Multistep evolution of harzburgitic mantle underneath pipe 200 kimberlite, northern Lesotho: a study on xenoliths and their implication on diamond-barren nature of pipe 200 kimberlite

The Pipe 200 kimberlite in northern Lesotho on the southeast margin of the Kaapvaal Craton is a diamond-poor deposit despite its proximity to economically viable kimberlites like the Liqhobong kimberlite. We study harzburgite xenoliths' mineral composition, geochemistry, and pressure–temperature evolution to understand factors influencing diamond destruction. The xenoliths are classified into five types based on their petrography and geochemistry. The diversity in the mineral assemblage correlates with a sampling depth of ~ 100 to 175 km (~ 2.8 to