Cenozoic vertical-axis rotation of the Altyn Tagh fault system

Abstract

Cenozoic vertical-axis rotation of the Altyn Tagh fault system Email alerting services articles cite this article to receive free e-mail alerts when new www.gsapubs.org/cgi/alerts click Subscribe to subscribe to Geology www.gsapubs.org/subscriptions/ click Permission request to contact GSA http://www.geosociety.org/pubs/copyrt.htm#gsa click official positions of the Society. citizenship, gender, religion, or political viewpoint. Opinions presented in this publication do not reflect presentation of diverse opinions and positions by scientists worldwide, regardless of their race, includes a reference to the article's full citation. GSA provides this and other forums for the the abstracts only of their articles on their own or their organization's Web site providing the posting to further education and science. This file may not be posted to any Web site, but authors may post works and to make unlimited copies of items in GSA's journals for noncommercial use in classrooms requests to GSA, to use a single figure, a single table, and/or a brief paragraph of text in subsequent their employment. Individual scientists are hereby granted permission, without fees or further

New paleomagnetic constraints on central Asian kinematics: Displacement along the Altyn Tagh fault and rotation of the Qaidam Basin

“… Gilder et al [2001] considered that the mean tilt‐corrected paleomagnetic direction from the footwall was more representative for the Subei section (D = 341.5°, I = 43.4°, n = 95 specimens, α 95 = 4.0°) than the overall mean result. Both this direction and the overall mean direction are very similar to that found by Rumelhart et al [1999] for Subei (D = 344.7°, I = 39.7°, α 95 = 6.6°) from a somewhat smaller data set (n = 50).…”

“…Second, one can sample time‐progressive sequences to determine when (or if) a particular block had (or had not) rotated. A paleomagnetic study along the Altyn Tagh fault by Rumelhart et al [1999] argued that no significant offset occurred along the Altyn Tagh fault since the Oligocene; however, their interpretations were jaded by a miscalculation of the amplitude and sign of rotation [ Yin et al , 2000]. Changes in the rock magnetic record of Subei (near the eastern flank of the Altyn Tagh fault) suggest that the nearby Tanghenan Mountains uplifted rapidly at 23 to 21 Ma and that Subei rotated 27° ± 5° counterclockwise after 19 Ma [ Gilder et al , 2001].…”

Reconstruction of the Altyn Tagh fault based on U‐Pb geochronology: Role of back thrusts, mantle sutures, and heterogeneous crustal strength in forming the Tibetan Plateau

“…Second, as Figure 7 indicates, the extrusion model predicts ∼35° of clockwise, vertical axis rotation of the western Kunlun Shan and Karakax fault. Paleomagnetic directions measured from Cretaceous and early Tertiary strata north and south of the western Kunlun batholith (Table 4 and Figure 5) [ Chen et al , 1992, 1993; Gilder et al , 1996; Rumelhart et al , 1999; Yin et al , 2000] are inconsistent with such rotation. Because rocks to the north and south of the western Kunlun belt have not been appreciably rotated, it is likely that the intervening Kunlun belt also has not been rotated.…”

The impact of vertical-axis rotations on shortening estimates

“…Additionally, Berberian et al (2000) suggested that a strike-slip fault connecting thrusts with opposite vergence took up verticalaxis rotations in the Sefi dabeh area of the Sistan ranges in eastern Iran. Outof-plane motion can also be accommodated by "thrust segmentation," such that an otherwise continuous thrust sheet is broken up by secondary structures, and/or variation in the along-strike nature of a fault or fault system, such as the Altyn Tagh in China (Rumelhart et al, 1999) or the southwestern Pyrenees in Spain (Pueyo et al, 1997). These investigations, as well as recent analogue modeling data (Soto et al, 2006), suggest that if the nature of along-strike shortening changes due to vertical-axis rotations, geologic structures that accommodate those changes will develop.…”

“…In areas where thrust terminations are unavailable (e.g., eroded or covered), or to determine more precise pivot locations, high-resolution arrays of paleomagnetic vertical-axis rotation measurements need to be collected and merged with structural studies that yield transport directions. We propose that, rather than having a unique geological marker, suites of geologic structures can help identify whether or not a rotation occurred (e.g., Allerton, 1998;Rumelhart et al, 1999;Onderdonk et al, 2005), when the rotation took place with respect to translation, and the approximate location of the rotational pivot.…”