量等特征,判别出热液锆石存在3种成因类型,包括流体的溶解—再沉淀、富Zr热液的直接结晶及流体的交代改造。它们共同具有高U、P、Y、Nb、Hf、Ta含量与低Th/U比值特征,前两种热液锆石还强烈富集稀土元素,其球粒陨石标准化配分曲线平坦。而第3类热液锆石具有亏损LREE、强烈富集HREE的特征,其配分曲线高度倾斜,不但有别于岩浆锆石与前两类热液锆石,也与前人对此类锆石的认识不一致。分析结果显示,高普通铅含量的热液锆石无法获得合理年龄,而大多数极低普通铅含量热液锆石则给出147 Ma左右的可靠年龄,略晚于岩脉的侵位时间（155～147 Ma）,有效地记录了区内晚侏罗世构造—岩浆事件的阶段。     

内蒙古毛登地区碎斑熔岩LA-ICP-MS锆石U-Pb年龄与地球化学特征

在内蒙古毛登地区发现碎斑熔岩发育,其具有熔岩和熔结凝灰岩的双重结构。毛登碎斑熔岩岩体呈近圆形穹状,可划分出中心相、过渡相和边缘相,不同相带岩石特征明显。LA-ICP-MS锆石U-Pb年龄为139.20Ma±0.73Ma,属早白垩世火山—岩浆活动的产物。岩石富硅、碱,轻稀土元素富集,Eu强烈亏损,富集Rb、Th,亏损Ba、K,与同期流纹岩的地球化学特征相同,研究表明其形成于造山后板内伸展环境。     

树轮记录的自公元1200年以来强火山喷发事件与高亚洲南部河流源区气候水文变化的关联

强火山喷发作为气候变化重要的外强迫因素,其所造成的气候环境效应一直是气候变化研究热点,而其对于流域水循环影响较少受关注。本文利用采自高亚洲南部河流源区麦吊云杉（Picea brachytyla）树轮样本,研制出一个长达885 a的树木年轮标准宽度年表。基于树轮气候响应分析结果,利用线性回归模型重建研究区自公元1200年上年11月至当年2月平均最低气温变化,重建方程方差解释量47.1%。该气温重建序列显示,研究区自公元1200年经历了8个冷期和9个暖期,包含有10个极冷年和23个极暖年。同时,该气温重建序列验证了自公元1200年来27次强火山喷发（VEI≥5）对于青藏高原东南部河流源区气候的影响,包括1257年Samalas和1815年Tambora等强火山喷发事件。该气温重建序列与相关河流径流数据对比结果表明强火山喷发在引起高亚洲南部河流源区气温出现明显下降的同时,也可能会进一步导致水循环减缓,使得高亚洲南部河流径流量出现减少。

     

Heating effects of the matrix of experimentally shocked Murchison CM chondrite: Comparison with micrometeorites

Abstract— Micrometeorites have been significantly altered or melted by heating, which has been mainly ascribed to aerodynamic drag during atmospheric entry. However, if a major fraction of micrometeorites are produced by impacts on porous asteroids, they may have experienced shock heating before contact with the Earth's atmosphere (Tomeoka et al. 2003). A transmission electron microscope (TEM) study of the matrix of Murchison CM chondrite experimentally shocked at pressures of 10–49 GPa shows that its mineralogy and texture change dramatically, mainly due to shock heating, with the progressive shock pressures. Tochilinite is completely decomposed to an amorphous material at 10 GPa. Fe‐Mg serpentine is partially decomposed and decreases in amount with increasing pressure from 10 to 30 GPa and is completely decomposed at 36 GPa. At 49 GPa, the matrix is extensively melted and consists mostly of aggregates of equigranular grains of Fe‐rich olivine and less abundant low‐Ca pyroxene embedded in Si‐rich glass. The mineralogy and texture of the shocked samples are similar to those of some types of micrometeorites. In particular, the samples shocked at 10 and 21 GPa are similar to the phyllosilicate (serpentine)‐rich micrometeorites, and the sample shocked at 49 GPa is similar to the olivine‐rich micrometeorites. The shock heating effects also resemble the effects of pulse‐heating experiments on the CI and CM chondrite matrices that were conducted to simulate atmospheric entry heating. We suggest that micrometeorites derived from porous asteroids are likely to go through both shock and atmospheric‐entry heating processes.     

MORPHOMETRIC ANALYSIS OF KARST DEPRESSIONS ON A MEDITERRANEAN KARST MASSIF

Dolines are the most typical landform in karst landscapes. They play an important role in karst hydrogeology; they are effective sediment traps that provide information about past climates and karst evolution, and can also be indicators of tectonic activity. The morphometic analysis of those depressions can help in their study and interpretation. However, detailed identification and delineation of dolines becomes increasingly difficult when the study area is very large, of limited access or covered by vegetation. Here, we have used a method developed by the authors for automatic identification and delineation of karst depressions based on the use of a pit removal algorithm. Next a complete morphometric analysis of the karst depressions has been carried out. The main advantage of the methodology is that by delineating and identifying the depth of each doline from its rim, many morphometric statistics can be obtained, including the relation of doline depth and area with respect to altitude, the main doline orientations, doline density, the fractal dimension of doline area and frequency, and point field analysis, among others. The results are interpreted from a geomorphological point of view and the mapped dolines can be easily integrated into geomorphological mapping. A case study is presented from the large Sierra Gorda karst massif in southern Spain, where 3100 depressions have been identified. A strong structural control of doline shape and orientation is demonstrated; the main areas of doline density are highlighted and doline size is shown to follow a fractal law.