This contribution presents a model that links the observed distribution of surface faults to the spatial distribution of marsquakes. The annual seismic moment budget is computed based on the as-sumption that global cooling and subsequent shrink-ing of Mars is the main source of strain today [1]. A truncated Gutenberg-Richter distribution is used to re-late the seismic moment budget to marsquake frequen-cies. We have derived a theoretical relation for the limitation of quake size by the lengths of the individual faults. This relation is used for the simulation of epi-center catalogs that may serve as input data for the development of seismological experiments.
Abstract The Periadriatic fault system (PFS) is an array of late orogenic faults (35-15 Ma) in the retro-wedge of the Alpine orogen that accommodated dextral transpression during oblique indentation by the southern Alpine crust. Decoupling along the leading edges of the southern Alpine indenter occurred where inherited lithological and rheological contrasts were accentuated by lateral thermal gradients during emplacement of the warm orogenic retro-wedge next to the cold indenter. In contrast, decoupling within the core and retro-wedge of the orogen occurred in a network of folds and mylonitic faults. In the Eastern Alps, this network comprises conjugate sets of upright, constrictional folds, strike-slip faults and low-angle normal faults that accommodated nearly coaxial NNE-SSW shortening and E-W extensional exhumation of the Tauern thermal dome. The dextral shear component of oblique convergence was taken up by a discrete, brittle fault parallel to the indenter surface. In the Central and Western Alps, a steep mylonitic backthrust, upright folds, and low-angle normal faults effected transpressional exhumation of the Lepontine thermal dome. Mylonitic thrusting and dextral strike-slip shearing along the steep indenter surface are transitional along strike to low-angle normal faults that accommodated extension at the western termination of the PFS. The areal distribution of poles to mylonitic foliation and stretching lineation of these networked structures is related to the local shape and orientation of the southern Alpine indenter surface, supporting the interpretation of this surface as the macroscopic shearing plane for all mylonitic segments of the PFS. We propose that mylonitic faults nucleate as viscous instabilities induced by cooling, or more often, by folding and progressive rotation of pre-existing foliations into orientations that are optimal for simple shearing parallel to the eigenvectors of flow. The mechanical anisotropy of the viscous continental crust makes it a preferred site of decoupling and weakening. Networking of folds and mylonitic fault zones allow the viscous crust to maintain strain compatibility between the stronger brittle crust and upper mantle, while transmitting plate forces through the lithosphere. Decoupling within the continental lithosphere is therefore governed by the symmetry and kinematics of strain partitioning at, and below, the brittle-to-viscous transition.
Research Article| January 01, 2006 Fracture-driven intrusion and upwelling of a mid-crustal pluton fed from a transpressive shear zone—The Rieserferner Pluton (Eastern Alps) Ralph Wagner; Ralph Wagner 1Institut für Geowissenschaften, Freie Universität Berlin, Malteserstrasse 74-100, 12249 Berlin, Germany Search for other works by this author on: GSW Google Scholar Claudio L. Rosenberg; Claudio L. Rosenberg 1Institut für Geowissenschaften, Freie Universität Berlin, Malteserstrasse 74-100, 12249 Berlin, Germany Search for other works by this author on: GSW Google Scholar Mark R. Handy; Mark R. Handy 1Institut für Geowissenschaften, Freie Universität Berlin, Malteserstrasse 74-100, 12249 Berlin, Germany Search for other works by this author on: GSW Google Scholar Christoph Möbus; Christoph Möbus 2Institut für Geowissenschaften, Justus Liebig Universität Giessen, Senckenbergstraße 3, 35390 Giessen, Germany Search for other works by this author on: GSW Google Scholar Markus Albertz Markus Albertz 3Oceanography Department, Dalhousie University, Halifax, Nova Scotia B3H 4R2, Canada Search for other works by this author on: GSW Google Scholar GSA Bulletin (2006) 118 (1-2): 219–237. https://doi.org/10.1130/B25842.1 Article history received: 04 May 2005 accepted: 16 Jun 2005 first online: 08 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation Ralph Wagner, Claudio L. Rosenberg, Mark R. Handy, Christoph Möbus, Markus Albertz; Fracture-driven intrusion and upwelling of a mid-crustal pluton fed from a transpressive shear zone—The Rieserferner Pluton (Eastern Alps). GSA Bulletin 2006;; 118 (1-2): 219–237. doi: https://doi.org/10.1130/B25842.1 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGSA Bulletin Search Advanced Search Abstract The Rieserferner Pluton was emplaced at a depth of 12–15 km into steeply dipping, greenschist-facies mylonitic rocks of the Austroalpine basement, just south of the Tauern Window (Eastern Alps). Intrusion occurred during north-south–directed shortening and east-west horizontal extension in front of the rigid Southern Alpine Indenter. The regional strain field is transpressive, with a strong coaxial component, and is characterized by east-west stretching. Tonalitic melt ascended through a feeder channel preserved in the steep southern part of the Rieserferner Pluton, within and adjacent to the steep mylonitic foliation of a major shear zone, the Defereggen-Antholz-Vals (DAV) Line. Melt ascent was perpendicular to the north-south shortening direction in the country rocks. Magma emplacement involved melt-induced hydro-fracturing to form a subhorizontal, tabular pluton that protruded northward from the DAV Line into the previously folded country rocks. During the late stage of emplacement, buoyant upwelling of the partly recrystallized magma induced doming of the pluton roof as well as vertical ductile shortening of the directly overlying country rocks. Magma pressure therefore locally exceeded the lithostatic pressure. Thermal modeling constrains the maximum time for doming and solidification of the pluton to have been 32,000 yr. The wavelength of the domes in the pluton roof indicates the viscosity contrast between country rock and partly crystallized tonalite in the pluton to have been at least 100:1. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.
