Trace element ratios hardly modify during extreme metamorphism of pelitic sediments as evidenced from the Highland Complex, Sri Lanka.

Earth's deep crustal granulites, in particular, metamorphosed clastic sedimentary rocks, are important to decode the composition of the pelitic lower crust. General understanding is that granulite-facies metamorphism extensively removes trace elements from the protolith sediments, resulting their high depletion in newly generated granulites. However, there has been no systematic appraisal on the budget of the trace elements in newly-born granulites compared against that of their pre-metamorphic sediments. A demonstrative example taken from the Highland Complex of Sri Lanka, showing the trace element budget including highly incompatibles of pelitic-granulites remain unmodified, attesting that even ultra-high temperature metamorphism does not cause large-scale removal of trace elements from the sedimentary protoliths, is presented here. Our results reveal that a regional-scale chemical modification during granulite generation in some parts of the mid-lower crust does not enhance the mobility of trace elements in whole rock scale. This finding may impart an important message to researchers that high/ultra-high temperature metamorphism of deep crustal granulites does not necessarily disturb inherited trace element characteristics from their source sediments. • No significant alkaline, HFSE and REE fractionations in granulite formation. • Trace element budget of pelitic-granulites remain unmodified at UHT metamorphism. • Pelitic lower crust is chemically analogous to their sedimentary protoliths. [ABSTRACT FROM AUTHOR]