Controls of lithospheric structure and plate kinematics on rift architecture and evolution: An experimental modeling of the Baikal rift

Abstract

[1] Analog models investigate the evolution and architecture of the Baikal rift in relation to the rheology of the extending lithosphere and rift kinematics. The models focus on the development of the narrow, deep, and asymmetric basins composing Lake Baikal and reproduce the extension between the strong Siberian craton and the weaker Sayan-Baikal belt. Model results suggest that the presence of a near-vertical weak suture separating the cratonic keel from the mobile belt represents the more convenient rheological configuration leading to a narrow rift characterized by prominent vertical motions and deep depressions. These depressions are typically asymmetric, and model results suggest that this asymmetry is a consequence of lateral variations in lithospheric rheology, which is in turn related to both the variation in thickness of the strong mantle and, more importantly, the variation in the brittle-ductile transition depth between the craton and the belt. A significant shallowing of the brittle-ductile transition in the crust passing from the craton to the belt is required to fit the asymmetric architecture of the Baikal basins, with a master fault on the craton side and a monocline with no significant faulting on the belt side. Analysis of the model deformation pattern suggests that the overall architecture of the basins hosting Lake Baikal is best fitted for a N140°E directed extension, similar to the current GPS-derived motion and compatible with the stress field inferred on the basis of fault and focal mechanism data. This kinematics (along with the shape of the Siberian craton) exerted the major control on the plan view fault architecture and its along-axis variations.

The time scales of continental rifting: Implications for global processes

“…Rifting in the Baikal rift started ca. 30 Ma, resulting in a series of narrow and elongated basins in the central and southwestern parts of the rift and narrow but shorter basins in the north (Delvaux et al, 1997;van der Beek, 1997;Corti et al, 2011). The orientation of the stress fi eld in the late Oligocene-Miocene that resulted in the onset of rifting was generally transtensional, with localized areas of transpression (Delvaux et al, 1997).…”

“…Pure extension resulted in a change in fault kinematics in the central part of the Baikal rift, while the southern part underwent strike-slip motion. The change in stress orientation has been attributed to a change in the intraplate stress fi eld related to the India-Eurasia collision zone and subduction in the western Pacifi c (Corti et al, 2011), although some rotation may have been spe 500-11 1st pgs page 16 related to evolving basin linkage zones. Stress fi eld rotations also may have affected parts of the East African Rift System as rifting propagated along-axis, and Africa moved relative to the mantle upwelling (e.g., Strecker et al, 1990;Mortimer et al, 2007).…”

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“…In the Lake Baikal region, deformation is strongly localized at the craton border and characterized by a prominent asymmetry with the master fault on the craton side; conversely, to the northeast, a more diffuse deformation affects the weaker Sayan-Baikal belt, away from the craton border. Both numerical (Petit et al, 2008) and analog (Chemenda et al, 2002;Corti et al, 2011) models have suggested that the lateral variation in rheology of the lithosphere between the strong craton and the weaker belt together with the presence or absence of a weak suture in between may have strongly controlled the rift characteristics.…”

“…This infl uence has been tested in a limited number of previous analogue models (Chemenda et al, 2002;Bonini et al, 2007;Corti et al, 2011); however, these works focused on the analysis of specifi c natural rift settings (Baikal rift, West Antarctic Rift System), and thus reproduced boundary conditions (e.g., plan-view geometry, thickness, and rheology on crustal and/or mantle layers) specifi c to the studied natural prototypes. In this paper, we expand and generalize these previous results by presenting analog models of rifting at craton margins.…”

The Digital Map of the Pliocene–quaternary Crustal Faults in the Southern East Siberia and the Adjacent Northern Mongolia

“…При удалении на запад-юго-запад и северо-восток размеры области акти-визации увеличиваются до нескольких сотен ки-лометров, что совпадает с изменением конфигура-ции южной границы древней плиты. Влияние по-следней на развитие Байкальской рифтовой зоны не раз обсуждалось в предшествующих публикаци-ях [Logatchev, Florensov, 1978;Zorin et al, 2003;Petit, Déverchère, 2006;Seminsky, 2009;Corti et al, 2011]. Однако в этой работе наглядно показано влияние геометрии краевого шва на кинематику и ширину зоны локализации активных разломов.…”