Figueiral I.,French National Center for Scientific Research |
Mosbrugger V.,Institute For Geologie Und Palaontologie |
Rowe N.P.,UMR 5120 |
Utescher T.,Institute For Geologie |
And 2 more authors.
Palaios | Year: 2014
The potential of fossilwood and charcoal frombrowncoaldeposits as sources of reliable paleoenvironmental information is explored with material fromthe Lower Rhine Embayment (Germany). The presence of charcoalified material demonstrates proof of natural wildfires in Tertiary mire environments, most probably during, or after periods of increased drainage and drying of surface vegetation and litter. The results presented suggest that sampling from charcoal layers may provide a more statistically reliable data set for study of such environments. Inclusion of taxa recovered from charcoal layers might compensate for the taphonomic and preservational bias of Tertiary lignitic floras based solely on the collection of lignitic wood. These data confirm the hypothesis that, during certain intervals of the Miocene, both monocotyledonous and dicotyledonous angiosperms might have dominated or represented significant portions of the peat-forming vegetation. The importance of palms and shrubby woody taxa, such as 'Cyrilla', is particularly striking from new evidence of charcoalified remains. In addition, certainwood anatomical features observed fromwell preserved lignitic wood and charcoal may be used as indicators of environmentally modulated growth: (1) clear growth rings testify to the existence of a seasonal climate; (2) wide variations in growth ring characters indicate variable environmental conditions; and (3) high incidence of dicotyledonous taxa, with abundant small vessels and scalariform perforation plates, is interpreted as evidence of a mesic environment.
Schefer S.,Geologisch Palaontologisches Institute |
Cvetkovic V.,University of Belgrade |
Fugenschuh B.,Institute For Geologie Und Palaontologie |
Kounov A.,Geologisch Palaontologisches Institute |
And 4 more authors.
International Journal of Earth Sciences | Year: 2011
Two age groups were determined for the Cenozoic granitoids in the Dinarides of southern Serbia by high-precision single grain U-Pb dating of thermally annealed and chemically abraded zircons: (1) Oligocene ages (Kopaonik, Drenje, Željin) ranging from 31.7 to 30.6Ma (2) Miocene ages (Golija and Polumir) at 20.58-20.17 and 18.06-17.74Ma, respectively. Apatite fission-track central ages, modelling combined with zircon central ages and additionally, local structural observations constrain the subsequent exhumation history of the magmatic rocks. They indicate rapid cooling from above 300°C to ca. 80°C between 16 and 10Ma for both age groups, induced by extensional exhumation of the plutons located in the footwall of core complexes. Hence, Miocene magmatism and core-complex formation not only affected the Pannonian basin but also a part of the mountainous areas of the internal Dinarides. Based on an extensive set of existing age data combined with our own analyses, we propose a geodynamical model for the Balkan Peninsula: The Late Eocene to Oligocene magmatism, which affects the Adria-derived lower plate units of the internal Dinarides, was caused by delamination of the Adriatic mantle from the overlying crust, associated with post-collisional convergence that propagated outward into the external Dinarides. Miocene magmatism, on the other hand, is associated with core-complex formation along the southern margin of the Pannonian basin, probably associated with the W-directed subduction of the European lithosphere beneath the Carpathians and interfering with ongoing Dinaridic-Hellenic back-arc extension. © 2010 Springer-Verlag.
Spikings R.,University of Geneva |
Reitsma M.J.,HRH Geology |
Boekhout F.,Institute For Geologie Und Palaontologie |
Miskovic A.,University of British Columbia |
And 4 more authors.
Gondwana Research | Year: 2016
Triassic igneous and sedimentary rocks exposed within the basement of the Andes were deposited in a series of rifts, and may record the early disassembly of western Pangaea. These rocks are sporadically exposed along almost the entire length of western South America, although reliable geochronological and isotopic data are sparse. We combine new geochronological (zircon U-Pb), isotopic (Hf, Nd) and geochemical data with stratigraphic observations to constrain the age and tectonic setting of the Mitu Rift of southern Peru. The Peruvian Mitu Rift is compared with other Triassic rifts in Colombia and Ecuador (Palanda Rift; 240-225 Ma), Bolivia (Mitu Rift; Triassic), Bolivia, Chile and Argentina (e.g. Cuyo Basin; 246-230 Ma), and conclusions are reached regarding the relationship between Triassic extension along the western margin of Pangaea, and the eventual formation of the Proto-Caribbean and Central Atlantic oceans. The Mitu Rift (Peru) was active during ~245-240 to ~220 Ma and was synchronous with rifting along the Pacific margin of Colombia and Ecuador, along the Chilean margin and western Argentina, and probably rifting within Bolivia. Rifting north of the Huancabamba Deflection was accompanied by subduction and led to seafloor spreading, whereas rifting along the Peruvian and Chilean margins mainly occurred in the absence of subduction and terminated prior to the formation of extensive transitional crust. Extension within Peru and Chile probably occurred via a combination of transtension, steepening and detachment of an arrested slab. We propose that plate tectonic forces initiated the early break-up of Pangaea by attenuating its margins and enhancing mantle upwelling. Prolonged extension may have propagated along pre-existing weak zones that extended into the continental interior, captured melts derived from the upwelled mantle forming a LIP (e.g. Central Atlantic Magmatic Province), became hot and weak and eventually lead to the formation of a juvenile ocean (e.g. Central Atlantic). © 2016 International Association for Gondwana Research.
Nebelsick J.H.,Institute Undmuseum For Geologie Und Palaontologie |
Kroh A.,Institute For Geologie Und Palaontologie
Palaios | Year: 2014
Clypeasteroids can be very common in Recent, shallow water environments in a variety of biogeographic settings and represent important members of benthic invertebrate communities. Mass deposits of fossil clypeasteroids are also common and characteristic of many Cenozoic shallowwater deposits. Their distribution and formation, however, has receivedmuch less attention thanmolluscan counterparts, although fossil examples are found within all three of the clypeasteroid suborders. A comparison of two mass deposits of scutellid clypeasteroids from the Miocene of the Mediterranean (Gebel Gharra section, Eastern Desert, Egypt; Alahan Section,Mut Basin, Turkey) shows common features, but also significant differences. Both were formed in high energy, coarse sandy, shoreface environments. The Gebel Gharra section consists of a thick, multi-event accumulation with numerous sedimentary features dominated by complete and fragmented skeletal remains of a single taxon (Parascutella). The accumulations in Alahan represents a single, thin, multi-taxon (Amphiope, Parascutella) deposit dominated by very well preserved, complete specimens. Both units are interpreted as proximal storm deposits based on the general sedimentary environment, clast relationships, and taphonomic features. Four factors contributing to mass deposits of clypeasteroid sea urchins in Cenozoic sediments include: (1) their gregarious nature with very high density populations; (2) their relatively robust skeletalmorphology; (3) the high transport capacity of their flattened, low density skeletons; and (4) their habitat in shoreface environments which is conducive to physical concentrations of skeletal material. The presence of mass clypeasteroid accumulations is compared to other echinoderm deposits and discussed within the context of their rapid evolution in the Cenozoic.
Bockwinkel J.,Dechant Fein Str. 22 |
Becker R.T.,Institute For Geologie Und Palaontologie
Fossil Record | Year: 2013
The Hassi Nebech area of the SE Tafilalt (Tafilalt Basin, Anti-Atlas, Morocco) yielded the richest and most diverse late Givetian ammonoid fauna on a global scale. Above the distinctive regional "Lower Marker Bed" (Synpharciceras clavilobum Zone), abundant loosely collected limonitic specimens derive from hypoxic shales of the Taouzites taouzensis to Petteroceras errans zones. The ontogenetic morphometry and intraspecific variability of a total of 30 species representing five families, the Acanthoclymeniidae, Taouzitidae, Pharciceratidae, Petteroceratidae, and Tornoceratidae, are documented. New taxa are: Pseudoprobeloceras praecox n. sp., Scaturites minutus n. gen. n. sp., Darkaoceras velox n. sp., Pharciceras decoratum n. sp., Ph. fornix n. sp., Ph. subconstans n. sp., Ph. involutum n. sp., Lunupharciceras incisum n. sp., Transpharciceras procedens n. gen. n. sp., Stenopharciceras progressum n. sp., Pluripharciceras n. gen. (type species: Synpharciceras plurilobatum Petter, 1959), Plu. orbis n. sp., Synpharciceras frequens n. sp., Lobotornoceras bensaidi n. sp., Nebechoceras eccentricum n. gen. n. sp., and Phoenixites lenticulus n. sp.. The documentation of conch and particularly suture ontogeny and intraspecific variability necessitates a revised diagnosis for ten taxa. Manticoceras pontiformis Termier & Termier, 1950, Probeloceras costulatum Petter, 1959, and Pseudoprobeloceras nebechense Bensad, 1974 are regarded as subjective junior synonyms of Ps. pernai (Wedekind, 1918). Sandbergeroceras acutum Termier & Termier, 1950 is a subjective synonym of Taouzites taouzensis (Termier & Termier, 1950). Pharciceras applanatum Bensad, 1974 is transferred to Extropharciceras. Other forms (Ph. aff. tridens, Ph. cf. subconstans n. sp., Extropharciceras n. sp. 2, Ex. cf. arenicum, Ex. cf. applanatum, Synpharciceras sp., Plu. cf. plurilobatum) are described in open nomenclature. © 2013 WILEY-VCH Verlag GmbH & Co. KGaA, Weinheim.
Amir Hassan M.H.,University of Malaya |
Aung A.-K.,University of Malaya |
Becker R.T.,Institute For Geologie Und Palaontologie |
Abdul Rahman N.A.,University of Malaya |
And 3 more authors.
Journal of Asian Earth Sciences | Year: 2014
The stratigraphy of the Devonian to Permian succession in Northwest Peninsular Malaysia is revised. The Timah Tasoh Formation consists of black mudstone containing graptolites and tentaculitids indicating a Pragian or earliest Emsian age. The Sanai Limestone overlies the Timah Tasoh Formation at Sanai Hill B and contains conodonts indicating a Late Devonian (Frasnian to possibly early Famennian) age. In other places, Late Tournaisian chert of the Telaga Jatoh Formation overlies the Timah Tasoh Formation. The overlying Kubang Pasu Formation is predominantly composed of mudstone and sandstone, and can be divided into 3 subunits, from oldest to youngest: (1) Chepor Member; (2) Undifferentiated Kubang Pasu Formation; (3) Uppermost Kubang Pasu Formation. The ammonoid Praedaraelites tuntungensis sp. nov. is reported and described from the Chepor Member of Bukit Tuntung, Pauh. The genus indicates a Late Viséan age for part of the subunit. Dropstones and diamictites from the Chepor Member indicate a glacial marine depositional environment. The Carbo-Permian, undifferentiated Kubang Pasu Formation consists of similar interbedded mudstone and sandstone. The uppermost Kubang Pasu Formation of Kungurian age consists of coarsening upward cycles of clastics, representing a shallow marine, wave- and storm-influenced shoreline. The Permian Chuping Limestone also represents shallow marine, wave- and storm-influenced deposits. A Mid-Palaeozoic Unconformity separating Early-Late Devonian rocks from overlying Late Devonian-Carboniferous deposits probably marks initiation of rifting on Sibumasu, which eventually led to the separation of Sibumasu from Australian Gondwana during the late Sakmarian (Early Permian). © 2014 Elsevier Ltd.