Seismic characterization of switching platform geometries and dominant carbonate producers (Miocene,Las Negras,Spain)          下载免费PDF全文

Lucas M. Kleipool  Koos de Jong  Eveline L. de Vaal  John J. G. Reijmer 《Sedimentology》2017,64(6):1676-1707

The primary goals of seismic interpretation and quantification are to understand and define reservoir architecture and the distribution of petrophysical properties. Since seismic interpretation is associated with major uncertainties, outcrop analogues are used to support and improve the resulting conceptual models. In this study, the Miocene carbonates of Cerro de la Molata (Las Negras, south‐east Spain) have been selected as an outcrop analogue. The heterogeneous carbonate rocks of the Cerro de la Molata Platform were formed by a variety of carbonate‐producing factories, resulting in various platform morphologies and a wide range of physical properties. Based on textural (thin sections) and petrophysical (porosity, density, carbonate content and acoustic properties) analyses of the sediments, eleven individual facies types were determined. The data were used to produce synthetic seismic profiles of the outcrop. The profiles demonstrate that the spatial distribution of the facies and the linked petrophysical properties are of key importance in the appearance of the synthetic seismic sections. They reveal that carbonate factory and facies‐specific reflection patterns are determined by porosity contrasts, diagenetic modifications and the input of non‐carbonate sediment. The reflectors of the seismograms created with high‐frequency wavelets are coherent with the spatial distribution of the predefined facies within the depositional sequences. The synthetic seismograms resulting from convolution with lower frequency wavelets do not show these details – the major reflectors coincide with: (i) the boundary between the volcanic basement and the overlying carbonates; (ii) the platform geometries related to changes in carbonate factories, thus sequence boundaries; and (iii) diagenetic zones. Changes in seismic response related to diagenesis, switching carbonate producers and linked platform geometries are important findings that need to be considered when interpreting seismic data sets.  相似文献   

Geochemical characteristics and evaluation of minor and trace elements pollution in groundwater of Tuticorin city,Tamil Nadu,India using geospatial techniques     

S. Selvam  S. Venkatramanan  P. Sivasubramanian  S. Y. Chung  C. Singaraja 《Journal of the Geological Society of India》2017,90(1):62-68

In this work the major and trace elements pollution levels in groundwater of Tuticorin city of Tamil Nadu was investigated. This coastal city with numerous large and small scale industries has increasingly affected the water quality by dumping effluents. The mean major and trace elements levels in groundwater in descending order: Si > Sr > Zn > Fe > Rb > Se > Al > Mn > Cu > As > Cr > Ba > V > Ni > Pb > Mo > Co > Sb > Cd > Ag. The concentrations of As, Se, Pb, Ba, Al, Fe and V (0.084, 0.150, 0.057, 0.837, 0.357 and 0.052) in some of the groundwater samples exceed the standard value of world health organization (WHO, 2004). Interrelationship between the elements was done by correlation matrix and factor analysis which indicates the contribution from industrial and irrigation fields. Spatial interpolation of inverse distance method (IDW) maps of all the elements suggested that discharge of effluents from chemical factory (STERLITE, TAC, SPIC, HEAVY WATER PLANT, NILA SEA FOODS), municipal wastewater, fertilizers were added to the natural sources. Results of this research suggests that proper measures should be taken to protect the vital groundwater resources in the Tuticorin city.  相似文献   

Mid-Miocene (post 12 Ma) displacement along the central Karakoram fault zone in the Nubra Valley,Ladakh, India from spot LA-ICPMS U/Pb zircon ages of granites     

Michael E. Brookfield  Sun-Lin Chung  J. Gregory Shellnutt 《Journal of the Geological Society of India》2017,89(3):231-239

The Karakoram fault zone is a prominent right lateral fault that connects the frontal thrust of the North Pamir with the Indus suture zone near Mount Kailas. Its nature and age of initiation is controversial. In the Nubra valley, Ladakh, India, a Karakoram range granite is thrust over Cretaceous magmatic arc rocks and this thrust is cut by a western strand of the Karakoram fault zone. Three different lithologies from this granite gave weighted mean zircon U/Pb ages of 12.92±0.77 Ma, 12.41±0.43 Ma, and 11.72±0.31 Ma. The ages indicate a relatively short intrusive history of about 1 Ma for the phases: the geochemistry is practically identical to the Pangong leucogranites in the same tectonic block. The Karakoram fault zone in this area is thus less than ~12 Ma old which supports a post middle Miocene (Serravallian) age of Karakoram fault initiation in this area.  相似文献   

Subduction-related 200 Ma Talun metagranite,SE Taiwan: an age constraint for palaeo-Pacific plate subduction beneath South China Block during the Mesozoic   总被引：1，自引：0，他引：1  

T. F. Yui  H. T. Chu  K. Suga  C. Y. Lan  S. H. Chung  K. L. Wang 《International Geology Review》2017,59(3):333-346

Various tectonic models have been proposed to account for the widely distributed igneous activities in the southeastern part of the South China Block (SCB) during the Triassic–Jurassic period. One of the major contending debates is on the timing of initiation of the palaeo-Pacific plate subduction under the SCB, due to lack of unequivocal evidence for arc magmatism during the period in this region.

The 191 ± 10 Ma (N = 5, MSWD = 12) calc-alkalic high-K I-type Talun metagranite occurs in the southern Tailuko belt of the Tananao metamorphic complex, Taiwan. In terms of age, this metagranite belongs to the Early Yanshanian igneous activity in the southeastern part of the SCB. However, its geographic position does not accord with the well-known general oceanward younging trend of the Yansnanian igneous rocks. In view of the large age uncertainty reported, this metagranite is redated in this study. Some zircons of this metagranite are high in U content and are metamict. Zircons with low U contents are analysed by SHRIMP yielding a more precise age of 200 ± 2 Ma (N = 10, MSWD = 4). In particular, the εHf(t) of these dated zircons ranges from +4.5 to +12.9. The metagranite mainly consists of quartz, K-feldspar, plagioclase, with minor amounts of garnet, biotite, zircon, apatite, and pyrrhotite. Chlorite and calcite are secondary phases overprinted by the later tectonic event(s). Its initial Sr isotope compositional range is 0.70473–0.70588, and εNd(t), +2.4 to +3.6. The results demonstrate that the genesis of this metagranite could be attributed to the assimilation-fractionation of a depleted mantle-derived basaltic magma, which was most likely related to arc magmatism. The present study therefore offers key evidence that during the Mesozoic, the palaeo-Pacific plate subduction underneath the SCB would have taken place no later than the very early Jurassic.  相似文献   

Selecting suitable sites for mountain ginseng (<Emphasis Type="Italic">Panax ginseng</Emphasis>) cultivation by using geographically weighted logistic regression     

Hee Han  Kwang-min Jang  Joo-sang Chung 《山地科学学报》2017,14(3):492-500

With the well-being trends to pursue a healthy life, mountain ginseng (Panax ginseng) is rising as one of the most profitable forest products in South Korea. This study was aimed at evaluating a new methodology for identifying suitable sites for mountain ginseng cultivation in the country. Forest vegetation data were collected from 46 sites and the spatial distribution of all sites was analyzed using GIS data for topographic position, landform, solar radiation, and topographic wetness. The physical and chemical properties of the soil samples, including moisture content, pH, organic matter, total nitrogen, exchangeable cations, available phosphorous, and soil texture, were analyzed. The cultivation suitability at each site was assessed based on the environmental conditions using logistic regression (LR) and geographically weighted logistic regression (GWLR) and the results of both methods were compared. The results show that the areas with northern aspect and higher levels of solar radiation, moisture content, total nitrogen, and sand ratio are more likely to be identified as suitable sites for ginseng cultivation. In contrast to the LR, the spatial modeling with the GWLR results in an increase in the model fitness and indicates that a significant portion of spatial autocorrelation in the data decreases. A higher value of the area under the receiver operating characteristic (ROC) curve presents a better prediction accuracy of site suitability by the GWLR. The geographically weighted coefficient estimates of the model are non-stationary, and reveal that different site suitability is associated with the geographical location of the forest stands. The GWLR increases the accuracy of selecting suitable sites by considering the geographical variations in the characteristics of the cultivation sites.  相似文献   

利用卫星长波长地球物理位场对东亚地区深部结构的研究          下载免费PDF全文

Jong Sun Hwang  Hyung Rae Kim  Mancheol Suh  Jan Kutina  胡卫剑 《地球物理学报》2010,53(6):1327-1335

有研究表明从中国北部经黄海、朝鲜半岛、日本海至日本本州岛存在一个大型断裂带,被称为“北纬40°断裂带”.为了验证该断裂带的存在性,本文通过GRACE和CHAMP卫星的位场数据中的大尺度区域重力和磁力异常来研究该区的大型构造特征.区域性研究范围为24°N~56°N,90°E~150°E,详细研究范围为32°N~42°N,122°E~132°E.2008年Taylor等利用CHAMP卫星2005年6月至12月收集的轨道数据,从测量数据中消除地核和外部产生磁场效应,经化磁极之后得到磁异常图,从中来追踪构造特征,并根据地质和地球物理资料建立了数学模型来进行解释.本文在此基础上,增加了GRACE卫星2003年10月份测量的重力异常场数据.实测差分位场数据利用高斯-勒让德求积法转换为垂向重力异常值,通过减去最新地球重力场模型（EGM96）的场值来去除波长超过1100 km的长波长异常,所得的重力异常数据和磁场数据进行比较.为了能从中得到研究区的共同构造特征,建立一个球面棱柱模型进行正演模拟、并进行重、磁异常场的波数相关性分析.研究发现在重、磁异常中均发现一个呈负相关的纬向构造特征,东亚地区“北纬40°断裂带”横穿了整个朝鲜半岛.  相似文献   

Reconstruction of historical nutrient levels in Korean and Japanese coastal areas based on dinoflagellate cyst assemblages     

Hyeon Ho Shin  Koichiro Mizushima  Jong Sick Park  Mitsunori Iwataki  Yang Ho Yoon 《Marine pollution bulletin》2010,60(8):1243-1258

Dinoflagellate cysts acquired from sediment cores were analyzed in order to reconstruct historical nutrient levels in Gamak Bay, Korea and Ariake Bay, Japan. Dinoflagellate cyst assemblages in Gamak Bay were characterized by high proportions of heterotrophic cysts such as Brigantedinium spp., Protoperidinium americanum and Polykrikos cysts, which suggested that nutrients levels may have already been high before 1970s, and then increased further to the hypertrophic conditions of the 1990s. In contrast, dinoflagellate cyst assemblages in Ariake Bay were characterized by high relative abundances of Lingulodinium machaerophorum and Spiniferites spp., which suggested that nutrient levels in Ariake Bay had increased gradually since the mid 1960s, and may have been significantly enhanced by the mid 1980s. Dinoflagellate cyst assemblages reflecting environmental changes in the two bays are contrasting, perhaps due to different nutrient enrichment mechanisms. This suggests that the indicators of nutrient levels encoded in dinoflagellate cyst assemblages may exhibit site-specific information.  相似文献   

Soft‐sediment deformation structures in Cretaceous non‐marine deposits of southeastern Gyeongsang Basin,Korea: Occurrences and origin     

Hee‐Cheol Kang  In Sung Paik  Ho Il Lee  Jeong Eun Lee  Jong‐Hwa Chun 《Island Arc》2010,19(4):628-646

A variety of soft‐sediment deformation structures formed during or shortly after deposition occurs in the Cretaceous Seongpori and Dadaepo Formations of the southeastern Gyeongsang Basin exposed along coastal areas of southeastern Korean Peninsula for 0.5–2 km. These are mostly present in a fluvial plain facies, with interbedded lacustrine deposits. In this study, the features of different kinds of soft‐sediment deformation structures have been interpreted on the basis of sedimentology of structure‐bearing deposits, comparison with normal sedimentary structures, timing and mechanism of deformation, and triggering mechanisms. The soft‐sediment deformation structures can be classified into four morphological groups: (i) load structures (load casts, ball‐and‐pillow structures); (ii) soft‐sediment intrusive structures (dish‐and‐pillars, clastic dykes, sills); (iii) ductile disturbed structures (convolute folds, slump structures); and (iv) brittle deformation structures (syndepositional faulting, dislocated breccia). The most probable triggering mechanisms resulting in these structures were seismic shocks. These interpretations are based on the following field observations: (i) location of the study area within tectonically active fault zone reactivated several times during the Cretaceous; (ii) deformation structures confined to single stratigraphic levels; (iii) lateral continuity and occurrences of various soft‐sediment deformation structures in the deformed level over large areas; (iv) absence of depositional slope to indicate gravity sliding or slumping; and (v) similarity to the structures produced experimentally. The soft‐sediment deformation structures in the study areas are thus interpreted to have been generated by seismic shocks with an estimated magnitude of M > 5, representing an intermittent record of the active tectonic and sedimentary processes during the development and evolution of two formations from the late Early Cretaceous to the Late Cretaceous.  相似文献   

Application of bivariate frequency analysis to the derivation of rainfall–frequency curves     

Chang Hwan Lee  Tae-Woong Kim  Gunhui Chung  Minha Choi  Chulsang Yoo 《Stochastic Environmental Research and Risk Assessment (SERRA)》2010,24(3):389-397

Bivariate distributions have been recently employed in hydrologic frequency analysis to analyze the joint probabilistic characteristics of multivariate storm events. This study aims to derive practical solutions of application for the bivariate distribution to estimate design rainfalls corresponding to the desired return periods. Using the Gumbel mixed model, this study constructed rainfall–frequency curves at sample stations in Korea which provide joint relationships between amount, duration, and frequency of storm events. Based on comparisons and analyses of the rainfall–frequency curves derived from univariate and bivariate storm frequency analyses, this study found that conditional frequency analysis provides more appropriate estimates of design rainfalls as it more accurately represents the natural relationship between storm properties than the conventional univariate storm frequency analysis.  相似文献   

Incorporation of Heavy Metals Bioavailability into Risk Characterization     

Hyerim Ryu  Jae Shik Chung  Taekwoo Nam  Hee Sun Moon  Kyoungphile Nam 《洁净——土壤、空气、水》2010,38(9):812-815

The bioavailability of field‐aged Cd and Cu was calculated, and compared to the total concentrations determined by acid digestion. Only 0.60–4.15% for Cd and 0.59–9.43% for Cu were found to be bioavailable when determined by stomach‐phase extraction. The incorporation of bioavailability reduced more than 90% of the calculated risk of the metals at the site of study. It should be noted that such a reduction may not be generalized and the site‐specific bioavailability needs to be determined case by case.  相似文献