G. Zanchetta, M. Bini, I. Isola, E. Regattieri, A. Ribolini, I. Milevski, R. Sulpizio
In this paper, we describe the first finding of the Campanian Ignimbrite tephra layer in a subaerial succession in the Former Yugoslav Republic of Macedonia. The tephra is interbedded within slope deposits mixed with colluvial loess. The identification of this fundamental stratigraphic marker is based on major elements. The investigated succession is correlated to lacustrine records from Ohrid and Prespa lakes, several archives of the central and eastern Mediterranean, and mainland Ukraine and Russia. Field observations and correlation with lacustrine records (i.e. pollen) indicate that accumulation of the volcanic ash occurred in a dry environment characterized by low vegetation cover and important wind activity, which promoted loess deposition. The recognition of the Campanian Ignimbrite tephra allows the correlation of the loess sediments to the H4 event, as defined in the North Atlantic event climatic stratigraphy.
{"title":"New findings of the Campanian Ignimbrite ash within slope deposits of the Treska valley (former Yugoslav Republic of Macedonia)","authors":"G. Zanchetta, M. Bini, I. Isola, E. Regattieri, A. Ribolini, I. Milevski, R. Sulpizio","doi":"10.3301/IJG.2016.16","DOIUrl":"https://doi.org/10.3301/IJG.2016.16","url":null,"abstract":"In this paper, we describe the first finding of the Campanian Ignimbrite tephra layer in a subaerial succession in the Former Yugoslav Republic of Macedonia. The tephra is interbedded within slope deposits mixed with colluvial loess. The identification of this fundamental stratigraphic marker is based on major elements. The investigated succession is correlated to lacustrine records from Ohrid and Prespa lakes, several archives of the central and eastern Mediterranean, and mainland Ukraine and Russia. Field observations and correlation with lacustrine records (i.e. pollen) indicate that accumulation of the volcanic ash occurred in a dry environment characterized by low vegetation cover and important wind activity, which promoted loess deposition. The recognition of the Campanian Ignimbrite tephra allows the correlation of the loess sediments to the H4 event, as defined in the North Atlantic event climatic stratigraphy.","PeriodicalId":55341,"journal":{"name":"Bollettino Della Societa Geologica Italiana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"84525118","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The Monte Alpi is a key area to decipher the structural setting of the southern Apennines fold-and-thrust belt. There, high-angle faults juxtapose Mesozoic carbonates of the inner Apulian Platform, and their terrigenous Messinian sedimentary cover, against the allochthon terranes. In the recent past, two main tectonic models related to the evolution of the Monte Alpi area ascribed the significant exhumation of the Apulian carbonates to two different mechanisms. The first one, highlighted the role of high-angle faults, which affect and cross-cut both carbonates and allochthon terranes. The second model, inferred the significant exhumation of the Apulian Platform carbonates as due to low-angle extensional faulting. In light of the aforementioned discrepancies, the present work shows the results of original field and laboratory analyses aimed at reconstructing the structural setting of both Apulian carbonates and allochton terranes. In particular, two different folding stages and the geometry of the thrust sheets are assessed, by means of detailed field and micro-structural analyses, for the allochton terranes. In the Apulian carbonates, both attitude and kinematics of the syn-sedimentary high-angle faults bounding the Upper Messinian deposits are documented. Furthermore, the tectonic structures associated to the contractional, strike-slip and extensional stages are distinguished based on their abutting and crosscutting relationships. Finally, the results of such a work are discussed in terms of the time-space evolution of deformation in the Monte Alpi area; five main tectonic stages are deciphered for the Pre-Pliocene to Holocene times.
{"title":"New insights on the structural setting of the Monte Alpi area, Basilicata, Italy","authors":"V. L. Bruna, F. Agosta, G. Prosser","doi":"10.3301/IJG.2017.03","DOIUrl":"https://doi.org/10.3301/IJG.2017.03","url":null,"abstract":"The Monte Alpi is a key area to decipher the structural setting of the southern Apennines fold-and-thrust belt. There, high-angle faults juxtapose Mesozoic carbonates of the inner Apulian Platform, and their terrigenous Messinian sedimentary cover, against the allochthon terranes. In the recent past, two main tectonic models related to the evolution of the Monte Alpi area ascribed the significant exhumation of the Apulian carbonates to two different mechanisms. The first one, highlighted the role of high-angle faults, which affect and cross-cut both carbonates and allochthon terranes. The second model, inferred the significant exhumation of the Apulian Platform carbonates as due to low-angle extensional faulting. In light of the aforementioned discrepancies, the present work shows the results of original field and laboratory analyses aimed at reconstructing the structural setting of both Apulian carbonates and allochton terranes. In particular, two different folding stages and the geometry of the thrust sheets are assessed, by means of detailed field and micro-structural analyses, for the allochton terranes. In the Apulian carbonates, both attitude and kinematics of the syn-sedimentary high-angle faults bounding the Upper Messinian deposits are documented. Furthermore, the tectonic structures associated to the contractional, strike-slip and extensional stages are distinguished based on their abutting and crosscutting relationships. Finally, the results of such a work are discussed in terms of the time-space evolution of deformation in the Monte Alpi area; five main tectonic stages are deciphered for the Pre-Pliocene to Holocene times.","PeriodicalId":55341,"journal":{"name":"Bollettino Della Societa Geologica Italiana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"83035010","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
R. Giordano, A. Caggianelli, R. Sulpizio, M. Balestrieri, P. Maiorano, L. Solari
Two volcaniclastic deposits, ROC and SBA, in the Oligo-Miocene succession of the Southern Apennines, between the Apulia and Campania regions, have been studied for the first time. Mineral composition, SEM-EDS and LA-ICP-MS analyses, for major and trace elements, respectively, allowed recognizing magmatic products of typical calc-alkaline to high-K calc-alkaline affinity. ROC glasses have a restricted compositional range in the rhyolitic field whereas SBA glasses show a wide compositional range from andesite to rhyolite, with dacite as the most common composition. Fission-track dating of apatite in the SBA deposits yielded an age of 21.7 ± 2.2 Ma, which is comprised between the Chattian and the Burdigalian. Biostratigraphic analyses in sedimentary layers adjacent to ROC layers indicate they were deposited not before Burdigalian. A provenance analysis of the studied volcaniclastics in relation to the possible source areas of the Mediterranean and neighbouring areas was performed. On the basis of time constraints, mineral and trace element composition a convincing correlation of the ROC deposits with potential source areas did not emerge. Instead, a provenance from the southwestern and northwestern Sardinian volcanic centres was favoured for the SBA volcaniclastic deposits. This hypothesis is compatible with the Oligo-Miocene paleogeographic reconstructions, that show the proximity of the Apennine sedimentary basins to Sardinia before the opening of the Tyrrhenian sea.
{"title":"Magmatic and geodynamic significance of two volcaniclastic deposits in the Oligo-Miocene successions of the Southern Apennines (Italy)","authors":"R. Giordano, A. Caggianelli, R. Sulpizio, M. Balestrieri, P. Maiorano, L. Solari","doi":"10.3301/IJG.2016.08","DOIUrl":"https://doi.org/10.3301/IJG.2016.08","url":null,"abstract":"Two volcaniclastic deposits, ROC and SBA, in the Oligo-Miocene succession of the Southern Apennines, between the Apulia and Campania regions, have been studied for the first time. Mineral composition, SEM-EDS and LA-ICP-MS analyses, for major and trace elements, respectively, allowed recognizing magmatic products of typical calc-alkaline to high-K calc-alkaline affinity. ROC glasses have a restricted compositional range in the rhyolitic field whereas SBA glasses show a wide compositional range from andesite to rhyolite, with dacite as the most common composition. Fission-track dating of apatite in the SBA deposits yielded an age of 21.7 ± 2.2 Ma, which is comprised between the Chattian and the Burdigalian. Biostratigraphic analyses in sedimentary layers adjacent to ROC layers indicate they were deposited not before Burdigalian. A provenance analysis of the studied volcaniclastics in relation to the possible source areas of the Mediterranean and neighbouring areas was performed. On the basis of time constraints, mineral and trace element composition a convincing correlation of the ROC deposits with potential source areas did not emerge. Instead, a provenance from the southwestern and northwestern Sardinian volcanic centres was favoured for the SBA volcaniclastic deposits. This hypothesis is compatible with the Oligo-Miocene paleogeographic reconstructions, that show the proximity of the Apennine sedimentary basins to Sardinia before the opening of the Tyrrhenian sea.","PeriodicalId":55341,"journal":{"name":"Bollettino Della Societa Geologica Italiana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"76680368","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
Tilt measurements represent one of the earliest methods to detect ground deformation on volcanoes with the first acquisition being made on Kilauea (Hawaii) in 1912-13. Tilt is a powerful tool for volcano monitoring enabling to obtain signals with high precision. Tilt has proved its worth especially in understanding dike intrusions, fracture propagation, lava fountains, strombolian activity, dome growing and volume and amplitude changes in magmatic/hydrothermal systems.This paper is a review of tilt studies performed worldwide on volcanoes in the last 105 years. We highlighted the methodologies used and the improvements and developments made over recent years to augment the possibility to detect volcanic processes.We review the results obtained on about 40 volcanic areas in which tilt measurements have played a major role in volcanic process knowledge.
{"title":"Tilt measurements on volcanoes: more than a hundred years of recordings","authors":"S. Gambino, L. Cammarata","doi":"10.3301/IJG.2017.07","DOIUrl":"https://doi.org/10.3301/IJG.2017.07","url":null,"abstract":"Tilt measurements represent one of the earliest methods to detect ground deformation on volcanoes with the first acquisition being made on Kilauea (Hawaii) in 1912-13. Tilt is a powerful tool for volcano monitoring enabling to obtain signals with high precision. Tilt has proved its worth especially in understanding dike intrusions, fracture propagation, lava fountains, strombolian activity, dome growing and volume and amplitude changes in magmatic/hydrothermal systems.This paper is a review of tilt studies performed worldwide on volcanoes in the last 105 years. We highlighted the methodologies used and the improvements and developments made over recent years to augment the possibility to detect volcanic processes.We review the results obtained on about 40 volcanic areas in which tilt measurements have played a major role in volcanic process knowledge.","PeriodicalId":55341,"journal":{"name":"Bollettino Della Societa Geologica Italiana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88368400","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
The recharge settings of aquifers (as those of the carbonate ridges in central Apennines) is strongly dependent on hydrogeological and geo-structural complexity; in fact, geochemical data, hydrographs interpretation, hydrogeological and geo-structural surveys, tracer and isotope data are usually not so developed and quite difficult to put into relation each other. In this paper, the importance of relating isotope techniques to hydrogeological survey on the recharge area evaluation is demonstrated by studying the system of the Mt Conero limestone ridge, located in central Italy close to the Adriatic sea. A closed system, at a pilot scale, with sufficiently well defined outcropping areas of aquifer, which is offering a contribution to the aquifer recharge area evaluation. In this study a hydrogeological investigation was performed to identify the infiltration areas in the aquifer, analysing the entire geological formation divided into several members, each of them showing different hydrogeological behaviour. In addition, periodic sampling of groundwater and of precipitation at different elevations were carried out to study the isotopic composition over a period of about 4 years. Weighted mean and arithmetic mean of isotopes were used in the gradient calculation and compared giving actually different results. The mean recharge altitude of the aquifer, as evaluated by weighted mean of isotopes, is about 100 m higher than the average elevation of the aquifer outcrop; moreover, it was proven that the vast majority of the recharge is due to the more permeable members of the aquifer (about 20% of the outcropping rocks, located at higher elevation). The recharge mechanism of the aquifer is therefore depending both on the isotope values of the local precipitation and on the distinct infiltration conditions existing in the lithotypes.
{"title":"The Mt Conero limestone ridge: the contribution of stable isotopes to the identification of the recharge area of aquifers","authors":"M. Mussi, T. Nanni, A. Tazioli, P. Vivalda","doi":"10.3301/IJG.2016.15","DOIUrl":"https://doi.org/10.3301/IJG.2016.15","url":null,"abstract":"The recharge settings of aquifers (as those of the carbonate ridges in central Apennines) is strongly dependent on hydrogeological and geo-structural complexity; in fact, geochemical data, hydrographs interpretation, hydrogeological and geo-structural surveys, tracer and isotope data are usually not so developed and quite difficult to put into relation each other. In this paper, the importance of relating isotope techniques to hydrogeological survey on the recharge area evaluation is demonstrated by studying the system of the Mt Conero limestone ridge, located in central Italy close to the Adriatic sea. A closed system, at a pilot scale, with sufficiently well defined outcropping areas of aquifer, which is offering a contribution to the aquifer recharge area evaluation. In this study a hydrogeological investigation was performed to identify the infiltration areas in the aquifer, analysing the entire geological formation divided into several members, each of them showing different hydrogeological behaviour. In addition, periodic sampling of groundwater and of precipitation at different elevations were carried out to study the isotopic composition over a period of about 4 years. Weighted mean and arithmetic mean of isotopes were used in the gradient calculation and compared giving actually different results. The mean recharge altitude of the aquifer, as evaluated by weighted mean of isotopes, is about 100 m higher than the average elevation of the aquifer outcrop; moreover, it was proven that the vast majority of the recharge is due to the more permeable members of the aquifer (about 20% of the outcropping rocks, located at higher elevation). The recharge mechanism of the aquifer is therefore depending both on the isotope values of the local precipitation and on the distinct infiltration conditions existing in the lithotypes.","PeriodicalId":55341,"journal":{"name":"Bollettino Della Societa Geologica Italiana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81671523","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
We welcome the discussion of our paper on the geological map of the central sector of the Montagna dei Fiori by Santantonio and co-workers, because this will contribute to improving the understanding of the complex geological setting of the area and, eventually, helping to disentangle the pre-orogenic and syn-orogenic evolutionary history that is recorded in the tectono-sedimentary pattern exposed in the Montagna dei Fiori anticline.
{"title":"Reply to: Discussion on «Geological map of the partially dolomitized Jurassic succession exposed in the central sector of the Montagna dei Fiori Anticline, Central Apennines, Italy» by M. Santantonio, S. Fabbi & S. Bigi","authors":"F. Storti, F. Balsamo, A. Koopman","doi":"10.3301/IJG.2017.09","DOIUrl":"https://doi.org/10.3301/IJG.2017.09","url":null,"abstract":"We welcome the discussion of our paper on the geological map of the central sector of the Montagna dei Fiori by Santantonio and co-workers, because this will contribute to improving the understanding of the complex geological setting of the area and, eventually, helping to disentangle the pre-orogenic and syn-orogenic evolutionary history that is recorded in the tectono-sedimentary pattern exposed in the Montagna dei Fiori anticline.","PeriodicalId":55341,"journal":{"name":"Bollettino Della Societa Geologica Italiana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-06-01","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"85277451","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
V. Olivetti, M. Balestrieri, C. Faccenna, F. Stuart
The Sila Massif is a small part of an orogenic wedge that sits on top of the narrow and active Calabrian subduction zone. The topography of the Sila Massif is characterized by a plateau region whose age and origin has been long debated. Here we integrate new apatite (U-Th)/He data from the eastern flank of the massif with existing apatite fission-track (AFT) data, to constrain the topographic evolution of the massif. The new AHe ages range from 9.7 Ma to 49.8 Ma and overlap the AFT ages indicating that a phase of rapid Cenozoic exhumation was followed by an abrupt decrease of the exhumation rate. A steep/inverse AFT age-elevation relationship from a vertical profile on top of the summit area of the north-eastern Sila may records post-exhumation relief degradation, which is consistent with the low-relief upland topography. To test this hypothesis we performed inverse numerical modeling using Pecube code. Integrating the new AHe ages and the numerical modelling results with the geological constraints we propose a new model for the regional topographic evolution from 30 Ma to the present.
{"title":"Dating the topography through thermochronology: application of Pecube code to inverted vertical profile in the eastern Sila Massif, southern Italy","authors":"V. Olivetti, M. Balestrieri, C. Faccenna, F. Stuart","doi":"10.3301/IJG.2016.09","DOIUrl":"https://doi.org/10.3301/IJG.2016.09","url":null,"abstract":"The Sila Massif is a small part of an orogenic wedge that sits on top of the narrow and active Calabrian subduction zone. The topography of the Sila Massif is characterized by a plateau region whose age and origin has been long debated. Here we integrate new apatite (U-Th)/He data from the eastern flank of the massif with existing apatite fission-track (AFT) data, to constrain the topographic evolution of the massif. The new AHe ages range from 9.7 Ma to 49.8 Ma and overlap the AFT ages indicating that a phase of rapid Cenozoic exhumation was followed by an abrupt decrease of the exhumation rate. A steep/inverse AFT age-elevation relationship from a vertical profile on top of the summit area of the north-eastern Sila may records post-exhumation relief degradation, which is consistent with the low-relief upland topography. To test this hypothesis we performed inverse numerical modeling using Pecube code. Integrating the new AHe ages and the numerical modelling results with the geological constraints we propose a new model for the regional topographic evolution from 30 Ma to the present.","PeriodicalId":55341,"journal":{"name":"Bollettino Della Societa Geologica Italiana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"81399606","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
M. Tiberti, P. Vannoli, U. Fracassi, P. Burrato, V. Kastelic, G. Valensise
For any scientist working in seismotectonics, the Calabrian Arc represents the most challenging area of Italy. Lying on top of a subduction zone, it is characterised by a complex geological structure largely inherited from the early stages of the collision between the Africa and Eurasia plates. The current and extremely vigorous seismogenic processes, although generated by a mechanism driven by the subduction, are no longer a direct consequence of plate convergence. About one fourth of the largest Italian earthquakes concentrates in a narrow strip of land (roughly 200×70 km) corresponding to the administrative region of Calabria. The present-day seismicity, both shallow and deep, provides little help in detecting the most insidious seismogenic structures, nor does the available record of GPS-detected strains. In addition to its fierce seismicity, the Calabrian Arc also experiences uplift at rates that are the largest in Italy, thus suggesting that active tectonic processes are faster here than elsewhere in the country. Calabrian earthquakes are strong yet inherently elusive, and even the largest of those that have occurred over the past two centuries do not appear to have caused unambiguous surface faulting. The identified active structures are not sufficient to explain in full the historical seismicity record, suggesting that some of the main seismogenic sources still lie unidentified, for instance in the offshore. As a result, the seismogenic processes of Calabria have been the object of a lively debate at least over the past three decades. In this work we propose to use the current geodynamic framework of the Calabrian Arc as a guidance to resolve the ambiguities that concern the identification of the presumed known seismogenic sources, and to identify those as yet totally unknown. Our proposed scheme is consistent with the location of the largest earthquakes, the recent evolution of the regions affected by seismogenic faulting, and the predictions of current evolutionary models of the crust overlying a W-dipping subduction zone.
{"title":"Understanding seismogenic processes in the Southern Calabrian Arc: a geodynamic perspective","authors":"M. Tiberti, P. Vannoli, U. Fracassi, P. Burrato, V. Kastelic, G. Valensise","doi":"10.3301/IJG.2016.12","DOIUrl":"https://doi.org/10.3301/IJG.2016.12","url":null,"abstract":"For any scientist working in seismotectonics, the Calabrian Arc represents the most challenging area of Italy. Lying on top of a subduction zone, it is characterised by a complex geological structure largely inherited from the early stages of the collision between the Africa and Eurasia plates. The current and extremely vigorous seismogenic processes, although generated by a mechanism driven by the subduction, are no longer a direct consequence of plate convergence. About one fourth of the largest Italian earthquakes concentrates in a narrow strip of land (roughly 200×70 km) corresponding to the administrative region of Calabria. The present-day seismicity, both shallow and deep, provides little help in detecting the most insidious seismogenic structures, nor does the available record of GPS-detected strains. In addition to its fierce seismicity, the Calabrian Arc also experiences uplift at rates that are the largest in Italy, thus suggesting that active tectonic processes are faster here than elsewhere in the country. Calabrian earthquakes are strong yet inherently elusive, and even the largest of those that have occurred over the past two centuries do not appear to have caused unambiguous surface faulting. The identified active structures are not sufficient to explain in full the historical seismicity record, suggesting that some of the main seismogenic sources still lie unidentified, for instance in the offshore. As a result, the seismogenic processes of Calabria have been the object of a lively debate at least over the past three decades. In this work we propose to use the current geodynamic framework of the Calabrian Arc as a guidance to resolve the ambiguities that concern the identification of the presumed known seismogenic sources, and to identify those as yet totally unknown. Our proposed scheme is consistent with the location of the largest earthquakes, the recent evolution of the regions affected by seismogenic faulting, and the predictions of current evolutionary models of the crust overlying a W-dipping subduction zone.","PeriodicalId":55341,"journal":{"name":"Bollettino Della Societa Geologica Italiana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"86888813","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
G. Bortoluzzi, A. Polonia, L. Torelli, A. Artoni, M. Carlini, Savino Carone, G. Carrara, M. Cuffaro, F. Bianco, Fabrizio D'Oriano, V. Ferrante, L. Gasperini, R. Ivaldi, A. Laterra, M. Ligi, M. Locritani, F. Muccini, Paola Mussoni, F. Priore, F. Riminucci, S. Romano, G. Stanghellini
The Calabrian Arc is a narrow subduction-rollback system resulting from Africa/Eurasia plate convergence. We analysed the structural style of the frontal accretionary wedge through a multi-scale geophysical approach. Pre-stack depth-migrated crustal-scale seismic profiles unravelled the overall geometry of the subduction complex; high-resolution multi-channel seismic and sub-bottom CHIRP profiles, together with morpho-structural maps, integrated deep data and constrained the fine structure of the frontal accretionary wedge, as well as deformation processes along the outer deformation front.We identified four main morpho-structural domains in the western lobe of the frontal wedge: the proto-deformation area at the transition with the abyssal plain; two regions of gentle and tight folding; a hummocky morphology domain with deep depressions and intervening structural highs; a highstanding plateau at the landward limit of the salt-bearing accretionary wedge, where the detachment cuts through deeper levels down to the basement. Variation of structural style and seafloor morphology in these domains are related to a progressively more intense deformation towards the inner wedge, while abrupt changes are linked to inherited structures in the lower African plate. Our data suggest focusing of intense shallow deformation in correspondence of deeply rooted faults and basement highs of the incoming plate.Back-arc extension in the Southern Tyrrhenian Sea has recently ceased, producing a slowdown of slab rollback and plate-boundary re-organization along trans-tensional lithospheric faults segmenting the continental margin. In this complex setting, it is not clear if the accretionary wedge is still growing through frontal accretion. Our data suggest that shortening is still active at the toe of the wedge, and uplift rates along single folds are in the range of 0.25-1.5 mm/yr. An unconformity within the Plio-Quaternary sediments suggests a discontinuity in sedimentation and tectonic processes, i.e. a slowdown of shortening rate or an increase in sedimentation rate, but not a real inactivation of frontal accretion, which still contributes to the migration of the outer deformation front towards the foreland.
{"title":"Styles and rates of deformation in the frontal accretionary wedge of the Calabrian Arc (Ionian Sea): controls exerted by the structure of the lower African plate","authors":"G. Bortoluzzi, A. Polonia, L. Torelli, A. Artoni, M. Carlini, Savino Carone, G. Carrara, M. Cuffaro, F. Bianco, Fabrizio D'Oriano, V. Ferrante, L. Gasperini, R. Ivaldi, A. Laterra, M. Ligi, M. Locritani, F. Muccini, Paola Mussoni, F. Priore, F. Riminucci, S. Romano, G. Stanghellini","doi":"10.3301/IJG.2016.11","DOIUrl":"https://doi.org/10.3301/IJG.2016.11","url":null,"abstract":"The Calabrian Arc is a narrow subduction-rollback system resulting from Africa/Eurasia plate convergence. We analysed the structural style of the frontal accretionary wedge through a multi-scale geophysical approach. Pre-stack depth-migrated crustal-scale seismic profiles unravelled the overall geometry of the subduction complex; high-resolution multi-channel seismic and sub-bottom CHIRP profiles, together with morpho-structural maps, integrated deep data and constrained the fine structure of the frontal accretionary wedge, as well as deformation processes along the outer deformation front.We identified four main morpho-structural domains in the western lobe of the frontal wedge: the proto-deformation area at the transition with the abyssal plain; two regions of gentle and tight folding; a hummocky morphology domain with deep depressions and intervening structural highs; a highstanding plateau at the landward limit of the salt-bearing accretionary wedge, where the detachment cuts through deeper levels down to the basement. Variation of structural style and seafloor morphology in these domains are related to a progressively more intense deformation towards the inner wedge, while abrupt changes are linked to inherited structures in the lower African plate. Our data suggest focusing of intense shallow deformation in correspondence of deeply rooted faults and basement highs of the incoming plate.Back-arc extension in the Southern Tyrrhenian Sea has recently ceased, producing a slowdown of slab rollback and plate-boundary re-organization along trans-tensional lithospheric faults segmenting the continental margin. In this complex setting, it is not clear if the accretionary wedge is still growing through frontal accretion. Our data suggest that shortening is still active at the toe of the wedge, and uplift rates along single folds are in the range of 0.25-1.5 mm/yr. An unconformity within the Plio-Quaternary sediments suggests a discontinuity in sedimentation and tectonic processes, i.e. a slowdown of shortening rate or an increase in sedimentation rate, but not a real inactivation of frontal accretion, which still contributes to the migration of the outer deformation front towards the foreland.","PeriodicalId":55341,"journal":{"name":"Bollettino Della Societa Geologica Italiana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"88509657","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
F. Brozzetti, D. Cirillo, F. Liberi, E. Piluso, Elena Faraca, R. Nardis, G. Lavecchia
New geological field data, integrated with commercial seismic lines, allowed us to constrain the geometry and time-space evolution of the fault system that ruled the tectono-sedimentary evolution of the NS-striking Crati graben, in the axial portion of the northern Calabrian Arc.We highlight that this basin is controlled by a 60-km long east-dipping master fault, referred to as the Crati Graben Detachment Fault (CGDF).On the seismic sections, the CGDF appears as an east-dipping low-angle reflection reaching the surface along the eastern slope of the Catena Costiera Calabra. Its surface expression corresponds to an alignment of moderately-inclined (30° to 45°) left-stepping en-echelon faults.More to the East, a number of E- and W-dipping high-angle normal faults branch upward from the CGDF. Their reconstructed timing suggest that the westernmost faults are active since the Early Pleistocene and show a progressive eastward rejuvenation trend.The conversion to depth of a W-E oriented seismic section, crossing the entire Crati graben, highlights that the CGDF has a staircase geometry, with an average angle of 30°, and reaches a depth of 7-8 km below the east side of the basin. The evolutionary stages of the related fault system were reconstructed by restoring the section through the Move suite software (Midland Valley Exploration), in order to verify the kinematic consistency of our subsurface interpretation and estimate the amount of associate extension.Finally, the present activity and the possible seismogenic role of the CGDF is preliminarily discussed, by comparing the geometry of the extensional fault system with the available historical and seismological instrumental datasets.
新的地质现场数据，结合商业地震线，使我们能够约束断裂系统的几何和时空演化，这些断裂系统支配着北卡拉布里亚弧轴向部分的ns走向的克拉蒂地堑的构造-沉积演化。该盆地受一条60 km长的东倾主控断裂控制，即克拉蒂地堑滑脱断裂(CGDF)。在地震剖面上，CGDF表现为沿Catena Costiera Calabra东部斜坡东倾的低角度反射。其地表表现为中等倾斜(30°~ 45°)左步雁列断层走向。在偏东方向，有多条东西向的高角度正断层向上分支。它们的重建时间表明，最西端断裂自早更新世以来就处于活跃状态，并表现出逐渐向东恢复的趋势。横贯整个克拉蒂地堑的东西向地震剖面的深度转换表明，CGDF具有阶梯几何形状，平均角度为30°，深度为盆地东侧下方7-8 km。通过Move套件软件(Midland Valley Exploration)恢复剖面，重建了相关断层系统的演化阶段，以验证我们的地下解释的运动学一致性并估计相关扩展的数量。最后，通过与现有的历史和地震仪器资料进行对比，初步讨论了中国大地断层带目前的活动和可能的孕震作用。
{"title":"Structural style of Quaternary extension in the Crati Valley (Calabrian Arc); evidence in support of an east-dipping detachment fault","authors":"F. Brozzetti, D. Cirillo, F. Liberi, E. Piluso, Elena Faraca, R. Nardis, G. Lavecchia","doi":"10.3301/IJG.2017.11","DOIUrl":"https://doi.org/10.3301/IJG.2017.11","url":null,"abstract":"New geological field data, integrated with commercial seismic lines, allowed us to constrain the geometry and time-space evolution of the fault system that ruled the tectono-sedimentary evolution of the NS-striking Crati graben, in the axial portion of the northern Calabrian Arc.We highlight that this basin is controlled by a 60-km long east-dipping master fault, referred to as the Crati Graben Detachment Fault (CGDF).On the seismic sections, the CGDF appears as an east-dipping low-angle reflection reaching the surface along the eastern slope of the Catena Costiera Calabra. Its surface expression corresponds to an alignment of moderately-inclined (30° to 45°) left-stepping en-echelon faults.More to the East, a number of E- and W-dipping high-angle normal faults branch upward from the CGDF. Their reconstructed timing suggest that the westernmost faults are active since the Early Pleistocene and show a progressive eastward rejuvenation trend.The conversion to depth of a W-E oriented seismic section, crossing the entire Crati graben, highlights that the CGDF has a staircase geometry, with an average angle of 30°, and reaches a depth of 7-8 km below the east side of the basin. The evolutionary stages of the related fault system were reconstructed by restoring the section through the Move suite software (Midland Valley Exploration), in order to verify the kinematic consistency of our subsurface interpretation and estimate the amount of associate extension.Finally, the present activity and the possible seismogenic role of the CGDF is preliminarily discussed, by comparing the geometry of the extensional fault system with the available historical and seismological instrumental datasets.","PeriodicalId":55341,"journal":{"name":"Bollettino Della Societa Geologica Italiana","volume":null,"pages":null},"PeriodicalIF":0.0,"publicationDate":"2017-04-12","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":null,"resultStr":null,"platform":"Semanticscholar","paperid":"80337655","PeriodicalName":null,"FirstCategoryId":null,"ListUrlMain":null,"RegionNum":0,"RegionCategory":"","ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":"","EPubDate":null,"PubModel":null,"JCR":null,"JCRName":null,"Score":null,"Total":0}
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