6:15 PM - 7:30 PM
[SCG58-P10] Geochronology of detrital zircon from the Highland Complex, Sri Lanka: Implications for Gondwana reconstruction
Keywords:Gondwana, Sri Lanka, The Highland Complex, Detrital Zircon, LA-ICP-MS, Suture Zone
We collected four samples of quartzite and pelitic gneiss from the Highland Complex, separated detrital zircons from them, and analyzed U-Pb ratios using LA-ICP-MS. The detrital zircon ages are distributed from ca. 3500 Ma to ca. 1700 Ma with strong peaks at around 2700 Ma, 2500 Ma, and 2000 Ma. These age distributions of detrital zircons are consistent with those from the Palghat-Cauvery Suture Zone (e.g., Raith et al., 2010; Sato et al., 2011), but different from those of the Trivandrum Block and the Achancovil Shear Zone (Collins et al., 2007), South India, because they have Mesoproterozoic detrital age not found in the Highland Complex zircons. Thus, the Highland Complex could be correlated with the Palghat-Cauvery Suture Zone as a sedimentary basin rather than the Trivandrum Block or the Achancovil Shear Zone in southern India.
The precursor of the Wanni Complex could be a possible source of the Highland Complex before it was reworked based on available Hf crustal model ages of zircon (Santosh et al., 2014). The Dharwar Craton (ca. 3400-2500 Ma; Chadwik et al., 2000; Collins et al., 2003), the Salem Block (ca. 2750, 2600, 2500 Ma; e.g., Collins et al., 2014; Ghosh et al., 2004; Saitoh et al., 2011), and northern Madurai Block (ca. 2500 Ma; Collins et al., 2014, Plavsa et al., 2012, Teale et al., 2011) are also possible provenances of sediments of the Highland Complex. In contrast, crustal blocks in East Africa are difficult to be source regions of the Highland Complex because they are composed of rock units younger than Mesoproterozoic (Kibaran belt; ~1400 Ma; Kokonyangi et al., 2004).