Implications For Palaeoenvironment Research Articles

Petrography and geochemistry of the Upper Cretaceous Gryphaea Limestones, Kallankurichi Formation, Ariyalur Group, Trichinopoly, Southern India: Implication for palaeoenvironment

Sub-surface Kallankurichi gryphaea limestone formation is observed between Archaean and Quaternary outcrops. Petrographic observation reveals that mega fossils are absent and it contains abundant skeletal fragments of pelecypods, gastropods, foraminifera, bryozoa, and symbiotic algae. X-ray diffraction (XRD) analyses reveal the mineralogical components of both carbonate and clay minerals. Carbonate minerals include calcite, siderite, witherite, malachite, smithsonite, and rhodochrosite. Clay minerals detected are kaolin, montmorillonite, and palygorskite. Major element composition represents predominance of CaO, SiO2, Al2O3, and Fe2O3 oxides, while MgO, MnO, Na2O, K2O, TiO2, and P2O5 oxides are depleted. Statistical analyses of correlation coefficient, principal component analysis, and cluster analysis represent the geochemical affinities and aerial distribution similarities among major elements. Palaeoclimate inferred through biotic proxies, major element geochemistry, and clay minerals represents arid and semi-arid climate.

Biomarker signatures of the Middle Jurassic coals from the Zhangjialiang mine in Dongsheng coalfield, North China: Implications for palaeoenvironment and palaeovegetation

The study on the Zhangjialiang No. 2 coal of Middle Jurassic Yan'an Formation in the northeastern Ordos Basin has been analyzed by gas chromatography-mass spectrometry (GC-MS) to determine geochemical characteristics and reconstruct palaeovegetation and palaeoclimate changes. The distribution of n-alkanes is mainly unimodal, with a medium and high molecular weight. Pr/Ph ratio (2.03–10.6) is high in most samples. The values of Tm/Ts ratio are between 1.42 and 4.92, and a predominance of C29 over C27 steranes has been found for the analyzed samples. These parameters indicate that all samples were deposited in an oxidizing freshwater environment, and the organic matter was mainly derived from terrestrial higher plants, with a small amount of aquatic organisms. Thermal maturity parameters such as C3122S/(22S + 22R) homohopane, C30αβ/(αβ + βα) hopane, together with the total organic carbon (TOC) contents (43.1% - 58.6% (except floor 2-13)) and the detected of C2717β(H)-22, 29, 30-trisnorhopane (βTm), suggest that most of samples have a relatively low maturity in the early stage. Besides, gymnosperm-derived biomarkers, including labdane, norpimarane, isopimarane, phyllocladane, abietane, rimuane, ent-beyerane, ent-kaurane, suggest that the vegetation during the Middle Jurassic Yan’an Formation was characterized by conifers.

Ichnodiversity and facies of Triassic red beds in the Irohalene area (Argana Basin, Western High Atlas, Morocco): implications for palaeoenvironment

ABSTRACT From Middle-Late Triassic continental deposits of the Timezgadiouine Formation (Argana Basin, Morocco), 17 lithofacies are identified, with alluvial fan, fluvial, floodplain and lacustrine associations. Invertebrate traces include Archaeonassa fossulata, Arenicolites isp., cf. Arenituba, Beaconites isp., cf. Camborygma, Cruziana problematica, Diplocraterion isp., Fuersichnus isp., Helminthoidichnites tenuis, Lockeia isp., Palaeophycus striatus, Palaeophycus tubularis, Planolites isp., Rusophycus carbonarius, Scoyenia gracilis, Skolithos isp., Spongeliomorpha carlsbergi, Taenidium isp. and Taenidium barretti. Additionally, rhizoliths were observed. Six ichnoassemblages were distinguished: overbank facies with (1) Rhizolith ichnoassemblage in a low-energy floodplain environment and (2) Scoyenia-Palaeophycus ichnoassemblage in crevasse splay deposits. The fluvial ichnoassociation is of moderate ichnodiversity consisting of the following assemblages: (3) Arenicolites, developed under higher flow velocities of active channels, (4) Taenidium-Scoyenia, formed by the colonisation of inactive channels, (5) Arenicolites-horizontal meniscate burrows, reflecting a rapid transition between active and abandoned channels and (6) Lockeia-vertebrate footprint, formed in littoral lakes. The Aglegal and Irohalene members indicate climatic shifts between arid dry, semiarid and subhumid in a dryland river environment. The sudden onset and the high frequency of lacustrine deposits in the lower Irohalene Member point to a rapid climate change from dry to intermittent wet and dry. This change is discussed in terms of the Carnian Pluvial Event.

Alluvial ichnofacies from Upper Triassic red beds in India: Implications for palaeoenvironment and palaeoclimate

Trace fossils are highly sensitive to the hydrodynamic conditions of depositional systems, substrate, and climate and hence yield information about spatio-temporal changes in palaeoenvironment and palaeoclimate. In this paper, we report alluvial trace fossil assemblages from the Upper Triassic Tiki Formation of the Rewa Basin, central India. Based on detailed facies analysis and architecture, two depositional environments are identified in this formation: (1) perennial braided channel belts and (2) extensive and complex floodplains containing ephemeral small fluvial channels, lakes, and crevasse splay deposits. Upper flow regime primary structures in laterally extensive sandstones encased in the floodplain deposits indicate short-lived high magnitude flood discharge, suggestive of seasonal climates. Trace fossils are sporadically distributed through these facies, generally in suites of low abundance, although in places the bioturbation index is higher. Three major ichnofacies, namely Skolithos, Scoyenia and Mermia are recognized, based on the association of different trace fossils preserved in the channel, crevasse splay of proximal floodplain and pond/lake of distal floodplain deposits, respectively. Vertical Beaconites in palaeosols and an abrupt change from Skolithos to Scoyenia ichnofacies indicate a highly variable water table, controlled by seasonal precipitation. The transitions between the Skolithos, Scoyenia and Mermia ichnofacies reveal that trace fossil preservation was variously controlled by channel abandonment, floodplain dewatering, substrate desiccation or periodic waterlogging of overbank areas. Specifically, increased water discharge over the floodplain during high precipitation, followed by post-flood recovery of hot, dry, low-water table conditions may have been a key controlling factor in shaping the ichnological characteristics of these Upper Triassic red beds.

Ichnological Model of the Upper Triassic Continental Red Bed from India: Implications for Palaeoenvironment and Palaeoclimate

Ichnological Model of the Upper Triassic Continental Red Bed from India: Implications for Palaeoenvironment and Palaeoclimate

Sulphur study of the Palaeogene coals from Jaintia Hills, Meghalaya, NE India: Implications for palaeoenvironment, utilisation prospects, and environmental impacts

Coal samples of Eocene age (Shella Formation) from four different mines (Bapung, Jaintia, Sutunga, and Lakadong) of the Jaintia Hills of Meghalaya, Northeast India, were collected and investigated to observe the sulphur content and to understand the palaeoenvironment, utilisation prospects, and environmental impact. The study reveals that these coal samples contain sulphur in higher concentration (4.46% to 7.26%) both organic and inorganic forms. There are 3 coal seams exposed in the area. The organic sulphur is higher (2.53%-5.49%) than the inorganic forms (1.26%-1.77%). The upper seam is found to contain higher concentration of sulphur than the lower seam. Intra seam pyritic sulphur also shows an upward increasing trend. The high sulphur content in the coal seams suggests the marine influence in the peat-forming swamps. These coals are classified as High Sulphur coal (>1%) which is the main obstacle in the utilization although high volatile matter and hydrogen content strongly suggest that these coals are good for liquefaction. Moreover, during coal combustion emissions of sulphur dioxide produce acid rain, affecting the environment of the mine areas.

The Late Permian clastic–dominated carbonate shelf, Northwestern Pakistan: Implications for palaeoenvironments, palaeoclimate, and reservoir modelling

The Indus Basin of Pakistan has archived thick and laterally extensive Permian carbonates. The current study focuses on constraining the palaeoenvironments, reservoir potential, and ambient climatic conditions during the deposition of Late Permian clastic–dominated carbonates of the Chhidru Formation, Indus Basin, Pakistan. At outcrop, the unit shows laterally variable thicknesses of dominantly thick‐bedded, fossiliferous, channelized calcareous sandstone, and sandy limestone. The microscopic textural, compositional, and biotic attributes divulged four microfacies, arguing for the deposition in a range of diverse depositional environments including lagoonal to delta‐dominated middle shelf. The deposition of clastic‐rich carbonates of the Chhidru Formation on the underlying pure carbonates of the Wargal Formation hints strongly towards a sea‐level fall on the northwestern margin of the Indian Plate. The regression tightly correlates with the stratigraphic record of the adjacent continents, including South China, the Persian Gulf, and northern Gondwana regions. The abundance of detrital material indicates terrestrial influx to the basin, inhibiting the benthic activity and consequently resulting in poor microfossil content. Nevertheless, 11 age‐diagnostic foraminiferal taxa were identified, suggesting a Late Wuchiapingian to Changhsingian age. The X‐ray diffraction analysis of argillaceous horizons revealed several climate‐sensitive clay minerals. Based on the dominance of illite, palygorskite, sepiolite, and chlorite, an extremely arid and cold climate is suggested for the region during the time of deposition of the Chhidru Formation. Petrographic observations suggest reworking of sediments shed from the Indian Shield of the Aravalli system and Malani Range. The petrography, scanning electron microscopy, and energy dispersive X‐ray spectroscopy revealed multiple diagenetic phases including marine, meteoric, and burial that have shaped the unit into a poor to moderate reservoir.

Geochemistry and detrital zircon geochronology of the Lower Jurassic clastic rocks of the northern Qiangtang Basin, northern Tibet: Implications for palaeoenvironment, provenance, and tectonic setting

The Lower Jurassic clastic rocks in the Qiangtang Basin, northern Tibet, are generally regarded as the early sediments of the new Mesozoic Qiangtang Basin (Late Triassic to Early Cretaceous). However, little attention has been paid to the palaeoenvironment, provenance, and tectonic setting of this unit. The QZ‐16 well, located in the east of the northern Qiangtang Basin, firstly recovered the Lower Jurassic strata (Quemo Co Formation) in the Qiangtang Basin. In this paper, the whole‐rock major‐trace elemental characteristics of 34 mudstone samples and detrital zircon geochronology of one sandstone, collected from the Quemo Co Formation of the QZ‐16 well, are reported in order to infer the palaeoenvironment, provenance, and tectonic setting. Quemo Co mudstones are dominated by SiO2 and Al2O3, while Fe2O3, CaO, K2O, and MgO are the second most abundant oxides. They are generally characterized by high REE concentrations, enrichment in light rare earth elements (LREEs), marked negative Eu and Ce anomalies. The REE contents of the mudstones are mainly controlled by terrigenous detrital minerals input. The Lower Jurassic mudstones have relatively high chemical index of alteration (79.1–83.6) values, indicating moderate to high degree of chemical weathering conditions of the source area. Sr/Ba and Rb/K ratios reflect that the marine transgression impact was limited and the mudstones were generally deposited in a brackish water environment. Major, trace, and REE contents indicate that the mudstones were mainly derived from intermediate igneous rocks with subordinate felsic igneous rocks. Prominent age peaks at ca. 200 ~ 400 Ma, 700 ~ 970 Ma, 1,700 ~ 1,900 Ma, and 2,100 ~ 2,700 Ma of the detrital zircon grains suggest that the Lower Jurassic clastic rocks were derived from the Central Qiangtang and Songpan–Ganzi complex. Moreover, tectonic discrimination diagrams based on major and trace elements show that the source of the Lower Jurassic sediments were most likely derived from a collision tectonic setting.

Palynofacies, micropalaeontology, and source rock evaluation of non-marine Jurassic–Cretaceous boundary deposits from northern Germany - Implications for palaeoenvironment and hydrocarbon potential

Abstract The Jurassic–Cretaceous boundary interval of northern Germany is characterised by non-marine deposits attributed to the Purbeck and Wealden facies. These organic-rich sediments were deposited under restricted, brackish-lacustrine conditions in a palaeogeographically isolated basin (Lower Saxony Basin). Rock-Eval and δ13Corg measurements were performed to characterise the composition and distribution of the organic matter, to determine the kerogen type chemically, and to define the quantity and maturity of the organic matter. A strong correlation between the optical characteristics, documented by the palynofacies analysis, and the chemical kerogen analyses have led to a better understanding of the palaeoenvironment and the processes which caused the organic matter enrichment. The samples studied from the basin center show a high petroleum generation potential, their estimated maturity is close to the onset of oil generation. Total organic carbon (TOC) concentrations of up to 18% have been measured, hydrogen index values reach up to 1185 mg HC/g TOC. The kerogen assemblages in two basinal successions are dominated by granular amorphous organic material (AOM), dinoflagellate cysts, and Botryococcus algae. In a more marginal succession continent-derived debris (phytoclasts, pollen and spores) is dominant. The AOM is interpreted to have originated either from phytoplankton (probably dinoflagellate cysts and Botryococcus), or its bacterial/archaeal degradation products formed under anoxic conditions. TOC-rich samples which are dominated by these amorphous kerogens show the highest petroleum potential, the AOM therefore plays a key role for the petroleum generation. The long-term climatic and hydrological evolution of the Lower Saxony Basin, which is based on palynomorphs, ostracods, and benthic foraminifera, is here interpreted by a five-stage model. Fluctuations in the salinity of the water bodies are directly reflected by the ratio between different freshwater and brackish-marine organisms as well dinoflagellate cyst diversity; five different cyst morphogroups are used for palaeoenvironmental interpretations. The deposition of TOC-rich beds in the German Wealden can be best explained by both high primary productivity and the establishment of prolonged phases of bottom water anoxia in a brackish-lacustrine depositional environment. Ecological conditions supporting enhanced productivity and preservation of the algal/bacterial-derived organic matter were most favourable during the mid–late Berriasian (Wealden 1–4).

Trace Fossils from Oligocene Barail Sediments in and Around Jotsoma, Kohima, Nagaland: Implications for Palaeoenvironment

Trace Fossils from Oligocene Barail Sediments in and Around Jotsoma, Kohima, Nagaland: Implications for Palaeoenvironment

Late Pleistocene–Holocene clay mineral record from the Great Rann of Kachchh basin, Western India: Implications for palaeoenvironments and sediment sources

The present study uses clay mineralogy to delineate a ∼17 ka record of palaeoenvironmental/palaeoclimatic changes in the recently uplifted palaeogulf of Arabian Sea i.e. Great Rann of Kachchh (GRK). Situated on continental margin of Indian subcontinent and flanked by Indus delta, the GRK basin has preserved continuous record of post glacial sedimentation. Clay mineral studies on two long cores (∼60 m and 50 m long) show more abundance of physical weathering products (illite and chlorite) over the chemical weathering products (smectite and kaolinite). We show that the GRK sediments depict multiple sources of sediment input. Dominance of illite-chlorite suggests GRK received sediments dominantly from the Himalayan terrain with minor contribution from adjacent regions. We present the oldest clay mineralogical signature of an interval of intensified monsoon conditions during the late Pleistocene (∼17.7–16.3 cal ka B.P.). Monsoon became stronger before ∼8.4 cal ka B.P., and whereas the mid Holocene weakening of monsoon occurred after ∼7 cal ka B.P. Despite the differences in source region and composition of clay mineral records from the GRK with northeastern and southeastern Arabian Sea, the sedimentation responded to major climatic shifts that have occurred since the LGM.

Geochemical features of the black shales from the Wuyu Basin, southern Tibet: implications for palaeoenvironment and palaeoclimate

AbstractThe Mangxiang Formation black shales are the most important hydrocarbon source rocks in the Wuyu Basin. Trace and rare earth element (REEs) of the black shales from the Wuyu Basin were studied in order to understand their depositional environments and palaeoclimate. Thirty one black shale samples from the Wuyu Basin were analysed by inductively coupled plasma–mass spectrometry and X‐ray fluorescence. The black shales are characterized by moderate SiO2 (52.55–58.73%) contents and medium K2O/Na2O (2.21–4.83) ratio values but relatively high MgO + Fe2O3 (5.8–6.91%) and Al2O3 (15.1–17.5%) contents. The Chemical Weathering Index of Alternation (CIA) ranges from 57 to 70, together with medium Th/U (2.66–4.97) ratio values, reflecting a weak to moderate degree of chemical weathering of the source area. The palaeoredox condition of black shale was slightly oxic (or dysoxic) during black shale deposition as evidenced by slightly Ce anomalies (0.92–0.99) and Mn enrichment (EF = 1.6). The moderate palaeosalinity values (9.32‰–17.75‰), together with medium B/Ga (3.90–5.57) ratio values, indicate a brackish water environment. The palaeoclimate index ∑(Fe + Mn + Cr + Ni + V + Co)/∑(Ca + Mg + Sr + Ba + K + Na) ranges from 0.28 to 0.50 and low Sr/Ba (0.15–1.22) ratio values, indicating a semiarid to semimoist climatic condition during the sedimentation of the black shale. The high ω(La)N/ω(Yb)N ratio values (1.02–1.09) indicate a fast sedimentary rate during black shale deposition. In this study, a preservation model of the Mangxiang Formation black shale was established. The model indicates that excellent preservation may be the major controlling factor for the accumulation of organic matter. Copyright © 2015 John Wiley & Sons, Ltd.

Phytolith analysis of selected wetland plants from Changbai mountain region and implications for palaeoenvironment

The application of phytolith analysis in wetlands to reconstruct the paleoenvironment relies on the research of phytoliths of modern wetland plants. In this paper, 31 selected wetland plant species, belonging to 14 families and 26 genera, were studied. An inventory of phytolith types is provided and type-frequencies are assessed. There are 19 main kinds of phytoliths in this paper: elongate, cross, bilobate, scutiform phytoliths, lanceolate, fusiform phytolith, rondels, achene phytolith, silicified stomata, conical phytoliths, tracheid phytoliths, epidermal cells, trapeziform crenate, cylindrical polylobate, wavy trapezoid, cuneiform bulliform cells, sleeper-type, saddle and silicified hair cells. The taxonomic diagnostic potential of phytoliths (where the silicified stomata are outside) was tested by cluster analysis, which, to a certain extent supported the hypothesis that plant species can be identified on the basis of type, presence and frequency. Conical phytoliths were analyzed separately and results showed that Cyperaceae species can be distinguished by conical phytoliths at the species level. Silicified stomata dimensions were analyzed using one-way ANOVA, which found large disparities in the length and width, and a size category system of silicified stomata dimensions was developed, classifying the major groups into four subgroups. The current study shows that size and shape can be used to assign some of the silicified stomata to their respective genera. The percentage of stomata was also analyzed and the results revealed that there are more stomata in hydrophytes than mesophytes. These results reinforce the utility of using phytoliths as significant indicators for wetland plants and offer the potential of phytolith analysis for paleoenvironment and paleoclimate reconstruction in this region.

Biostratigraphy and sedimentology of the Fluviatile Untere Serie (Early and Middle Miocene) in the central part of the North Alpine Foreland Basin: implications for palaeoenvironment and climate

The Early to Middle Miocene Fluviatile Untere Serie lithostratigraphic unit of the Upper Freshwater Molasse (UFM) in the North Alpine Foreland Basin (NAFB) crops out in a 40 m long section at Untereichen-Altenstadt (central part of the NAFB). This section yields a unique superposition of two vertebrate assemblages belonging to different biostratigraphic units: early part OSM C + D (Karpatian) and OSM E (Early Badenian). Detailed taxonomic analyses reveal different diversity patterns in the two assemblages. Nine small mammal and six ectothermic vertebrate taxa occur in the older level UA 540 m, while 20 small mammal and 23 ectothermic vertebrate taxa are recorded for the younger level UA 565 m. From the latter locality comes a small-sized representative of the biostratigraphically significant Megacricetodon lappi lineage. This evolutionary level has not been documented previously for the eastern part of the NAFB. Bioclimatic analysis combined with lithofacies and architectural element analysis indicates that significant changes in the fluvial sedimentation style, surface-water runoff and tectonics occurred between the Early Karpatian and Early Badenian. A meandering fluvial system (marly unit) is erosively overlain by sandy braided river deposits (sandy unit). Overbank deposits of the marly unit revealed that the older vertebrate fossil assemblage (UA 540 m) is deposited in an animal burrow that was presumably produced by owls. Both reptilian and mammalian taxa are indicative of a relatively open environment and dry, probably semi-arid climate. Conversely, vertebrates from the sandy unit (UA 565 m), which are accumulated in channel fill deposits, suggest closed as well as open habitats with a subtropical humid climate and mean annual rainfall of about 1,000 mm. According to the sequence stratigraphic analysis the marly unit is interpreted as a highstand-system-tract of the TB 2.2 global 3rd order sequence. The new results add support to the hypothesis that the erosional unconformity between both sedimentary units spanning the Karpatian-Badenian transition corresponds to the pre-Riesian hiatus, which has been interpreted as part of the Styrian Tectonic Phase, and was previously identified only in the eastern and northeastern part of the NAFB. The biostratigraphic data further indicate that this hiatus lasted longer in the eastern than in the central part of the basin.

Element geochemical characteristics of the Cretaceous dinosaur eggshell fossils and their implications for palaeoenvironment

Dinosaur eggshells from the Cretaceous red beds of southern China were selected for element geochemical study. The concentrations of the major elements indicates that the eggshells did not change much in their chemical composition after they were formed. Variations in the contents of trace elements and REEs imply that a palaeoclimatic anomaly might occur during Late Cretaceous.