Miocene structural inversion of the Adjara-Trialeti back-arc basin as a far-field effect of the Arabia-Eurasia collision

2021 ◽  
Author(s):  
Thomas Gusmeo ◽  
William Cavazza ◽  
Victor Alania ◽  
Onise Enukidze ◽  
Massimiliano Zattin ◽  
...  
Keyword(s):  
Late Miocene ◽  
Field Effect ◽  
Stress Transfer ◽  
Normal Faults ◽  
Far Field ◽  
Magmatic Arc ◽  
Late Middle Miocene ◽  
Structural Inversion ◽  
Lesser Caucasus ◽  
Back Arc

<p>Young back-arc rift basins, because of the not yet dissipated extensional thermal signature, can be easily inverted following changes in the geodynamic regime and/or far-field stress transmission. Structural inversion of such basins mainly develops through reactivation of normal faults, particularly if the latter are favourably oriented with respect to the direction of stress transfer. The Adjara-Trialeti fold-and-thrust belt of SW Georgia is an example of this mechanism, resulting from the structural inversion of a continental back-arc rift basin developed on the upper plate of the northern Neotethys slab in Paleogene times, behind the Pontides-Lesser Caucasus magmatic arc. New low-temperature thermochronological data [apatite fission-track (AFT) and (U-Th)/He (AHe) analyses] were obtained from a number of samples, collected across the Adjara-Trialeti belt from the former sedimentary fill of the basin and from syn-rift plutons. AFT central ages range between 46 and 15 Ma, while AHe ages cluster mainly between 10 and 3 Ma. Thermal modelling, integrating AFT and AHe data with independent geological constraints (e.g. depositional/intrusion age, other geochronological data, thermal maturity indicators and stratigraphic relationships), clearly indicates that the Adjara-Trialeti back-arc basin was inverted starting from the late Middle Miocene, at 14-10 Ma. This result is corroborated by many independent geological evidences, found for example in the adjacent Rioni, Kartli and Kura foreland basins and in the eastern Black Sea offshore, which all suggest a Middle-Late Miocene phase of deformation linked with the Adjara-Trialeti FTB building. Adjara-Trialeti structural inversion can be associated with the widespread Middle-to-Late Miocene phase of shortening and exhumation that is recognised from the eastern Pontides to the Lesser Caucasus, the Talysh and the Alborz ranges. This tectonic phase can in turn be interpreted as a far-field effect of the Arabia-Eurasia collision, developed along the Bitlis suture hundreds of kilometres to the south.</p>

scholarly journals Structural inversion of back-arc basins–The Neogene Adjara-Trialeti fold-and-thrust belt (SW Georgia) as a far-field effect of the Arabia-Eurasia collision

2021 ◽  
Vol 803 ◽  
pp. 228702
Author(s):  
Thomas Gusmeo ◽  
William Cavazza ◽  
Victor M. Alania ◽  
Onise V. Enukidze ◽  
Massimiliano Zattin ◽  
...  
Keyword(s):  
Field Effect ◽  
Far Field ◽  
Thrust Belt ◽  
Fold And Thrust Belt ◽  
Structural Inversion ◽  
Back Arc

scholarly journals Inverted Basins by Africa–Eurasia Convergence at the Southern Back-Arc Tyrrhenian Basin

Geosciences ◽  
2021 ◽  
Vol 11 (3) ◽  
pp. 117
Author(s):  
Maria Filomena Loreto ◽  
Camilla Palmiotto ◽  
Filippo Muccini ◽  
Valentina Ferrante ◽  
Nevio Zitellini
Keyword(s):  
Seismic Reflection ◽  
Magnetic Data ◽  
Normal Faults ◽  
Sedimentary Sequence ◽  
Initiation Zone ◽  
Arc Setting ◽  
Seismic Reflection Profiles ◽  
Back Arc ◽  
Flower Structures ◽  
Tyrrhenian Basin

The southern part of Tyrrhenian back-arc basin (NW Sicily), formed due to the rifting and spreading processes in back-arc setting, is currently undergoing contractional tectonics. The analysis of seismic reflection profiles integrated with bathymetry, magnetic data and seismicity allowed us to map a widespread contractional tectonics structures, such as positive flower structures, anticlines and inverted normal faults, which deform the sedimentary sequence of the intra-slope basins. Two main tectonic phases have been recognised: (i) a Pliocene extensional phase, active during the opening of the Vavilov Basin, which was responsible for the formation of elongated basins bounded by faulted continental blocks and controlled by the tear of subducting lithosphere; (ii) a contractional phase related to the Africa-Eurasia convergence coeval with the opening of the Marsili Basin during the Quaternary time. The lithospheric tear occurred along the Drepano paleo-STEP (Subduction-Transform-Edge-Propagator) fault, where the upwelling of mantle, intruding the continental crust, formed a ridge. Since Pliocene, most of the contractional deformation has been focused along this ridge, becoming a good candidate for a future subduction initiation zone.

scholarly journals The distribution of <i>Triebelina raripila</i> and <i>Carinocythereis carinata</i> (Ostracoda) from the Middle Miocene of the Central Paratethys and their palaeogeographic implications

1998 ◽  
Vol 17 (2) ◽  
pp. 125-130 ◽  
Author(s):  
J. Szczechura
Keyword(s):  
Shallow Water ◽  
Late Miocene ◽  
Middle Miocene ◽  
Early Miocene ◽  
Central Paratethys ◽  
Eastern Paratethys ◽  
Main Species ◽  
Late Middle Miocene ◽  
The Mediterranean

Abstract. Late Middle Miocene (Upper Badenian) strata of the Fore-Carpathian Depression of Poland yield a shallow-water ostracod fauna which contains the species Triebelina raripila (G. W. Müller, 1894) and Carinocythereis carinata (Roemer, 1838). The palaeobiogeographic distribution of the two main species suggests, that in the late Middle Miocene, Central Paratethys was still connected to the Mediterranean, although still separated from the Eastern Paratethys and from southeastern Eurasia. The continuous occurrence of Triebelina raripila and Carinocythereis carinata in the Mediterranean basins, from the Early Miocene to Recent, indicates that marine conditions existed throughout, thereby allowing them to survive the Late Miocene salinity crisis.

The Late Miocene-Early Pliocene out-of-sequence thrusting event: new insights into the tectonic evolution of the southern Apennines (Italy)

2021 ◽  
Author(s):  
Vitale Stefano ◽  
Prinzi Ernesto Paolo ◽  
Francesco D'Assisi Tramparulo ◽  
Sabatino Ciarcia
Keyword(s):  
Late Miocene ◽  
Hanging Wall ◽  
Early Pleistocene ◽  
Normal Faults ◽  
Southern Apennines ◽  
Campania Region ◽  
Early Pliocene ◽  
Upper Miocene ◽  
Thrust System ◽  
Tectonic Windows

&lt;p&gt;We present a structural study on late Miocene-early Pliocene out-of-sequence thrusts affecting the southern Apennine chain. The analyzed structures are exposed in the Campania region (southern Italy). Here, leading thrusts bound the N-NE side of the carbonate ridges that form the regional mountain backbone. In several outcrops, the Mesozoic carbonates are superposed onto the unconformable wedge-top basin deposits of the upper Miocene Castelvetere Group, providing constraints to the age of the activity of this thrusting event. We further analyzed the tectonic windows of Giffoni and Campagna, located on the rear of the leading thrust. We reconstructed the orogenic evolution of this part of the orogen. The first was related to the in-sequence thrusting with minor thrusts and folds, widespread both in the footwall and in the hanging wall. A subsequent extension has formed normal faults crosscutting the early thrusts and folds. All structures were subsequently affected by two shortening stages, which also deformed the upper Miocene wedge top basin deposits of the Castelvetere Group. We interpreted these late structures as related to an out-of-sequence thrust system defined by a main frontal E-verging thrust and lateral ramps characterized by N and S vergences. Associated with these thrusting events, LANFs were formed in the hanging wall of the major thrusts. Such out-of-sequence thrusts are observed in the whole southern Apennines and record a thrusting event that occurred in the late Messinian-early Pliocene. We related this tectonic episode to the positive inversion of inherited normal faults located in the Paleozoic basement. These envelopments thrust upward crosscut the allochthonous wedge, including, in the western zone of the chain, the upper Miocene wedge-top basin deposits. Finally, we suggest that the two tectonic windows are the result of the formation of an E-W trending regional antiform, associated with a late S-verging back-thrust, that has been eroded and crosscut by Early Pleistocene normal faults.&lt;/p&gt;

Tethys Belt in the Anatolia-Caucasus-Black Sea Region: Basins, Magmatic Arcs, Ophiolites, and LIPs

2021 ◽  
Author(s):  
Vahid Teknik ◽  
Irina Artemieva ◽  
Hans Thybo
Keyword(s):  
Sedimentary Cover ◽  
Arabian Plate ◽  
Magnetic Data ◽  
Poor Correlation ◽  
Black Sea Region ◽  
Nw Iran ◽  
Magmatic Arc ◽  
Sedimentary Sequences ◽  
Mafic Intrusions ◽  
Lesser Caucasus

&lt;p&gt;We interpret the paleotectonic evolution and structure in the Tethyan belt by analyzing magnetic data sensitive to the presence of iron-rich minerals in oceanic fragments and mafic intrusions, hidden beneath sedimentary sequences or overprinted by younger tectono-magmatic events. By comparing the depth to magnetic basement (DMB) as a proxy for sedimentary thickness with average crustal magnetic susceptibility (ACMS), we conclude:&lt;/p&gt;&lt;p&gt;&amp;#160;(1) Major ocean and platform basins have DMB &gt;10 km. Trapped ocean relics may be present below Central Anatolian micro-basins with DMB at 6-8 km and high ACSM.&amp;#160; In intra-orogenic basins, we identify magmatic material within the sedimentary cover by significantly smaller DMB than depth to seismic basement.&lt;/p&gt;&lt;p&gt;(2) Known magmatic arcs (Pontides and Urima-Dokhtar) have high-intensity heterogeneous ACMS. We identify a 450 km-long buried (DMB &gt;6 km) magmatic arc or trapped oceanic crust along the western margin of the Kir&amp;#351;eh&amp;#305;r massif from a strong ACMS anomaly. Large, partially buried magmatic bodies form the Caucasus LIP at the Transcaucasus and Lesser Caucasus and in NW Iran.&lt;/p&gt;&lt;p&gt;(3) Terranes of Gondwana affinity in the Arabian plate, S Anatolia and SW Iran have low-intensity homogenous ACMS.&lt;/p&gt;&lt;p&gt;(4) Local poor correlation between known ophiolites and ACMS anomalies indicate a small volume of presently magnetized material in the Tethyan ophiolites, which we explain by demagnetization during recent magmatism.&lt;/p&gt;&lt;p&gt;(5) ACMS anomalies are weak at tectonic boundaries and faults. However, the Cyprus subduction zone has a strong magnetic signature which extends ca. 500 km into the Arabian plate.&lt;/p&gt;

Geochemistry and tectonic environment of the Şarkışla area volcanic rocks in central Anatolia, Turkey

1987 ◽  
Vol 51 (362) ◽  
pp. 553-559 ◽  
Author(s):  
E. Gökten ◽  
P. A. Floyd
Keyword(s):  
Upper Cretaceous ◽  
Active Continental Margin ◽  
Volcanic Rocks ◽  
Central Anatolia ◽  
Magmatic Arc ◽  
Early Tertiary ◽  
Tectonic Environment ◽  
Geochemical Study ◽  
Lithological Composition ◽  
Back Arc

AbstractThe volcanic rocks of the Şarkışla area in northeastern central Anatolia are associated with volcaniclastics, turbiditic limestones and pelagic-hemipelagic shales of Upper Cretaceous-Palaeocene age. A preliminary geochemical study was undertaken to constrain local tectonic models, and due to the variable altered nature of the volcanics, determine the lithological composition and magma type. Chemically the volcanics are an andesite-dominated suite of calc-alkali lavas, probably developed adjacent to an active continental margin in a local (ensialic back-arc?) basinal area. The volcanic activity was probably related to a postulated magmatic arc just south of the area during the early Tertiary.

scholarly journals Evolution of the early Mesozoic Cordilleran arc: The detrital zircon record of back-arc basin deposits, Triassic Buckskin Formation, western Arizona and southeastern California, USA

Geosphere ◽  
2020 ◽  
Vol 16 (4) ◽  
pp. 1042-1057
Author(s):  
N.R. Riggs ◽  
T.B. Sanchez ◽  
S.J. Reynolds
Keyword(s):  
North America ◽  
Detrital Zircon ◽  
Colorado Plateau ◽  
Depositional Environments ◽  
Coarse Grained ◽  
Land Bridge ◽  
Magmatic Arc ◽  
Early Mesozoic ◽  
Northern Nevada ◽  
Back Arc

Abstract A shift in the depositional systems and tectonic regime along the western margin of Laurentia marked the end of the Paleozoic Era. The record of this transition and the inception and tectonic development of the Permo-Triassic Cordilleran magmatic arc is preserved in plutonic rocks in southwestern North America, in successions in the distal back-arc region on the Colorado Plateau, and in the more proximal back-arc region in the rocks of the Buckskin Formation of southeastern California and west-central Arizona (southwestern North America). The Buckskin Formation is correlated to the Lower–Middle Triassic Moenkopi and Upper Triassic Chinle Formations of the Colorado Plateau based on stratigraphic facies and position and new detrital zircon data. Calcareous, fine- to medium-grained and locally gypsiferous quartzites (quartz siltstone) of the lower and quartzite members of the Buckskin Formation were deposited in a marginal-marine environment between ca. 250 and 245 Ma, based on detrital zircon U-Pb data analysis, matching a detrital-zircon maximum depositional age of 250 Ma from the Holbrook Member of the Moenkopi Formation. An unconformity that separates the quartzite and phyllite members is inferred to be the Tr-3 unconformity that is documented across the Colorado Plateau, and marks a transition in depositional environments. Rocks of the phyllite and upper members were deposited in wholly continental depositional environments beginning at ca. 220 Ma. Lenticular bodies of pebble to cobble (meta) conglomerate and medium- to coarse-grained phyllite (subfeldspathic or quartz wacke) in the phyllite member indicate deposition in fluvial systems, whereas the fine- to medium-grained beds of quartzite (quartz arenite) in the upper member indicate deposition in fluvial and shallow-lacustrine environments. The lower and phyllite members show very strong age and Th/U overlap with grains derived from Cordilleran arc plutons. A normalized-distribution plot of Triassic ages across southwestern North America shows peak magmatism at ca. 260–250 Ma and 230–210 Ma, with relatively less activity at ca. 240 Ma, when a land bridge between the arc and the continent was established. Ages and facies of the Buckskin Formation provide insight into the tectono-magmatic evolution of early Mesozoic southwestern North America. During deposition of the lower and quartzite members, the Cordilleran arc was offshore and likely dominantly marine. Sedimentation patterns were most strongly influenced by the Sonoma orogeny in northern Nevada and Utah (USA). The Tr-3 unconformity corresponds to both a lull in magmatism and the “shoaling” of the arc. The phyllite and upper members were deposited in a sedimentary system that was still influenced by a strong contribution of detritus from headwaters far to the southeast, but more locally by a developing arc that had a far stronger effect on sedimentation than the initial phases of magmatism during deposition of the basal members.

New insights into the geologic evolution of the Grenvillian Trenton Prong inlier, Central Appalachian Piedmont, USA

2020 ◽  
Vol 57 (7) ◽  
pp. 840-854
Author(s):  
Richard A. Volkert
Keyword(s):  
Tectonic Setting ◽  
Hanging Wall ◽  
Sediment Source ◽  
Slow Cooling ◽  
Grenville Province ◽  
Magmatic Arc ◽  
Metamorphic History ◽  
Arc Setting ◽  
Appalachian Piedmont ◽  
Back Arc

New geochemical and 40Ar/39Ar hornblende and biotite data from the Grenvillian Trenton Prong inlier provide the first constraints for the identification of lithotectonic units, their tectonic setting, and their metamorphic to post-metamorphic history. Gneissic tonalite, diorite, and gabbro compose the Colonial Lake Suite magmatic arc that developed along eastern Laurentia prior to 1.2 Ga. Spatially associated low- and high-TiO2 amphibolites were formed from island-arc basalt proximal to the arc front and mid-ocean ridge basalt-like basalt in a back-arc setting, respectively. Supracrustal paragneisses include meta-arkose derived from a continental sediment source of Laurentian affinity and metagraywacke and metapelite from an arc-like sediment source deposited in a back-arc basin, inboard of the Colonial Lake arc. The Assunpink Creek Granite was emplaced post-tectonically as small bodies of peraluminous syenogranite produced through partial melting of a subduction-modified felsic crustal source. Prograde mineral assemblages reached granulite- to amphibolite-facies metamorphic conditions during the Ottawan phase of the Grenvillian Orogeny. Hornblende 40Ar/39Ar ages of 935–923 Ma and a biotite age of 868 Ma record slow cooling in the northern part of the inlier following the metamorphic peak. Elsewhere in the inlier, biotite 40Ar/39Ar ages of 440 Ma and 377–341 Ma record partial to complete thermal resetting or new growth during the Taconian and Acadian orogens. The results of this study are consistent with the Trenton Prong being the down-dropped continuation of the Grenvillian New Jersey Highlands on the hanging wall of a major detachment fault. The Trenton Prong therefore correlates to other central and northern Appalachian Grenvillian inliers and to parts of the Grenville Province proper.

scholarly journals Coulomb stress transfer and fault interaction over millennia on non-planar active normal faults: the Mw 6.5–5.0 seismic sequence of 2016–2017, central Italy

2017 ◽  
Vol 210 (2) ◽  
pp. 1206-1218 ◽  
Author(s):  
Zoe K. Mildon ◽  
Gerald P. Roberts ◽  
Joanna P. Faure Walker ◽  
Francesco Iezzi
Keyword(s):  
Main Shock ◽  
Central Italy ◽  
Stress Transfer ◽  
Historical Record ◽  
Normal Faults ◽  
Coulomb Stress ◽  
Seismic Sequence ◽  
Fault Interaction ◽  
Slip Rates ◽  
Stress Changes

Abstract In order to investigate the importance of including strike-variable geometry and the knowledge of historical and palaeoseismic earthquakes when modelling static Coulomb stress transfer and rupture propagation, we have examined the August–October 2016 A.D. and January 2017 A.D. central Apennines seismic sequence (Mw 6.0, 5.9, 6.5 in 2016 A.D. (INGV) and Mw 5.1, 5.5, 5.4, 5.0 in 2017 A.D. (INGV)). We model both the coseismic loading (from historical and palaeoseismic earthquakes) and interseismic loading (derived from Holocene fault slip-rates) using strike-variable fault geometries constrained by fieldwork. The inclusion of the elapsed times from available historical and palaeoseismological earthquakes and on faults enables us to calculate the stress on the faults prior to the beginning of the seismic sequence. We take account the 1316–4155 yr elapsed time on the Mt. Vettore fault (that ruptured during the 2016 A.D. seismic sequence) implied by palaeoseismology, and the 377 and 313 yr elapsed times on the neighbouring Laga and Norcia faults respectively, indicated by the historical record. The stress changes through time are summed to show the state of stress on the Mt. Vettore, Laga and surrounding faults prior to and during the 2016–2017 A.D. sequence. We show that the build up of stress prior to 2016 A.D. on strike-variable fault geometries generated stress heterogeneities that correlate with the limits of the main-shock ruptures. Hence, we suggest that stress barriers appear to have control on the propagation and therefore the magnitudes of the main-shock ruptures.

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