India (Tethyan Himalaya Series) in Central Myanmar: Implications for the Evolution of the Eastern Himalayan Syntaxis and the Sagaing Transform‐Fault System

• Published in: Geophysical research letters Vol. 49; no. 12
• Main Authors: Min, Myo, Ratschbacher, Lothar, Franz, Leander, Hacker, Bradley R., Enkelmann, Eva, Toreno, Eko Yoan, Härtel, Birk, Schurr, Bernd, Tichomirowa, Marion, Pfänder, Jörg A.
• Format: Journal Article
• Language: English
• Published: Washington John Wiley & Sons, Inc 28.06.2022
• Subjects: Affinity; Continental crust; Cooling; Deformation; High pressure; Jurassic; Low temperature; Metamorphism; Ordovician; Outcrops; Plates; Rock; Rocks; Subduction; Subduction (geology); Tectonics; Tracers; Tibet; Myanmar (Burma); India
• ISSN: 0094-8276; 1944-8007
• DOI: 10.1029/2022GL099140

In the Katha Range of central Myanmar, lithologic tracers and pressure‐temperature‐deformation‐time data identify Cambro‐Ordovician, Indian‐affinity Tethyan Himalaya Series, located ∼700 km from their easternmost outcrop in S‐Tibet, and ∼450 km from Himalayan rocks in the Eastern Himalayan Syntaxis. Metamorphism began at ∼65 Ma, peaked at ∼45 Ma (∼510°C, 0.93 GPa), and exhumation/cooling (∼25°C/Myr) occurred until ∼30 Ma in a subduction‐early collision tectonic setting. When the Burma microplate—part of the intra‐Tethyan Incertus arc—accreted to SE‐Asia, its eastern boundary, the southern continuation of the Indus‐Yarlung suture (IYS), was reactivated as the Sagaing fault (SF), which propagated northward into Indian rocks. In the Katha rocks, this strike‐slip stage is marked by ∼4°C/Myr exhumation/cooling. Restoring the SF system defines a continental collision‐oceanic subduction transition junction, where the IYS bifurcates into the SF at the eastern edge of the Burma microplate and the Jurassic ophiolite‐Jadeite belts that include the Incertus‐arc suture. Plain Language Summary Central Myanmar hosts rocks typical for the northernmost continental crust of the Indian continent—the Tethyan Himalaya Series. These rocks are now located ∼700 km from their easternmost outcrop in S‐Tibet and ∼450 km from Himalayan rocks in the Eastern Himalayan Syntaxis (EHS)—the northeastern edge of India. They record a high pressure‐low temperature oceanic subduction‐continental collision tectonic setting from ∼65 to 30 Ma, formed at the northern front of India. They moved around the EHS and were involved in the northward growth of the Sagaing transform‐fault (SF) system. The SF system imbricated the Indian‐affinity rocks, and the Burma microplate—part of the intra‐Tethyan Incertus‐arc system. Key Points Indian‐affinity Tethyan Himalaya Series occur in central Myanmar, ∼450 km south of the Himalayan rocks in the Eastern Himalayan Syntaxis A low temperature‐high pressure subduction‐early collision system was active at ∼65 Ma, peaked at ∼45 Ma, and ended at ∼30 Ma The Sagaing transform fault reactivated the Indus‐Yarlung suture, and imbricated the Indian rocks and the Burma microplate from ∼30 Ma on