Strain localization at the margins of strong lithospheric domains: Insights from analog models

Abstract

The lateral variation of the mechanical properties of continental lithosphere is an important factor controlling the localization of deformation and thus the deformation history and geometry of intraplate mountain belts. A series of three-layer lithospheric-scale analog models, with a strong domain (SD) embedded at various depths, are presented to investigate the development of topography and deformation patterns by having lateral heterogeneities within a weak continental lithosphere. The experiments, performed at a constant velocity and under normal gravity, indicate that the presence or absence of the SD controls whether deformation is localized or distributed at a lithospheric scale. Deformation and topography localize above the edges of the SD, while the SD region itself is characterized by minor amounts of surficial deformation and topography. The depth of the SD (within the ductile crust, ductile mantle lithosphere, or both) controls the pattern of deformation and thus the topography. The presence of a SD in the ductile crust or in the mantle results in limited surficial topographic effects but large variations in the Moho topography. Strong Moho deflection occurs when the SD is in the ductile crust, while the Moho remains almost flat when the SD is in the mantle. When the SD occupies the ductile lithosphere, the SD is tilted. These analog experiments provide insights into intraplate strain localization and could in particular explain the topography around the Tarim Basin, a lithospheric-scale heterogeneity north of the India-Asia collision zone.

Asymmetric vs. symmetric deep lithospheric architecture of intra-plate continental orogens

“…The mechanical properties of continental lithosphere are strongly heterogeneous in space, as documented by observations and suggested by mechanical models (Burov, 2011;Cloetingh et al, 2005;Gueydan et al, 2014;Ranalli, 1997). The reactivation of lithospheric heterogeneities controlled the evolution of intra-plate orogens in Iberia (Pyrenees, Spanish Central System, Iberian Range), Australia (Petermann and Alice Spring orogens), Central America (Laramide orogen), and Central Asia (Tian Shan) (Beaumont et al, 2000;Cerca et al, 2004;Cloetingh et al, 2005;Delvaux et al, 2013;Fernández-Lozano et al, 2011;Gorczyk et al, 2013;Kennett and Iaffaldano, 2013;Raimondo et al, 2014;Sainz and Faccenna, 2001). At lithospheric scale the nature of the reactivated heterogeneities is diverse and debated.…”

“…Previous modelling studies focused on initiation of intra-plate deformation by reactivation of mechanically and rheologically weak pre-existing structures (Brun and Nalpas, 1996;Buiter et al, 2009;Cerca et al, 2004;Gerbault and Willingshofer, 2004;Jammes and Huismans, 2012;Willingshofer et al, 2005).…”

“…Previous modelling studies investigated the reactivation of lithospheric scale weak zones in compression in order to study rifts inversion (Brun and Nalpas, 1996;Buiter et al, 2009;Cerca et al, 2004) or deformation of weak orogenic wedges (Gerbault and Willingshofer, 2004;Jammes and Huismans, 2012;Willingshofer et al, 2005). A more limited number of studies focused on the role of strong domains in the origin of intra-plate mountain belts (Calignano et al, 2015;Keep, 2000).…”

Contrasting Mesozoic evolution across the boundary between on and off craton regions of the South African plateau inferred from apatite fission track and (U‐Th‐Sm)/He thermochronology

“…Changes in the deep Earth structure and/or composition may induce edge-driven convection or focus upwellings in the mantle around the craton [Guillou-Frottier et al, 2012] or may well result in the off-craton and oncraton regions responding differently to unloading and stress [Gilchrist and Summerfield, 1990;Pérez-Gussinyé and Watts, 2005]. Moreover, additional contrasting geophysical characteristics at craton margins such as lateral variations in lithospheric strength, rheology, heat flow, and the presence of pre-existing weak zones have been shown to cause intraplate stresses to build up at the craton margins [Redfield and Osmundsen, 2014;Gueydan et al, 2014;Lenardic et al, 2003;Baptiste et al, 2012;Wang et al, 2014;Calignano et al, 2015;Janney et al, 2010].…”

The role of passive margins on the evolution of Subduction‐Transform Edge Propagators (STEPs)

“…Passive margins therefore represent major discontinuities in lithospheric strength. Analog and numerical models in convergent settings, which include two (or possibly more) domains with different material properties, indicate localization of strain along heterogeneities [e.g., England and Houseman, 1985;Dayem et al, 2009;Calignano et al, 2015]. This localization occurs in the weaker material adjacent to the stronger material.…”