A storm event during the Maastrichtian in the Cauvery basin, South India

Sedimentary structures in the Kallankurichchi Formation of the Ariyalur Group, South India have been examined with a view of assessing the depositional setting of these rocks. Of the different sedimentary structures such as cross bedding, cut and fill, etc., hummocky cross stratification is significant as it resulted from a major storm event. This paper deals with the recognized sedimentary structures, their genesis and environmental implications

Cretaceous sea level rise : down memory lane and the road ahead /

Cretaceous Sea Level Rise delves into the question of whether the observed short-term sea-level changes are regional (tectonic) or global (eustatic) and determines their possible relation to climate cycles; to assess the role of feedback mechanisms, i.e. thermal expansion/contraction of seawater, subsidence due to loading by water, changing vegetation of the Earth System and to investigate the relation of sea-level highs and lows to ocean anoxia and oxidation events, represented by black shales and oceanic red beds, and to evaluate the evidence for ephemeral glacial episodes or other climate events. Though research has been, and is being, conducted in these fields since the introduction of sea level cycles and sequence development concepts in the 1970"s, the available information is scattered. Cretaceous Sea Level Rise presents the current understanding and future directions of the research on Cretaceous sea level cycles in a single source, forming a reference work for beginners, graduates and postgraduates who are interested in this subject.Includes bibliographical references.Online resource; title from PDF title page (EBSCO, viewed November 24, 2015).Cretaceous Sea Level Rise delves into the question of whether the observed short-term sea-level changes are regional (tectonic) or global (eustatic) and determines their possible relation to climate cycles; to assess the role of feedback mechanisms, i.e. thermal expansion/contraction of seawater, subsidence due to loading by water, changing vegetation of the Earth System and to investigate the relation of sea-level highs and lows to ocean anoxia and oxidation events, represented by black shales and oceanic red beds, and to evaluate the evidence for ephemeral glacial episodes or other climate events. Though research has been, and is being, conducted in these fields since the introduction of sea level cycles and sequence development concepts in the 1970"s, the available information is scattered. Cretaceous Sea Level Rise presents the current understanding and future directions of the research on Cretaceous sea level cycles in a single source, forming a reference work for beginners, graduates and postgraduates who are interested in this subject.Front Cover; Cretaceous Sea Level Rise; Copyright Page; Contents; Preface; Acknowledgments; 1 Introduction; 2 Trends, Timings, and Magnitudes; 3 Causes and Mechanisms; 3.1 Endogenic Processes and Causes; 3.2 Eustasy and Related Causes; 3.2.1 Eustasy Under Greenhouse Conditions?; 3.2.2 Limno-eustasy; 3.2.3 Eustasy Due to Thermal Expansion-Contraction of Sea Water; 4 Methods, Tools and Techniques; 4.1 Sedimentary Proxies; 4.2 Physical Proxies; 4.3 Biological Proxies; 4.4 Geochemical Proxies; 4.5 Integrated Analyses for Documenting Sea Level Fluctuations; 5 Where It Stands and Where Is It Headed.Elsevie

Hydrocarbon reserves of the South China Sea: Implications for regional energy security

International audienceThe countries such as China, Vietnam, Philippines, Malaysia, Indonesia and Brunei that border South China Sea region have immense stakes in exploring and exploiting the natural resources of the region including hydrocarbon. More than the hydrocarbon reserves, the South China Sea is home to World's high-networth trade route that brings the interests of non-geographic entities to this region. Further, the purported reserves of hydrocarbon in the region are in the orders of Persian Gulf but are not yet properly explored and the reserves recovered owing to territorial and non-claimant stakeholder's influences/in-terventions. This paper is a synopsis of information on the hydrocarbon reserves of the South China Sea region, and evaluates the territorial and extraterritorial interests in the light of energy security and equitable development and utilization of natural resources from a geological perspective. We also suggest several measures for future consideration and implementation

Assessment of heavy metal contamination of sediments in popular tourist beaches of the Kerala State, southern India: Implications on textural and mineralogical affinities and mitigation

Beaches form one of the most contaminated sedimentary environments by a myriad variety of anthropogenic activities, including tourism and recreational activities. The concentrations of metals and their pollution levels were studied for four tropical tourist beaches in Kerala state, Southern India. Bulk geochemical and mineralogical analyses of 16 sediment samples were performed to determine the environmental status and the environmental risk level using various geochemical indices. Based on the enrichment of TiO2 and SiO2 concentrations, the samples were grouped into ilmenite-rich samples (IRS) and quartz-rich samples (QRS) respectively and the geochemical signatures are significantly different. Mineralogically, the IRS group is dominated by ilmenite, quartz, sillimanite, zircon and rutile while the QRS group consists of quartz, spinel and calcite and garnets are common in both groups of sediments. Despite the variation in the trends of pollution indices, it has been found that Kovalam beach sediments are enriched with W, Th and U where, IRS with enrichment of W, U and Th while QRS only enriched with W and Th and not U. The mineralogical affinity of W with secondary tungsten-bearing minerals has been documented by the XRD analysis and these metals are mainly controlled by the geogenic sourced minerals. However, in terms of ecological risk, Pb, As and Cu have a considerable to moderate risk in both groups of sediments. Overall, both group of sediments shows a moderate risk. Based on the biological effect assessment the elements of concern are Pb and Zn in IRS and possible effect by the Cr, Cu and As in IRS and only by Cu in QRS. Though the prevalence of geogenic and anthropogenic processes and influences of metal enrichments are documented by the study, their relative influences, mobility and bioavailability need to be systematically studied

High resolution facies architecture and digital outcrop modeling of the Sandakan formation sandstone reservoir, Borneo: Implications for reservoir characterization and flow simulation

Advances in photogrammetry have eased the acquisition of high-resolution digital information from outcrops, enabling faster, non-destructive data capturing and improved reservoir modeling. Geocellular models for flow dynamics with in the virtual outcrop in siliciclastic deposits at different sets of sandstone facies architecture remain, however, a challenge. Digital maps of bedding, lithological contrast, spatial-temporal variations of bedding and permeability characteristics make it more easy to understand flow tortuosity in a particular architecture. An ability to precisely model these properties can improve reservoir characterization and flow modeling at different scales. Here we demonstrate the construction of realistic 2D sandstone facies based models for a pragmatic simulation of flow dynamics using a combination of digital point clouds dataset acquired from LiDAR and field investigation of the Sandakan Formation, Sabah, Borneo. Additionally, we present methods for enhancing the accuracy of outcrop digital datasets for producing high resolution flow simulation. A well-exposed outcrop from the Sandakan Formation, Sabah, northwest Borneo having a lateral extent of 750 m was chosen in order to implement our research approach. Sandstone facies and its connectivity are well constrained by outcrop observations, data from air-permeability measurements, bilinear interpolation of permeability, grid construction and water vector analysis for flow dynamics. These proportions were then enumerated in terms of static digital outcrop model (DOM) and facies model based on sandstone facies bedding characteristics. Flow simulation of water vector analysis through each of the four sandstone facies types show persistent spatial correlation of permeability that align with either cross-bedded orientation or straight with more dispersion high quality sandstone (porosity 21.25%–41.2% and permeability 1265.20–5986.25 mD) and moderate quality sandstone (porosity 10.44%–28.75% and permeability 21.44–1023.33 mD). Whereas, in more heterolithic sandstone (wavy- to flaser-bedded and bioturbated sandstone), lateral variations in permeability show spatially non-correlated patterns over centimeters to tens of meters with mostly of low quality sandstone (porosity 3.4%–12.31% and permeability < 1 mD to 3.21 mD). These variations reflect the lateral juxtaposition in flow dynamics. It has also been resulted that the vertical connectivity and heterogeneities in terms of flow are mostly pragmatic due to the interconnected sandstone rather than the quality of sandstone. Keywords: Siliciclastic sandstone facies, Connectivity, Heterogeneity, Digital outcrop model, Flow dynamic

Impact of Late Quaternary climatic fluctuations on coastal systems: Evidence from high-resolution geophysical, sedimentological and geochronological data from the Java Island

The major climatic oscillations during the Quaternary Period significantly influenced the evolution and distribution of ancient and modern coastal systems. Here we investigate the morphology and sedimentary infilling of submerged Late Quaternary incised valleys along the northern coast of Java Island (Indonesia) using highresolution geophysical, sedimentological and geochronological data. Our results indicate that the spatial development and morphology of the incised valleys are predominantly controlled by Quaternary glacial-interglacial eustatic fluctuations, within a marked subsiding setting. The valleys were incised during prominent Quaternary lowstands and most of the valley fill was emplaced during the last postglacial sea level rise. The valley fill forms a transgressive succession, consisting mainly of fluvial deposits at the base (possibly amalgamated from older sequences) overlain by shallow marine sediments and capped by hemipelagic deposits. The valley-fill architecture is strongly dependent on the valley morphology (depth of incision, width of the valleys, and extent of the intertidal zone). The shallow marine deposits contained within the narrow and linear valleys are mostly aggrading muds. The vertical incision and valley formation was chiefly controlled by the extent of glacial sea-level fluctuations. The studied sections represent the continental-offshore extension of a paleodeltaic system. The implication of our work is that even in predominantly enclosed shallow marine systems that are located distal to the shelf break, the response of the sedimentary system and ensuing stratigraphic configuration can be effectively impacted by the rapid and abrupt Quaternary global climatic transition and eustatic sea-level fluctuations

Impact of Late Quaternary climatic fluctuations on coastal systems: Evidence from high-resolution geophysical, sedimentological and geochronological data from the Java Island

International audienceThe major climatic oscillations during the Quaternary Period significantly influenced the evolution and distribution of ancient and modern coastal systems. Here we investigate the morphology and sedimentary infilling of submerged Late Quaternary incised valleys along the northern coast of Java Island (Indonesia) using high-resolution geophysical, sedimentological and geochronological data. Our results indicate that the spatial development and morphology of the incised valleys are predominantly controlled by Quaternary glacial–interglacial eustatic fluctuations, within a marked subsiding setting. The valleys were incised during prominent Quaternary lowstands and most of the valley fill was emplaced during the last postglacial sea level rise. The valley fill forms a transgressive succession, consisting mainly of fluvial deposits at the base (possibly amalgamated from older sequences) overlain by shallow marine sediments and capped by hemipelagic deposits. The valley-fill architecture is strongly dependent on the valley morphology (depth of incision, width of the valleys, and extent of the intertidal zone). The shallow marine deposits contained within the narrow and linear valleys are mostly aggrading muds. The vertical incision and valley formation was chiefly controlled by the extent of glacial sea-level fluctuations. The studied sections represent the continental-offshore extension of a paleodeltaic system. The implication of our work is that even in predominantly enclosed shallow marine systems that are located distal to the shelf break, the response of the sedimentary system and ensuing stratigraphic configuration can be effectively impacted by the rapid and abrupt Quaternary global climatic transition and eustatic sea-level fluctuations

Structural controls on polyphase hydrothermal dolomitization in the Kinta Valley, Malaysia: Paragenesis and regional tectono-magmatism

In the eastern side of the Malay Peninsula, thick successions of limestone formations preserve important records of the Mesozoic and Cenozoic tectonic events. Here we investigate the strata- and fracture-bound hydrothermal dolomites in the Palaeozoic carbonates of the Kinta Valley, western Peninsular Malaysia. Based on their textural and morphologic characteristics, structural relationships with the host rock, different facies types, and associations with hydrothermal calcite and low-grade metamorphic marble, we attempt to trace their polyphase origin and relationship with thereto-tectonic events of the region. A detailed evaluation of the nature of brecciation and crystallization of polyphase dolomites, dolomitic limestones, limestones and marble, under the influences of episodic faulting, is associated with the regional structural geology with emphasis on pre-existing fault reactivations, granitic emplacement and progressive thermal influence. Supply of Mg2+ from the host rock for dolomitization, limited and episodic influx of circulating fluids and cessation of thereto-tectonic evolution with progressive cooling are also inferred. Correlating the geological events in western Peninsular Malaysia with regional structural dynamics reveals that the major deformation episodes exerted first order controls on the loci of dolomite occurrences. The occurrence, geometry and structural relationships of the dolomites were controlled by successive magmatic events, whereas, the intensity of replacement dolomitization was controlled by host rock texture and varied bulk chemistry, together with the nature of circulating fluids

Total vulnerability of the littoral zone to climate change-driven natural hazards in north Brittany, France

International audienceCurrent worldwide projections of sea-level rise show a staggering increase in water level of up to 2 m by 2100 owing to global warming exacerbated by anthropogenically induced climate change. While amplified rates of sea-level rise is an immense hazard to coastal communities, storm surges are expected to increase in intensity and frequency making it an equally significant threat to coastal populations. In France, these hazards are not uncommon with records of extreme tempests every thousand years in the Holocene. Despite these recurring devastating events, in the Bay of Saint-Brieuc, Brittany, legislated laws for coastal management do not entirely focus on protecting littoral zones from such calamities. 130,739 people are concentrated in 21 municipalities with major cities located at close proximity to the shoreline with numerous socio-economic activities, which increases the vulnerability of the coastal population and infrastructures; thus, affirming the indispensable need of a thorough vulnerability assessment. Here, we conduct a mechanistic appraisal of the vulnerability of the bay considering thirteen parameters within three governing sub-systems that demonstrate the multidimensional dynamics in these municipalities. In the occasion of an extreme climatic event, our results of total vulnerability show risks in the sub-systems highlighting erosional processes due to augmented hydrodynamics, socio-economic and administrative vulnerabilities associated with anthropogenic development. Eight municipalities of the bay portray moderate to very high vulnerability and the remaining exhibits a lower risk; however, not devoid of high vulnerabilities for certain sub-systems. We posit that a more accurate fit for predicting the total vulnerability of the region can be achieved by exclusively integrating physical-natural and administrative sub-system vulnerabilities. We propose generic but requisite recommendations for Integrated Coastal Zone Management such as surveillance of urban development along the coast, implementation of coastal defense systems and appropriate industrial corridors to attenuate and dispose hazardous refuse