The crustal architecture of Myanmar imaged through zircon U-Pb, Lu-Hf and O isotopes: Tectonic and metallogenic implications

Abstract

The Tethys margin in central and eastern Asia is comprised of continental terranes separated by suture zones, some of which remain cryptic. Determining the crustal architecture, and therefore the geological history, of the Eastern Tethyan margin remains challenging. Sited in the heart of this region, Myanmar is a highly prospective but poorly explored minerals jurisdiction. A better understanding of Myanmar's mineralization can only be realized through a better understanding of its tectonic history, itself reflected in at least four major magmatic belts. The Eastern and the Main Range Provinces are associated with the Late Permian to Early Triassic closure of Palaeo-Tethys. The Mogok-Mandalay-Mergui Belt and Wuntho-Popa Arc are a response to the Eocene closure of Neo-Tethys. However, magmatic ages outside these two orogenic events are also recorded. We present new zircon U-Pb, Lu-Hf and O isotope data from magmatic rocks across Myanmar, which we append to the existing dataset to isotopically characterize Myanmar's magmatic belts. Eastern Province Permian I-type magmatism has evolved Hf (-10.9 to-6.4), while Main Range Province Triassic S-type magmatism also records evolved Hf (-13.5 to-8.8). The Mogok-Mandalay-Mergui Belt is here divided into the Tin Province and the Mogok Metamorphic Belt. The Tin Province hosts ca. 77-50 Ma magmatism with evolved Hf (-1.2 to-15.2), and  18 O of 5.6-8.3 ‰. The Mogok Metamorphic Belt exhibits a more complex magmatic and metamorphic history, and granitoids record Jurassic, Late Cretaceous, and Eocene to Miocene phases of magmatism, all of which exhibit evolved Hf values between-4.6 and-17.6, and  18 O between 6.3 and

Burma Terrane Collision and Northward Indentation in the Eastern Himalayas Recorded in the Eocene‐Miocene Chindwin Basin (Myanmar)

“…Modern river sands from the Upper Irrawaddy River draining the MMMB in northern Myanmar and in the Eastern Himalayan Syntaxis are dominated by Paleogene grains (Garzanti et al, 2016), display young grains (30–17 Ma) and are notably poor in pre‐Cretaceous zircons despite draining pre‐Cretaceous metamorphics, further suggesting that this area could be an important source. The occurrence of ultramafic and high‐grade metamorphic minerals, including the abundance of large detrital magnetite grains, in the Letkat deposits (section 4.2.2) and the appearance of Cenozoic zircons with negative εHf ( t ) values also support input from the MMMB (Gardiner et al, 2018). Finally, Ar‐Ar ages on MMMB rocks in northern Myanmar and in the Eastern Himalayan Syntaxis indicate early Miocene exhumation, coeval to AFT ages of Letkat sandstones (Bertrand et al, 2001; Haproff et al, 2019).…”

Data analysis of the U–Pb geochronology and Lu–Hf system in zircon and whole-rock Sr, Sm–Nd and Pb isotopic systems for the granitoids of Thailand

“… 207 Pb/ 204 Pb (i) against 206 Pb/ 204 Pb (i) (Fig. 5d in [1] ) Grid of εNd (t) including converted εHf (t) [Published data from [9] , [37] , [38] , [40] , [44] , [46] , [48] , [49] , [51] , [52] , [55] , [60] , [64] , [65] , [66] , [67] ]. (Fig.…”

Age determination of oriented rutile inclusions in sapphire and of moonstone from the Mogok metamorphic belt, Myanmar

“…Garnier et al (2006) reported 40 Ar/ 39 Ar ages of 18.7-17.1 Ma for phlogopite in ruby-bearing marble near Mogok, which is 4 My older than our samples. The Kabaing microgranite yielded a magmatic U-Pb zircon age of 16.8 ± 0.5 Ma (Gardiner et al 2016(Gardiner et al , 2018, almost the same as the 16 Ma age reported by Searle and Haq (1964), and the biotite 40 Ar/ 39 Ar age of 15.8 ± 1.1 Ma reported by Bertrand et al (2001). Another similarly young age is the 16.1 ± 0.5 Ma, U-Th-Pb dating of zircon age for painite-bearing skarn at the contact between the Pingutaung leucogranite and marble (Thu 2007).…”