Crustal-scale cross-sections across the NW Zagros belt: Implications for the Arabian margin reconstruction

Quantified balanced and restored crustal cross-sections across the NW Zagros Mountains are presented in this work integrating geological and geophysical local and global datasets. The balanced crustal cross-section reproduces the surficial folding and thrusting of the thick cover succession, including the near top of the Sarvak Formation (∼90 Ma) that forms the top of the restored crustal cross-section. The base of the Arabian crust in the balanced cross-section is constrained by recently published seismic receiver function results showing a deepening of the Moho from 42 ± 2 km in the undeformed foreland basin to 56 ± 2 km beneath the High Zagros. The internal parts of the deformed crustal cross-section are constrained by new seismic tomographic sections imaging a ∼50° NE-dipping sharp contact between the Arabian and Iranian crusts. These surfaces bound an area of 10800 km2 that should be kept constant during the Zagros orogeny. The Arabian crustal cross-section is restored using six different tectonosedimentary domains according to their sedimentary facies and palaeobathymetries, and assuming Airy isostasy and area conservation. While the two southwestern domains were directly determined from well-constrained surface data, the reconstruction of the distal domains to the NE was made using the recent margin model of Wrobel-Daveau et al. (2010) and fitting the total area calculated in the balanced cross-section. The Arabian continental-oceanic boundary, at the time corresponding to the near top of the Sarvak Formation, is located 169 km to the NE of the trace of the Main Recent Fault. Shortening is estimated at ∼180 km for the cover rocks and ∼149 km for the Arabian basement, including all compressional events from Late Cretaceous to Recent time, with an average shortening rate of ∼2 mm yr-1 for the last 90 Ma. © 2011 Cambridge University Press.We thank the following projects for their additional support: DARIUS Programme and its sponsors, TopoMed CGL2008– 03474-E/BTE, ESF-Eurocores 07-TOPOEUROPE-FP006, TopoAtlas (CGL2006–05493/BTE), ATIZA (CGL2009– 09662-BTE) and Consolider-Ingenio 2010 Topo-Iberia (CSD2006–00041).Peer Reviewe

A New Southern North Atlantic Isochron Map: Insights Into the Drift of the Iberian Plate Since the Late Cretaceous

This paper presents a new southern North Atlantic plate model from Late Cretaceous to present, with the aim of constraining the kinematics of the Iberian plate during the last 83.5 Myr. This model is presented along with a detailed isochron map generated through the analysis of 3 aeromagnetic tracks and ~400 ship tracks from the National Centers for Environmental Information database. We present a new technique to obtain well‐constrained estimates of the Iberia‐North America plate motions from magnetic anomalies, overcoming the scarcity of large‐offset fracture zones and transform faults. We build an integrated kinematic model for NW Africa, Morocco, Iberia, Europe, and North America, which shows that the deformation is partitioned between Pyrenees and Betic‐Rif orogenic domain during the Late Cretaceous‐Oligocene time interval. In the Eastern Betics domain, the calculated amount of NW Africa‐Iberia convergence is ~80 km between 83.5 and 34 Ma, followed by ~150 km since the Oligocene. The motion of Iberia relative to Europe in the Central Pyrenees is characterized by overall NE directed transpressional motion during the Campanian and the Paleocene, followed by NW directed transpressional movement until the Lutetian and overall NNW directed convergence from Bartonian to Chattian. This motion occurs along the axis of the Bay of Biscay from the Santonian–Campanian boundary to the middle Priabonian, subsequently jumping to King's Trough at Anomaly 17 (36.62 Ma)

Fault & Fracture Development in Foreland Fold and Thrust Belts - Insight from the Lurestan Province, Zagros Mountains, Iran

Second Arabian Plate Geology Workshop Abu Dhabi, UAE, 24 - 27 January 2010The Simply Folded Belt of the Zagros Mountains, Iran, represents one of the best examples of foreland fold and thrust belt. A regional fault and fracture analysis of the Cenomanian ¿ Coniacian Ilam and Sarvak formations, exposed in southern Lurestan Province, is presented as a case study for fault and fracture development in folded belts. The area is characterised by the occurrence of gentle to tight anticlines and synclines whose NW-SE axial traces are parallel to the general trend of the belt. Fold style is intimately related to both vertical and lateral facies distribution. The two formations belong to the Bangestan Group and, in this area, they represent the oldest strata exposed in the core of most anticlines outcropping at surface. Distribution, kinematics and timing of faults and fractures have been characterised through extensive fieldwork and interpretation of orthorectified QuickBird imagery and 3-D virtual outcrop models based on LiDAR technology. Data have been collected from 10 anticlines covering an area of approximately 150 x 150 km. Key outcrops for fracture and fault kinematics interpretations are presented. Field observations and interpretation of QuickBird and 3-D photorealistic models suggest a complex fault and fracture geometry and timing relationship. Both fractures and faults record pre-folding to uplift-related deformations. Pre-folding structures are typically represented by small-scale, flat-ramp-flat geometry thrusts, systematic veins and stylolites, which are superimposed on inherited syn-sedimentary normal faults. Folding-related structures generally reactivated pre-existing fracture and fault planes. Strike-slip faulting is typically recorded as the last faulting event and is probably related to late stage of fold tightening. All structures are geometrically and kinematically consistent with the trend of the Arabian passive margin and its subsequent tectonic inversion. Uplift and stress release induced opening and propagation of through-going fractures. Faults and fracture orientations generally change accordingly with local fold trend. Symmetry between fracture and fold orientation, although commonly interpreted as evidence for folding-related fracture development, is here interpreted as evidence of syn- to post-folding local vertical axis passive rotation

Diapiric growth within an Early Jurassic rift basin: The Tazoult salt wall (central High Atlas, Morocco)

The central High Atlas (Morocco) constitutes a diapiric province that hosts a complex array of elongated diapirs and minibasins that formed during the Lower Jurassic rift of the Atlas Basin. This paper aims to study the structure and growth evolution of the Tazoult diapiric wall, located in the central High Atlas, by means of structural and sedimentological fieldwork integrated with remote sensing mapping. The Tazoult salt wall is a 20km long×3km wide NE-SW trending ridge that exposes Upper Triassic red beds and basalts along its core. The succession flanking the salt wall ranges from Hettangian to Bajocian ages displaying spectacular sedimentary wedges in the SE and NW flanks. The Hettangian-early Sinemurian carbonates mainly crop out as blocks embedded in the core rocks. The ~1km thick Pliensbachian platform carbonates display large subvertical flap structures along the flanks of the Tazoult salt wall with unconformities bounding tapered composite halokinetic sequences. In contrast, the ~2.5km thick late Pliensbachian-Aalenian mixed deposits form tabular composite halokinetic sequences displaying small-scale hook halokinetic sequences. Passive diapirism resulted in the lateral extrusion of the evaporite-bearing rocks to form an allochthonous salt sheet toward the adjacent SE Amezraï minibasin. The Bajocian platform carbonates partially fossilized the Tazoult salt wall and thus constitute a key horizon to constrain the timing of diapir growth and discriminate diapirism from Alpine shortening. The Pliensbachian carbonate platform evolved as a long flap structure during the early growth of the Tazoult salt wall, well before the onset of the Alpine shortening. © 2016. American Geophysical Union. All Rights Reserved.Additional funding was provided by the Spanish Ministry of Education and Science (MEC) through the projects Intramural Especial (CSIC 201330E030) and 201530E082), Atiza (CGL2009-1355), Tecla (CGL2011-26670), and the postdoctoral research contract to E.S. (CSIC-FSE 2007-2013 JAE-Doc), as well as by the Generalitat de Catalunya (2014GSR251).Peer reviewe

New morpho-stratigraphic constraints for the evolution of the alluvial fan system along the northern slopes of the Taburno-Camposauro Mountains (Calore River basin, Southern Italy)

The Lower Calore River Valley is a morphostructural depression located in the inner sector of the Campanian Apennine, between the Taburno-Camposauro and the Matese carbonate massifs. The river is the main left tributary of the Volturno River, it has a meandering channel partially structural-controlled. Numerous morphotectonic clues and historical seismicity data suggest that this part of the Apennine chain was particularly active during the late-Quaternary. In detail, the valley is E-W oriented and presents an asymmetry of the opposed valley slopes. The left side, corresponding to the northern flank of the Camposauro massif, is characterized by a steep slope (70 ◦-35◦), partially controlled by a∼E-W oriented fault system, and by a wide less-inclined piedmont aggradation zone.The latter started growing since middle Pleistocene, with the deposition of alluvial fans and slope deposits over the well cemented early Pleistocene breccias of Laiano Synthem. The alluvial fan deposition has been active until present giving rise to three main generations of alluvial fans. The right side of the valley, instead, is characterized by seven orders of fluvial terraces, both of erosional and depositional origin. The quaternary morpho-stratigraphic evolution of alluvial fans and fluvial terraces has been strongly conditioned by the interaction of tectonic phases and climatic variations. A detailed geomorphological study (1:5.000 in scale) was carried out with the aim to map the main depositional and erosional fluvial landforms and to identify the main tectonic lineaments of the area. A detailed field survey allowed to better define the stratigraphic and paleoenvironmental context in which the alluvial deposits developed and also to find chrono-stratigraphic markers. Tephra-stratigraphic analyses were performed on pyroclastic deposits interbedded into the alluvial fan and fluvial successions. At the moment the age of the first generation of alluvial fans is still under consideration and is only tentatively constrained to the end of Middle Pleistocene on the base of one sample. Instead the second and third generation of alluvial fans can be constrained to the Late Pleistocene and Holocene, based on interbedded tephra layers referred to Campanian Ignimbrite (39 Ky BP) and the Neapolitan Yellow Tuff (15 Ky BP).Peer Reviewe

Stratigraphic and structural studies on the simply folded belt of the Zagros Mountain Range, Lurestan provice, Iran.

Evolution of the Zagros-Makran Fold Belts, Darius Workshop,14 mayo 2012

Kinematic evolution models for the Betic-Alboran-Rif System, Western Mediterranean

8th workshop of the ILP-Task Force on Sedimentary Basin , Marseille / 14-18 October 201

Lower plate geometry controlling the development of a thrust-top basin: The tectonosedimentary evolution of the ofanto basin (Southern Apennines)

The Ofanto basin is a Pliocene-Pleistocene thrust-top basin that formed with an unusual east-west orientation along the frontal part of the Southern Apennine Allochthon during the latest stages of tectonic transport. Its tectonic and sedimentary evolution was studied integrating field surveys, biostratigraphic analyses and the interpretation of a large seismic grid. Well data and seismic interpretation indicate that a large east-west-trending normal fault underlies the northern margin of the basin, displacing the Apulian carbonates that form the foreland and the footwall of the Southern Apennine Allochthon. In our reconstruction the Ofanto basin formed at the rear of the bulge caused by buttressing of the Southern Apennine Allochthon against this normal fault. In a second stage of contraction, the footwall of the Southern Apennine Allochthon was involved in deformation with a different trend from the normal faulting and buttressing. This caused eastward tilting of the basin and broad folding around its eastern termination. Good stratigraphic constraints permit the age of buttressing to be defined as Early Pliocene, and that of the shortening in the Apulian carbonates as Early Pleistocene. This study highlights the importance of early orogenic normal faults in conditioning the evolution of the frontal parts of orogenic wedges.This is a contribution of the Group of Dynamics of the Lithosphere (GDL) supported by the projects TopoMed CGL2008e03474-E/BTE, ESF-Eurocores 07-TOPOEuROPE-FP006, and Consolider-Ingenio 2010 Topo-Iberia (CSD2006e00041).Peer Reviewe

Evidence for mantle heterogeneities in the westernmost Mediterranean from a statistical approach to volcanic petrology

The geological evolution of the westernmost Mediterranean region is characterised by widespread volcanic activity, with subduction (orogenic) or intraplate (anorogenic) geochemical imprints. Major, trace elements and isotopic ratios of 283 orogenic and 310 anorogenic volcanic samples from the western and central Mediterranean areas were merged in a single database that was processed using a statistical approach. Factor analysis, performed using the Principal Component Analysis (PCA) method, reduced the original 36 geochemical parameters that were expressed as oxides, elements or isotopic ratios to seven factors that account for ~. 84% of the variance. Combining these factors in binary diagrams clearly separates the anorogenic and orogenic fields. Anorogenic samples usually fall into a narrow compositional range, while orogenic rocks are characterised by greater variability and by alignment along different trends. These different trends are a result of large heterogeneities of the lithospheric mantle beneath the Mediterranean area because of extensive recycling of geochemically different lithologies, at least since Palaeozoic times. The results support the requirement for different mantle reservoirs in the origin of the Mediterranean volcanism. We find that the double subduction polarity model, recently proposed for the westernmost Mediterranean area, is compatible with the volcanic petrology of the last 30 My

Modeling the flexural evolution of the Amiran and Mesopotamian foreland basins of NW Zagros (Iran-Iraq)

©2015. American Geophysical Union. All Rights Reserved. The evolution of the Amiran and Mesopotamian flexural basins of the Zagros belt is approached by coupled 2-D forward modeling of orogenic wedge formation, lithospheric flexural isostasy, and stream power erosion/transport/sedimentation. Thrust geometries and sequence of emplacement derived from geometric and kinematic models presented here are the inputs to our evolutionary model, constrained by basin geometry, sediment volume, and topography. Modeling results confirm that the Zagros flexural basins evolution is consistent with two stages of deformation: (1) the obduction stage involving the Kermanshah accretionary complex and a basement unit and (2) the collision stage, emplacing the Gaveh Rud and Sanandaj-Sirjan domains in the hinterland and forming a basement duplex in the outer part. Results provide quantitative insights into processes involved in mountain and basin building. The lithospheric equivalent elastic thickness (Te) changed from 20 km during the Amiran stage (~90-50 Ma) to 55 km during the Mesopotamian subsidence stage (last 20 Myr). The Amiran basin results from flexure of the Arabian plate below the load of the Kermanshah cover and basement thrust sheets. During this stage, material eroded in the inner parts was enough to fill the flexural trough. The Mesopotamian basin formed in front of the outermost basement units flexing the Arabian plate. During this latter stage, material eroded from the orogenic wedge was not enough to fill the Mesopotamian basin. An additional longitudinal sediment supply of up to 200 m/Myr is required to fill the flexural basin.This research was carried out with the aid of grants by CSIC-FSE 2007–2013 JAE-Doc postdoctoral research contract (E.S.) and with funding from the Spanish Research Agency through project Tecla (CGL2011-26670).Peer Reviewe