Chapter 16 Karen–Tenasserim Unit

Abstract

In Bender's comprehensive account of the geology of Myanmar (Bender 1983), he introduced the term Karen–Tenasserim Unit (KTU) for a fault-bounded block extending from the central area southwards to the southern tip of Myanmar. He recognized its stratigraphic distinctiveness from regions to the east (including the Shan Plateau), interpreting the sedimentary rocks of the unit as essentially deep-water deposits, whereas those east of the unit (i.e. his East Kachin–Shan Unit) he saw essentially as shelf deposits. In Thailand, Ridd (2009) identified the Phuket Terrane as a stratigraphically distinct fault-bounded tectono-stratigraphic block that was later traced northwards into Myanmar (Fig. 16.1), adopting the name Phuket-Slate Belt Terrane for the combined entity (Ridd & Watkinson 2013). It is clear that the Phuket-Slate Belt Terrane is the same as Bender's Karen–Tenasserim Unit (with some differences, involving the bounding faults); in recognition of Bender's (1983) priority his term is adopted here. Fig. 16.1. The Karen–Tenasserim Unit of central Myanmar, showing its relations with the equivalent tectono-stratigraphic block in Thailand, the Phuket Terrane. Ridd (2016) has proposed that the boundary of the Phuket Terrane in southern Thailand is not the Khlong Marui Fault as previously thought (Ridd 2009), but is a line further east through Surat Thani. Bender (1983) observed that the unit is bounded on its east by the Panlaung Fault as far south as latitude c. 19° 45′ N, by splays of the Mae Ping Fault Belt beyond that into Thailand, and on its west by what he called the Shan Boundary Fault, but which is now known widely as the Sagaing Fault. Later work (Ridd 2009; Ridd & Watkinson 2013) showed the eastern bounding fault on the Thai border to be the Three Pagodas Fault, and not the Mae Ping Fault Belt. Early accounts of the geology of this belt of country, west …