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Thrust System (thrust + system)
Selected AbstractsTIMING AND MODES OF DEFORMATION IN THE WESTERN SICILIAN THRUST SYSTEM, SOUTHERN ITALYJOURNAL OF PETROLEUM GEOLOGY, Issue 2 2001L. Tortorici Imbricate units in the western Sicilian fold-and-thrust belt originated on the southern continental margin of Neotethys, and were deformed during the Neogene-Recent in response to convergence between the African and European Plates. Neogene-Pleistocene synorogenic sediments, deposited in flexural foredeeps and satellite piggy-back basins, contain a record of the belt's evolution. Progressive migration of the thrust front southwards into the foreland has been documented, beginning in the Tortonian and continuing to the present-day particularly in western parts of the belt. In the eastern part, activity on Quaternary strike-slip fault zones has produced asymmetric flower structures and other interference structures. In this paper, we present two regional sections across the western Sicilian foreland-thrust belt system. These structural cross-sections extend down as far as the top of the Hercynian basement and integrate our field observations with previously-acquired well log, magnetic and seismic data. We show that complex interactions between the foreland-migrating thrust belt, which developed between the Late Miocene and the Pleistocene, and Pleistocene strike-slip faults led to the development of structural traps which constitute potential targets for hydrocarbon exploration. [source] The Romagna Apennines, Italy: an eroded duplexGEOLOGICAL JOURNAL, Issue 1 2001A. Cerrina Feroni Abstract The study of clast composition carried out on the alluvial gravels of the Romagna Apennines of northern Italy has provided evidence for an extensive covering of allochthonous units (Ligurian nappe and Epiligurian succession) above the Miocene foredeep deposits (Marnoso-Arenacea Formation), which has been subsequently eroded during the Late Miocene,Pleistocene uplift. This result is confirmed by the burial history outlined in the Marnoso-Arenacea Formation through vitrinite reflectance and apatite fission-track analyses. The Romagna Apennines represent, therefore, a regional tectonic window where the thrust system that displaced the Marnoso-Arenacea Formation crops out. The geometric relations between this thrust system and the basal thrust of the Ligurian nappe, exposed at the boundaries of the Romagna Apennines (Sillaro Zone and Val Marecchia klippe), are consistent with a duplex structure. Thus, the Romagna Apennines thrust system is an eroded duplex. The duplex roof-thrust corresponds to the surface of the synsedimentary overthrust of the Ligurian nappe on the Marnoso-Arenacea Formation; the floor-thrust is located in the pelagic pre-foredeep deposits (Schlier Formation). Copyright © 2001 John Wiley & Sons, Ltd. [source] The 1994 Sefidabeh earthquakes in eastern Iran: blind thrusting and bedding-plane slip on a growing anticline, and active tectonics of the Sistan suture zoneGEOPHYSICAL JOURNAL INTERNATIONAL, Issue 2 2000M. Berberian Summary In 1994 a sequence of five earthquakes with Mw 5.5,6.2 occurred in the Sistan belt of eastern Iran, all of them involving motion on blind thrusts with centroid depths of 5,10 km. Coseismic ruptures at the surface involved bedding-plane slip on a growing hanging-wall anticline displaying geomorphological evidence of uplift and lateral propagation. The 1994 earthquakes were associated with a NW-trending thrust system that splays off the northern termination of a major N,S right-lateral strike-slip fault. Elevation changes along the anticline ridge suggest that displacement on the underlying thrust dies out to the NW, away from its intersection with the strike-slip fault. This is a common fault configuration in eastern Iran and accommodates oblique NE,SW shortening across the N,S deforming zone, probably by anticlockwise rotations about a vertical axis. This style of fault kinematics may be transitional to a more evolved state that involves partitioning of the strike-slip and convergent motion onto separate subparallel faults. [source] NEOGENE TECTONIC HISTORY OF THE SUB-BIBANIC AND M'SILA BASINS, NORTHERN ALGERIA: IMPLICATIONS FOR HYDROCARBON POTENTIALJOURNAL OF PETROLEUM GEOLOGY, Issue 2 2007H. L. Kheidri The southern Bibans region in northern Algeria is located in the external zone of the Tell fold-and-thrust belt. Field observations in this area together with seismic data integrated with previous studies provide evidence for a number of Tertiary deformation phases. Late Eocene Atlassic deformation was followed by Oligocene (?)-Aquitanian-Burdigalian compression, which was associated with the development of a foreland basin in front of a southerly-propagating thrust system. Gravity-driven emplacement of the Tellian nappes over the basin margin probably occurred during the Langhian-Serravallian-Tortonian. The Hodna Mountains structural culmination developed during the Miocene-Pliocene. Analysis of brittle structures points to continued north-south shortening during the Neogene, consistent with convergence between the African and Eurasian Plates. The unconformably underlying Mesozoic-Cenozoic autochthonous sequence in this area contains two potential source rock intervals: Cenomanian-Turonian and Eocene. Reservoir rocks include Lower Cretaceous siliciclastics and Upper Cretaceous to Palaeogene carbonates. Structural style has controlled trap types. Thus traps in the Tell fold-and-thrust belt are associated with folds, whereas structural traps in the Hodna area are associated with reactivated normal faults. In the latter area, there is also some evidence for base-Miocene stratigraphic traps. [source] The Miocene Saint-Florent Basin in northern Corsica: stratigraphy, sedimentology, and tectonic implicationsBASIN RESEARCH, Issue 4 2007William Cavazza ABSTRACT Late early,early middle Miocene (Burdigalian,Langhian) time on the island of Corsica (western Mediterranean) was characterized by a combination of (i) postcollisional structural inversion of the main boundary thrust system between the Alpine orogenic wedge and the foreland, (ii) eustatic sealevel rise and (iii) subsidence related to the development of the Ligurian-Provençal basin. These processes created the accommodation for a distinctive continental to shallow-marine sedimentary succession along narrow and elongated basins. Much of these deposits have been eroded and presently only a few scattered outcrop areas remain, most notably at Saint-Florent and Francardo. The Burdigalian,Langhian sedimentary succession at Saint-Florent is composed of three distinguishing detrital components: (i) siliciclastic detritus derived from erosion of the nearby Alpine orogenic wedge, (ii) carbonate intrabasinal detritus (bioclasts of shallow-marine and pelagic organisms), and (iii) siliciclastic detritus derived from Hercynian-age foreland terraines. The basal deposits (Fium Albino Formation) are fluvial and composed of Alpine-derived detritus, with subordinate foreland-derived volcanic detritus. All three detrital components are present in the middle portion of the succession (Torra and Monte Sant'Angelo Formations), which is characterized by thin transitional deposits evolving vertically into fully marine deposits, although the carbonate intrabasinal component is predominant. The Monte Sant'Angelo Formation is characteristically dominated by the deposits of large gravel and sandwaves, possibly the result of current amplification in narrow seaways that developed between the foreland and the tectonically collapsing Alpine orogenic wedge. The laterally equivalent Saint-Florent conglomerate is composed of clasts derived from the late Permian Cinto volcanic district within the foreland. The uppermost unit (Farinole Formation) is dominated by bioclasts of pelagic organisms. The Saint-Florent succession was deposited during the last phase of the counterclockwise rotation of the Corsica,Sardinia,Calabria continental block and the resulting development of the Provençal oceanic basin. The succession sits at the paleogeographic boundary between the Alpine orogenic wedge (to the east), its foreland (to the west), and the Ligurian-Provençal basin (to the northwest). Abrupt compositional changes in the succession resulted from the complex, varying interplay of post-collisional extensional tectonism, eustacy and competing drainage systems. [source] Thrust geometries in unconsolidated Quaternary sediments and evolution of the Eupchon Fault, southeast KoreaISLAND ARC, Issue 3 2004Young-Seog Kim Abstract The Korean peninsula is widely regarded as being located at the relatively stable eastern margin of the Asian continent. However, more than 10 Quaternary faults have recently been discovered in and reported from the southeastern part of the Korean Peninsula. One of these, the Eupchon Fault, was discovered during the construction of a primary school, and it is located close to a nuclear power plant. To understand the nature and characteristics of the Quaternary Eupchon Fault, we carried out two trench surveys near the discovery site. The fault system includes one main reverse fault (N20°E/40°SE) with approximately 4 m displacement, and a series of branch faults, cutting unconsolidated Quaternary sediments. Structures in the fault system include synthetic and antithetic faults, hanging-wall anticlines, drag folds, back thrusts, pop-up structures, flat-ramp geometries and duplexes, which are very similar to those seen in thrust systems in consolidated rocks. In the upper part of the fault system, several tip damage zones are observed, indicating that the fault system propagates upward and terminates in the upper part of the section. Pebbles along the main fault plane show a preferred orientation of long axes, indicating the fault trace. The unconformity surface between the Quaternary deposits and the underlying Tertiary andesites or Cretaceous sedimentary rocks is displaced by this fault with a reverse movement sense. The stratigraphic relationship shows normal slip sense at the lower part of the section, indicating that the fault had a normal slip movement and was reversely reactivated during the Quaternary. The inferred length of the Quaternary thrust fault, based on the relationship between fault length and displacement, is 200,2000 m. The current maximum horizontal compressive stress direction in this area is generally east-northeast,west-southwest, which would be expected to produce oblique slip on the Eupchon Fault, with reverse and right-lateral strike-slip components. [source] Palaeoproterozoic high-pressure granulite overprint of the Archean continental crust: evidence for homogeneous crustal thickening (Man Rise, Ivory Coast)JOURNAL OF METAMORPHIC GEOLOGY, Issue 1 2010P. PITRA Abstract The character of mountain building processes in Palaeoproterozoic times is subject to much debate. Based on the discovery of high-pressure granulites in the Man Rise (Côte d'Ivoire), several authors have argued that Eburnean (Palaeoproterozoic) reworking of the Archean basement was achieved by modern-style thrust-dominated tectonics. A mafic granulite of the Kouibli area (Archean part of the Man Rise, western Ivory Coast) displays a primary assemblage (M1) containing garnet, diopsidic clinopyroxene, red-brown pargasitic amphibole, plagioclase (andesine), rutile, ilmenite and quartz. This assemblage is associated with a subvertical regional foliation. Symplectites that developed at the expense of the M1 assemblage contain orthopyroxene, clinopyroxene, plagioclase (bytownite), green pargasitic amphibole, ilmenite and magnetite (M2). Multiequilibrium thermobarometric calculations and P,T pseudosections calculated with thermocalc suggest granulite facies conditions of , 13 kbar, 850 °C and <7 kbar, 700,800 °C for M1 and M2, respectively. In agreement with the qualitative information obtained from reaction textures and chemical zoning of minerals, this suggests an evolution dominated by decompression accompanied by moderate cooling. A Sm,Nd garnet , whole-rock age of 2.03 Ga determined on this sample indicates that this evolution occurred during the Palaeoproterozoic. It is argued that from the geodynamic point of view the observed features are best explained by homogeneous thickening of the margin of the Archean craton, re-heated and softened due to the accretion of hot, juvenile Palaeoproterozoic crust, as well as coeval intrusion of juvenile magmas. Crustal shortening was mainly accommodated by transpressive shear zones and by lateral crustal spreading rather than large-scale thrust systems. [source] | ||||||||||