The missing arcs of the India-Asia collision

Abstract

Sedimentary provenance studies indicate a Paleocene age for the India-Asia collision, based on the arrival of allochthonous sediment onto the Indian shelf. To account for this age, geodynamic models propose either an extra-large pre-collisional India or an initial collision between India and a Trans-Tethyan Arc situated offshore of Asia. The Burma Terrane is one of the proposed remnants of this arc. However, the existence of this arc has not been thoroughly investigated in regional sedimentary records. We gathered a large dataset (n > 40,000) of detrital zircon ages, including new and previously published data from eastern India, the Burma Terrane, and the Asian margin to identify age populations that could indicate the presence of this arc. Our synthesis suggests that the arrival of allochthonous material onto India is best explained by input from the Asian forearc (specifically, the Xigaze Forearc) alone, without requiring input from an additional missing arc. These constraints are compatible with Trans-Tethyan models only if they incorporate the Xigaze Forearc into the Trans-Tethyan Arc. Additionally, we show that the Burmese sedimentary record necessitates a missing Cretaceous-Paleogene arc located between Myanmar and Asia. Including the Burma Terrane and its missing arc in the Trans-Tethyan Arc is consistent with provenance and paleomagnetic data but implies a complex assembly history for the arc. Ultimately, a Trans-Tethyan Arc is not required to explain the history of the Burma Terrane and its detrital zircon record. Kinematic models involving an extra-large India and a Burma Terrane located offshore of Asia during the Paleogene are also compatible with these constraints.