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1
Cuif, J. P., Y. Dauphin, B. Farre, G. Nehrke, J. Nouet, and M. Salomé. "Distribution of sulphated polysaccharides within calcareous biominerals suggests a widely shared two-step crystallization process for the microstructural growth units." Mineralogical Magazine 72, no. 1 (February 2008): 233–37. http://dx.doi.org/10.1180/minmag.2008.072.1.233.
Повний текст джерелаАнотація:
AbstractSynchrotron-based XANES characterization of sulphated sulphur combined with atomic force microscopy and transmission electron microscopy (imaging and diffraction) allow insights into the crystallization of the calcareous units produced by invertebrates. As a result of a series of converging data, reticulate crystallization of the amorphous Ca-carbonate molecules conveyed to the micron-thick growth layer by the sumicrometric organo-mineral units seems a reasonable hypothesis, providing us with a method of explaining the multiple and taxonomy-linked ‘vital effects’ which have long been recognized among the calcareous biocrystals.
2
Li, Guohua, Haigang Li, Peter A. Leffelaar, Jianbo Shen, and Fusuo Zhang. "Dynamics of phosphorus fractions in the rhizosphere of fababean (Vicia faba L.) and maize (Zea mays L.) grown in calcareous and acid soils." Crop and Pasture Science 66, no. 11 (2015): 1151. http://dx.doi.org/10.1071/cp14370.
Повний текст джерелаАнотація:
The dynamics of soil phosphorus (P) fractions were investigated, in the rhizosphere of fababean (Vicia faba L.) and maize (Zea mays L.) grown in calcareous and acid soils. Plants were grown in a mini-rhizotron with a thin (3 mm) soil layer, which was in contact with the root-mat, and considered as rhizosphere soil. Hedley sequential fractionation was used to evaluate the relationship between soil pH and P dynamics in the rhizosphere of fababean and maize. Soil pH influenced the dynamics of P fractions in both calcareous and acid soils. Fababean and maize roots decreased rhizosphere pH by 0.4 and 0.2 pH units in calcareous soil, and increased rhizosphere pH by 1.2 and 0.8 pH units in acid soil, respectively, compared with the no-plant control. The acid-soluble inorganic P fraction in the rhizosphere of calcareous soil was significantly depleted by fababean, which was probably due to strong rhizosphere acidification. In contrast, maize had little effect on this fraction. Both fababean and maize significantly depleted the alkali-soluble organic P fractions in calcareous soil, but not in acid soil. Fababean and maize utilised different P fractions in soil, which was partly due to their differing abilities to modify the rhizosphere. This study has decoupled successfully the effects of chemically induced pH change from plant growth effects (such as mineralisation and P uptake) on P dynamics. The effect of soil pH on plant exudation response in P-limited soils has been demonstrated in the present study.
3
Milosevic, Rajko. "Typological classification and the existing condition of artificially established sycamore maple and Norway maple stands in the protective forest belt." Bulletin of the Faculty of Forestry, no. 104 (2011): 143–54. http://dx.doi.org/10.2298/gsf1104143m.
Повний текст джерелаАнотація:
The study results on the typological classification of the artificially established sycamore maple and Norway maple stands included in the shelterbelt along the ?Belgrade-Zagreb? highway are presented. The environmental conditions of the sycamore and Norway maple plantation have been typologically defined in specific typological entitities at the ecological level (ecological units). In this context, the specific site conditions were characterised and defined as: a) Forest of common oak (Tilio-Quercetum crassiusculae typicum) on leached chernozem, b) Forest of common oak (Tilio-Quercetum crassiusculae typicum) on moderately deep to deep calcareous chernozem, c) Forest of common oak (Tilio-Quercetum crassiusculae typicum) on shallow to moderately deep calcareous chernozem. The inter-relationship between sycamore maple and Norway maple regarding the ecological and coenological optimum differs within the above ecological units. The diversity reflects the sycamore and Norway maple bioecology and the site typology of the particular ecological units.
4
Luitel, Prakash, and Suman Panthee. "Geological study in Tal - Talekhu section of Manang District along the Besisahar – Chame Road." Bulletin of the Department of Geology 22 (December 15, 2020): 25–28. http://dx.doi.org/10.3126/bdg.v22i0.33411.
Повний текст джерелаАнотація:
The section between Tal to Talekhu of Manang District lacks the detailed geological study. The geological mapping in the scale of 1:50,000 followed by the preparation of geological cross-section and lithostratigraphic column has been done in the present study. The studied area lies partially in the Higher Himalayan Crystalline and the Tibetan Tethys Sequence. The units of the Higher Himalayan Group from Tal to Talekhu consists mainly of vigorous to faintly calcareous gneiss, migmatitic gneiss, quartzite, granite, etc. They are named as the Calc. Silicate Gneiss and Paragneiss and the Orthogneiss and Granite units. The lowermost part of the Tibetan Tethys consisted of metamorphosed calcareous rocks containing silicates and feldspar, so this unit is termed as the Marble and Calc. Gneiss. The section is about 9 km in thickness and is highly deformed with presence of igneous rocks at many places.
5
Luitel, Prakash, and Suman Panthee. "Geological study in Tal - Talekhu section of Manang District along the Besisahar – Chame Road." Bulletin of the Department of Geology 22 (December 15, 2020): 25–28. http://dx.doi.org/10.3126/bdg.v22i0.33411.
Повний текст джерелаАнотація:
The section between Tal to Talekhu of Manang District lacks the detailed geological study. The geological mapping in the scale of 1:50,000 followed by the preparation of geological cross-section and lithostratigraphic column has been done in the present study. The studied area lies partially in the Higher Himalayan Crystalline and the Tibetan Tethys Sequence. The units of the Higher Himalayan Group from Tal to Talekhu consists mainly of vigorous to faintly calcareous gneiss, migmatitic gneiss, quartzite, granite, etc. They are named as the Calc. Silicate Gneiss and Paragneiss and the Orthogneiss and Granite units. The lowermost part of the Tibetan Tethys consisted of metamorphosed calcareous rocks containing silicates and feldspar, so this unit is termed as the Marble and Calc. Gneiss. The section is about 9 km in thickness and is highly deformed with presence of igneous rocks at many places.
6
Al-Bahry, S. N., I. Y. Mahmoud, K. Melghit, and I. Al-Amri. "Analysis of Elemental Composition of the Eggshell before and after Incubation in the Loggerhead Turtle (Caretta caretta) in Oman." Microscopy and Microanalysis 17, no. 3 (April 27, 2011): 452–60. http://dx.doi.org/10.1017/s1431927611000298.
Повний текст джерелаАнотація:
AbstractTo date, there are limited studies on loggerhead turtle (Caretta caretta) eggshell ultrastructure and its elemental composition. Eggs were collected from turtle nests immediately after oviposition and post hatching. Three eggshell layers were recognized. The outer calcareous layer consists of loose nodular units of different shapes and sizes with loose attachment between the units, resulting in numerous spaces and openings. Each unit consists of CaCO3crystals in aragonite (99%) and calcite (1%). The middle layer has several strata with numerous openings connecting the calcareous and the inner shell membrane. Crystallites of the middle layer are a mix of amorphous material with aragonite (62%) and calcite (38%). The inner shell membrane has numerous reticular fibers mixed predominantly with halite (NaCl) and small amounts of sylvite. Thermogravimetry analysis of the calcareous showed a low exothermic peak at 425°C, which corresponds to a transitional phase from aragonite to calcite. A high endothermic peak at 814°C corresponds to decomposition of calcite CaCO3to CaO and CO2. Electron diffraction confirmed the presence of NaCl halite crystal. A significant difference was found in the percentage of elements and crystal configurations in the three layers. This study has value in assessing the emergence success in this endangered species.
7
Kilian, Sinah, and Hugo Ortner. "Structural evidence of in-sequence and out-of-sequence thrusting in the Karwendel mountains and the tectonic subdivision of the western Northern Calcareous Alps." Austrian Journal of Earth Sciences 112, no. 1 (January 1, 2019): 62–83. http://dx.doi.org/10.17738/ajes.2019.0005.
Повний текст джерелаАнотація:
AbstractWe present the results of a field study in the Karwendel mountains in the western Northern Calcareous Alps, where we analysed the boundary between two major thrust sheets in detail in a key outcrop where nappe tectonics had been recognized already at the beginning of the 20th century. We use the macroscopic structural record of thrust sheet transport in the footwall and hanging wall of this boundary, such as folds, foliation and faults. In the footwall, competent stratigraphic units tend to preserve a full record of deformation while incompetent units get pervasively overprinted and only document the youngest deformation.Transport across the thrust persisted throughout the deformation history of the Northern Calcareous Alps from the late Early Cretaceous to the Miocene. As a consequence of transtensive, S-block down strike-slip tectonics, postdating folding of the major thrust, new out-of-sequence thrusts formed that climbed across the step, and ultimately placed units belonging to the footwall of the initial thrust onto its hanging wall.One of these out-of-sequence thrusts had been used to delimit the uppermost large thrust sheet (Inntal thrust sheet) of the western Northern Calcareous against the next, tectonically deeper, (Lechtal) thrust sheet. Based on the structural geometry of the folded thrust and the age of the youngest sediments below the thrust, we redefine the thrust sheets, and name the combined former Inntal- and part of the Lechtal thrust sheet as the new Karwendel thrust sheet and the former Allgäu- and part of the Lechtal thrust sheet as the new Tannheim thrust sheet.
8
Baliniak, Weronika. "Paleocene-Eocene calcareous agglutinated foraminifera from slope marl assemblages of the Fore-Magura Thrust Sheet (Polish Outer Carpathian)." Micropaleontology 64, no. 6 (2018): 379–89. http://dx.doi.org/10.47894/mpal.64.6.04.
Повний текст джерелаАнотація:
Organic-cemented benthic agglutinated foraminifera are a highly dominant component of flysch-type DWAF assemblages, while agglutinated foraminifera that use calcareous cement are rare or almost absent. However, in mixed assemblages, consisting of both benthic and planktonic forms, the agglutinated foraminiferal assemblages usually include calcareous agglutinants and display higher taxonomic diversity than coeval flysch-type agglutinated foraminiferal assemblages. Late Paleocene - Late Eocene mixed foraminiferal assemblages from 45 samples collected from the Fore-Magura Thrust Sheet of the Polish Outer Carpathians, were examined for taxonomic identification of characteristic agglutinated foraminifera with calcareous material in their tests. The following 11 species are reported herein: Vulvulina eocaena Montagne, Plectina elongata Cushman and Bermudez, Gaudryina laevigata Franke, Gaudryina pyramidata Cushman, Arenobulimina d'orbignyi (Reuss), Remesella varians (Glaessner), Dorothia beloides Hillebrandt, Karreriella chapapotensis (Cole), Karreriella subglabra (Gumbel), Clavulinoides havanensis Cushman and Bermudez, Pseudoclavulina clavata (Cushman) and an additional 10 taxa are left in open nomenclature. The species assigned to Vulvulina, Plectina, Gaudryina and Pseudogaudryinella reveal calcareous material within their tests, though the descriptions of these genera do not always specify this feature. The results of this study reveal higher diversity and abundance of calcareous agglutinated foraminifera occurring in themarly deposits of the Fore-Magura Thrust Sheet in comparison with other units of the Polish Outer Carpathians. The studied group of agglutinated foraminifera with calcareous material may be regarded as a characteristic component of DWAF assemblages indicative of the slope marl foraminiferal assemblages.
9
Shoval, S., and O. Zlatkin. "Climatic changes during the Pliocene as observed from climate-sensitive rocks and clay minerals of the Sedom formation, the Dead Sea Basin." Clay Minerals 44, no. 4 (December 2009): 469–86. http://dx.doi.org/10.1180/claymin.2009.044.4.469.
Повний текст джерелаАнотація:
AbstractThe climatic history of the Dead Sea region during the Pliocene and its global connection are observed from climate-sensitive rocks and clay minerals of the Sedom formation. The Sedom formation consists of evaporative halitic rock salt units and calcareous shale units that were deposited in the Dead Sea Basin during the Pliocene. The precipitation of the rock salts took place in the hypersaline sabkha environment of the Sedom Lagoon. The extensive evaporative conditions are related to an extremely dry and warm arid climate at that time. In the arid climate, the influx of meteoric water by the drainage system of the Sedom Lagoon was limited and permitted a large concentration of lagoonal brine as well as a small rate of detritus transportation to the lagoon. Accessory sepiolite found in the rock salt appears to be neoformed from brine enriched with Mg and poor in Al under the extreme salinity condition. The small amounts of Al are in accordance with the small number of detrital minerals in the rock salts. The replacement in the deposition of the rock salt members with the calcareous shale members demonstrates a decrease in the salinity of the brine in the Sedom Basin and an increase in the deposition of detritus. The change in conditions was related to a period of deposition under a more humid climate where the erosion and the transport of detritus by the drainage system to the Sedom Basin was higher, causing the deposition of calcareous shales. Palygorskite found in the calcareous shales appears to be neoformed from brine enriched with Mg and containing Al in conditions of reduced salinity of the Sedom Basin. The larger amounts of Al are in accordance with the abundance of detrital minerals in the calcareous shales.The depositional cycles of the Sedom formation, the cyclic fluctuation of the climatic-hydrologic conditions from an arid to a more humid climate and their correlation with sea-level fluctuations and transgression-regression cycles of the Mediterranean Sea seem to be a response to corresponding global interglacial and glacial periods during the Pliocene.
10
Mikuláš, Radek, Petr Skupien, Miroslav Bubík, and Zdeněk Vašíček. "Ichnology of the Cretaceous Oceanic Red Beds (Outer Western Carpathians, Czech Republic)." Geologica Carpathica 60, no. 3 (June 1, 2009): 233–50. http://dx.doi.org/10.2478/v10096-009-0016-1.
Повний текст джерелаАнотація:
Ichnology of the Cretaceous Oceanic Red Beds (Outer Western Carpathians, Czech Republic)Large differences in the intensity and overall character of bioturbational structures were found in five facies containing hemipelagic red beds. Red beds (CORB) of the Godula facies of the Silesian Unit and their equivalents (mostly not red) in the Kelč facies of the Silesian Unit and the CORB in the non-calcareous sediments of the Rača Unit display a very low degree of bioturbation. The CORB facies of the Rača Unit, containing calcareous intercalations, displays a very high degree of bioturbation as expressed by a high ichnofabric index. They contain trace fossilsChondrites, Zoophycos, Planolites, Thalassinoides, Palaeophycus, TeichichnusandPhycosiphon.The supply of food obviously acted as the controlling factor. The "calcareous" facies of the CORB of the Rača Unit has a considerably higher proportion of sand-dominated interbeds and also carbonates than the non-calcareous facies. This (especially the presence of carbonates) suggests a relative proximity of food-rich environments and an easy transport of nutrition-rich substrate by turbidite currents into the basin directly, not only by periodical fall-out of dead plankton (which is probably responsible for the rhythmicity of poor colonization horizons in weakly bioturbated units).
11
Salari, Kolsum Rahman, Mohammad Amir Delavar, Mehrdad Esfandiari, and Ebrahim Pazira. "Morphological, physical, and clay mineralogy of calcareous and gypsiferous soils in North of Lorestan, Iran." Canadian Journal of Soil Science 99, no. 4 (December 1, 2019): 485–94. http://dx.doi.org/10.1139/cjss-2018-0141.
Повний текст джерелаАнотація:
There is limited information about the genesis, classification, and properties of calcareous and gypsiferous soils of western Iran. This study investigated the morphological, physical, and mineralogical characteristics of soils on different physiographic units, including plateau, colluvial fans, and piedmont plain in the Aleshtar region. The results indicated that the parent materials (calcareous and gypsiferous) as well as topographic conditions had the most influence on the soil profile development, pedogenic processes, and clay mineralogy. Illite, chlorite, smectite, palygorskite, and kaolinite clay minerals were identified using X-ray powder diffraction, transmission electron microscopy, and scanning electron microscopy. Illite, chlorite, and kaolinite have genetically been inherited from parent rocks. Neoformation of smectite and palygorskite other than genetic inheritance was formed as a result of calcite and gypsum precipitation and poor drainage. Calcareous soils with the petrocalcic horizon and gypsiferous soils contained more pedogenic palygorskite. In conclusion, we suggest adding a new great group of Gypsixerepts to the soil taxonomy to reflect the presence of pedogenic gypsum in Inceptisols.
12
Kostecki, Robert, and Teresa Radziejewska. "The foraminiferal record in the Holocene evolution of the Mecklenburg Bay (south-western Baltic Sea)." Oceanological and Hydrobiological Studies 50, no. 2 (June 1, 2021): 169–83. http://dx.doi.org/10.2478/oandhs-2021-0016.
Повний текст джерелаАнотація:
Abstract Foraminiferal assemblages were analyzed in a 620-cm long core retrieved from the central part of the Mecklenburg Bay (MB, south-western Baltic Sea) to aid in the reconstruction of environmental changes occurring in the area during the Holocene and to complement a set of previously investigated palaeoenvironmental proxies. A total of five foraminifera-based stratigraphic units were identified, including an initial 80-cm thick layer devoid of foraminifera. The next two units featured an increasing abundance of the foraminiferal assemblage dominated by the calcareous Ammonia group species. Nearly all the calcareous foraminifera found in the core were decalcified. Following the maximum abundance within the 470–410 cm layer, the foraminiferal abundance declined sharply and the assemblage’s dominance structure changed to domination of the agglutinated foraminiferal species, Eggerelloides scaber, which continued up to the top of the core and marked a pronounced shift in environmental conditions (shallower depth, lower salinity, more dynamic sedimentation conditions). The foraminifera-based stratigraphy of the core proved to be complementary to that emerging from previous analyses of diatoms and sediment geochemistry.
13
Abdi, Asad, Emanuela Mattioli, and Beatriz Bádenas. "A New Calcareous Nannofossil Record from the Lower Jurassic of Kermanshah, Western Iran: Implications for Biostratigraphy and Evolutionary Reconstructions." Geosciences 12, no. 2 (January 27, 2022): 59. http://dx.doi.org/10.3390/geosciences12020059.
Повний текст джерелаАнотація:
Calcareous nannofossils are used here for the first time in order to establish a precise biostratigraphic framework for the Kermanshah Radiolarite Formation, an outcropping in Western Iran. The new data presented here challenge the previous tentative age interpretations (Pliensbachian to early Toarcian) based upon radiolarians. Calcareous nannofossil assemblages and events unequivocally indicated that the pelagic limestones and marls are late Sinemurian in age (NJT 3b nannofossil subzone), and that these are thrusted over shales and cherts dated as uppermost Sinemurian (NJT 3b-c nannofossil subzone) and lowermost Pliensbachian (NJT 4 nannofossil zone). This result leads not only to reconsideration of the age of the radiolarite formations, which are widespread in the Zagros orogenic system, but also a better understanding of the stratigraphic relationships between the various lithological units known in the area. Besides these new stratigraphic inferences, the calcareous nannofossil assemblages of the uppermost Sinemurian–lowermost Pliensbachian successions revealed the common presence of new morphologies of the Mitrolithus genus, never described before. These findings allow for the description of three new species, M. montgolfieri, M. pseudonannoconus, and M. tethysiensis, and reveal the existence of homeomorphy between the spine structure of conical Lower Jurassic coccoliths and the widespread Cretaceous nannoconids.
14
Nauer, P. A., B. Dam, W. Liesack, J. Zeyer, and M. H. Schroth. "Activity and diversity of methane-oxidizing bacteria in glacier forefields on siliceous and calcareous bedrock." Biogeosciences 9, no. 6 (June 25, 2012): 2259–74. http://dx.doi.org/10.5194/bg-9-2259-2012.
Повний текст джерелаАнотація:
Abstract. The global methane (CH4) cycle is largely driven by methanogenic archaea and methane-oxidizing bacteria (MOB), but little is known about their activity and diversity in pioneer ecosystems. We conducted a field survey in forefields of 13 receding Swiss glaciers on both siliceous and calcareous bedrock to investigate and quantify CH4 turnover based on soil-gas CH4 concentration profiles, and to characterize the MOB community by sequencing and terminal restriction fragment length polymorphism (T-RFLP) analysis of pmoA. Methane turnover was fundamentally different in the two bedrock categories. Of the 36 CH4 concentration profiles from siliceous locations, 11 showed atmospheric CH4 consumption at concentrations of ~1–2 μL L−1 with soil-atmosphere CH4 fluxes of –0.14 to –1.1 mg m−2 d−1. Another 11 profiles showed no apparent activity, while the remaining 14 exhibited slightly increased CH4 concentrations of ~2–10 μL L−1 , most likely due to microsite methanogenesis. In contrast, all profiles from calcareous sites suggested a substantial, yet unknown CH4 source below our sampling zone, with soil-gas CH4 concentrations reaching up to 1400 μL L−1. Remarkably, most soils oxidized ~90 % of the deep-soil CH4, resulting in soil-atmosphere fluxes of 0.12 to 31 mg m−2 d−1. MOB showed limited diversity in both siliceous and calcareous forefields: all identified pmoA sequences formed only 5 operational taxonomic units (OTUs) at the species level and, with one exception, could be assigned to either Methylocystis or the as-yet-uncultivated Upland Soil Cluster γ (USCγ). The latter dominated T-RFLP patterns of all siliceous and most calcareous samples, while Methylocystis dominated in 4 calcareous samples. Members of Upland Soil Cluster α (USCα) were not detected. Apparently, USCγ adapted best to the oligotrophic cold climate conditions at the investigated pioneer sites.
15
Brozzetti, Francesco, Daniele Cirillo, and Lucina Luchetti. "Timing of Contractional Tectonics in the Miocene Foreland Basin System of the Umbria Pre-Apennines (Italy): An Updated Overview." Geosciences 11, no. 2 (February 19, 2021): 97. http://dx.doi.org/10.3390/geosciences11020097.
Повний текст джерелаАнотація:
A large dataset of lithostratigraphic and biostratigraphic data, concerning the Early-Late Miocene turbidite succession of the Umbria pre-Apennines, is presented and analyzed. The data come from the study of 24 sections that are representative of all the main tectonic units cropping out between the front of the Tuscan allochthon and the Umbria-Marche calcareous chain. The sections have been dated using quantitative calcareous nannofossil biostratigraphy and, wherever possible, they were correlated through key-beds recognition. Such a multidisciplinary approach allowed us to reconstruct the evolution of the Umbria foredeep over time and to unveil the chronology of compressive deformations by defining: (i) the onset of the foredeep stage in each structural unit, (ii) the age of depocenter-shifting from a unit to the adjacent one, (iii) the progressive deactivation of the western sector of the foredeep due to the emplacement of allochthon units, and (iv) the internal subdivisions of the basin due to the presence of foreland ramp faults or thrust-related structures. A further original outcome of our study is having brought to light the Late Burdigalian “out-of-sequence” reactivation of the Tuscan allochthon which bounded westward the foredeep, and the subsequent protracted period of tectonic stasis that preceded the deformations of the Umbrian parautochthon.
16
Boucot, Arthur J., Ed Landing, W. Douglas Boyce, Sandra M. Barr, and Chris E. White. "Provenance of fossiliferous clasts in Carboniferous conglomerate, Isle Madame, southern Cape Breton Island, Nova Scotia." Canadian Journal of Earth Sciences 43, no. 3 (March 1, 2006): 295–302. http://dx.doi.org/10.1139/e05-110.
Повний текст джерелаАнотація:
Fossiliferous clasts occur in Carboniferous conglomerate in the Horton Group on western Isle Madame and in the Mabou Group on eastern Isle Madame. Most of the clasts (21 of 23 examined) are calcareous siltstone and sandstone that contain Silurian Lower Devonian faunas comparable to those in the Arisaig area, northern mainland Nova Scotia, although the lithologies are coarser grained and less calcareous than those of the Arisaig section. These middle Paleozoic faunas are well constrained to the Silurian (uppermost Llandovery through Pridoli) and lowest Devonian and are characteristic of those known from shallow siliciclastic-dominated platforms of the Avalon microcontinent in Wales and England. The remaining two clasts have abundant inarticulate brachiopod shells that indicate provenance from Middle Cambrian proximal marine facies on the Avalonian marginal platform. No clasts were found that are likely to have been derived from the Torbrook Formation, and thus from the Meguma terrane in southwestern Nova Scotia, as has been previously reported. The association of relatively large, reworked fossiliferous clasts in Carboniferous conglomerate on Isle Madame suggests local derivation from lower and middle Paleozoic units not presently exposed, although probably present as subcrop under the Carboniferous units, in southwestern Cape Breton Island and adjacent mainland Nova Scotia.
17
Brogly, P. J., I. P. Martini, and G. V. Middleton. "The Queenston Formation: shale-dominated, mixed terrigenous-carbonate deposits of Upper Ordovician, semiarid, muddy shores in Ontario, Canada." Canadian Journal of Earth Sciences 35, no. 6 (June 1, 1998): 702–19. http://dx.doi.org/10.1139/e98-021.
Повний текст джерелаАнотація:
The Upper Ordovician Queenston Formation constitutes the westernmost part of the Taconic clastic wedge of eastern North America. In Ontario, the Queenston Formation consists of a mixed terrigenous-carbonate succession composed primarily of red silty shales, which are locally gypsiferous, alternating, in the middle and lower parts of the formation, with thin grey shales, calcareous siltstone and sandstone, and bioclastic limestone. Brachiopods, some ostracodes, and, in the lower beds, bryozoans constitute the body fossil assemblage. Diplocraterion, Skolithos, Chondrites, and occasional large vertical burrows of unknown origin form the ichnofauna. Plane beds, ripple marks, and occasional swaley and hummocky cross-stratifications are present in the calcareous units. Mudcracks, gypsum nodules, occasional halite hopper casts, and gilgai-like structures typically occur in horizons where shales alternate with siltstone and limestone. These features are indicative of prograding muddy and storm- and tide-affected shores. In southernmost Ontario, the upper part of the formation is mostly composed of a red shale, with local recognizable shale-filled channels. This shale is of paralic origin, and it is truncated by the unconformity separating the Ordovician from the Silurian units in this region. This last event may, in part, be related to a eustatic sea-level drop due to the contemporaneous Saharan glaciation, if not exclusively due to tectonic movements.
18
Raza, Sajjad, Xuesong Li, Na Miao, Muneer Ahmed, Zhanjun Liu, and Jianbin Zhou. "Dicyandiamide increased ammonia volatilisation and decreased carbon dioxide emission from calcareous soil during wheat–maize rotation on the Loess Plateau." Soil Research 57, no. 7 (2019): 767. http://dx.doi.org/10.1071/sr18088.
Повний текст джерелаАнотація:
Nitrification inhibitors (NIs) have been found to retard the nitrification process, reduce N losses and increase nitrogen use efficiency; however, their effect on carbon dioxide (CO2) emission from calcareous soil has rarely been reported. A 2-year field experiment was conducted to study whether nitrification inhibition by dicyandiamide (DCD) has any effect on CO2 release from calcareous soil. The experiment comprised five treatments: a control (0 kg N ha–1) and two levels of N fertiliser applied on wheat (160 and 220 kg N ha–1) and maize (180 and 280 kg N ha–1) crops, with and without DCD. Compared with the control, a decrease in soil pH (mean 0.21 units in N fertiliser treatments without DCD and 0.11 units with DCD) and increases in cumulative CO2 emission (mean 17% and 23% in wheat and maize respectively) and cumulative ammonia (NH3) volatilisation (mean 28% and 446% in wheat and maize respectively) was recorded under all N fertilised treatments (with and without DCD). The application of DCD with N fertiliser retarded the nitrification process, as indicated by a higher NH4+-N and lower NO3–-N content, as well as a relatively higher soil pH, compared with application of N fertiliser without DCD. In addition, DCD application significantly reduced CO2 emission in both wheat (10–20%) and maize (13–14%) crops compared with crops grown with N fertiliser without DCD. However, the losses from NH3 volatilisation increased when DCD was applied at both N fertiliser levels in both wheat (38–41%) and maize (24–36%) crops. Inhibition of nitrification by DCD was more effective during the wheat than during maize season. Controlling nitrification using DCD is an effective approach to minimise CO2 emission from calcareous soils on the Loess Plateau; however, DCD application increases in NH3 volatilisation.
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Rezapour, S., A. A. Jafarzadeh, A. Samadi, and S. Oustan. "Impacts of clay mineralogy and physiographic units on the distribution of potassium forms in calcareous soils in Iran." Clay Minerals 44, no. 3 (September 2009): 327–37. http://dx.doi.org/10.1180/claymin.2009.044.3.327.
Повний текст джерелаАнотація:
AbstractThe potassium pools of five major physiographic units of the Urmia region situated in western Azerbaijan province, north-west Iran, were studied to determine the distribution of K forms as functions of clay mineralogy and physiographic units. Soil samples from horizons of ten pedons were selected and analysed for physiochemical properties, clay mineralogy and forms of K. X-ray diffraction patterns revealed that the soils were similar in clay-mineral compositions, consisting of illite, smectite, chlorite, and kaolinite, for the different physiographic units, but vary in the relative amounts of these minerals. The illite content was highest in piedmont plain (P.P) followed by plateau (Pl), river alluvial plain (R.A.P), colluvial alluvial plain (C.A.R) and lowland (L.L) units. Smectite content was highest in Pl followed by P.P, L.L, R.A.P and C.A.P units. Several processes, such as the diversity of weathering rate, biocyclying processes of K accumulation, geomorphologic conditions and soil formation processes, caused significant differences in most K forms in the soils. A wide variation in total K (HF-extractable K) (0.54–1.1%), non-exchangeable K (280–450 mg kg–1) and exchangeable K (217–330 mg kg–1) occurred among the physiographic units, corresponding to variations in their mineralogical compositions, mainly the abundance of illite. Significant differences (P ⩽ 0.05) were found for K, HNO3-extractable K and non-exchangeable K between the soils with large illite contents (30–50%) and with small illite contents (10–30%). A significant positive relationship existed between mineral K and illite content (r2 = 0.85, P ⩽ 0.001) and non-exchangeable K and illite content (r2 = 0.84, P ⩽ 0.001). The results indicated that these pools of K are mainly released from the frayed edges and wedge zones of illite.
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Sallam, Magdy. "Benthic foraminifera from the Oligocene offshore Nile Delta, Egypt and its implications." Micropaleontology 59, no. 2-3 (2013): 167–75. http://dx.doi.org/10.47894/mpal.59.2.08.
Повний текст джерелаАнотація:
The detailed micropaleontological analysis carried out on four offshore Oligocene (Tineh Formation) Nile Delta successions revealed the identification of 44 foraminiferal species and subspecies. Nine benthic and two planktonic zones are identified. The established benthic zonation has been chronostratigraphically calibrated with those based on the planktonic foraminiferal ones. This sequence is assigned to the Oligocene (Chattian), and possibly extends to the upper part ofRupelian.Aremarkable feature of thisOligocene succession is the almost complete absence of planktonic foraminifera in its major lower part, a situation that caused a difficulty of subdividing it into smaller units. The environmental interpretation for theOligocene succession implies deposition under a background of persistent subsidence with remarkable paucity or complete absence of any calcareous fauna, probably related to deposition in carbon dioxide-rich marine conditions hostile to the precipitation of any calcareous material and caused by volcanic activity, lowered temperature or situation under the lysocline or carbonate-compensation depth.
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Sasvari, Agoston, Laura Davies, Andrew Mann, Jawad Afzal, Gabor Vakarcs, and Eugene Iwaniw. "Dachstein-type Avroman Formation: An indicator of the Harsin Basin in Iraq." GeoArabia 20, no. 4 (October 1, 2015): 17–36. http://dx.doi.org/10.2113/geoarabia200417.
Повний текст джерелаАнотація:
ABSTRACT A field survey was carried out in 2012 focusing on the tectonic position and the role of Upper Triassic (Upper Norian–Rhaetian) Avroman Formation outcrops located in the Zalm area of Iraq, close to the Iraq-Iran border. At this location, the Cretaceous chert-bearing strata of the Qulqula Formation are overlain by sheared mafic bodies, which are in turn topped by the cliffs of the megalodontaceae-bearing Upper Triassic Avroman Formation. Similarities in lithology, sequence and tectonics position, suggest that the Triassic section of the Bisotoun Unit from the Kermanshah Zone of Iran can be used as a tectonic analogue of the Avroman Formation. According to our model, both the Avroman and the Bisotoun units formed an intra-oceanic carbonate platform, built-up by a characteristic megalodontaceae-bearing carbonate platform assemblage during the Late Triassic. The Harsin oceanic basin, which separated the Avroman-Bisotoun Platform from the Arabian Platform, was characterised by deep-marine sedimentation, the remnants of which form the Qulqula Formation in Iraq, and the Radiolaritic Nappe and the Harsin Mélange in the Kermanshah Zone. This tectonic setting is not unique; numerous authors suggest the existence of an oceanic rim basin, separating carbonate platform units (e.g. Oman ‘exotics’) from the Arabian Platform. The age of the deformation could be Late Cretaceous (Maastrichtian), but using analogues from Iran, a Palaeogene deformation also seems possible. The Avroman Formation was interpreted to be a Dachstein-type sediment, similar to the well-studied Dachstein Formation of the Northern Calcareous Alps, Austria. Rock units, with similar lithology, or identical depositional environment and macroscopic fauna, were described by numerous authors along the Neo-Tethys suture zone from Austria to Japan, and from several tectonic units along the Panthalassa margin. The implication of this correlation is important for future studies: using well-described type localities of the marine units from the Northern Calcareous Alps as a reference, it is possible to significantly extend the available background knowledge, and to gain better insight into the Triassic regional depositional environment of the Middle East.
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Sarkar, Suman, Amit K. Ghosh, and Madhav Kumar. "Recognition of algal rich facies from the Umlatdoh Limestone of Shella Formation, Jaintia Group, Meghalaya." Journal of Palaeosciences 60, no. (1-2) (December 31, 2011): 315–21. http://dx.doi.org/10.54991/jop.2011.178.
Повний текст джерелаАнотація:
The carbonate rocks of the Shella Formation (Middle Eocene) belonging to the Jaintia Group in the Jaintia Hills of Meghalaya are represented by two sandstone units in alternation with three limestone units, viz. Lakadong Limestone, Umlatdoh Limestone and Prang Limestone respectively in chronological order. Umlatdoh Limestone, the middle limestone unit of Shella Formation is conformably underlain by the Lakadong Sandstone and overlain by Narpuh Sandstone. Samples from the Umlatdoh Limestone were collected from the outcrop on the Jowai-Badarpur Road, about 1 km southwest of Lumshnong. Calcareous algae have been recovered from four samples and two distinct facies have been recognized. One of the facies is dominated by non-geniculate coralline red algae and benthic foraminifera. The non-geniculate corallines are represented by Lithothamnion and Mesophyllum (Family Hapalidiaceae), Lithoporella (Family Corallinaceae) and Sporolithon (Family Sporolithaceae). The other facies is rich in calcareous green algae along with benthic foraminifera. The green algal genera belong to families Dasycladaceae, Udoteaceae and Halimedaceae. Previously, a green algal assemblage was recorded from the Umlatdoh Limestone Member of Shella Formation exposed in the low lying hills between Sutnga and Litang valleys of Jaintia Hills. However, this is the first report on the occurrence of non-geniculate coralline red algae from the Umlatdoh Limestone Member of the Shella Formation. Based on the algal-foraminiferal assemblages, interpretation has been made on the palaeoenvironment and palaeobathymetry.
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KUCERA, Peter, and Peter BARANCOK. "CONTRIBUTION TO KNOWLEDGE ON THE VARIABILITY OF AROLLA PINE WOODLANDS OF THE NORTH-EASTERN TATRA MOUNTAINS." Contribuţii Botanice 56 (November 19, 2021): 29–43. http://dx.doi.org/10.24193/contrib.bot.56.3.
Повний текст джерелаАнотація:
Knowledge of the overall syntaxonomic and habitat variability of forest communities with Arolla pine (Pinus cembra) within the Tatra Mountains (Western Carpathians) is still insufficient as field research was hindered by their hardly accessible localities and deforestation for high mountain grazing. Arolla pine woodlands were traditionally classified within the association Pino cembrae-Piceetum Myczkowski et Lesinski 1974, but recent surveys recognize more numerous units. Hitherto unpublished releves from the north-eastern part of the Tatra Mountains document the occurrence of several floristically and ecologically distinct Arolla pine communities: (1) acid woodland of Homogyno alpinae-Pinetum cembrae on nutrient-poor habitats over quartzitic bedrock, and (2) calcareous woodlands of species-poor Pyrolo rotundifoliae-Pinetum cembrae of sites with a well-developed, tangled humus soil horizon, Cystopterido montanae-Pinetum cembrae on habitats influenced by both limestones and quartzites, Primulo elatioris-Pinetum cembrae bound to sites with the most favourable humidity, and Seslerio tatrae-Pinetum cembrae with the most pronounced calcareous character.
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Martin, Sophie, Riccardo Rodolfo-Metalpa, Emma Ransome, Sonia Rowley, Maria-Christina Buia, Jean-Pierre Gattuso, and Jason Hall-Spencer. "Effects of naturally acidified seawater on seagrass calcareous epibionts." Biology Letters 4, no. 6 (September 9, 2008): 689–92. http://dx.doi.org/10.1098/rsbl.2008.0412.
Повний текст джерелаАнотація:
Surface ocean pH is likely to decrease by up to 0.4 units by 2100 due to the uptake of anthropogenic CO 2 from the atmosphere. Short-term experiments have revealed that this degree of seawater acidification can alter calcification rates in certain planktonic and benthic organisms, although the effects recorded may be shock responses and the long-term ecological effects are unknown. Here, we show the response of calcareous seagrass epibionts to elevated CO 2 partial pressure in aquaria and at a volcanic vent area where seagrass habitat has been exposed to high CO 2 levels for decades. Coralline algae were the dominant contributors to calcium carbonate mass on seagrass blades at normal pH but were absent from the system at mean pH 7.7 and were dissolved in aquaria enriched with CO 2 . In the field, bryozoans were the only calcifiers present on seagrass blades at mean pH 7.7 where the total mass of epiphytic calcium carbonate was 90 per cent lower than that at pH 8.2. These findings suggest that ocean acidification may have dramatic effects on the diversity of seagrass habitats and lead to a shift in the biogeochemical cycling of both carbon and carbonate in coastal ecosystems dominated by seagrass beds.
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Hentati, Faiez, Latifa Tounsi, Guillaume Pierre, Mohamed Barkallah, Alina Violeta Ursu, Hajer Ben Hlima, Jacques Desbrières, et al. "Structural Characterization and Rheological and Antioxidant Properties of Novel Polysaccharide from Calcareous Red Seaweed." Marine Drugs 20, no. 9 (August 25, 2022): 546. http://dx.doi.org/10.3390/md20090546.
Повний текст джерелаАнотація:
A novel sulfated xylogalactan (JASX) was extracted and purified from the rhodophyceae Jania adhaerens. JASX was characterized by chromatography (GC/MS-EI and SEC/MALLS) and spectroscopy (ATR-FTIR and 1H/13C NMR) techniques. Results showed that JASX was constituted by repeating units of (→3)-β-d-Galp-(1,4)-3,6-α-l-AnGalp-(1→)n and (→3)-β-d-Galp-(1,4)-α-l-Galp-(1→)n substituted on O-2 and O-3 of the α-(1,4)-l-Galp units by methoxy and/or sulfate groups but also on O-6 of the β-(1,3)-d-Galp mainly by β-xylosyl side chains and less by methoxy and/or sulfate groups. The Mw, Mn, Đ, [η] and C* of JASX were respectively 600 and 160 kDa, 3.7, 102 mL.g−1 and 7.0 g.L−1. JASX exhibited pseudoplastic behavior influenced by temperature and monovalent salts and highly correlated to the power-law model and the Arrhenius relationship. JASX presented thixotropic characteristics, a gel-like viscoelastic behavior and a great viscoelasticity character. JASX showed important antioxidant activities, outlining its potential as a natural additive to produce functional foods.
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A. A., Ibrahim, I., Ibrahim, M.M.M., Sulieman, H. A., Elsheikh M.A., Dafalla M S, and Ibrahim I. S. "Land Suitability Evaluation for Rainfed Agriculture in Abu Hamra Area, South Darfur State, Sudan." IRA-International Journal of Applied Sciences (ISSN 2455-4499) 11, no. 1 (April 27, 2018): 1. http://dx.doi.org/10.21013/jas.v11.n1.p1.
Повний текст джерелаАнотація:
This study was carried out in Abu Hamra Area, south Darfur State (Latitude 12˚26ʹ to 13˚10ʹ E and longitude<br />24˚24ʹ to 25˚56ʹ N and), Sudan where the area falls in semi-arid climate. The study aimed to evaluate the<br />land suitability for rainfed agriculture and to scan crop suitability. Through the analysis of satellite image<br />and direct field observations, the study area was divided into non-cracking clay soil (unit A) classified as<br />Sodic Haplocambid, alluvial soil (unit B) classified as Ustic Torrifluvent and loamy sand soil (unit C)<br />classified as Typic Torripsamments. 46 soil samples were collected from 12 auger holes and 3 representative<br />profiles, then analyzed for some physical and chemical properties which were matched with climatic factors<br />and topographic features to define the requirements of rainfed crops, particularly Sorghum, Millet, Maize,<br />Sesame, Groundnuts, Watermelon and Tomato. Duncan Multiple Range Test was used to determine<br />significance of differences in soil properties within and among the three units. Results showed that the soils<br />were non-saline, non-sodic (except unit A), calcareous to slightly calcareous and low in fertility. Results also<br />indicated no significant differences among soil properties except for texture, salinity and sodicity. The soils<br />were found to be marginally suitable (S3) for rainfed agriculture because of presence of fertility, drainage,<br />organic matter, texture and sodicity limitations and unit B proved to be the best soils of the three units. For<br />crop suitability, the soils of the three units had same suitability for some crops and differ for others.
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Kidder, G., M. J. Holsinger, and T. H. Yeager. "Lowering of Calcareous Soil pH in Field-Grow Containers." Journal of Environmental Horticulture 8, no. 1 (March 1, 1990): 1–4. http://dx.doi.org/10.24266/0738-2898-8.1.1.
Повний текст джерелаАнотація:
Abstract Wettable sulfur (S) mixed with a Pineda fine sand (an Arenic Glossaqualf with 7.8 pH and 1.5% calcium carbonate equivalent) quickly acidified the soil, but the effect was lost within 8 weeks at low application rates and within 21 weeks at the highest rate (1 g S/kg soil or 1 lb S/1000 lb soil). Granular S mixed with the soil took one year to produce maximum pH reduction of 0.3, 0.4, and 0.9 pH units at 250, 500, and 1000 mg S/kg soil (1/4, 1/2, and 1 lb S/1000 lb soil), respectively . Wettable sulfur (S), surface-applied at 100 g/m2 (0.036 oz/10 ft2), lowered the pH of the upper 5 cm (2 in) of soil to the 5.6 to 5.8 range for one to two months before the pH returned to > 7.0; granular S took about five months to lower the pH to 6.7 but the soil pH was 6.2 two years after application. Wettable S at 20 g/kg soil (0.32 oz S/lb soil) in a small cylindrical zone resulted in a temporary depression of pH within the treated zone but had no effect on pH in other areas of the container. Mixing up to 1.0 g iron sulfate/kg soil (0.016 oz/lb soil) failed to reduce soil pH. Live-oak trunk diameter and plant height were not affected by any of the soil treatments in the two-year experiment.
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Karakitsios, V., M. Triantaphyllou, and P. Panoussi. "PRELIMINARY STUDY ON THE SLUMP STRUCTURES OF THE EARLY OLIGOCENE SEDIMENTS OF THE PRE-APULIAN ZONE (ANTIPAXOS ISLAND, NORTH-WESTERN GREECE)." Bulletin of the Geological Society of Greece 43, no. 2 (January 23, 2017): 634. http://dx.doi.org/10.12681/bgsg.11226.
Повний текст джерелаАнотація:
A spectacular slump is observed in the Alpine sediments of the Antipaxos Island (Pre-Apulian zone, Western Greece). It can be followed in a zone of about 2000 m, in the eastern coast of the island. The slumped unit exposure length extends for more than 200 m, and is directly overlain and underlain by undeformed strata. The slump has an average thickness of 15 m and is composed, as the surrounding undeformed units, of calcareous mudstones and fine-grained calcareous sandstones. Synsedimentary folds that very often are transformed to contorted beds affect slump sediments. Fold and contorted bed axes present a NNW-SSE direction, coinciding with the general direction of the Pre-Apulian zone. Slump and overlain/underlain undeformed sediments originate from the flux of clastic mainly pelagic/neritic biogenic particles, emanating from turbidity currents. More than 50 samples have been collected and analyzed for calcareous nannofossil content. All samples were featured by the contemporaneous presence of abundant nannofossil flora implying the biostratigraphic correlation with the NP23 nannofossil biozone. The biostratigraphic assignment places the slump and the surrounding sediments to the Early Oligocene. As the Pre-Apulian zone corresponds to the slope between the Apulian Platform and the Ionian Basin, the presence of the slump is directly related to the same age sloping and tectonic mobility of this domain. The Antipaxos turbidites sediments are well integrated to the flysch deposition of the external Hellenide foreland basin system.
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Collins, Richard N., Graham Merrington, Mike J. McLaughlin, and Jean-Louis Morel. "Transformation and fixation of Zn in two polluted soils by changes of pH and organic ligands." Soil Research 41, no. 5 (2003): 905. http://dx.doi.org/10.1071/sr02121.
Повний текст джерелаАнотація:
Although the movement of Zn from the solid to the solution phase of soils is a significant process preceding plant uptake, the quantity of metal that can be solubilised through rhizosphere processes is also extremely important. Therefore, the consequences of plant-derived organic ligands, and changes in pH on the isotopically exchangeable quantity of Zn (E value) were examined in a polluted acid and calcareous soil. Variations in pH were facilitated through the use of dilute NaOH or HNO3 solutions. The organic ligands studied included 0.25–5 mM concentrations of sodium tartrate, the free acid and sodium salt of citrate, histidine, and deoxymugineic acid. As expected, the organic ligands and a reduction in pH increased the solution concentration of Zn in these soils. Furthermore, through the application of isotopic dilution techniques, it was determined that some of these organic ligands could significantly increase the quantity of isotopically exchangeable Zn. However, with the exception of the 5 mM sodium citrate treatment in the calcareous soil, pH was the overriding parameter that effected changes in the E value. Reducing the pH by approximately 2 units increased the E value by 39 and 80%, respectively, in the acid and calcareous soil. Conversely, evidence for Zn fixation (a decrease of the E value) was observed in the acid soil when pH was increased. The exudation of organic ligands and variations of pH induced by plants have the potential to significantly vary the quantity of phytoavailable Zn in these 2 polluted soils.
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Akanji, Mutair A., Munir Ahmad, Mohammad I. Al-Wabel, and Abdullah S. F. Al-Farraj. "Soil Phosphorus Fractionation and Bio-Availability in a Calcareous Soil as Affected by Conocarpus Waste Biochar and Its Acidified Derivative." Agriculture 12, no. 12 (December 14, 2022): 2157. http://dx.doi.org/10.3390/agriculture12122157.
Повний текст джерелаАнотація:
Biochar possesses more profound effects on the availability of soil P in acidic soil than in alkaline and/or calcareous soil, mainly due to P fixation. Therefore, biochar derived from Conocarpus waste (BC) was acidified with sulfuric acid to produce acidified biochar (ABC) and incorporated into a calcareous soil planted with alfalfa in order to investigate P availability and fractionation. Additionally, the changes in some other soil chemical properties were investigated. Both BC and ABC were applied at three rates (0%, 2.5%, and 5%) along with P fertilizer application at four rates (0, 75, 150 and 300 ppm). The results showed that acidification remarkably reduced the pH of ABC by 6.84 units. The application of ABC considerably lowered the soil pH; however, it did not significantly increase P availability in the studied soil. Furthermore, BC, especially at a higher application rate, increased the extractable soil K. Similarly, the amendments increased the soil cation exchangeable capacity (CEC) and soil organic matter (OM), where a profound increase was observed at a higher application rate in the case of soil OM. Similarly, soil-available micronutrients were increased over the control, where a more profound increase was observed in soils treated with ABC. The NaHCO3–P (exchangeable) fraction increased with increasing fertilizer application rate while the residual–P decreased. Therefore, BC and ABC could be used to improve soil quality and enhance soil nutrient availability. However, further studies are required on how to significantly improve soil available P in calcareous soil.
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Osorio, Lina Liliana, Darlly Erika Silva dos Reis, and René Rodrigues. "AROMATIC STEROIDS BIOMARKERS APPLIED TO HIGH RESOLUTION STRATIGRAPHY: IRATI FORMATION, SOUTHERN OF PARANÁ BASIN, BRAZIL." Journal of Sedimentary Environments 2, no. 4 (January 28, 2018): 174–82. http://dx.doi.org/10.12957/jse.2017.32495.
Повний текст джерелаАнотація:
The use of aromatic steroids in geochemical studies is almost absent in Brazilian sedimentary basins. For this reason, it is intended to test the application of these compounds in high-resolution stratigraphy in the relatively well known Lower Permian Irati Formation. The Irati Formation is about 40 meters thick. It is thermally immature, and comprise two lithological distinct members: the lower siliciclastic Taquaral Member and the upper calcareous-siliciclastic Assistência Member. Based on the whole rock data, mostly TOC, total sulfur, Rock-Eval pyrolysis and alkanes biomarkers, was possible to split the Irati Formation into seven chemostratigraphic units, named from A to C in the Taquaral Member and from D to G in the Assistência Member. Each of these units represents: distinct inputs of land derived organic matter type (chemostratigraphic units C and F) and/or; the response of living organisms to salinity changing of the water system (chemostratigraphic unit D) and; anoxia (chemostratigraphic unit E) during sedimentation. The methodology applied in this work can be used in other sedimentary basins but considering the lithology and sedimentary environment particularities.
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Nelson, Walter W., and Stephen A. Sonnenberg. "Sequence stratigraphy and regional context of the Mancos-Niobrara in the northern San Juan Basin." Mountain Geologist 58, no. 2 (April 1, 2021): 105–57. http://dx.doi.org/10.31582/rmag.mg.58.2.105.
Повний текст джерелаАнотація:
In the northern San Juan Basin, the Niobrara Formation is represented by the upper half of the Mancos Shale (the Smoky Hill Member and Cortez Member). This section is generally equivalent to the Niobrara Formation along the Colorado Front Range. Although the Fort Hays Limestone is absent west of Pagosa Springs, the C Chalk and B Chalk are well-expressed as two resistant bench-forming calcareous units in the northern San Juan Basin. These two calcareous units have also been established as prospective hydrocarbon targets by operators in the area. Calcareous facies equivalent to the A Chalk were not deposited in the northern San Juan Basin due to siliciclastic dilution during the regressive latter half of the Niobrara marine cycle. The overall third-order Niobrara marine cycle includes these members of the Mancos Shale: the Juana Lopez, Montezuma Valley, Smoky Hill, and Cortez members. The Smoky Hill Member sits just above the basal Niobrara unconformity in most of the study area, and the entire section also has greater thickness and siliciclastic content than its equivalent farther east along the Front Range. Several extensive outcrop locations (in and around Pagosa Springs, Piedra, and Durango, CO) along with three new cores along the CO-NM border form the foundation for sequence stratigraphic interpretation of the Niobrara marine cycle in this study. All these locations and cores were tied back to the Mancos reference section at Mesa Verde National Park established by Leckie et al. (1997) which provides detailed description and biostratigraphy for the entire Mancos Shale. Establishing and applying a sequence stratigraphic framework to any section creates consistent reference standards for communication, research, and further correlation. Comparisons of chemostratigraphic data from equivalent strata between the northern San Juan Basin and Denver-Julesburg (DJ) Basin reveal significant differences in the timing and style of source-rock deposition (and associated low-oxygen conditions). The sequence stratigraphic framework also emphasizes tremendous lateral facies changes in the basal Niobrara section (i.e., Fort Hays Limestone to Tocito Sandstone). Once refined and applied, this stratigraphic framework can be used for predicting the distribution of reservoir properties, in addition to enhancing understanding of the Niobrara marine cycle and the Western Interior Seaway.
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Miller, Michael J., Matthew J. Pranter, Ishank Gupta, Deepak Devegowda, Kurt J. Marfurt, Carl Sondergeld, Chandra Rai, Chris T. McLain, James Packwood, and Richard E. Larese. "Mississippian Meramec lithologies and petrophysical property variability, stack trend, Anadarko Basin, Oklahoma." Interpretation 9, no. 2 (April 7, 2021): SE1—SE21. http://dx.doi.org/10.1190/int-2020-0161.1.
Повний текст джерелаАнотація:
Mississippian Meramec reservoirs of the Sooner Trend in the Anadarko (Basin) in Canadian and Kingfisher Counties (STACK) play are comprised of silty limestones, calcareous siltstones, argillaceous calcareous siltstones, argillaceous siltstones, and mudstones. We found that core-defined reservoir lithologies are related to petrophysics-based rock types derived from porosity-permeability relationships using a flow-zone indicator approach. We classified lithologies and rock types in noncored wells using an artificial neural network (ANN) with overall accuracies of 93% and 70%, respectively. We observed that mudstone-rich rock type 1 exhibits high clay and relatively low calcite, whereas calcareous-rich rock type 3 has high calcite and low clay content with rock type 2 falling in between as a balance between rock types 1 and 3. Results of the ANN were applied to a suite of well logs in noncored wells in which we generated lithology and rock-type logs for the Meramec. We identified that the Meramec consists of seven stratigraphic units characterized as strike-elongate, shoaling-upward parasequences; each parasequence is capped by a marine-flooding surface. The lower three parasequences (lower Meramec) form a retrogradational parasequence set that back steps to the northwest and is capped by a maximum flooding surface. The upper Meramec is characterized by parasequences that form an aggradational to progradational stacking pattern followed again by a retrogradational trend. We predict that the parasequence stacking, associated lithology distribution, and diagenetic cements appear to control the spatial distribution of petrophysical properties (porosity, permeability, and water saturation), pore volume, and hydrocarbon pore volume (HCPV). Calcareous-rich lithologies exhibit lower porosity, permeability, HCPV, and higher water saturation. We deduced that argillaceous-rich lithologies that occur near the maximum flooding surface are the most favorable reservoir intervals because they exhibit relatively higher porosity, permeability, HCPV, and lower water saturation. Productivity could not be directly correlated to rock types as operational and completion factors as well as overpressure and oil phase play important roles on production.
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Young, T., F. Martin, W. T. Dean, and A. W. A. Rushton. "Cambrian stratigraphy of St Tudwal's Peninsula, Gwynedd, northwest Wales." Geological Magazine 131, no. 3 (May 1994): 335–60. http://dx.doi.org/10.1017/s0016756800011109.
Повний текст джерелаАнотація:
AbstractLithostratigraphic units of early to late Cambrian age established by T. C. Nicholas in 1915 in the St Tudwal's Peninsula are revised. They comprise, in ascending order: Hell's Mouth Formation (> 190 m); Trwyn y Fulfran Formation (37 m);Cilan Formation (400 m); Ceiriad Formation (40 m seen); Nant-y-big Formation (> 110 m seen); Maentwrog Formation (in part, 50 m seen, an estimated 250 m concealed); Ffestiniog Flags Formation (in part, c. 120m seen). The ‘calcareous grit’ at the top of Nicholas's Nant-pig Mudstones spans the unconformable boundary between the Nant-y-big and Maentwrog formations. Previously described limestone clasts in the ‘grit’ are probably erosional remnants of an in situ bioclastic limestone bed; their contained trilobites include genera and species found in the Andrarum Limestone (late Middle Cambrian) of Scania, Sweden. Acritarchs are documented and compared particularly with those from eastern Newfound-land. Those from the highest part of the ‘calcareous grit’ include Cymatiogalea sp. and are of late Cambrian age. One new species, Heliosphaeridium? llynense Martin, comes from the lower part of the Nant-y-big Formation (middle Middle Cambrian), where it appears a little earlier than the Adara alea Biozone.
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Mejía-Quintero, Katherine, Cristina Cedeño-Posso, Santiago Millán, and Luis Chasqui. "Mapping Ecological Units in Mesophotic Coral Ecosystems of San Andrés Island (Southwestern Caribbean)." Diversity 14, no. 8 (August 19, 2022): 679. http://dx.doi.org/10.3390/d14080679.
Повний текст джерелаАнотація:
To map ecological units in mesophotic coral ecosystems on the western side of San Andrés Island (Colombia) considering biotic components and geomorphic zonation among 30–140 m deep, 27 video transects were done using an ROV. In total, 14 h of video were recorded and 5742 still images were extracted from them, from which 753 met quality criteria for bottom coverage and organisms’ abundance estimations. These estimates were calculated from images through the Planar-Point Intercept method (PPI) using a 1 m × 0.5 m quadrant gridded 0.1 m × 0.1 m. CLUSTER, SIMPROF, and SIMPER analysis of benthic composition considering depth ranges in the group’s formation were done. The clusters formed were simplified and generalized using a color matrix to support the mapping process. Two geomorphological units were found, the deep reef terrace (30–60 m) and the reef slope (60–357 m), overlapping with five ecological units spanning 268 ha. The units Bioturbed sediments–Calcareous algae, Octocorals–Mixed corals, and Octocorals–Sponges sited on the deep reef terrace have been previously described in the shallow waters of the island, and the units Octocorals–Sponges–Antipatharians and Encrusting Sponges sited on the reef slope are described as new here. These findings contribute to the knowledge of Caribbean mesophotic coral ecosystems and are useful to update the Colombian coral reef atlas.
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Dunčić, Milena, Ivan Dulić, Olivera Popov, Goran Bogićević, and Alan Vranjković. "The Campanian–Maastrichtian foraminiferal biostratigraphy of the basement sediments from the southern Pannonian Basin (Vojvodina, northern Serbia): implications for the continuation of the Eastern Vardar and Sava zones." Geologica Carpathica 68, no. 2 (April 1, 2017): 130–46. http://dx.doi.org/10.1515/geoca-2017-0011.
Повний текст джерелаАнотація:
Abstract Micropalaeontological and biostratigraphical studies included Campanian-Maastrichtian complexes from five oil exploration wells drilled in northern Serbia (Vojvodina): the first is a carbonate-clastic complex and second is a complex containing ophiolites intercalated with hemipelagic and pelagic sediments. Within the studied complexes, rich associations of planktonic and benthic foraminifera, calcareous nannoplankton, palynomorphs, as well as shallow and deep-water fossil detritus were determined. The presence of relatively rich associations of planktonic foraminifera allowed recognition of two biozones: the Globotruncana ventricosa Zone, observed in the sediments of the carbonate-clastic complex and the Gansserina gansseri Zone, observed in both complexes. Except biozones, based on documented index species, for some units in both complexes, larger benthic foraminifera species had special biostratigraphical value, and in some of them, the calcareous nannoplankton zones were recognized. The studied complexes represent deep-water formations, generated in oceanic island arc and trough zones. The presence of limestones, which originate from destroyed rudist reefs, is explained by transfer by means of gravitational transport mechanisms of shallow-water sediments to deep-water depositional environments. In this paper, the results of more detailed biostratigraphical and palaeo-ecological studies of foraminifera associations in Campanian-Maastrichtian complexes in Vojvodina are presented. Combined with lithological studies, seven units were determined within the complexes. The obtained results are important as a part of multidisciplinary, regional exploration of both complexes, generated in specific geological conditions, that today constitute a part of the pre-Neogene basement complex in the southeastern part of the Pannonian Basin. The Campanian- Maastrichtian carbonate-clastic complex represents sedimentary cover of the Eastern Vardar Ophiolitic Unit, while the ophiolites intercalated with hemipelagic and pelagic limestones belongs to the Sava Zone.
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ΑΛΕΞΟΠΟΥΛΟΣ, Α., and Ε. ΜΩΡΑΪΤΗ. "Contribution to the knowledge of the geology of Attica. The Peninsula of Lomvarda (Zostir)." Bulletin of the Geological Society of Greece 34, no. 1 (January 1, 2001): 3. http://dx.doi.org/10.12681/bgsg.16927.
Повний текст джерелаАнотація:
In deposits of coherent, foliaceous marls, in Lomvarda's Peninsula (Attica), the biozones NN15 (Reticulofenestra Pseudoumbilica zone) till NN19 (Pseudoemiliania lacunosa zone) were determined, based on a rich calcareous nannoplankton fauna. These deposits are part of irregular alternations of reefal limestones, conglomerates, marls, and red sandstones. After the upper Pleistocene, an extensional faulting took place, created small grabbens and horsts. These events follow a compressional stage, which gave up mesoscopic folds. A numerous discontinuous (bedding planes, joins and faults) controls the shape of the coast. These discontinuities in combination with the different weathering degree of the various lithological units are responsible for the fallings rocks which take place along the steepness coast.
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Alarcón Olave, Helmer Fernando, and Edwar Hernando Herrera Otero. "Petrophysical properties of bypassed Cenozoic clastic reservoirs in the Cesar sub-basin, Colombia." Earth Sciences Research Journal 25, no. 3 (October 27, 2021): 275–84. http://dx.doi.org/10.15446/esrj.v25n3.89293.
Повний текст джерелаАнотація:
The Cesar-Ranchería basin has all the necessary elements for the generation, expulsion, and migration of hydrocarbons and considerable potential for coal bed methane (CBM) in Colombia. Previous studies in the Cesar basin focused on understanding the tectonic evolution, stratigraphy, hydrocarbon generation potential, and evaluation of reservoir potential in Cretaceous calcareous units and quartzose sandstones from the Paleocene Barco Formation. These studies had confirmed the existence of an effective petroleum system, with several episodes of oil expulsion and re-emigration in the Miocene period, turning the Cenozoic clastic succession (Barco, Los Cuervos, La Loma, and Cuesta formations) into an element of significant exploratory interest to clarify the potentiality of the basin in terms of hydrocarbon accumulation. The petrophysical parameters of Cenozoic units (shale volume, porosity, water, and oil saturation) were determined by integrating wells log and core samples analyses from three stratigraphic wells. The integration of these results synthesizes the petrophysical behavior of the units. It defines intervals with clay volumes of less than 30%, effective porosity around 20%, which means favorable characteristics as reservoir rocks that need to be considered in future exploratory projects.
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Bahk, Jang-Jun, In-Kwon Um, and Kyung-Hoon Shin. "Contrasting developments of Pleistocene calcareous clay units in the middle Bengal Fan and their implications for paleoenvironmental changes." Geosciences Journal 23, no. 6 (July 18, 2019): 867–79. http://dx.doi.org/10.1007/s12303-019-0012-0.
Повний текст джерела
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Bucur, Ioan I., and Iuliana Lazăr. "UPPER JURASSIC TO LOWERMOST CRETACEOUS MICROFOSSILS FROM THE HĂGHIMAŞ MOUNTAINS (EASTERN CARPATHIANS, ROMANIA)." Acta Palaeontologica Romaniae, no. 19 (1) (August 21, 2022): 13–26. http://dx.doi.org/10.35463/j.apr.2023.01.02.
Повний текст джерелаАнотація:
The limestones of the Upper Jurassic to lowermost Cretaceous from the Hăghimaş Mountains were studied in two sections from the upper part of the Fagu Oltului valley, a tributary of the Olt River. The lower part of the succession is remarkable for the rich brachiopod fauna contained in a red limestone buildup, documented previously as a stromatactis mud-mound. The mound consists of bioclastic wackestones and packstones with numerous brachiopods, crinoids, and sponges. The mud-mound is covered with intraclastic grainstones and fine-grained limestones with pelagic bivalves. The following lithological units pass into shallow water limestone with nerineid gastropods, calcareous algae and foraminifera, in a regressive sequence. The micropaleontological association identified in the Upper Jurassic to lowermost Cretaceous limestones from Fagul Oltului includes calcareous algae, foraminifera, saccocomid crinoid fragments, annelid worm tubes, sponge fragments, rare calpionellids and microorganisms with an uncertain systematic position. The identified microfossils have a wide stratigraphic distribution. The most important stratigraphic landmarks are Trocholina conica (which does not extend younger than Kimmeridgian) and Calpionella alpina (which does not appear before the upper Tithonian). Based on the whole micropaleontological assemblage, the lower part of the succession (the skeletal mud-mound) can be ascribed to the Kimmeridgian – lower-middle Tithonian, and the upper part to the upper Tithonian – Berriasian.
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Athanasiou, M., M. Triantaphyllou, M. Dimiza, A. Gogou, I. Bouloubassi, E. Tsiolakis, and G. Theodorou. "Early-Middle Miocene from Kotaphi hill section (Nicosia, Cyprus): preliminary biostratigraphy and paleoceanographic implications." Bulletin of the Geological Society of Greece 47, no. 1 (December 21, 2016): 62. http://dx.doi.org/10.12681/bgsg.10899.
Повний текст джерелаАнотація:
Calcareous nannofossil biostratigraphy from Kotaphi Hill section allowed not only the biostratigraphic zonation of the Miocene units but also provided evidence for a distinct warm phase known as the Middle Miocene Climate Optimum (MMCO). Kotaphi Hill section is located in Agrokipia village (Nicosia region, Cyprus) and consists of cyclic marine deposits of the Pakhna Formation. High resolution sampling has been conducted and 84 samples were collected. Preliminary results indicated that several important calcareous nannofossil events can be consistently recognized along the studied section. High abundances of Discoaster druggii and Highest occurrence (HO) of Sphenolithus procerus suggest the presence of NN2 biozone while, LO of Sphenolithus belemnos has been used to recognize the base of biozone NN3. Upwards, Lowest Common Occurrence (LCO) of Sphenolithus heteromorphus marked the NN3-4 boundary-level. Biozone NN4 in Kotaphi Hill section is featured by high abundance of S. heteromorphus whereas total absence of the species together with the LO of Helicosphaera walbedorfensis mark the Paracme Beginning (PB) of S. heteromorphus interval. High abundance of warm indicators such as Discoasterids, S. heteromorphus, S. moriformis and Helicosphaera carteri observed in our material may partly reflect the warm phase of MMCO. Key words: Agrokipia village, Pakhna Formation, Cyprus, Sphenolithus heteromorphus, Middle Miocene Climate Optimum.
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MINGRAM, BIRGIT. "The Erzgebirge, Germany, a subducted part of northern Gondwana: geochemical evidence for repetition of early Palaeozoic metasedimentary sequences in metamorphic thrust units." Geological Magazine 135, no. 6 (November 1998): 785–801. http://dx.doi.org/10.1017/s0016756898001769.
Повний текст джерелаАнотація:
One of the major metamorphic terranes of the Bohemian Massif, the Erzgebirge, is interpreted to record a subducted part of a Palaeozoic margin of Gondwana. A geochemical study on non-calcareous metasediments from the various metamorphic units from lower greenschist to granulite facies metamorphism supports a recently established thrust model. Geochemical discrimination and correlation from the metasediments of the Erzgebirge suggest repetition of an early Palaeozoic metasedimentary sequence in metamorphic thrust units. This new finding is in line with recent radiometric dating of intercalated metarhyolitic rocks, which yielded ages of around 480 Ma. It is furthermore supported by correlation with a low-grade standard section in Thuringia, which represents the transition from an orogenic belt to a passive margin setting, with highly mature sediments. Significant geochemical signatures have been identified in three different lithotypes, which reappear in at least three metamorphic units of the Erzgebirge. Geochemical correlation of these units was established using simple comparison of averages and with statistical techniques. The identification of significant geochemical signatures from different lithotypes in metamorphic suites has important implications for terrane analysis and reconstruction of ancient tectonic settings.The repetition of lithologies and their distinct chemical compositions in progressively metamorphosed units is useful for examining element mobility during Barrovian metamorphism. Statistical comparison implies that Li is progressively depleted from the greenschist to amphibolite facies, whereas Ca exhibits some enrichment. All the other elements studied are considered to be immobile.
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Pszonka, Joanna, Katarína Žecová, and Marek Wendorff. "Oligocene turbidite fans of the Dukla Basin: New age data from the calcareous nannofossils and paleoenvironmental conditions (Cergowa beds, Polish–Slovakian borderland)." Geologica Carpathica 70, no. 4 (August 1, 2019): 311–24. http://dx.doi.org/10.2478/geoca-2019-0018.
Повний текст джерелаАнотація:
Abstract Calcareous nannofossils found in the Cergowa beds of the Dukla and Fore-Dukla tectonic units in the Outer Carpathians indicate a time of deposition in the range of the NP23–NP24 nannoplankton zones of the Lower Oligocene. Nannoplankton assemblages reflect the paleoecological changes at the Eocene–Oligocene transition from: (i) a greenhouse to an icehouse climate; (ii) brackish to normal salinity suggesting open sea conditions, which were controlled by the Paratethys Basin closure followed by opening and connection with the Tethyan Ocean. The absence of nannofossils of NP25 zone, but their presence in the tectonic windows between 40 and 80 km to the west, shows that deposition of the Cergowa beds in the western part of the basin lasted longer than in the east. Occurrences of nannofossils indicating zones NP16 and NP21, found in the uppermost mudstone-rich parts of studied sections, may prove the remobilization and redeposition of sediments of this stratigraphic age. Potentially, eroded material could be derived from some of the following lithostratigraphic units: NP16 — the Hieroglyphic beds, Przybyszów sandstones and Upper variegated shales; NP21 — the Globigerina marls, Mszanka sandstones and sub-Chert marls and shales and/or fine-grained equivalent of these units. Reworked specimens derived from the older Mesozoic strata occur occasionally in various samples.
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Tal, Adi, Yishai Weinstein, Stuart Wollman, Mark Goldman, and Yoseph Yechieli. "The Interrelations between a Multi-Layered Coastal Aquifer, a Surface Reservoir (Fish Ponds), and the Sea." Water 10, no. 10 (October 11, 2018): 1426. http://dx.doi.org/10.3390/w10101426.
Повний текст джерелаАнотація:
This research examines the interrelations in a complex hydrogeological system, consisting of a multi-layered coastal aquifer, the sea, and a surface reservoir (fish ponds) and the importance of the specific connection between the aquifer and the sea. The paper combines offshore geophysical surveys (CHIRP) and on land TDEM (Time Domain Electro Magnetic), together with hydrological measurements and numerical simulation. The Quaternary aquifer at the southern Carmel plain is sub-divided into three units, a sandy phreatic unit, and two calcareous sandstone (‘Kurkar’) confined units. The salinity in the different units is affected by their connection with the sea. We show that differences in the seaward extent of its clayey roof, as illustrated in the CHIRP survey, result in a varying extent of seawater intrusion due to pumping from the confined units. FEFLOW simulations indicate that the FSI (Fresh Saline water Interface) reached the coastline just a few years after pumping has begun, where the roof terminates ~100 m from shore, while no seawater intrusion occurred in an area where the roof is continuous farther offshore. This was found to be consistent with borehole observations and TDEM data from our study sites. The water level in the coastal aquifer was generally stable with surprisingly no indication for significant seawater intrusion although the aquifer is extensively pumped very close to shore. This is explained by contribution from the underlying Late Cretaceous aquifer, which increased with the pumping rate, as is also indicated by the numerical simulations.
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Holford, ICR, M. Chater, and GEG Mattingly. "Effects of decalcification on the phosphate sorption characteristics of eight calcareous soils." Soil Research 28, no. 6 (1990): 919. http://dx.doi.org/10.1071/sr9900919.
Повний текст джерелаАнотація:
Phosphate sorption isotherms and parameter values were determined on eight calcareous soils which were carefully decalcified using a procedure which minimized changes in cation saturation. Calcite content of the original soils varied from 0.8 to 24 2% and calcite surface areas from 4 . 0 to 8.5 m2 g-1. Sorption parameters were derived from the Langmuir 'two-surface' equation. Decalcification increased phosphate sorption at low residual P concentrations (<0.8 mg L-1) but decreased it at higher concentrations. The higher P sorption was associated with an increase in affinity because the calculated sorption capacities of high-affinity surfaces were not increased. These sorption capacities were well correlated with iron oxide contents of the soils, so the increase in phosphate affinity of these surfaces was consistent with the decrease in pH (0.5 to 1.5 units) of the decalcified soils. The lower P sorption at higher concentrations was associated with a substantial decrease in sorption capacity of the postulated low-affinity surfaces. These latter decreases were quantitatively correlated with the calcite surface areas of the original soils. These and other changes in phosphate sorption characteristics support the utility of the Langmuir 'two-surface' equation in providing information, compatible with what would be expected from more complex mechanistic models, and which exceeds what one would expect from other simpler models such as the Freundlich equation. They also support an hypothesis that an important component of low-affinity surfaces of these calcareous soils is calcite on which organic anions are co-adsorbed.
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Podobina, V. M., and G. M. Tatyanin. "BOUNDARY DEPOSITS OF THE TURONIAN–CONIACIAN OF WESTERN SIBERIA (ACCORDING TO THE FORAMINIFERA STUDY DATA)." Geology and mineral resources of Siberia, no. 1 (2021): 25–31. http://dx.doi.org/10.20403/2078-0575-2021-1-25-31.
Повний текст джерелаАнотація:
New materials on the microfauna and lithology of the Kuznetsovskaya and Sedelnikovskaya Formations of the same horizons are presented. These data have allowed us to clarify the age of the boundary Turonian–Coniacian deposits of the Middle and Upper series of the Cretaceous system. Based on a comparison with geological units of marginal regions, where finds of secretion-calcareous foraminiferal shells are known, the Сoniaсian age of the Sedelnikovskaya Formation was established. The time interval of the regional break between the Turonian and Coniacian stages was determined, apparently, corresponding to the Early Сoniacian. The studied sections of the northern region are characterized by the absence of foraminiferal assemblage known in the sections of Kamyshlovskiye wells of the Omsk depression and in some places of the Trans-Urals.
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Ryasnoy, A. A., and V. Yu Prokofyev. "CONDITIONS FOR THE FORMATION OF SECONDARY LOWER SILURIAN DOLOMITES AND PECULIARITIES OF THE DISTRIBUTION OF VOID SPACE IN THEM (NORTH-EAST OF THE TUNGUSKA SYNECLISE)." Geology and mineral resources of Siberia, no. 2 (2021): 24–45. http://dx.doi.org/10.20403/2078-0575-2021-2-24-45.
Повний текст джерелаАнотація:
New materials on the microfauna and lithology of the Kuznetsovskaya and Sedelnikovskaya Formations of the same horizons are presented. These data have allowed us to clarify the age of the boundary Turonian–Coniacian deposits of the Middle and Upper series of the Cretaceous system. Based on a comparison with geological units of marginal regions, where finds of secretion-calcareous foraminiferal shells are known, the Сoniaсian age of the Sedelnikovskaya Formation was established. The time interval of the regional break between the Turonian and Coniacian stages was determined, apparently, corresponding to the Early Сoniacian. The studied sections of the northern region are characterized by the absence of foraminiferal assemblage known in the sections of Kamyshlovskiye wells of the Omsk depression and in some places of the Trans-Urals.
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Kozhoukharova, Evgenia. "Reconstruction of the primary stratigraphy and correlation of the Precambrian metamorphic complexes in the Rhodope massif." Geologica Balcanica 37, no. 1-2 (June 30, 2008): 19–31. http://dx.doi.org/10.52321/geolbalc.37.1-2.19.
Повний текст джерелаАнотація:
The lithological analysis of the metamorphic rocks in the Rhodope massif, taking into consideration the lateral variability of their primary composition, polymetamorphic effects and tectonic deformations, demonstrates that prior to the metamorphism the upper Rhodopian Supergroup is composed of two complexes: lower volcano-sedimentary and upper calcareous ones. The lower complex after the metamorphism is composed of metaophiolites (serpentinites, amphibolites, metagabbroids) in the lower levels), mica schists, marbles, quartzites, jaspilites, called Variegated Formation. The upper complex is composed of marbles interlayered with schists. There are two types of Variegated Formation: à. Western Rhodopian (Satovcha) type with ophiolites prevailing in lower layers and b. Central Rhodopian (Lukovitsa) type with sedimentary rocks prevailing. A new correlation scheme of the lithostratigraphic units from Precambrian blocks in South Bulgaria is presented.
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Ekdale, A. A. "Late Cenozoic Rocks in the Puerto Penasco Area." Paleontological Society Special Publications 2 (1987): 34–43. http://dx.doi.org/10.1017/s2475262200004706.
Повний текст джерелаАнотація:
Pleistocene-Holocene sedimentary rocks, which outcrop along the northern Gulf of California coast in the vicinity of Puerto Peñasco, Sonora, have a very heterogeneous, mixed carbonateclastic composition. Carbonate grains are primarily molluscan, echinoderm, bryozoan and calcareous algal fragments. Terrigenous grains are primarily silicate minerals (e.g., quartz and feldspar) derived from three nearby igneous prominences (the basaltic Punta Peñasco and Cerro Prieto and the granitic Punta Pelicano).Porosity of the sedimentary rocks, which commonly exceeds 50% in many units, may be intergranular and/or moldic. Cements in eolianite, precipitated within the vadose zone, are mainly of the meniscus spar type at grain contacts. Cements in beachrock, precipitated within the intertidal or shallow subtidal zone, include isopachous calcite spar and/or acicular aragonite.
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Leckie, R. Mark, Robert W. Scott, Timothy J. Bralower, and William V. Sliter. "Relationship between sequence boundaries and the evolutionary history of planktonic foraminifera, calcareous nannofossils, and reef communities in the mid-Cretaceous (Barremian-Cenomanian)." Paleontological Society Special Publications 6 (1992): 179. http://dx.doi.org/10.1017/s2475262200007395.
Повний текст джерелаАнотація:
Planktonic foraminifera first evolved in the middle Jurassic but did not experience a major radiation until the mid-Cretaceous. The mid-Barremian to late Aptian was characterized by a steady increase in species richness and by the appearance of new morphological forms including planispiral coiling, clavate and radially elongate chambers, and culminating in the first appearance of taxa with complex apertural structures and the keeled morphotype in late Aptian time. This broad interval of radiation was abruptly ended by evolutionary turnover and low diversification rates in the latest Aptian and early Albian prior to a second explosive episode of radiation in the middle and late Albian. The evolutionary history of mid-Cretaceous calcareous nannofossils generally parallels the trends observed in planktonic foraminifera, although the latest Aptian-early Albian turnover event is not as pronounced. Reef communities in the Caribbean/Gulf of Mexico and Mediterranean provinces show a change in dominance from coral-algal-rudist reefs in the Barremian-early Albian to rudist domiance by the late Albian time. These changes in calcareous plankton and reef communities are related to complex oceanographic changes of the mid-Cretaceous including structure of the upper water column, productivity, sea level, atmospheric and oceanographic circulation, and changes in the chemistry of the ocean.Changes in eustatic sea level influenced many of these factors including nutrient delivery to the oceans, climate, sites and rates of deep water formation, and ocean chemistry. What is the relationship between changes in sea level, as expressed by major seismic sequence boundaries, and the changes observed in marine biota? We have compared major changes of eustatic sea level within this interval of generally rising global sea level (Scott et al., 1988), with equivalent sequence boundaries (Haq et al., 1988) and the records of calcareous plankton (Roth, 1987; Leckie, 1989) and reef communities (Scott, 1988). What is most striking about these relationships is the apparent lack of direct correlation between sequence boundaries and turnover events in the marine biota. The calcareous plankton alternate in phase between relatively high rates of diversification and low rates of diversification, with the major sequence boundaries falling within intervals of change rather than at intervals of change. However, we acknowledge the potential of missing or condensed intervals in deep sea settings which may influence the record of evolutionary rates (e.g., Loutit, et al., 1988). Only the basal Albian sequence boundary appears to correlate with a major turnover event in the planktonic foraminifera, and the rapid change in Gulf Coast reef communites between the middle and upper Albian may correlate with a eustatic sea level change and a major sequence boundary. Based on high-resolution calcareous nannofossil, planktonic foraminiferal, sedimentologic, and geochemical data of Bralower et al. (submitted), the lower Aptian, basal Albian, and lower upper Albian sequence boundaries appear to correlate more closely with widespread oceanic dysoxic/anoxic events OAE1a, OAE1b, and OAE1c, respectively. The correlations between evolutionary events, anoxic events, and sequence boundaries must be considered tentative at this time because major disparities exist between the correlation of calcareous plankton zones and mid-Cretaceous chronostratigraphic units used by Haq et al. (1988) and Bralower et al. (submitted).