1,721,171 research outputs found
Low entalpy geothermal suitability of North Sardinia (Italy)
No full textHeat flow density over Sardinia is relatively high. Tertiary geodynamics and radiogenic heating from the Variscan batholith are the possible concurrent causes. Major anomalies were thought confined to the Tertiary basins, where 180 mW/m2 are reported. New data ascertain that the occurrence of the hottest thermal springs does not mirror these basins, as they pour out from Variscan granites. Hence the high thermal flow from the basins can result from basin-wide heat redistribution by hot "granite" water flowing laterally in shallow aquifers. This scenario is particularly favourable for low-medium enthalpy fluids exploitation as well as for geoexchange
Influence of inherited superposed folding on back-thrusting development: a case study from the Variscan foreland fold-andthrust belt of Sardinia
No full textOrdovician tectonics in SE Sardinia: insights into geodynamic setting and paleogeography
No full text
The Sardic Phase: field evidence of Ordovician tectonics in SE Sardinia, Italy
Full text linkDetailed geological mapping, field observations and structural analyses demonstrate that Early Ordovician ('Sardic') deformation occurred in the early Palaeozoic successions that are now incorporated in the Variscan Nappe zone of SE Sardinia. This deformation is represented by folds that formed at a shallow depth, lack a significant syn-folding axial planar foliation, and do not affect the overlying Late Ordovician - Devonian sedimentary sequence. These deformation features can be related to the development of the Sardic Unconformity and to calc-alkaline volcanism in several now-scattered terranes of Ordovician northern Gondwana. This reflects a convergent geodynamic setting that in the study sector appears to have failed to reach a continental collisional end-stage. Associating the structural data from this study with those of several published research studies, a preliminary evaluation about which tectonic setting could better fit is proposed. These conditions affected the eastern side of the northern Gondwana margin more or less contemporaneously with the opening of the Rheic Ocean and the closure of the Qaidam Ocean, before the amalgamation of the Hunia terranes
Nota preliminare su un intervallo sedimentario all’interno del ciclo vulcanico calcalcalino dell’Ordoviciano medio della Sardegna SE: la Formazione di Su Muzzioni
No full textGEOLOGY AND STRUCTURAL SETTING OF THE LOWER FLUMENDOSA VALLEY. GUIDE BOOK TO FIELD TRIP SESSION: "PALYNOLOGICAL RESEARCH IN THE SARDINIAN BASEMENT"
No full textDevelopment of extensive back-thrusting in the Variscan fold-and-thrust belt of SW Sardinia (Italy): geometry, kinematics, and relationships with inherited structures
No full textForeland- and hinterland-verging structures in fold-and-thrust belt: an example from the Variscan foreland of Sardinia
No full textIn the Variscan foreland of SW-Sardinia
(Western Mediterranean sea), close to the leading edge of
the nappe zone, nappe emplacement caused folding and
repetition of stratigraphic successions, km-scale offset of
stratigraphic boundaries and an extensive brittle-ductile
shear zone. Thrusts assumed a significant role, accommodating
a progressive change of shortening direction and
forming complicated thrust triangle zones. During thrust
emplacement of the nappes, strong penetrative deformation
affected rocks beneath the basal thrust of the nappe stack
and produced coeval structures with both foreland-directed
and hinterland-directed (backthrusting) shear sense. Crosscutting
and overprinting relationships clearly show that the
shortening direction changed progressively from N–S to E–
W, producing in sequence: (1) E–W trending open folds
contemporaneous with early nappe emplacement in the
nearby nappe zone; (2) recumbent, quasi-isoclinal folds
with axial plane foliation and widespread, ‘‘top-towardsthe-
SW’’, penetrative shearing; (3) N–S trending folds with
axial plane foliation, contemporaneous with late nappe
emplacement; (4) backthrusts and related asymmetrical
folds developed during the final stages of shortening,
postdating foreland-verging structures. Structures at (3)
and (4) occurred during the same tectonic transport ‘‘toptowards-
the-E’’ of the nappe zone over the foreland. The
several generations of folds, thrusts, and foliations with
different orientations developed, result in a complex finite
structural architecture, not completely explicable by the
theoretical model proposed up to date
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