rss_2.0Geologos FeedSciendo RSS Feed for Geologos Feed Middle Jurassic (Bajocian–Bathonian) flora of the Tabas Block, central Iran<abstract> <title style='display:none'>Abstract</title> <p>The present study discusses the outcome of palynlogical and palaeobotanocal investigations of Middle Jurassic strata of the Tabas Block. The most commonly identified spore type is a trilete spore, <italic>Klukisporites</italic>, which accounts for 30 per cent, and the genus <italic>Ischyosporites</italic> which makes up 12 per cent of the spore collection. Plant fossils recovered from the borehole studied are indicative of a varied assemblage, starting with a diverse range of ferns and followed by Cycadophytes, Ginkgophytes and Coniferophytes. The predominance of the Lowland group in the Tabas Block during the Bajocian–Bathonian, as indicated by the Sporomorph EcoGroup (SEG) and Plant EcoGroup (PEG) models, suggests that the strata studied were laid down mainly in a lowland environment. Dinoflagellate cysts were found in locations that correspond to river and coastal ecogroups, hinting at marine influence.</p> </abstract>ARTICLEtrue reviews: Introduction to hydrogeology reviews: GIS cartography. A guide to effective map design (third edition) Encke comet impact/airburst and the Younger Dryas Boundary: Testing the impossible hypothesis (YDIH)<abstract> <title style='display:none'>Abstract</title> <p>Many have tagged the Younger Dryas Impact Hypothesis (YDIH), a supposition, lacking convincing evidence in support. The core of criticism lies squarely on uniformitarianism, that is, uniform processes moving uniformly with no room for catastrophic events, specifically cosmic catastrophic forces. Beyond philosophically based aversion to the YDIH, specific criticism comes from megafauna and archaeologic corners, related to the near coeval disappearance of specific Late Pleistocene species on the one hand, and relation to disruption and temporary disappearance of the Clovis people et al. on the other. The Younger Dryas geologic paradigm, originally in place with meltwater release into the Atlantic in tow, attention slowly drifted to explanation of an innocuous looking, thin (~1–3 cm), black sediment bed found in lacustrine and fluvial deposits of the American southwest, and other intercontinental places. Thus, with thin dark beds of Gubbio in mind, the quest to explain black mat (BM) beds took on a cosmic aspect, one with growing, supporting evidence on several continents. The impossible hypothesis, now the probable explanation of the Younger Dryas climatic reversal, is at center stage, set at 12.8 ka, with a burgeoning corpus of evidence its cornerstone.</p> </abstract>ARTICLEtrue, Rb-Sr whole rock age and Sr-Nd isotopic constraints on the Variscan A-type granite from Azegour area in the Marrakech High Atlas (Moroccan Meseta) and their geodynamic implications<abstract> <title style='display:none'>Abstract</title> <p>In the northern part of the Marrakech High Atlas (MHA), along the southern Variscan segment of the Western Meseta, a Variscan granitic intrusion crops out, intruding metasediments and meta-volcanosedimentary rocks of Early Cambrian to Ordovician age. A new whole-rock Rb-Sr isochron age of 268 ± 9 Ma for the granite, combined with a previously published whole-rock Rb-Sr radiometric dating (271 ± 3 Ma), reveals a post-kinematic (tectonic) character with regard to the main Variscan deformational event, belonging within the tectonic context of the Moroccan Variscan orogenic belt. Geochemically, the Azegour intrusion is metaluminous to peraluminous and exhibits a calc-alkaline affinity with a ferruginous composition. The massif shows an extremely differentiated character (SiO<sub>2</sub> = 77.53–78.14 per cent), K<sub>2</sub>O and high total alkali contents, FeO<sub>t</sub>/(FeO<sub>t</sub> + MgO) and Ga/Al ratios, which have typical characteristics of an A-type granite. In addition, the granite contains high concentrations of LREE (La<sub>N</sub>/Sm<sub>N</sub>= 7.9–13.67) relative to HREE (La<sub>N</sub>/Yb<sub>N</sub>= 4.81–11.61) and a well-defined Eu negative anomaly (Eu/Eu* = 0.44–0.75). The granitic samples exhibit a strong enrichment of the most incompatible elements (Rb<sub>N</sub>/Yb<sub>N</sub> = 69.84–159.98) and a strong depletion of Ba, Sr, Eu, Nb, P and Ti. These characteristics are similar to those of A<sub>1</sub>-type granites. The absence of mineralogy typical of an S-type granite, combined with its weakly peraluminous character [A/CNK (molar Al<sub>2</sub>O<sub>3</sub>/CaO+Na<sub>2</sub>O+K<sub>2</sub>O) = 1,013–1,045], suggest that there is little or no significant involvement of supracrustal sources in the petrogenesis of the intrusion studied. Despite the strongly differentiated character of Azegour granitic rocks samples, their multi-element patterns shows many similarities to those of I-type granitoids, which has led to postulate that the parental liquids of A<sub>1</sub>-type were derived from partial melting of mafic magmas. The representative samples studied show less depleted εNd<sub>(t = 270 Ma)</sub> values of −0.94 to −4.85 and lower positive to slightly negative εSr<sub>(t = 270 Ma)</sub> values of −1.45 to 9.32. The isotopic data suggest that the Azegour granite was emplaced 270 myr ago, apparently generated by partial melting of a mafic/intermediate magma source in the lower crust as a result of the underplating of the asthenosphere mantle-derived Oceanic Island Basalt-like magmas. Alternatively, their isotopic signatures also can be attributed to the interaction and/or hybridisation of basaltic liquids derived from the mantle with these lower crust materials. The generated parental magma probably occurred at deep structural levels and involved fractional crystallisation processes by the separation of a mineralogical association composed of plagioclase + potassium feldspar ± biotite ± amphibole ± sphene ± apatite. The whole-rock Rb-Sr age of 268 ± 9 Ma, whole-rock geochemistry and Sr-Nd isotopic compositions of εNd<sub>(t = 270 Ma)</sub> and εSr<sub>(t = 270 Ma)</sub>, combined with fieldwork data, suggest that the Azegour granite was emplaced during the later stage of compressional Variscan events in the MHA.</p> </abstract>ARTICLEtrue from the Albian–Cenomanian (Cretaceous) of Mexico<abstract> <title style='display:none'>Abstract</title> <p>Two serpulid species, <italic>Protula</italic>? <italic>antiquata</italic>? and <italic>Propomatoceros</italic>? sp., are recorded from the Morelos Formation (mid-Cretaceous) in Mexico. Serpulid tube structure is microcrystalline; the examined tubes are slightly diagenetically altered, but growth layers are well preserved. The short, straight growth layers with slightly curved distal ends in <italic>Protula</italic>? <italic>antiquata</italic>? occur also in some other serpulids such as the genus <italic>Josephella</italic>. The Mexican serpulid tubes are of a calcitic composition. The diversity of the present serpulid association is low for shallow tropical seas of the Cretaceous in comparison to rich assemblages recorded from Europe. The low diversity presumably results from some local environmental conditions such as rapid sedimentation and low nutrient content of sea water.</p> </abstract>ARTICLEtrue record of trilobites (Arthropoda) from Carboniferous deposits of the Dnipro-Donets Depression, north-eastern Ukraine<abstract> <title style='display:none'>Abstract</title> <p>A small trilobite faunule consisting of Weberides mucronatus (M’Coy, 1844) and Waribole sp. is described from Serpukhovian (Upper Mississippian) strata of the Sribne-Krasnograd Zone in the Dnipro-Donets Depression (north-eastern Ukraine). Weberides mucronatus has previously been recorded from Serpukhovian levels in the Donets Basin and in the Lviv Palaeozoic Trough in Ukraine, whereas species of Waribole are here recorded from Carboniferous deposits of Ukraine for the first time. This genus is typical of faunal assemblages of the Mississippian-aged Kulm facies, formed under relatively deep-water marine conditions and widely distributed across western and central Europe.</p> </abstract>ARTICLEtrue and statistical analyses of a crevasse-splay complex at the Tomisławice opencast lignite mine in central Poland<abstract> <title style='display:none'>Abstract</title> <p>The studied crevasse-splay complex, situated within the 1<sup>st</sup> Mid-Polish lignite seam (MPLS-1), ranks amongst the best-developed and most readily accessible for direct research of all hard coal and lignite occurrences worldwide. The sandy-coaly sediments constituting it required a number of field and laboratory tests. However, the present article focuses solely on sedimentological and statistical analyses of sediments along a selected key section, the most important results of which are presented below. First of all, data obtained in previous sedimentological studies have been confirmed, in that individual segments of this complex represent both subaerial and subaqueous types of crevasse splays. On the one hand, their sediments are characterised by an extremely high content of coalified organic matter, reaching 20–40 wt.% in some samples; on the other, these crevasse splays are composed of fine sands with a median and mean grain size of 0.15 mm. In addition, the remaining statistical parameters (standard deviation, skewness and kurtosis) indicate a very good sorting of these sands, no significant so-called ‘tails’ and a better sorting close to the sediment mean grain size value, respectively.</p> </abstract>ARTICLEtrue assessment of Jenny’s soil forming equation in light of cosmic airbursts on the Viso Massif<abstract> <title style='display:none'>Abstract</title> <p>Jenny’s soil formation equation places soil morphogenesis as a response to climate (cl), biota (o), relief (r), parent material (p), and time (t), written thus: s= <italic>f</italic> (cl, o, r, p, t…), where each variable is considered independent. Because some soils and paleosols contain cosmic impact/airburst evidence, recent soil morphogenesis research requires a rewritten equation: s= <italic>f</italic> (cl, o, r, p, t, <bold>c</bold>…<bold>)</bold>, where c = cosmic. This addition serves to alert researchers to the presence of cosmic input to soils under investigation as part of geological and geomorphological projects. In particular, research targeting the cause of the Younger Dryas Climatic Divide (YDCD) might focus only on pollen in European glaciolacustrine sediments, reversal of the marine thermohaline circulation in the N. Atlantic Ocean, and possible reversal of postglacial warming at the Allerød termination (12.8 ka), when a search for cosmic grains may change the research outcome. Hence, the importance of the ‘c’ addition to Jenny’s factor analysis of soil morphogenesis.</p> </abstract>ARTICLEtrue, by Pedar W. Foss, 2022. Routledge, 1st edition; 334 pages. Hardback: price £136.00, e-book: price £39.99; ISBN: 978-0415705462. reviews, processes and models – an analytical review of current ambiguous interpretations of the evidence for pre-Pleistocene glaciations<abstract> <title style='display:none'>Abstract</title> <p>Models (paradigms) and former interpretations have often been presupposed when conducting field research. In the 19<sup>th</sup> century diamictites were for the first time interpreted to have originated from ancient glaciations. These interpretations have to a large part prevailed in the geological community, although there has been much progress in the areas of sedimentology, glaciology and physical geography. The present work is an effort to find criteria which most clearly discriminate between geological features produced by different processes, mainly glaciation and mass flow, the latter predominantly sediment gravity flows. Geological features which have been interpreted to have formed by glaciation throughout pre-Pleistocene Earth history are compared to similar-appearing geological features formed by mass flow and tectonics, so as to uncover variations in the appearance between features resulting from these different processes. The starting point for this comparison is documentation of the appearance of Quaternary products of erosion and deposition, in order to discern the origin of older formations. It is shown that the appearance and origin of pavements, dropstones, valleys, small-scale landforms, surface microtextures and most other geological features may in some cases be equivocal, but in others the details are indicative of the process which generated the feature. Detailed geological field data which have been compiled by geologists from outcrops of pre-Pleistocene strata, more often than is considered in most papers, commonly point to a mass flow origin, mainly a sediment gravity flow origin, rather than a glaciogenic origin. A process of multiple working hypotheses or interpretations is therefore advocated, based mainly on a comparison of the appearance of features formed by different geological processes documented from different research disciplines. Instead of starting with current interpretations or models, this multiple working hypothesis or methodology helps to avoid confirmation bias and jumping to conclusions.</p> </abstract>ARTICLEtrue record of blister pearls in the oyster (Linné, 1758) from Pliocene deposits at Sidi Brahim, Lower Chelif Basin (north-west Algeria)<abstract> <title style='display:none'>Abstract</title> <p>Fossil pearls are rare but important palaeoecological indicators in proving the former presence of parasites. A single right valve of <italic>Hyotissa hyotis</italic> from the Pliocene of Sidi Brahim shows numerous blister pearls inside the adductor muscle imprint. At the same locality, numerous shells with smooth adductor scars and without any blisters, have been collected. The structures in the studied valve can be assigned to blister pearls with high confidence due to their similarity to other Cenozoic pearls from Austria. The blister pearls likely formed as a reaction to parasite infestation. It is possible that some parasites especially targeted areas associated with the adductor muscles in the oyster genus <italic>Hyotissa</italic>, because similar blister pearls have previously been described in a congeneric species, <italic>H. squarrosa</italic>, from the Miocene of Austria.</p> </abstract>ARTICLEtrue to the journal’s reviewers of articles published in Geologos in 2023 – brief information role of oxygen in the functioning of the Earth system: past, present and future<abstract> <title style='display:none'>Abstract</title> <p>In the Solar System, the coming into existence of a peculiar, fully developed atmosphere on Earth was determined by the ‘Great Oxidation Event’ at the turn of the Proterozoic and Palaeozoic. Within about 600 million years, there were large changes in oxygen concentrations in this atmosphere, ranging from 15 to 35 per cent, having been determined by a combination of cosmic-climatic, tectonic-volcanic and biological phenomena. A particular environmental change occurred at the beginning of the 19th century, as a result of the overlap of the end of the natural Little Ice Age and the beginning of anthropogenic warming of the ‘industrial revolution’. According to the author, the rate of human impact on environmental changes is estimated at about 15 per cent. The appearance of mankind brought new changes in the natural environment, including the oxygen content of the air. The current scale of anthropogenic impact justifies the introduction of a new time slice in the planet’s history - the Anthropocene. The functioning of civilisation is conditioned by meeting energy needs, to be implemented by creating a system of energy generators, among which the heat of the Earth should be an important component. The energy generated from this inexhaustible and cost-free geo-resource should be seen as the most ecological among all currently used energy carriers.</p> </abstract>ARTICLEtrue and crystallization of magma: fundamentals of the volcanic eruption process, by Atsushi Toramaru, 2022. Springer [Advances in Volcanology]; xxxii + 427 pages; hardcover price €149.79, paperback price €149.79; eBookprice €117.69, ISBN 978-981-16-4208-1 of proposed geosites in the Betong District, Yala Province, Southern Thailand<abstract> <title style='display:none'>Abstract</title> <p>This study aims to analyse the geosite candidates of the Betong District (Yala Province) in Southern Thailand by means of several methods including inventory, characterisation, classification, assessment and SWOT analysis. Results of the present study are illustrated through seven proposed geosites that become resources for the development of the Betong District, namely Betong Hot Spring, Inthasorn Waterfall, Chaloem Phra Kiat Waterfall, Mount Silipat and Nakor Hot Spring, as well as Piyamit Tunnel and Aiyerweng Skywalk, two human-modified sites which can be used to observe geological and geomorphological features. The present study is expected to promote the conservation and development of these resources as geological heritage of the district.</p> </abstract>ARTICLEtrue reviews: Climate change and life: The complex co-evolution of climate and life on Earth, and beyond, by Gabriel Filippelli, 2022. Elsevier, Amsterdam. 275 pages. Paperback: price $135.00, ISBN 978-0-12-822568-4. palaeogeographical structures in the Cantabrian Zone, Spain: some critical considerations regarding their origin, location and significance<abstract> <title style='display:none'>Abstract</title> <p>An update of the main Devonian pre-Variscan palaeogeographical features of the southern Cantabrian Zone is presented. The approximal locations of these features are recorded in sections studied, with thin, incomplete developments for the highs and thick successions for the troughs. Generally, pre-Variscan palaeogeographical features were affected by Variscan and Alpine orogenic deformations, but with a different impact. Oroclinal bending, tectonic shortening by thrusts, movements along strike-slip faults and bending by folds all affected the Devonian palaeogeographical features, and only an approximation of their location and shape can be given. Nevertheless, the palaeogeography recorded in pre-Variscan sedimentary successions and their relative positions, provide specific, clear and objective evidence of the pre-Variscan elements.</p> </abstract>ARTICLEtrue