Search results for "rock"

Tectono-sedimentary constraints to the Oligocene-to-Miocene evolution of the Peloritani thrust belt (NE Sicily)

1999

Abstract The Peloritani thrust belt belongs to the southern sector of the Calabrian Arc and is formed by a set of south-verging tectonic units, including crystalline basement and sedimentary cover (from the top: Aspromonte U.; Mela U.; Mandanici U.; Fondachelli U.; Longi-Taormina U.), piled up starting from Late Oligocene. At least two main terrigenous clastic formations lie with complicated relationships on top of the previous units: the Frazzano Fm (Oligocene) and the Stilo-Capo d'Orlando Fm (Late Oligocene?–Early Miocene), as syn-to-post-tectonic deposits. These clastic deposits have different characteristics, in space and time, representing or flysch-like sequences involved in several t…

Early Pan-African evolution of the basement around Elat, Israel,and the Sinai Peninsula revealed by single-zircon evaporation dating, and implication…

1990

We report 2<r7Pb/206Pb single-zircon evaporation ages for early Pan-African rocks from southern Israel and the northeastern Sinai Peninsula, the northernmost extension of the Arabian-Nubian shield. The oldest rocks are metamorphic schists of presumed island-arc derivation; detrital zircons date the source terrain at ca. 800-820 Ma. A major phase of tonalite-trondhjemite plutonism occurred at ca. 760-780 Ma; more evolved granitic rocks were emplaced at about 745 Ma. A metagabbro-met adiorite complex reflects the youngest igneous phase at ca. 640 Ma. We Find no evidence for pre-Pan-African crust, and our data document important crust-forming events that correlate with similar episodes elsewhe…

Séries charbonneuses dans des séquences rétrogradantes: cas du bassin houiller paralique westphalien de Jérada (Maroc)

1998

Abstract Several orders of stacked genetic sequences in the Westphalian C of the Jerada Basin are defined from detailed sedimentological data. Eight coal seams were formed in this paralic basin as distal facies passed laterally into proximal facies in retrogradational stages. These stages are related to base level rises that curtailed detrital influx and induced the development of swamps and the preservation of organic matter below anoxic water levels. The base level variations are related to active faulting along the basin margins and to sea level changes in the Palaeo-Tethys.

Tectono-sedimentary evolution of the Pliocene to Lower Pleistocene succession of the Apricena-Lesina-Poggio Imperiale quarrying district (western Gar…

2010

The post-Miocene marine succession of the «Apricena horst» is described with the purpose to verify the chronostratigraphic constraints for the type-locality of the Pirro Nord Faunal Unit. The stratigraphic succession has been subdivided in four units bounded by ubiquitous unconformities with evidence of subaerial exposure. The two basal units (dated late Zanclean to at most early Piacenzian) are formally grouped in the Lago di Varano Fm. that on the whole consists of sediments ranging from lagoonal to circalittoral environments. Within the lowermost unit, a megabreccia is interpreted as the product of a tsunami event. The third unit, Gelasian in age, is informally cited as Calcari a Briozoi…

Devonian arc-related magmatism in the Tseel terrane of SW Mongolia: chronological and geochemical evidence

2009

Abstract: The Tseel terrane in the Gobi Desert of SW Mongolia consists of a composite crustal segment of imbricated sheets of high- and low-grade metamorphic rocks of predominantly middle Palaeozoic age. New sensitive high-resolution ion microprobe (SHRIMP) zircon ages of 396 ± 3 Ma (2σ) and 397 ± 3 Ma (2σ) for two calc-alkaline metarhyolite samples indicate arc volcanism during the early Devonian. An undeformed feldspar porphyry cross-cutting the early Devonian low-grade sequence yielded an emplacement age of 279 ± 2 Ma (2σ). Geochemical and Nd isotopic data for low-grade mafic metavolcanic rocks are consistent with melting of moderately depleted upper mantle sources in a transitional arc–…

Sedimentary dynamics and structural geology of pre-rift deposits of the interior basin of Gabon

2002

Abstract Recent studies combining field data (facies and paleocurrent analyses, structural surveys), sub-surface data (core analyses, well logs, seismic sections) and palynological data provide insight into the sedimentary dynamics of pre-rift deposits of the interior basin of Gabon and their structural and paleoclimatic setting. These sedimentary deposits belong to the Noya, Agoula and M’vone series of Late Precambrian to Jurassic age. Although these deposits are potential sources of petroleum, they are partly known because of poor outcrop in a wet equatorial climate, low density and uneven distribution of exploration wells and poor seismic survey coverage. The pre-rift deposits reflect fl…

Sicilian Lithostratigraphic Units

2018

This chapter includes the description of the Sicilian lithostratigraphic units (Fig. 2.1). They are grouped in a generally chronological order and the complete list of the worksheets is shown in the Table of contents. In each chronologic group the worksheets of the described formations are organized in alphabetic order. The Permo-Triassic units are the oldest deposits outcropping in Sicily that originated during the early stages of the Southern Tethyan continental rifting. The Meso-Cenozoic carbonate units represent the sedimentary sequences of the various stratigraphic successions differentiated in the field along the Sicilian outcrops. The deposits of the Sicilide Complex (Tethyan units) …

Erratum to “Sedimentary dynamics and extensional structuring related to Early Cretaceous rifting of Neocomian and Barremian deposits of the interior …

2013

1991

The Triassic of the NW Iberian Ranges consists of two carbonatic formations equivalent to the Upper Carbonatic Formation of the Muschelkalk Facies and pass laterally into siliciciastic deposits to the NW. Fossillocalities have been found in both formations. Taphonomic and sedimentologic studies allow for the interpretation as autochthonous associations of the infaunal Bivalves of shallow water marine environments with siliciciastic input. Three faunal associations have been distinguished: 1. Costatoria-Lyriomyophoria association, found in the lower carbonatic formation and the equivalent siliciciastic formation; 2. «Teruel Fauna» association, found in the upper carbonatic formation; 3. Ling…

Mass mortality or exceptional fossilization ? The case of the early and middle Toarcian fossiliferous beds from the Digne-Les-Bains area (southeaster…

2003

Abstract The latest Domerian to late Toarcian sedimentary series (from −190 Ma up to −180 Ma) from the « Réserve Géologique de Haute-Provence » (southeastern France) yields two kinds of remarkable fossiliferous beds. The greatest interest of the early Toarcian type is the occurrence of ichtyosaur remains (at least in six sites) among many other fossils such as ammonites, belemnites, bivalves, wood. The middle Toarcian type is specifically rich in ammonites and nautiluses. Litho- and biostratigraphical, palaeontological, sedimentological and geochemical analyses allow us to determine whether these fossiliferous beds are the results of mass mortalities, linked or not to biological crisis, o…