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1.
Baripada Marine Beds (BMB) have been studied extensively in terms of its mega fossil content. However, not much has been discussed about the foraminiferal content and the organic matter assemblage in these beds. The fossiliferous sequence of BMB consists of sandstone, shale and limestone units. The present study is persued on the limestone unit of BMB. Foraminiferal, thin section and rock-eval pyrolysis studies were performed on the 33 surface samples collected from five sections of Jamdapal and Mukurmatia region along the Budhabalang river bank. Foraminifera are less abundant in the samples of Jamdapal, whereas Mukurmatia is comparatively rich. First appearance datum of Globorotalia menardii[ranges since middle Miocene (12.6 Ma); FAD at planktic foraminiferal zone N12] and last appearance datum of Neogloboquadrina continuosa [ranges between early Miocene (23.2 Ma) to late Miocene (8.3 Ma); FAD at planktic foraminiferal zone N4B and LAD at N16] together suggest that the limestone unit was deposited in between 12.6 to 8.3 Ma within the upper Miocene. Also, the association of shallow water benthic foraminifera (Species of Ammonia, Asterorotalia, Bolivina, Buliminella, Cibicides, Challengerella, Criboelphidium, Cribononion, Elphidium, Hanzawaia, Nonionella) and planktic foraminifera (Globigerina falcoensis, Globigerina woodi, Globorotalia menardii, Neogloboquadrina continuosa) together with oyster bank and shark teeth suggest deposition of limestone within well oxygenated, tropical, shallow water, open marine condition (within 40m water depth). Lithological and thin section studies together with global sea level fluctuation history advocate that upper Miocene marine transgression promoted the formation of this unit. Bulk organic geochemical data obtained by the rock-eval pyrolysis studies on selected samples indicate a low total organic carbon (TOC), with low hydrogen index (HI), high oxygen index (OI). The organic facies is characterised by type-IV kerogen with major contribution from near shore terrestrial plants. This also suggests deposition in shallow, oxygenated environments that did not promote significant accumulation and preservation of organic content in sediments.  相似文献   

2.
A new species of fossil palm rhizome having root-mat under the organ genus Rhizopalamoxylon (Rhizopalmoxylon nypoides sp. nov.) is reported. The specimen shows the closest resemblance with the modern monotypic genus Nypa Wurmb of the Arecaceae. The specimen was collected from the late Maastrichtian–early Danian sediments of Deccan Intertrappean beds, Mothi, Sagar district, Madhya Pradesh, India. Nypa is a mangrove palm naturally found in estuaries and swamps of the tropical region and represents one of the oldest records of the genus from the Deccan Intertrappean beds of central India. The abundance of palms, including Nypa and previously recorded coastal and mangrove elements such as Acrostichum, Barringtonia, Cocos, Sonneratia and marine algae (Distichoplax and Peyssonellia) from the Deccan Intertrappean beds indicate marine influence and existence of tropical rainforest ecosystem in the vicinity of fossil locality in contrast to the deciduous forests occurring there at present.  相似文献   

3.
The crystal structure of mangan-neptunite, a manganese analogue of neptunite, has been refined in two space groups (Cc and C2/c). The mineral is monoclinic, with the correct space group Cc; the unit-cell dimensions are: a = 16.4821(6), b = 12.5195(4), c = 10.0292(3) Å, β = 115.474(1)°, and V = 1868.31 Å3. The crystal structure has been refined to R 1 = 0.0307 (wR 2 = 0.0901) on the basis of 4892 observed reflections with |F hkl | ≥ 4σ|F hkl |. The most plausible acentric model is caused by the Ti- and (Fe, Mn, Mg)-ordering in the structure. Ti-octahedrons are strongly distorted and consist of short bond Ti-O (1.7 Å), one long bond (2.2 Å), and four equal bonds (2.0 Å). Fe-octahedrons are regularly shaped, with all Fe-O bonds being approximately identical.  相似文献   

4.
Laboratory measurements are required to study geophysical properties of the subsurface because of lacking direct observation of Earth’s crust. In this research, compressional (P) and shear (S) wave velocity measurements have been conducted on cylindrical specimens of Quartz-micaschist cored using rock blocks taken from the zinc and lead Angouran mine, Zanjan, northwest of Iran. Cylindrical rock specimens were prepared from the blocks by coring in 0°, 30°, 45°, 60°, and 90° into the foliation direction. P- and S-wave velocities were measured along the cylindrical specimens with different foliation orientations. Percent variations of the P- and S-wave velocities (Thomsen’s anisotropic parameters ε and γ) and constant dynamic modulus of test results have been determined. Percent variations of the P-wave velocity (ε) increase with an increase of the foliation angle with respect to the propagating waves direction by a parabolic function as it shows P-wave velocity differences up to a maximum value of 50 %. Thomsen’s anisotropic parameter of γ has also the same function with the foliation angle. Meanwhile, foliation orientation has a much greater influence on ε than γ for foliation angle from 45° to 90° as \( \frac{\varepsilon }{\gamma } \) ratio increases with an increase of foliation angle. Values of dynamic elastic modulus (E), Poisson’s ratio (ν), shear modulus (μ), bulk modulus (K), and Lamé’s constant (λ) increase with the increase of foliation angle with the parabolic function. The results show that dynamic elastic modulus, Poisson’s ratio, shear modulus, bulk modulus, and Lamé’s constant have anisotropic behavior in relation with the foliation orientation.  相似文献   

5.
Paleogene sediments of the inner fold belt, Naga hills, have very well preserved ichnofossils. 16 ichnospecies have been documented among 13 ichnogenera such as Arenicolites isp., Chondrites targionii, Cylindrichnus isp., Diplocraterion parallelum, Gyrochorte isp., Ophiomorpha annulata, O. irregulaire, O. nodosa, O. rudis, Palaeophycus tubularis, Planolites beverleyensis, Scolicia palaeobullia, Skolithos linearis, Trypinites weisei, Thalassinoides horizontalis and Zoophycos isp. The ichnofossil assemblages comprise mostly domichnia and fodinichnia benthos of the Skolithos and Cruziana ichnofacies. A shallow marine nearshore to offshore marine environment with fluctuating energy condition has been envisaged.  相似文献   

6.
The present megafloral assemblage recorded from the Barakar sediments of Dholpahar section along Singda rivulet near Gopal Prasad Village in Talcher Basin comprises of equisetaceous stems, Gangamopteris buriadica, Palaeovittaria kurzii and 19 species of the genus Glossopteris. Record of Gangamopteris, Palaeovittaria and many narrow mesh forms of Glosspteris viz., G. angustifolia, G. churiensis, G. communis, G. recurva, G. spatulata, G. stenoneura, G. tenuifolia, G. vulgaris and G. zeilleri from two older fossiliferous horizons demonstrates that these fossils were preserved during Lower Barakar sedimentation. The report of middle and broad mesh forms of Glossopteris viz., G. barakarensis, G. browniana, G. indica, G. intermittens, G. karharbariensis, G. nakkarea, G. oldhamii, G. taeniensis and G. retifera in the youngest fossiliferous horizons reveals that these fossils were preserved during the deposition of Upper Barakar sediments. The continuation of some of the Karharbari plant fossils in the early phase of Barakar Formation and their disappearance in the flora of Late Barakar suggests a shift in the climatic setup. Palaeoclimate and palaeovegetation of this area are also summarised in this study. Moreover, the fossil assemblages of different fossiliferous beds of Dholpahar section demonstrate the evolution of midrib and meshes in different reticulate leaves.  相似文献   

7.
A new taxon, ?Crassodontidanus gen. nov. of Hexanchiformes (cow sharks) from the Jurassic of Germany is described. It is characterized by peculiar teeth combining apomorphic (serrated mesial cutting edge of the main cusp) and plesiomorphic features (deep root with convex mesial and distal margins in labial and lingual views; protruding lingual root bulge). This character combination readily distinguishes members of the new taxon from all other known extant (Heptranchias, Hexanchus, Notorynchus) and extinct (?Gladioserratus, ?Notidanodon, ?Notidanoides, ?Pachyhexanchus, ?Paraheptranchias, ?Weltonia) hexanchiforms. Currently, two species, ?C. serratus (type species; Late Jurassic, Late Kimmeridgian of Nusplingen, South Germany) and ?C. wiedenrothi (Early Jurassic, Early Pliensbachian of Gretenberg (Hanover), North Germany) are assigned to this taxon. ?Crassodontidanus gen. nov. is member of ?Crassonotidae fam. nov. and sister to ?Notidanoides Maisey, 1986 and ?Pachyhexanchus Cappetta, 1990. We consider ?Notidanus amalthei Oppel, 1854 from the Pliensbachian of South Germany, ?Notidanus insignis Seguenza, 1887 from the Oxfordian of Sicily (Italy) and ?Notidanus wagneri Agassiz, 1843 from the Early Tithonian of Solnhofen (South Germany) nomina dubia and nomina nuda, respectively. The family ?Crassonotidae comprises plesiomorphic hexanchiforms ranging from the Sinemurian (Early Jurassic) to the Hauterivian (Early Cretaceous).  相似文献   

8.
In determining the physical and mechanical parameters of clay, it is sometimes necessary to determine them indirectly from other parameters since they cannot be measured directly from laboratory or field tests. In order to determine the effect of temperature on the behavior of clay, an indirect approach is used here by analyzing the changes of mass (\(\Delta m\)), density (\(\rho\)), porosity (\(\phi\)), P-wave velocity (\({v_p}\)), thermal conductivity (\(\lambda\)), specific heat capacity (c), resistivity (R) and uniaxial compressive strength (f) of clay from eastern China for a temperature range between 20 and 800 °C. The results indicate that temperature has a significant effect on these parameters. Comparisons between \(\Delta m\) and \(\rho\), \(\Delta m\) and \({v_p}\), \(\rho\) and \({v_p}\), \(\phi\) and \(\lambda\), \({v_p}\) and f, R and f show a linear change among these parameters,whereas the relationships among \(\Delta m\) and \(\phi\), \(\phi\) and \({v_p}\), \(\phi\) and R, \({v_p}\) and \(\lambda\), \(\phi\) and f are exponential. It is difficult to obtain these relationships by using regression analysis with high levels of accuracy. Further refinement is therefore required.  相似文献   

9.
Micofloral study of Lameta sediments and associated sauropod coprolites in the Nand-Dongargaon basin in Maharashtra was conducted to understand the diet and habitat of sauropods. The study revealed the presence of pollen, spores, algal and fungal remains, well-preserved cuticles of Poaceae, and testate amoebae. Vegetation during Lameta included tall arboreal taxa, such as conifers (Podocarpus and Araucaria), Cycads (Cycas), Euphorian and Barringtonia and herbs and shrubs, such as Cheirolepidiaceae (Classopollis), Arecaceae (Palmaepollenites), Poaceae (Graminidites), Asteraceae (Compositoipollenites), Caryophyllaceae (Cretacaeiporites and Periporopollenites), and Acanthaceae (Multiareolites). Data suggest that the sauropods ate soft tissues of angiosperms and gymnosperms. The intake of testate amoeba, algal remains, sponge spicules, and diatoms might be through water intake.  相似文献   

10.
We present a new normalization for the linear density-perturbation spectrum in a multi-parameter model of the Universe. Using the differential mass function for the nearly galaxy clusters obtained from optical data, we have constructed a functional relation between the dispersion of the density contrast σ 8 on the scale 8h ?1 Mpc and the cosmological parameters Ω m , ΩΛ, h, n, f v for each of three theoretical approximations of the mass function: Press-Schechter, Sheth-Tormen and Jenkins. An extended class of models of the Universe with general spatial curvature include four parameters for the matter components: baryons (Ω b ), “cold” dark matter (Ω c ), “hot” dark matter (Ω v ), and the vacuum energy (ΩΛ). It is shown that the most accurate normalization of the power spectrum is achieved with the Sheth-Tormen approximation.  相似文献   

11.
The coal-bearing sequences of Barakar and Raniganj formations exposed in Bina and Jhingurdah open-cast collieries, respectively, are analysed for their macro- and miofloral content. The sediment successions primarily comprise of sandstones, shales, claystones and coal seams. In addition to the diverse glossopterid assemblage, four palynoassemblage zones, namely Zones I and II in Bina Colliery and Zones III and IV in Jhingurdah Colliery, have also been recorded in the present study. The megafossil assemblage from the Barakar strata of Bina Colliery comprises of three genera, namely Gangamopteris, Glossopteris and cf. Noeggerathiopsis. Palynoassemblage-I is characterised by the dominance of non-striate bisaccate pollen genus Scheuringipollenites and subdominance of striate bisaccate Faunipollenites and infers these strata to be of Early Permian (Artinskian) age (Lower Barakar Formation). The palynoassemblage has also yielded a large number of naked fossil spore tetrads, which is the first record of spore tetrads from any Artinskian strata in the world and has a significant bearing on the climatic conditions. The palynoassemblage-II is characterised with the dominance of Faunipollenites over Scheuringipollenites and is indicative of Kungurian age (Upper Barakar Formation). The megafossil assemblage from the Raniganj Formation of Jhingurdah Colliery comprises of five genera with 26 species representing four orders, viz., Equisetales, Cordaitales, Cycadales and Glossopteridales. The order Glossopteridales is highly diversified with 23 taxa and the genus Glossopteris, with 22 species, dominates the flora. The mioflora of this colliery is represented by two distinct palynoassemblages. The palynoassemblage-III is correlatable with the palynoflora of Early Permian (Artinskian) Lower Barakar Formation. The assemblage suggests the continuity of older biozones into the younger ones. The palynoassemblage-IV equates the beds with composition V: Striatopodocarpites–Faunipollenites–Gondisporites assemblage zone of Tiwari and Tripathi (1992) of Late Permian (Lopingian) Raniganj Formation in Damodar Basin. The FAD’s of Alisporites, Klausipollenites, Falcisporites, Arcuatipollenites pellucidus and Playfordiaspora cancellosa palynotaxa in this assemblage enhance the end Permian level of the Jhingurdah Top seam, as these elements are the key species to mark the transition of Permian into the Lower Triassic.  相似文献   

12.
The plant fossil records from the Siwalik Group of Arunachal Pradesh, India are far from satisfactory due to remoteness and dense vegetation of the area. We report seven fossil woods of which three belong to the Middle Siwalik (Subansiri Formation), while the rest are from the Upper Siwalik (Kimin Formation). The modern analogues of the fossils from the Middle Siwalik are Lophopetalum littorale (Celastraceae), Afzelia-Intsia and Sindora siamensis (Fabaceae) and from the Upper Siwalik are Miliusa velutina (Annonaceae), Calophyllum tomentosum and Kayea (Calophyllaceae) and Diospyros melanoxylon (Ebenaceae). The dominance of diffuse porosity in the fossil woods indicates a tropical climate with low seasonality (little variation) in temperature, while a high proportion of large vessels and simple perforation plates in the assemblage infer high precipitation during the deposition of the sediments. The aforesaid inference is in strong agreement with the previous quantitative reconstruction based on fossil leaves. Several modern analogues of the fossil taxa are now growing in low latitudes possibly due to an increase in seasonality (increased variation) in temperature caused by the rising Himalaya.  相似文献   

13.
14.
The stratigraphic distribution of microfossils and macroscopic fossil biota in Vendian deposits of the South Ladoga region (northwestern East European Platform) is analyzed. In the sequence of the Shotkusa- 1 well, three taxonomically heterogeneous microfossil assemblages are distinguished: two of them refer to the Redkinian age (Starorusskaya Fm.) and one to the Kotlinian age (Vasileostrovskaya Fm.). Deposits of the Starorusskaya Fm. contain Redkinian biota of macroscopic fossils, of which the most characteristic representatives are Chuaria circularis, Doushantuophyton lineare, Morania zinkovi, Orbisiana simplex, and Redkinia spinosa. These new findings expand the paleontological characteristics of Upper Vendian deposits, also providing additional criteria for distinguishing the Redkinian horizon in the northwestern East European Platform.  相似文献   

15.
Dam failure constitutes a grave threat to human life. However, there is still a lack of systematic and comprehensive research on the loss of life (L) caused by dam break in China. From the perspective of protecting human life, a new calculation method for L occurred in dam break floods is put forward. Fourteen dam failure cases in China are selected as the basic data by three-dimensional stratified sampling, balancing spatial, vertical elevation and temporal representations, as well as considering various conditions of the dam collapse. The method includes three progressive steps: Firstly, some impact factors of loss of life (IFL) are selected by literature survey, i.e., severity of dam break flood (S F), population at risk (P R), understanding of dam break (U B), warning time (T W) and evacuation condition (E C). And the other IFL of weather during dam break (W B), dam break mode (M B), water storage (S W), building vulnerability (V B), dam break time (T B) and average distance from affected area to dam (D D) are also taken into account to get a more comprehensive consideration. According to disaster system and disaster risk, these eleven IFL are divided into four categories. Through the improved entropy method, eight key IFL are further selected out of the eleven. Secondly, four L modules are built based on four categories, which are L-causing factor module (M 1), L-prone environment module (M 2), affected body module (M 3) and rescue condition module (M 4). Eventually, by using two methods of multivariate nonlinear regression and leave-one-out cross-validation in combination with coupled four modules, the calculation method for L is established. Compared with the results of Graham method and D&M method, the result of the proposed one is much closer to the actual value and performs better in fitting effect and regional applicability. In the application, L calculation and consequence assessment are carried out in the example of Hengjiang reservoir that has already broken down. At the same time, L calculation and risk prediction are used in the analysis of Yunshan reservoir, which is under planning. The proposed method can not only be applied to estimate L and its rate (f L ) under various types of dam break conditions in China, but also provide a reliable consequence assessment and prediction approach to reduce the risk of L.  相似文献   

16.
The high-pressure behavior of a vanadinite (Pb10(VO4)6Cl2, a = b = 10.3254(5), = 7.3450(4) Å, space group P63/m), a natural microporous mineral, has been investigated using in-situ HP-synchrotron X-ray powder diffraction up to 7.67 GPa with a diamond anvil cell under hydrostatic conditions. No phase transition has been observed within the pressure range investigated. Axial and volume isothermal Equations of State (EoS) of vanadinite were determined. Fitting the PV data with a third-order Birch-Murnaghan (BM) EoS, using the data weighted by the uncertainties in P and V, we obtained: V 0 = 681(1) Å3, K 0 = 41(5) GPa, and K′ = 12.5(2.5). The evolution of the lattice constants with P shows a strong anisotropic compression pattern. The axial bulk moduli were calculated with a third-order “linearized” BM-EoS. The EoS parameters are: a 0 = 10.3302(2) Å, K 0(a) = 35(2) GPa and K′(a) = 10(1) for the a-axis; c 0 = 7.3520(3) Å, K 0(c) = 98(4) GPa, and K′(c) = 9(2) for the c-axis (K 0(a):K 0(c) = 1:2.80). Axial and volume Eulerian-finite strain (fe) at different normalized stress (Fe) were calculated. The weighted linear regression through the data points yields the following intercept values: Fe a (0) = 35(2) GPa for the a-axis, Fe c (0) = 98(4) GPa for the c-axis and Fe V (0) = 45(2) GPa for the unit-cell volume. The slope of the regression lines gives rise to K′ values of 10(1) for the a-axis, 9(2) for the c-axis and 11(1) for the unit cell-volume. A comparison between the HP-elastic response of vanadinite and the iso-structural apatite is carried out. The possible reasons of the elastic anisotropy are discussed.  相似文献   

17.
Moissanites were found in tagamites of the Popigai meteorite crater along with impact diamonds. We have studied 55 samples including 49 individual polytypes and six intergrowths. The numbers of 6H, 15R, 4H, 6H/15R, and 6H/4H polytypes are 82, 7, 5, 4, and 2%, respectively. By the assemblage of polytypes, the moissanites of the Popigai astrobleme are distinct from kimberlite moissanites, as well as from synthetic SiC, which is characterized by the absence of the 4H polytype and the presence of more diverse inclusions (including Fe-bearing). The Popigai astrobleme is one of few objects with reliable natural moissanite. Technogenic contamination is excluded, since any researcher can find this mineral in tagamites.  相似文献   

18.
19.
Micropaleontological investigations on Permian successions in the NW of Iran based on algae led to the determination of taxa belonging to some families such as Ungdarellaceae (Ungdarella uralica), Gymnocodiaceae (Gymnocodium bellerophontis and Permocalculus sp.), Dasycladales (Mizzia cf. M. yabei), and some microproblematics (Vermiporella nipponica and Pseudovermiporella sodalica). These investigations are mainly focused on the Khachik Formation at the Ali Bashi Mountains. According to the algal community, a lagoon environment is offered for the studied successions.  相似文献   

20.
The stability of nonstoichiometric clinopyroxenes in the Di-CaEsk join was experimentally studied, and phase diagrams were constructed for this join at pressures of 2.0 and 3.0 GPa. It was found that melting in the diopside part of the join occurs at anomalously low temperatures, and nonstoichiometric clinopyroxene coexists with a phase approaching diopside in composition. Phase relations along the Di-CaEsk join can be described and consistently interpreted only assuming that the diopside phase (α-diopside) is thermodynamically stable. The following phase volumes were observed along the solidus of the join at a pressure of 3.0 GPa: Cpx, αDi+Cpx, αDi+Cpx+Qtz, αDi+Cpx+Grt+Qtz, Cpx+Grt+Qtz, Cpx+Grt+Ky+Qtz, Grt+Ky+Qtz. Melting occurs via the eutectic reaction αDi+Cpx+Grt+Qtz=L at a temperature of about 1200°C in the diopside part of the system and via the eutectic reaction Cpx+Grt+Ky+Qtz=L at a temperature of 1400°C in the calcium-rich part of the system. At a pressure of 2.0 GPa, melting occurs at temperatures of 1200–1300°C via the eutectic reaction αDi+Cpx+ An + Qtz=L. The invariant equilibrium (L, An, Cpx, Grt, αDi, Qtz) lies within the pressure range 2.0–3.0 GPa. Nonstoichiometric clinopyroxenes form complex solid solutions, the compositions of which are not strictly confined to the Di-CaEsk join and depend on temperature, pressure, and phase association. Grossular garnets coexist with nonstoichiometric clinopyroxenes and α-diopside.  相似文献   

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