I,m looking forward to estimate the paleo-reservoir age of the surface ocean using the radiocarbon dating method and chronostratigraphy tool. For I that I need dated tephra from Indian Ocean for the last 50,000 Years. My sediment core lies in the Central Equatorial Indian Ocean and Southern Bay of Bengal.
Within the 50 kyr, the period you are interested, unfortunaely widespread tephra are not available in your area of work. Major tephra which is widespread in the northern Indian Ocean is the Youngest Toba Tuff (YTT) which is considered to have an age of about 75 kyr. In Andaman Sea, you will get younger tephra markers. But if your sediment core has enough carbonate skeletons, with C14 technique you can easily date upto 35-40 kyr even without tephra. Good luck
Glass shards and tephras have been reported from the late Early Miocene sediments (ca. 20 my old) of Andaman Islands.