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Towards understanding long-term accretionary wedge dynamics: An integrated modelling and field study of the Tertiary Makran and southern Sistan of Iran

English title Towards understanding long-term accretionary wedge dynamics: An integrated modelling and field study of the Tertiary Makran and southern Sistan of Iran
Applicant Burg Jean-Pierre
Number 143295
Funding scheme Project funding (Div. I-III)
Research institution Departement Erdwissenschaften ETH Zürich
Institution of higher education ETH Zurich - ETHZ
Main discipline Geology
Start/End 01.01.2013 - 31.03.2014
Approved amount 131'312.00
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Keywords (1)

Sedimentation

Lay Summary (French)

Lead
Ce projet est une prolongation de 1 an pour les deux doctorants du projet PN 200020_126692. Cette extension est nécessaire pour compenser un retard des travaux sur un terrain aux conditions difficiles, dans le désert du Makran, au Balouchistan iranien. Ces retards se sont également répercutés sur les travaux analytiques.
Lay summary

Le Makran expose l’un des plus grands complexes d'accrétion actifs, au-dessus de la zone de subduction Omanaise. Cet ensemble fait partie, de la zone de convergence entre les plaques arabique et eurasienne depuis au moins la fin du Crétacé. Le prisme d’accrétion du Makran est essentiellement constitué de sédiments turbiditiques dont nous avons ré-établi la stratigraphie de l’Eocène à l’Holocène. Ces sédiments se sont  accumulés et empilés tectoniquement pendant la subduction de la lithosphère océanique du golfe d'Oman sous l’Iran et le Pakistan. Nous en étudions la partie iranienne. Notre projet vise à résoudre les questions cruciales telles que l'anatomie et la mécanique du prisme. Ces questions concernent d’abord la formation de ce système tectonique, dès le Crétacé, dans un contexte géodynamique mal connu ; elles concernent aussi l'influence des processus de surface sur les modes de déformation pendant l’évolution géologique du prisme. Nos études expérimentales ont testé les effets de la sédimentation et de l’érosion syntectoniques sur la répartition des masses dans le prisme avec toutes leurs conséquences géométriques et mécaniques. Cependant, ces expériences analogiques et les modèles numériques expliquent mal la géométrie des dépôts syntectoniques, leur relation aux chevauchements et l'influence qu'exercent ces structures sur la dynamique du prime. Ce projet intègre une modélisation numérique tectonique avec géologie de terrain en appliquant les différentes techniques de datation et l’analyse de la provenance sédimentaire pour élucider le couplage, à long terme, entre les processus tectoniques et la stabilité de la surface terrestre dans un système de subduction. Ces résultats ont une application immédiate sur l’évaluation des risques séismiques et les risques de tsunamis dans une région côtière de plus en plus peuplée, ce rappelant que le dernier tsunami sur les côtes du Golfe d’Oman date de 1945.

 

Direct link to Lay Summary Last update: 04.12.2012

Lay Summary (English)

Lead
Makran, SE Iran, exposes one of the biggest and still active accretionary complexes. Along with the linked Sistan Branch, it is part of the convergence zone between the Arabian and Eurasian plates since at least the Late Cretaceous. The essentially Eocene-Holocene wedge results from the on-going subduction of the oceanic lithosphere flooring the Gulf of Oman. This project integrates numerical modelling with geological fieldwork in the study of tectonic and surface processes.
Lay summary
 The essentially Eocene–Holocene wedge results from the on-going subduction of the oceanic lithosphere flooring the Gulf of Oman. A north-dipping thrust near the present shoreline separates an active and frontal southern half from a less active northern half. Our project aims to solve critical questions that emerged from field results concerning both the anatomy of the wedge and the wedge mechanics. These questions include the early, Cretaceous to Palaeogene history of the wedge and its geodynamic context at that time as well as the influence of surface processes on thrust wedges, which has drawn increasing attention only during recent years: Experimental studies have tested the effects of syntectonic erosion and sedimentation on the mass distribution in the wedge and thus its geometry and evolution. However, these models do not satisfactorily explain the geometries of growth strata, their relation to thrusting, and the influence that growing structures exert on wedge dynamics.This project integrates tectonic numerical modelling with geological fieldwork, applying different dating techniques and provenance analysis to study the long term coupling between tectonic and surface processes in a shallow-dipping subduction system. Outcomes already started clarifying the Tertiary geodynamics of the little studied Makran and Sistan, and the junction area. We want to draw a closer picture of accretionary wedge dynamics, using numerical models, and its stratigraphic development, using precise zircon dating and provenance analysis of the voluminous turbiditic sequences.
Direct link to Lay Summary Last update: 04.12.2012

Responsible applicant and co-applicants

Employees

Publications

Publication
Detrital zircon and provenance analysis of Late Cretaceous–Miocene onshore Iranian Makran strata: Implications for the tectonic setting.
Mohammadi A. Burg J.-P. Winkler W. Ruh J. von Quadt A.. (2016), Detrital zircon and provenance analysis of Late Cretaceous–Miocene onshore Iranian Makran strata: Implications for the tectonic setting., in Geological Society of America Bulletin, 128(9/10), 1481-1499.
U–Pb geochronology and geochemistry of Zahedan and Shah Kuh plutons, southeast Iran: Implication for closure of the South Sistan suture zone
Mohammadi A. Burg J.-P. Bouilhol P. Ruh J. (2016), U–Pb geochronology and geochemistry of Zahedan and Shah Kuh plutons, southeast Iran: Implication for closure of the South Sistan suture zone, in Lithos, 248-251, 293-308.
3D effects of strain vs. velocity weakening on deformation patterns in accretionary wedges
Ruh J.B. Gerya T. Burg J.-P. (2014), 3D effects of strain vs. velocity weakening on deformation patterns in accretionary wedges, in Tectonophysics, 615-616, 122-141.
Forward propagation of the Zagros Simply Folded Belt constrained from magnetostratigraphy of growth strata.
Ruh J.B. Hirt A.M. Burg J.-P. Mohammadi A. (2014), Forward propagation of the Zagros Simply Folded Belt constrained from magnetostratigraphy of growth strata., in Tectonics, 33(8), 1534-1551.
High-resolution 3D numerical modeling of thrust wedges: Influence of decollement strength on transfer zones
Ruh Jonas B., Gerya Taras, Burg Jean-Pierre (2013), High-resolution 3D numerical modeling of thrust wedges: Influence of decollement strength on transfer zones, in GEOCHEMISTRY GEOPHYSICS GEOSYSTEMS, 14(4), 1131-1155.
Detrital zircon and provenance analysis of Late Eocene–Oligocene strata in the South Sistan suture zone, southeast Iran: Implications for the tectonic setting.
Mohammadi A. Burg J.-P. Winkler W., Detrital zircon and provenance analysis of Late Eocene–Oligocene strata in the South Sistan suture zone, southeast Iran: Implications for the tectonic setting., in Lithosphere.
Towards 4D modelling of orogenic belts: example from the transpressive Zagros Fold Belt.
Ruh J.B. Gerya T. Burg J.-P., Towards 4D modelling of orogenic belts: example from the transpressive Zagros Fold Belt., in Tectonophysics.

Associated projects

Number Title Start Funding scheme
126692 Towards understanding long-term accretionary wedge dynamics - an integrated modelling and field study of the Tertiary Makran and southern Sistan of Iran 01.01.2010 Project funding (Div. I-III)
153124 The Neo-Tethyan subduction zone (s, ?) in Azarbaijan NW Iran 01.04.2014 Project funding (Div. I-III)

Abstract

We request a 1 year extension for 2 PhD students, offering Jonas Ruh to finish well his project without suffering the delay due to his kind help in installing the other PhD in course of the project FNS 200020_126692, and offering to the other PhD student, Mohammed Ali the appropriate time to finish his own work, which builds on the results obtained by his predecessor, Ali Jalali, during the starting year. We require 1 month field work for Ali Mohammadi to make far-distant sections we did not reach up to now, including 2 weeks with the P.I. for last control of areas where we have uncertain interpretations. Additional support for relevant laboratory work is also requested.
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