Geochemical characteristics of the mud volcano fluids in southwestern Taiwan and their possible linkage to elevated arsenic concentration in Chianan plain groundwater     

Chia-Chuan Liu  Jyoti Prakash Maity  Jiin-Shuh Jean  A. H. M. Selim Reza  Zhaohui Li  Bibhash Nath  Ming-Kuo Lee  Kao-Hung Lin  Prosun Bhattacharya 《Environmental Earth Sciences》2012,66(5):1513-1523

Fluid and mud samples were collected from Wushanting (WST), Hsiaokunshui (HKS), Yenshuikeng (YSK), Kuantzeling (KZL), and Kunshuiping (KSP) mud volcanoes of southwestern Taiwan. Concentrations of major ions and trace elements in mud volcanic fluids were analyzed to find the possible linkage to elevated arsenic (As) concentrations in the Chianan plain groundwater. The elevated Na⁺, K⁺, and Cl⁻ concentrations indicated possible marine origin of the fluids. The trace element concentrations in the mud volcanic fluids were generally low, but the As concentrations were up to 0.12 mg/L. High contents of As, Fe, and Mn were observed in the mud samples. Saturation index calculations indicated that both carbonate and oxide minerals acted as potential sinks for As in the mud volcanic fluids. Arsenic in the dewatering fluids and muds may be transported by the subsurface flow and surface streams as suspended solids and eventually deposited in the Chianan plain aquifers. Under reducing conditions, As may be released from the host minerals (such as Fe- and Mn-oxides/hydroxides), thereby causing widespread groundwater As pollution.  相似文献   

Alterations in Geochemical Associations in Artificially Disturbed Deep-Sea Sediments     

B. Nagender Nath  G. Parthiban  S. Banaulikar  Subhadeep Sarkar 《Marine Georesources & Geotechnology》2013,31(4):373-400

In view of the role of Sediment geochemistry in regulating the benthic ecosystem, diagenetic remobilization of dissolved constituents, bottom water redox, and regeneration of benthic fluxes, surficial sediments in and around the track disturbed by a “benthic disturber” were studied for metal variation in three phases: (1) before the disturbance, (2) immediately after the disturbance, and (3) during monitoring of restoration after ~44 months, from the same locations. Minor variations in metal concentrations before the disturbance ere noticed indicating the homogeneity in the area or supply from similar source areas. Terrigenous fraction determined normatively from titanium contents in these sediments ranges between 40 and 47%. Most of the elements analyzed showed reduced average concentrations immediately after the disturbance suggesting physical removal and resedimentation in other areas with the migration of the plume. All the elements showed positive relation and coherence in the sediments collected after the disturbance, irrespective of their susceptibility to changes in provenance and depositional environment, whereas elemental associations during the predisturbance and monitoring periods can be explained by the known geochemical processes. The changes in Al, Ti, excess aluminium contents, their interelement relations, and factor analyses, suggest the possible transformation of clay mineral type due to the benthic disturbance that would involve changes in surface chemistry of clays. Interelement relations among redox-sensitive elements have also changed with time. This includes decoupling of Co from Mn after 44 months, probably due to the varying oxidation kinetics of two major oxides, Fe and Mn. Model calculations suggest increased diagenetic remobilization rates of Mn during the monitoring phase. Substantial increase in redox-sensitive elements, especially Fe and Mn indicate oxygenation of bottom water due either to reduced activity of benthic burrowing organisms or to renewal of oxygen-rich Antarctic Bottom water (AABW). Increase in these elements is consistent with the results of the HEBBLE experiment, where the burrows seem to protect these elements from strong bottom currents. Restoration of predisturbance values in the terrigenous component is attributed to the influence of shifts in the direction of bottom flow and suggests that bottom currents would play a major role in restoring the lithogenic component by transporting it from other locations within the Basin during commercial mining operations.  相似文献   

Cyclic sedimentation of the Barren Measures Formation (Damuda Group), Talchir Gondwana basin: Statistical appraisal from borehole logs     

Rabindra Nath Hota  Bijay Kumar Das 《Journal of the Geological Society of India》2010,75(3):549-559

The succession of lithofacies of a part of the Barren Measures Formation of the Talchir Gondwana basin has been studied by statistical techniques. The lithologies have been grouped under five facies states viz coarse-, medium-, and fine-grained sandstones, shale and coal for statistical analyses. Markov chain analysis indicates the arrangement of Barren Measures lithofacies in the form of fining upward cycles. A complete cycle consists of conglomerate or coarse-grained sandstone at the base sequentially succeeded by medium-and fine-grained sandstones, shales and coal at the top. The entropy analysis puts the Barren Measures cycles into A-4 type cyclicity, which consists of different proportions of lower, upper and side truncated cycles of lithologic states. Regression analysis indicates a sympathetic relationship between total thickness of strata (net subsidence) and number of cycles and an antipathic relationship between average thickness and number of sedimentary cycles. The cyclic sedimentation of the Barren Measures Formation was controlled by autocyclic process which occurred due to the lateral migration of streams triggered by intrabasinal differential subsidence. In many instances, the clastic sediments from the laterally migrating rivers interrupted the cyclic sedimentation resulting in thinner cycles in areas where the number of cycles are more. Principal component and multivariate regression analyses suggest that the net subsidence of the basin is mostly controlled by the thickness of sandstones, shale beds and coal stringers.  相似文献   

Relationship between Net Subsidence and Coal Cycle Parameters—A Statistical Appraisal from Subsurface Logs of Damuda Group,Talchir Gondwana Basin,India     

Rabindra Nath Hota 《Mathematical Geosciences》2010,42(2):223-242

Total thickness of strata and coal cycle parameters of the three formations, i.e. Karharbari, Barakar, and Barren Measures of the Damuda Group of the Talchir Gondwana basin were subjected to bivariate and multivariate statistical analyses. Polynomial regression lines were fitted to data sets consisting of total thickness of strata, number of coal cycles, and average thickness of coal cycles of the three formations of the Damuda Group. A significant direct relationship is observed between total thickness (net subsidence) of strata and number of coal cycles, while a significant inverse relationship exists between the number of coal cycles and their average thickness. Principal component and multiple regression analyses suggest that lithological parameters of the coal bearing strata reflect the dynamic of the basin subsidence. The sedimentary distributive mechanism in the form of lateral migration of streams or drainage diversion caused in response to differential subsidence of the depositional surface seem to be appropriate mechanisms for the development of coal cycles and peat swamps in the Talchir basin. Often during Karharbari sedimentation, peat accumulated in abandoned channels was scoured away by high energy migrating channels. On the other hand, Barakar peat swamps developed in a distal part of the flood plain, as a result of which many of the coal seams could be of appreciable thickness. The advent of arid climatic condition retarded the growth of vegetation to a larger extent that prevented profuse development of coal seams during the Barren Measures Formation.  相似文献   

Glacial-interglacial changes in the surface water characteristics of the Andaman Sea: Evidence from stable isotopic ratios of planktonic foraminifera     

S. M. Ahmad  D. J. Patil  P. S. Rao  B. N. Nath  B. R. Rao  G. Rajagopalan 《Journal of Earth System Science》2000,109(1):153-156

Stable carbon and oxygen isotopic analyses of the planktonic foraminifera (Globigerinoides ruber) from a deep sea sediment core (GC-1) in the Andaman Sea show high glacial-to-Holocene δ¹⁸O amplitude of 2.1%o which is consistent with previously published records from this marginal basin and suggest increased salinity and/or decreased temperature in the glacial surface waters of this region. A pulse of¹⁸O enrichment during the last deglaciation can be attributed to a Younger Dryas cooling event and/or to a sudden decrease of fresh water influx from the Irrawady and Salween rivers into the Andaman Sea. High δ¹³C values observed during the isotopic stages 2 and 4 are probably due to the enhanced productivity during glacial times in the Andaman Sea.  相似文献   

Selection of Test and Reference Areas for the Indian Deepsea Environment Experiment (INDEX)     

Rahul Sharma  B. Nagender Nath 《Marine Georesources & Geotechnology》2000,18(3):177-187

The Indian Deepsea Environment Experiment (INDEX) was conducted in the Central Indian Ocean Basin, to assess the effects of a simulated disturbance on the marine ecosystem and to collect data to predict the effects of large-scale mining. To select the Test and Reference areas for benthic disturbance, detailed studies were carried out for a better understanding of the topgraphic undulations and nodule distribution in five preselected areas of 10 ×10 nautical miles each. Flat topography was one of the important considerations for selection of the areas, because this would allow further dispersion of sediment plume and offer easier maneuverability of the benthic disturber. Relatively low nodule abundances were also preferred, to prevent clogging of the suction device used for resuspension of sediment. On the basis of morphological analysis and nodule distribution, two areas, T1 and A1, were selected as the best suited pair for the disturbance and monitoring experiment.  相似文献   

Seismic source zoning and maximum credible earthquake prognosis of the Greater Kashmir Territory,NW Himalaya     

Hamid Sana  Sankar Kumar Nath 《Journal of Seismology》2017,21(2):411-424

We present the seismic source zoning of the tectonically active Greater Kashmir territory of the Northwestern Himalaya and seismicity analysis (Gutenberg-Richter parameters) and maximum credible earthquake (m _max) estimation of each zone. The earthquake catalogue used in the analysis is an extensive one compiled from various sources which spans from 1907 to 2012. Five seismogenic zones were delineated, viz. Hazara-Kashmir Syntaxis, Karakorum Seismic Zone, Kohistan Seismic Zone, Nanga Parbat Syntaxis, and SE-Kashmir Seismic Zone. Then, the seismicity analysis and maximum credible earthquake estimation were carried out for each zone. The low b value (<1.0) indicates a higher stress regime in all the zones except Nanga Parbat Syntaxis Seismic Zone and SE-Kashmir Seismic Zone. The m _max was estimated following three different methodologies, the fault parameter approach, convergence rates using geodetic measurements, and the probabilistic approach using the earthquake catalogue and is estimated to be M _w 7.7, M _w 8.5, and M _w 8.1, respectively. The maximum credible earthquake (m _max) estimated for each zone shows that Hazara Kashmir Syntaxis Seismic Zone has the highest m _max of M _w 8.1 (±0.36), which is espoused by the historical 1555 Kashmir earthquake of M _w 7.6 as well as the recent 8 October 2005 Kashmir earthquake of M _w 7.6. The variation in the estimated m _max by the above discussed methodologies is obvious, as the definition and interpretation of the m _max change with the method. Interestingly, historical archives (～900 years) do not speak of a great earthquake in this region, which is attributed to the complex and unique tectonic and geologic setup of the Kashmir Himalaya. The convergence is this part of the Himalaya is distributed not only along the main boundary faults but also along the various active out-of-sequence faults as compared to the Central Himalaya, where it is mainly adjusted along the main boundary fault.  相似文献