The Zagros thrust belt is a zone of deformed crustal rocks well exposed along the southwest region of Iran. To obtain a better knowledge of this mountain chain, we elaborated a 2D model reproducing the thermal structure of the “Mountain Front Fault”. This study, which is focused on the Lurestan region, is based on a model made by merging published sections and available information on the depth of the Moho. We present the isotherms and the geotherms calculated using an analytical methodology. The calculation procedure includes the temperature variation due to the re-equilibrated conductive state after thrusting, frictional heating, heat flow density data, and a series of geologically derived constraints. In order to perform the temperature calculations, the crustal structure in the Lurestan region is simplified as composed of two domains: A lower unit made by crystalline basement and an upper unit including all the lithostratigraphic units forming the sedimentary cover. The resulting model is compared with the numerical results obtained by previous studies to improve the description of the thermal structure of this geologically important area.
Despite their markedly different structural setting, the northern and southern outer Albanides share a common tectonic evolution from detachment‐dominated to ramp‐dominated, basement‐involved thrusting. The former process (mainly Oligocene to Miocene) is essentially related with the occurrence of a thick décollement level represented by Triassic evaporites, while the latter involves basement ramps splaying out from a middle crustal décollement. As this weak crustal layer is inherited from the Mesozoic rifting stage, the original continental margin architecture is interpreted to strongly influence subsequent convergent deformation. The profoundly different nature of the two dominant décollements in the study area controlled the structural style of the fold and thrust belt. The decoupling capacity of the upper décollement is strongly dependent on the thickness of the Triassic evaporites. Where this is significant (≫1 km; southern outer Albanides), the occurrence of such a thick incompetent layer at the base of competent carbonate units favored the development of break‐thrust folds and imbrication of the sedimentary cover. Fold and thrust belt propagation was instead hindered where original stratigraphic variations resulted in a reduced thickness (≤1 km) of Triassic evaporites. On the other hand, the deeper middle crustal décollement is controlled by basement rheology. Its reactivation during plate convergence was assisted by collision‐related thermal weakening of the crust. This process governed late‐stage (<5 Ma) crustal‐scale tectonic inversion and plays a major role in controlling present‐day seismicity.
The Zagros thrust belt is a large orogenic zone located along the southwest region of Iran. To obtain a better knowledge of this important mountain chain, we elaborated the first 3-D model reproducing the thermal structure of its northwestern part, i.e., the Lurestan arc. This study is based on a 3-D structural model obtained using published geological sections and available information on the depth of the Moho discontinuity. The analytical calculation procedure took into account the temperature variation due to: (1) The re-equilibrated conductive state after thrusting, (2) frictional heating, (3) heat flow density data, and (4) a series of geologically derived constraints. Both geotherms and isotherms were obtained using this analytical methodology. The results pointed out the fundamental control exerted by the main basement fault of the region, i.e., the Main Frontal Thrust (MFT), in governing the thermal structure of the crust, the main parameter being represented by the amount of basement thickening produced by thrusting. This is manifested by more densely spaced isotherms moving from the southwestern foreland toward the inner parts of orogen, as well as in a lateral variation related with an along-strike change from a moderately dipping crustal ramp of the MFT to the NW to a gently dipping crustal ramp to the SE. The complex structural architecture, largely associated with late-stage (Pliocene) thick-skinned thrusting, results in a zone of relatively high geothermal gradient in the easternmost part of the study area. Our thermal model of a large crustal volume, besides providing new insights into the geodynamic processes affecting a major salient of the Zagros thrust belt, may have important implications for seismotectonic analysis in an area recently affected by a Mw = 7.3 earthquake, as well as for geothermal/hydrocarbon exploration in the highly perspective Lurestan region.
The article deals with the investigation of geopolymer foams (GFs) synthesized using by-products coming from the (i) screening-, (iv) pyrolysis-, (iii) dust abatement- and (iv) fusion-processes of the secondary aluminum industry. Based on principles of the circular economy to produce new technological materials, the experimental study involves industrial by-products management through the recovery, chemical neutralization, and incorporation of these relatively hazardous waste into the GFs. The geopolymeric matrix, consisting of metakaolin (MK) and silica sand (SA) with a 1:1 wt.% ratio, and chopped carbon fibers (CFs, 1 wt.% MK), was doped with the addition of different aluminum-rich industrial by-products with a percentage from 1 to 10 wt.% MK. The gas (mainly hydrogen) produced during the chemical neutralization of the by-products represents the foaming agents trapped in the geopolymeric structure. Several experimental tests were carried out to characterize the mechanical (flexural, compressive, and Charpy impact strengths) and thermal properties (thermal conductivity, and diffusivity, and specific heat) of the GFs. Results identify GFs with good mechanical and thermal insulation properties, encouraging future researchers to find the best combination (for types and proportions) of the different by-products of the secondary aluminum industry to produce lightweight geopolymer foams. The reuse of these industrial by-products, which according to European Regulations cannot be disposed of in the landfill, also brings together environmental sustainability and safe management of hazardous material in workplaces addressed to the development of new materials.
Using an analytical methodology taking into account heat flow density data, frictional heating, temperature variations due to the re-equilibrated conductive state after thrusting and geological constrains, we calculated surface heat flow, geotherms and isotherms along a balanced and restored regional geological cross-section. Our results highlight the impact of frictional heating produced by thrusts on the thermal structure of the study area, leading to a raising of the isotherms both in the inner Albanides to the E and in the Adriatic sector offshore. Minimum values of Qs in the surroundings of Tirana and the reconstructed 2D thermal structure suggest less favorable conditions for exploitation of geothermal energy, besides the direct use (Borehole Heat Exchanger-Geothermal Heat Pump systems). Nevertheless, the occurrence of the “Kruja geothermal zone”, partially overlapping this area and including hot spring manifestations, emphasize the structural control in driving hot fluids to the surface with respect to the regional thermal structure.
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