The South Tibetan detachment system facilitates ultra rapid cooling of granulite‐facies rocks in Sikkim Himalaya

• DOI: 10.1002/tect.20014
• Publication Date: 2013-02-05T15:35:38Z
• Authors: Dawn A. Kellett; Djordje Grujic; Isabelle Coutand; John Cottle; Malay Mukul
• Keywords: Detachment fault; Thermochronology

ABSTRACT The eastern Himalaya is characterized by a region of granulites and local granulitized eclogites that have been exhumed via isothermal decompression from lower crustal depths during the India‐Asia collision. Spatially, most these regions are proximal to South Tibetan detachment system, an orogen‐parallel normal‐sense system operated Miocene, suggesting it played role in their exhumation. Here we use geo‐ thermochronological methods study deformation cooling history footwall rocks northern Sikkim, India. These data demonstrate was active Sikkim between 23.6 ~13 Ma, cooled rapidly ~700 ~120 °C ~15‐13 Ma. While active, mid‐crustal depths, but additional heat source such as strain heating, advected melt and/or thinning required explain observed decompression. Cessation movement on produced rapid isotherms relaxed. A regional comparison temperature‐time for indicates lack synchronicity Sa'er‐Sikkim‐Yadong section NW Bhutan section. To accommodate this requires either strike‐slip tear faulting or out‐of‐sequence thrusting younger segment orogen.