ROLE OF INHERITANCES IN SHAPING THE ZAGROS THRUST AND FOLD BELT

The claim that a place has a unique geology is made often, and never incorrectly. The Zagros fold and thrust belt represents an exceptional example where different structural and stratigraphic inheritances co-exist along the same mountain range, playing a key role in determining the lateral variability of the thrust and fold belt. To the south-east, the Zagros mountains are limited by the Makran subduction zone. The subduction is pinned laterally by the continental collision of Arabia and Asia in the Straits of Hormuz area, where the Zagros and Oman chains meet. This zone of transition forms a major structural reentrant where the Zagros deformation front and the main Zagros thrusts converge. This boundary represents the eastern limit of the Hormuz salt basin, characterized by a minimum of two kilometers thick salt unit deposited during the Neoproterozoic-Cambrian times. The Hormuz salt province aerially extends for over 500 km toward the north-west along the Fars Province, where spectacular diapirism developed previously to the Zagros contractive event. Besides, the presence of an effective basal decollement resulted in a wide detached thrust and fold belt shaping the structural salient of the Fars arc. The northwestern-ward thinning and finally pinchout of the Hormuz salt is progressively taken over by the presence of the Mountain Front Flexure, a major structure of the Zagros orogenic system underlain by the deeply rooted and seismically active Mountain Front Fault system. These coupled structural features divide the belt from its foreland and their trace is sinuous, forming a sequence of salients and recesses, formally named, Dezful embayment, Lurestan arc and Kirkuk embayment. In this work we combine the interpretation of on-shore and off-shore seismic reflection profiles, field data, earthquake data, geomorphic analysis, and, remote sensing interpretations, to build a series of geological maps, 3D geological reconstructions, geological and balanced cross-sections, and, sequential restorations in the eastern Fars province and the Lurestan region. We provide new evidence from different structures of the Zagros fold-and-thrust belt, to stress the role of inheritances related with the previous rift architecture and the presence of the lateral facies change to the Hormuz salt sequence, as an important lateral variations of the mechanical properties of the multilayer, and a dramatic change in the structural style related with the pre-contractional Hormuz salt diapirism. In the Fars province we propose new interpretations for several on-shore and off-shore pre-contractional salt structures. Our evolutional models show how the deformation of inherited salt structures predates thrust wedging and leads to squeezing, roof arching, crestal extension and finally extrusion. Further shortening result on secondary welding as evidenced by the collapse of the extrusion summit dome and reverse faulting nucleated at the secondary welds. Regional cross sections across the eastern Hormuz salt pinch-out aim to understand the switch in structural style from a salt-detached thin- to thick-skinned thrusting. In the Lurestan region we introduce a new interpretation of an hyperextended margin architecture segmented by inherited N-S and NE-SW striking faults, in an alternance of more proximal or distal rift domains. The integration of our results with previous knowledge indicates that the Mountain Front Fault system developed in the necking domain of the Jurassic rift system, ahead of an array of inverted Jurassic extensional faults, in a structural fashion which resembles that of a crustal-scale footwall shortcut. Within this structural context, the sinusoidal shape of the Mountain Front Flexure in the Lurestan area arises from the re-use of the original segmentation of the inverted Jurassic rift system

From downbuilding to contractional reactivation of salt-sediment systems: insights from analog modeling.

This work studies salt-detached fold-and-thrust belts involving minibasins by means of physical analogue modeling. The experimental set up consist of a series of minibasins and diapirs built by downbuilding into a regular polygonal framework. The minibasins-diapir framework were then submitted to contraction, and for some examples accompanied by different rates of syncontractional sedimentation. We aimed at evaluating the influence of an initial salt basin geometry (i.e. equal thickness vs. along-strike tapered) on the development of the salt-sediment system, and how this influences the geometries and kinematics of fold-and-thrust belts. We also tested how these are influenced by different syncontractional sedimentation rates. Results show that major differences on the early salt structures occur during downbuilding as a result of original salt budget (i.e. from pillows to diapirs), with a positive correlation between amount of original salt and salt structure development. Initial contractional deformation is localized on the weaker salt bodies, favoring salt extrusion. Shortening is then transferred forwards once vertical salt feeders are welded (i.e. secondary welds), while basal (primary) welds are sheared, rolled or delaminated. Changes on structural styles occur abruptly along-strike as controlled by degree of development of the precontractional salt structures. Relatively low syncontractional sedimentation rate delays forward propagation of deformation and promotes minibasins tilting. With larger sedimentation rates, a thicker cover inhibits minibasins deformation and secondary welding and, promotes a more coherent mechanical beam detached on the basal weld. Our modeling is compared to natural fold-and-thrust belts such as the Zagros and the European Alps

Influence on preexisting salt diapirs during thrust wedge evolution and secondary welding: insights from analogue modeling

Salt lithologies are mechanically weaker than other sedimentary rocks. Salt horizons usually act as décollements and precursor salt bodies preferentially deform early during contraction, concentrate deformation, and impact the structural style and kinematics during mountain building. Focusing on shortened isolated-diapir provinces, our analog modeling program investigates the influence of two salt walls on folding and thrusting. High resolution topographic scans and particle image analysis show that the presence of precursor diapirs impacts the layer parallel shortening patterns and presumably the stress field at the onset of contraction. Shortening concentrates on diapirs, leading to roof arching, crestal extension and salt extrusion. This sequence of events occurs earlier on thinner salt- sediment sequences including diapirs having well-developed pedestals, particularly when proximal to the deformation front. Folds and thrusts nucleate at salt walls if they feature a well-developed pedestal. Further shortening results in secondary welding as evidenced by the collapse of uplifted roof domes, cessation of indentation and reverse faulting nucleated at the secondary welds. Meanwhile, and depending upon the processes occurring on the diapir closer to the backstop, the deformation of the distal salt wall is discontinuous. Our modeling results are compared with experimental works and natural examples from the Fars (Zagros Mountains)

Measurements of the Higgs boson production and decay rates and coupling strengths using pp collision data at √S=7 and 8 TeV in the ATLAS experiment

Combined analyses of the Higgs boson production and decay rates as well as its coupling strengths to vector bosons and fermions are presented. The combinations include the results of the analyses of the H -> gamma gamma, ZZ*, WW*, Z gamma, b (b) over bar, tau tau and mu mu decay modes, and the constraints on the associated production with a pair of top quarks and on the off-shell coupling strengths of the Higgs boson. The results are based on the LHC proton-proton collision datasets, with integrated luminosities of up to 4.7 fb(-1) at root s = 7 TeV and 20.3 fb(-1) at root s = 8 TeV, recorded by the ATLAS detector in 2011 and 2012. Combining all production modes and decay channels, the measured signal yield, normalised to the Standard Model expectation, is 1.18(-0.14)(+0.15). The observed Higgs boson production and decay rates are interpreted in a leading-order coupling framework, exploring a wide range of benchmark coupling models both with and without assumptions on the Higgs boson width and on the Standard Model particle content in loop processes. The data are found to be compatible with the Standard Model expectations for a Higgs boson at a mass of 125.36 GeV for all models considered

Smartphone: An alternative to ground control points for orienting virtual outcrop models and assessing their quality

The application of structure from motion-multiview stereo (SfM-MVS) photogrammetry to map metric-to hectometric-scale exposures facilitates the production of three-dimensional (3-D) surface reconstructions with centimeter resolution and range error. In order to be useful for geospatial data interrogation, models must be correctly located, scaled, and oriented, which typically requires the geolocation of manually positioned ground control points with survey-grade accuracy. The cost and operational complexity of portable tools capable of achieving such positional accuracy and precision is a major obstacle in the routine deployment of SfM-MVS photogrammetry in many fields, including geological fieldwork. Here, we propose a procedure to overcome this limitation and to produce satisfactorily oriented models, which involves the use of photo orientation information recorded by smartphones. Photos captured with smartphones are used to: (1) build test models for evaluating the accuracy of the method, and (2) build smartphone-derived models of outcrops, used to reference higher-resolution models reconstructed from image data collected using digital single-lens reflex (DSLR) and mirrorless cameras. Our results are encouraging and indicate that the proposed workflow can produce registrations with high relative accuracies using consumer-grade smartphones. We also find that comparison between measured and estimated photo orientation can be successfully used to detect errors and distortions within the 3-D models

Open Plot Project: an open-source toolkit for 3-D structural data analysis.

In this work we present the Open Plot Project, an open-source software for structural data analysis, including a 3-D environment. The software includes many classical functionalities of structural data analysis tools, like stereoplot, contouring, tensorial regression, scatterplots, histograms and transect analysis. In addition, efficient filtering tools are present allowing the selection of data according to their attributes, including spatial distribution and orientation. This first alpha release represents a stand-alone toolkit for structural data analysis. The presence of a 3-D environment with digitalising tools allows the integration of structural data with information extracted from georeferenced images to produce structurally validated dip domains. This, coupled with many import/export facilities, allows easy incorporation of structural analyses in workflows for 3-D geological modelling. Accordingly, Open Plot Project also candidates as a structural add-on for 3-D geological modelling software. The software (for bothWindows and Linux O.S.), the User Manual, a set of example movies (complementary to the User Manual), and the source code are provided as Supplement. We intend the publication of the source code to set the foundation for free, public software that, hopefully, the structural geologists" community will use, modify, and implement. The creation of additional public controls/tools is strongly encouraged

Open Plot Project: an open-source toolkit for 3-D structural data analysis.

In this work we present the Open Plot Project, an open-source software for structural data analysis, including a 3-D environment. The software includes many classical functionalities of structural data analysis tools, like stereoplot, contouring, tensorial regression, scatterplots, histograms and transect analysis. In addition, efficient filtering tools are present allowing the selection of data according to their attributes, including spatial distribution and orientation. This first alpha release represents a stand-alone toolkit for structural data analysis. The presence of a 3-D environment with digitalising tools allows the integration of structural data with information extracted from georeferenced images to produce structurally validated dip domains. This, coupled with many import/export facilities, allows easy incorporation of structural analyses in workflows for 3-D geological modelling. Accordingly, Open Plot Project also candidates as a structural add-on for 3-D geological modelling software. The software (for bothWindows and Linux O.S.), the User Manual, a set of example movies (complementary to the User Manual), and the source code are provided as Supplement. We intend the publication of the source code to set the foundation for free, public software that, hopefully, the structural geologists" community will use, modify, and implement. The creation of additional public controls/tools is strongly encouraged