Search results for "Structural geology"

Extensive field mapping in Sicily in the frame of the CARG Project

2008

Rilievi geologici finalizzati alla compilazione di carte geologiche in Sicilia nord-occidentale (Progetto CARG) Vengono descritti i risultati del rilevamento di numerosi fogli geologici a scala 1:50.000 ubicati nella Sicilia settentrionale (dalle Isole Egadi fino ai Monti delle Madonie), eseguito nel quadro del Progetto CARG. I rilievi sul terreno sono stati integrati con i dati di sottosuolo provenienti da profili sismici a riflessione e perforazioni profonde. I risultati ottenuti offrono un quadro a scala regionale dell’assetto stratigrafico-strutturale di uno dei settori più complessi della Catena Siciliano-Maghrebide. Sono state ricostruite le successioni stratigrafiche dei paleodomini …

A Multidisciplinary approach to define the Plio-Quaternary tectonics in the Termini Imerese Mts. (Northern central Sicily)

2012

4D paleoenvironmental evolution of the Early Triassic Sonoma Foreland Basin (western USA)

2017

In the wake of the Mesozoic, the Early Triassic (~251.95 Ma) corresponds to the aftermath of the most severe mass extinction of the Phanerozoic: the end-Permian crisis, when life was nearly obliterated (e.g., 90% of marine species disappeared). Consequences of this mass extinction are thought to have prevailed for several millions of years, implying a delayed recovery lasting the whole Early Triassic, if not more. Several paradigms have been established and associated to a delayed biotic recovery scenario expected to have resulted from harsh and deleterious paleoenvironments. These paradigms include a global anoxia in the marine realm, a “Lilliput” effect, and the presence of “disaster” tax…

Fabric Development in Gneiss Terrains

1990

This chapter describes some aspects of the development of fabrics in gneiss terrains. It provides essential background information that should be read before attempting to map a gneiss terrain. Inevitably, the interpretations are ‘state of the art’ and not necessarily the absolute answer. Additional information can be found in the cited literature and various specialised journals such as the Journal of Structural Geology, the Journal of Metamorphic Geology, Tectonophysics, Tectonics and Precambrian Research.

Three-dimensional evolution of the Keuper of the Paris basin based on detailed isopach maps of the stratigraphic cycles: tectonic influences

1997

Detailed isopach maps of the stratigraphic cycles of the Keuper of the Paris basin are used to reconstruct the 3D evolution of the basin cycle by cycle and to investigate the influence of tectonic movements. The major base-level cycles record variations in the rate of subsidence in time and space. The area of greatest subsidence, which was confined to the east of the basin during the Scythian–Carnian cycle, shifted northwestwards during the Carnian–Liassic cycle. Within the “Marnes irisees inferieures”, the E–W faults abruptly limited the extent of salt deposits to the north and south by forming a “corridor” where subsidence was greater. The westward shift of areas of subsidence induced by …

Palaeomagnetic investigations of the tertiary and quaternary igneous rocks: IV The tertiary volcanic rocks of the Tokaji mountains, Hungary

1971

Measurements are reported from samples collected at twenty three sites in the Tokaj mountains of north-eastern Hungary. The simplest interpretation of the results is in terms of geomagnetic field reversals, for there is no petrological or magnetic evidence of self reversal or of correlation of oxidation state and magnetic sign. Four magnetic zones satisfy the minimum stratigraphic requirements, speculative use of these zones against theHeirtzler et al. magnetic time scale as a control suggests locating the Miocene-Pliocene boundary at 11.75 my. However it seems probable that much of the lower Sarmatian is not represented in the Tokaj samples, although the scatter of individual readings sugg…

Zircon dating of North Bohemian granulites, Czech Republic: Further evidence for the Lower Carboniferous high-pressure event in the Bohemian Massif

1996

U-Pb zircon and rutile multigrain ages and 207Pb/206Pb zircon evaporation ages are reported from high-pressure felsic and metapelitic granulites from northern Bohemia, Czech Republic. The granulites, in contrast to those from other occurrences in the Bohemian Massif, do not show evidence of successive HT/MPLP overprints. Multigrain size fractions of nearly spherical, multifaceted, metamorphic zircons from three samples are slightly discordant and yield a U-Pb Concordia intercept age of 348 ± 10 Ma, whereas single zircon evaporation of two samples resulted in 207Pb/206Pb ages of 339 ± 1.5 and 339 ± 1.4 Ma, respectively. A rutile fraction from one sample has a U-Pb Concordia intercept age of …

Structure, evolution, and dynamics of the Norwegian-Greenland Sea in the Blue Road Geotraverse area

1981

The orogeny of the Scandinavian and Greenland Caledonides is shortly reviewed, and a structural sketch map of the Scandinavian Caledonide part of the Geotraverse is presented. Post-Caledonian rifting episodes prior to the formation of the North Atlantic Ocean are briefly discussed, as well as the opening of the northern North Atlantic Ocean and its spreading rates. Computations of density models carried out on the basis of the Simplex-Algorithm which allows a least-squares solution under certain constraints show clearly a Moho-depression beneath the Caledonides and a comparatively thick oceanic crust in the Norwegian Sea. The transition zone oceanic continental crust has a complex structure…

Evidence from zircon dating for existence of approximately 2.1 Ga old crystalline basement in southern Bohemia, Czech Republic

1993

Zircon ages are reported for three Moldanubian amphibolite grade orthogneisses from the southern Bohemian Massif obtained by conventional U/Pb analyses. For two of these orthogneisses, conventional U/Pb data are supported by ion microprobe single zircon ages or single grain evaporation data. The amphibolite grade orthogneisses, occurring in three small tectonic lenses within the Varied Group close to the South Bohemian Main Thrust, are of tonalitic, granodioritic or quartz dioritic composition.

Geology of the Bozdag area, central Menderes massif, SW Turkey: Pan-African basement and Alpine deformation

1998

The Menderes massif consists of a Precambrian Core Series that preserves evidence for a polymetamorphic history and a Paleozoic/Mesozoic Cover Series that experienced only the Alpine tectonometamorphic evolution. Structural, petrographic, and geochronologic investigations in the central Menderes massif demonstrate that (a) part of the metamorphic and structural evolution of the Precambrian basement is older than the undeformed 551+/-1.4-Ma-old Birgi metagranite, and (b) inferred Alpine fabrics overprinting the Cover Series largely have the same attitudes as the old structures in the much older Core Series. The inferred Alpine fabrics include both contractional and extensional structures. Co…