Dating the onset of motion on the Sagaing fault: Evidence from detrital zircon and titanite U-Pb geochronology from the North Minwun Basin, Myanmar

Burma Terrane part of the Trans-Tethyan arc during collision with India according to palaeomagnetic data

“…East of the BT, there is a complex succession of metamorphic rocks called the Mogok-Mandalay-Mergui Belt (MMMB), forming the boundary of the BT with the Shan Plateau (Sibumasu Block), alongside the Sagaing Fault and the Jade Belt ophiolite 26 . Total dextral displacement along this fault system has been estimated to be between 400 and 1100 km [30][31][32] . Prior to the development of the Sagaing Fault, there is evidence for dextral deformation along the Shan Scarp, directly east of the Sagaing fault 33,34 , although the tectonic regime of Sibumasu was predominantly sinistral 35 .…”

“…However, the ~2000 km northward motion indicated by our paleomagnetic data is much more than the ~400 km of motion estimated along the active dextral Sagaing Fault at the eastern margin of the BT 31 . Furthermore, the age of the Sagaing Fault -Quaternary, Neogene, or older -remains debated [30][31][32] . A precursor dextral strike-slip system is thus required by our data, pathway and location of which remains enigmatic and has probably been obscured by posterior activity of the Sagaing Fault and opening of the Andaman Sea.…”

“…The latter could have effectively separated the BT to its west from the developing Eastern Andaman Basins and the predominantly sinistral tectonic regime of Sibumasu to its east, as the BT moved northward and passed west of these features (Fig. 4) 32,34,35 . This separation potentially explains why late Eocene sedimentary infill of the Central Myanmar Basins was predominantly derived from an Andean-type arc, likely the Wuntho-Popa Arc, with an increasing contribution of older metamorphic detritus in the Oligocene -Miocene 21 as the BT moved closer to Sibumasu and the eastern Himalayan syntaxis.…”

Quaternary Volcanism in Myanmar: A Record of Indian Slab Tearing in a Transition Zone From Oceanic to Continental Subduction

“…Global positioning system results indicate that northward motion of the Indian plate relative to the Sunda plate is accommodated primarily by slip on the CM and Sagaing right‐lateral strike‐slip faults (Gahalaut et al, 2013; Maurin et al, 2010l). Pull‐apart basins developed, and E‐W shortening is dominantly produced by strain partitioning of the major right‐lateral shearing deformation rather than thrusting (Licht et al, 2018; Maurin & Rangin, 2009; Morley & Arboit, 2019). These observations above indicate that subduction beneath the Indo‐Burmese Ranges has stopped and thus the E‐W corner flow of convective mantle wedge is almost stagnated or “locked” as a result of this unusual highly oblique subduction (Figure 9a; MaCaffery, 1992).…”

“…The timing for onset of strike‐slip deformation along the Sagaing Fault is unclear, but metamorphic ages of MMB gneisses indicate that the high‐grade metamorphism and deformation had started by at least the middle Eocene (Licht et al, 2018; Searle et al, 2007). The total dextral displacement along the Sagaing Fault could exceed 400 km (e.g., Mitchell, 1993; Morley & Arboit, 2019). The current slip rate is nearly half that of the relative motion between India and Sunda plates (Maurin et al, 2010).…”