Table A6.

Isotopic ages and data for rocks from the Yarlung–Tsangpo Suture Zone in Myanmar and the border area with India, including the Andaman Islands (Fig. A2)

Lithology (sample number) (number of mineral grains analysed)LocationDating methodAge ± error (Ma)MSWDCentral age (Ma)87Sr/86SrϵNd (T)Zircon ϵHfZircon δ18OReferencesNotes
Tagaung–Myitkyina Belt
Yarlung–Tsangpo sutureGabbro 13MD345 (zircons n = 18)25° 38′ 24″ N, 97° 28′ 53″ EWeighted 206Pb/238Pb172.8 ± 2.31.916.4 ± 1.05.1 ± 0.32Liu et al. (2016)Interpreted to be the ages of intrusions in the ophiolite, which is the continuation in north Myanmar of the Bangong–Nuliang (Mesotethys) suture of Tibet
(Neotethys suture)Diorite 13MD351 (zircons n = 18)25° 38′ 24″ N, 97° 28′ 53″ EWeighted 206Pb/238Pb171.6 ± 1.51.217.9 ± 0.94.8 ± 0.36Liu et al. (2016)
Near MyitkinaDiorite 13MD360 (zircons n = 19)25° 38′ 24″ N, 97° 28′ 53″ EWeighted 206Pb/238Pb173.0 ± 0.121.316.5 ± 1.05.02 ± 0.25Liu et al. (2016)
Yarlung–Tsangpo sutureAndesite basalt O9Y-40 (zircons n = 12)25° 23′ 50″ N, 97° 37′ 45″ ELA-ICP-MS weighted mean166 ± 31.5Yang et al. (2012)
(Neotethys suture)Leucogabbro O9-Y51 (zircons n = 40)25° 23′ 58″ N, 97° 38′ 91″ ELA-ICP-MS weighted mean177.09 ± 0.753.3Yang et al. (2012)Zircon core spot age range 172 ± 1 to 182 ± 2 Ma
NE of MyitkinaPlagiogranite O9Y-55 (zircons n = 34)25° 23′ 47″ N, 97° 39′ 46″ ELA-ICP-MS weighted mean176.25 ± 0.752.2Yang et al. (2012)Zircon core spot age range 172 ± 1 to 178 ± 2 Ma
Olivine pyroxenite O9Y-76 (zircons n = 15)25° 21′ 51.7″ N, 97° 45′ 31.8″ ELA-ICP-MS weighted mean171 ± 21.9Yang et al. (2012)Age data for intrusions and lavas in suture zone
Olivine pyroxenite O9Y-76 (zircons n = 2 zircon rims)LA-ICP-MS spot ages43.74 ± 0.72Yang et al. (2012)
Olivine pyroxenite O9Y-76 (n = 1 zircon core)LA-ICP-MS spot age42.86 ± 0.68Yang et al. (2012)Yang et al. (2012) also discuss the possibility that this suture zone is the extension of the Bangong–Nuliang (Mesotethys) suture of Tibet in north Myanmar
0.70367–0.70397c. +4 to +5.3Yang et al. (2012)
Nagaland–Manipur Ophiolite
Plagiogranite MGA1 (zircons n = 24) intruded in serpentinized upper mantle peridotites25° 9′ 50″ N, 94° 28′ 20″ ELA-ICP-MS118.6 ± 1.20.58Singh et al. (2017)These Early Cretaceous oceanic plagiogranites have trondhjemitic compositions, metaluminous affinities and had a subduction component in their source region.
Plagiogranite 8GA2 (zircons n = 24) intruded in serpentinized upper mantle peridotites25° 0′ 20″ N, 94° 27′ 33″ ELA-ICP-MS117.4 ± 1.60.56Singh et al. (2017)
Plagiogranite 8KM14 (zircons n = 24) intruded in serpentinized upper mantle peridotites24° 20′ 25″ N, 94° 17′ 40″ ELA-ICP-MS117.1 ± 1.31Singh et al. (2017)
PlagiograniteMK5A (zircons n = 9) intruded in serpentinized upper mantle peridotites25° 17′ 50″ N, 94° 15′ 59″ ELA-ICP-MS116.4 ± 2.20.52Singh et al. (2017)
Chin Hills Ophiolite
KalaymoRodingite 13MD16 (zircons n = 18) pod in serpentinite23° 31′ 46″ N, 94° 05′ 13″ EWeighted 206Pb/238Pb126.6 ± 1.01.118.9 ± 1.95.66 ± 0.27Liu et al. (2016)The zircons are magmatic, as they have high ϵHf and δO18 and pre-date the hydration episode
Yarlung–Tsangpo sutureRodingite 13MD17 (zircons n = 11) pod in serpentinite23° 31′ 46″ N, 94° 5′ 13″ EWeighted 206Pb/238Pb125.8 ± 1.71.418.4 ± 0.95.72 ± 0.26Liu et al. (2016)Kalaymo ophiolite formed in Early Cretaceous.
Amphibolite 13MD42 (zircons n = 14) underlying the Kalaymo ophiolite (Webula massif)22° 57′ 47″ N, 94° 1′ 09″ EWeighted 206Pb/238Pb114.7 ± 1.41.914.2 ± 2.48.11 ± 0.27Liu et al. (2016)Zircons formed in low-T metamorphic event attributed to ophiolite emplacement. Ages interpreted to be of ophiolitic rocks formed at a mid-oceanic ridge within the continuation in central Myanmar of the Yarlung-Tsangpo suture (Neotethys) of Tibet
East of Kennedy PeakGabbro’ (84K/4 342813); hornblende-bearing pegmatite associated with harzburgites and serpentinite sheets within Paung Chaung Limestone (c. 105 Ma)21° 9′ 01″ N, 94° 7′ 54″ EK–Ar hornblende158 ± 20United Nations (1978b)
Andaman IslandsTrondhjemite intruded into Andaman ophiolite11° 42′ N, 92° 31′ ELA-ICP-MS95 ± 23.7Pedersen et al. (2010)Geochemistry is similar to plagiogranite and age is time of ocean crust sequence.
Chiriya Tapu, South AndamanLas-141 (zircons n = 11)
South Andaman IslandPlagiogranite (zircons) in gabbro-unit of ophiolitec. 11° 42′ N, 92° 31′ ESHRIMP weighted mean 206Pb/238U93.6 ± 1.3Sarma et al. (2010)Age of crystallization of plagiogranite; ophiolite older.
Mithakhari GroupHope Town Conglomerate Formation (apatites)Hope Town quarryApatite fission age57 ± 9c. −7.2 to +3.1Allen et al. (2007)Single population of typical volcanic sourced apatites
Hope Town Conglomerate Formation (zircons)Zircon fission age61 ± 2Allen et al. (2007)Youngest of three populations; different source are to apatites. Deposition of Hope Town Cgl. Fm. c. 60 Ma. Provenance from a volcanic arc.
Namunagarh Grit Formation (apatites, n = 24)Namunagarh quarryApatite fission age40 ± 4Allen et al. (2007)
Namunagarh Grit Fm. (zircons)ChiriyatpatuZircon fission age40 ± 3Allen et al. (2007)Three provenance modes at 40 ± 3, 91 ± 7 and 329 Ma
33 mica grains on one sampleDetrital mica Ar data70 Ma min ageAllen et al. (2007)Range 70 Ma to Archaean
Andaman FlyschCorbyn's CoveApatite and zircon fission ages35–40 Mac. −11.1 to −8.2Allen et al. (2007)
Youngest 5 detrital zirconsU–Pb48 ± 5Allen et al. (2007)
60% of single grain analysis of apatitesc. −5 to +5Allen et al. (2007)Range typical of young volcanic whole-rock values
114 mica grain ages from 4 samplesDetrital mica Ar data30 Ma min ageAllen et al. (2007)Range 30 Ma to Proterozoic, 20 grains 30–60 Ma; 32 grains 60–80 Ma