A multidisciplinary approach combining multiscale geological-structural analyses(from field to microscale) and clay mineral transformations(clay mineralogy, illite and chlorite "crystallinity" and b cell dim...A multidisciplinary approach combining multiscale geological-structural analyses(from field to microscale) and clay mineral transformations(clay mineralogy, illite and chlorite "crystallinity" and b cell dimension(b_(0)) of K-white mica) was adopted to unravel the tectono-metamorphic evolution of low-and very low-grade tectono-metamorphic units from the Intra-Pontide suture zone in northern Turkey. The mineralogical study allowed to better evaluate the structural stacking outlined during the geological mapping, leading to distinguish three tectono-metamorphic units, two in epizone(Daday and Emirkoy units) and one in anchizone(Cifter Unit) metamorphic conditions. The mesostructural and microstructural analyses suggest a polyphase tectonic-metamorphic evolution. The different macroscopic features observed between the two units characterized by the same epizone metamorphism, can be justified by the evidence that these metamorphic conditions were acquired during the last stages of exhumation in the Daday Unit, while they constrained the metamorphic-peak conditions in the Emirkoy Unit. Contemporary analyses and comparison between structural and mineralogical data have thus proven to be a powerful tool to investigate the low-grade and very low-grade metamorphic environments, allowing at the same time to solve the apparent contradictions deriving from the mineralogical study and to significantly improve the detail of the geological mapping in the field.展开更多
The Anatolian peninsula is a key location to study the central portion of the Neotethys Ocean(s)and to understand how its western and eastern branches were connected.One of the lesser known branches of the Mesozoic oc...The Anatolian peninsula is a key location to study the central portion of the Neotethys Ocean(s)and to understand how its western and eastern branches were connected.One of the lesser known branches of the Mesozoic ocean(s)is preserved in the northern ophiolite suture zone exposed in Turkey,namely,the Intra-Pontide suture zone.It is located between the Sakarya terrane and the Eurasian margin(i.e.,Istanbul-Zonguldak terrane)and consists of several metamorphic and non-metamorphic units containing ophiolites produced in supra-subduction settings from the Late Triassic to the Early Cretaceous.Ophiolites preserved in the metamorphic units recorded pervasive deformations and peak metamorphic conditions ranging from blueschist to eclogite facies.In the nonmetamorphic units,the complete oceanic crust sequence is preserved in tectonic units or as olistoliths in sedimentary melanges.Geochemical,structural,metamorphic and geochronological investigations performed on ophiolite-bearing units allowed the formulation of a new geodynamic model of the entire"life"of the IntraPontide oceanic basin(s).The reconstruction starts with the opening of the Intra-Pontide oceanic basins during the Late Triassic between the Sakarya and Istanbul-Zonguldak continental microplates and ends with its closure caused by two different subductions events that occurred during the upper Early Jurassic and Middle Jurassic.The continental collision between the Sakarya continental microplate and the Eurasian margin developed from the upper Early Cretaceous to the Palaeocene.The presented reconstruction is an alternative model to explain the complex and articulate geodynamic evolution that characterizes the southern margin of Eurasia during the Mesozoic era.展开更多
In the Alpine Corsica(France),the Santa Lucia Nappe represents a peculiar unit preserving the unique relicts of Paleozoic lower to medium continental crust.It consists of composite basement affected by Permian granuli...In the Alpine Corsica(France),the Santa Lucia Nappe represents a peculiar unit preserving the unique relicts of Paleozoic lower to medium continental crust.It consists of composite basement affected by Permian granulite facies metamorphic conditions unconformably covered by a Late Cretaceous clastic sequence(Tomboni Conglomerate and Tralonca Flysch)affected by polyphase deformation and low-grade-metamorphism.In this work,we present a new reconstruction of the deformation events registered by the Tralonca Flysch during the Alpine orogeny.The D1 phase was testified by rare isoclinal folds.The D2 phase produced a continuous foliation and a map-scale sheath-fold with a top-to-W sense of shear.The D3 phase produced E-verging non-cylindrical folds and S3 crenulation cleavage that is not associated to metamorphic blastesis.We present the first temperature-pressure-deformation(P-T-d)path for the Tralonca Flysch,demonstrating that the Santa Lucia Nappe underwent accretion and then first stage exhumation in the Alpine wedge during the D1 phase with pressure and temperature peaks both occurred under blueschist metamorphic conditions.The D2 phase occurred at lower pressure-temperature conditions during a second stage exhumation.This pressure-temperaturedeformation path is comparable with those of the Lower Units(i.e.,the subducted continental units of Alpine Corsica)suggesting a common geodynamic history.展开更多
基金supported by the Universitàdi Pisa (Darius, PRA 2018, PRIN 2008 and PRIN 2010-11 projects) to Michele Marronithe CNR-IGG,Pisa to Alessandro Ellero。
文摘A multidisciplinary approach combining multiscale geological-structural analyses(from field to microscale) and clay mineral transformations(clay mineralogy, illite and chlorite "crystallinity" and b cell dimension(b_(0)) of K-white mica) was adopted to unravel the tectono-metamorphic evolution of low-and very low-grade tectono-metamorphic units from the Intra-Pontide suture zone in northern Turkey. The mineralogical study allowed to better evaluate the structural stacking outlined during the geological mapping, leading to distinguish three tectono-metamorphic units, two in epizone(Daday and Emirkoy units) and one in anchizone(Cifter Unit) metamorphic conditions. The mesostructural and microstructural analyses suggest a polyphase tectonic-metamorphic evolution. The different macroscopic features observed between the two units characterized by the same epizone metamorphism, can be justified by the evidence that these metamorphic conditions were acquired during the last stages of exhumation in the Daday Unit, while they constrained the metamorphic-peak conditions in the Emirkoy Unit. Contemporary analyses and comparison between structural and mineralogical data have thus proven to be a powerful tool to investigate the low-grade and very low-grade metamorphic environments, allowing at the same time to solve the apparent contradictions deriving from the mineralogical study and to significantly improve the detail of the geological mapping in the field.
基金supported by the Darius Project,PRIN 2008 and PRIN 2010-11 projects (resp.M.Marroni) and PRA 2018 from Universita di Pisa
文摘The Anatolian peninsula is a key location to study the central portion of the Neotethys Ocean(s)and to understand how its western and eastern branches were connected.One of the lesser known branches of the Mesozoic ocean(s)is preserved in the northern ophiolite suture zone exposed in Turkey,namely,the Intra-Pontide suture zone.It is located between the Sakarya terrane and the Eurasian margin(i.e.,Istanbul-Zonguldak terrane)and consists of several metamorphic and non-metamorphic units containing ophiolites produced in supra-subduction settings from the Late Triassic to the Early Cretaceous.Ophiolites preserved in the metamorphic units recorded pervasive deformations and peak metamorphic conditions ranging from blueschist to eclogite facies.In the nonmetamorphic units,the complete oceanic crust sequence is preserved in tectonic units or as olistoliths in sedimentary melanges.Geochemical,structural,metamorphic and geochronological investigations performed on ophiolite-bearing units allowed the formulation of a new geodynamic model of the entire"life"of the IntraPontide oceanic basin(s).The reconstruction starts with the opening of the Intra-Pontide oceanic basins during the Late Triassic between the Sakarya and Istanbul-Zonguldak continental microplates and ends with its closure caused by two different subductions events that occurred during the upper Early Jurassic and Middle Jurassic.The continental collision between the Sakarya continental microplate and the Eurasian margin developed from the upper Early Cretaceous to the Palaeocene.The presented reconstruction is an alternative model to explain the complex and articulate geodynamic evolution that characterizes the southern margin of Eurasia during the Mesozoic era.
基金supported by the PRIN 2020(P.I.M.Marroni)Fondi Ateneo Grant by The University of Pisa。
文摘In the Alpine Corsica(France),the Santa Lucia Nappe represents a peculiar unit preserving the unique relicts of Paleozoic lower to medium continental crust.It consists of composite basement affected by Permian granulite facies metamorphic conditions unconformably covered by a Late Cretaceous clastic sequence(Tomboni Conglomerate and Tralonca Flysch)affected by polyphase deformation and low-grade-metamorphism.In this work,we present a new reconstruction of the deformation events registered by the Tralonca Flysch during the Alpine orogeny.The D1 phase was testified by rare isoclinal folds.The D2 phase produced a continuous foliation and a map-scale sheath-fold with a top-to-W sense of shear.The D3 phase produced E-verging non-cylindrical folds and S3 crenulation cleavage that is not associated to metamorphic blastesis.We present the first temperature-pressure-deformation(P-T-d)path for the Tralonca Flysch,demonstrating that the Santa Lucia Nappe underwent accretion and then first stage exhumation in the Alpine wedge during the D1 phase with pressure and temperature peaks both occurred under blueschist metamorphic conditions.The D2 phase occurred at lower pressure-temperature conditions during a second stage exhumation.This pressure-temperaturedeformation path is comparable with those of the Lower Units(i.e.,the subducted continental units of Alpine Corsica)suggesting a common geodynamic history.
