A sedimentological study of diamondiferous Quaternary sediments in Southern Shandong, China

A sedimentological study of the lower Quaternary sediments in southern Shandong Province suggests that they were derived from a northern highland area of Archaean gneiss and Palaeozoic sediments. Diamond-bearing kimberlites, intruded during the Ordovician, occur in the highland area and are a possible source of diamonds found in the Quaternary sediments. A warm and humid climate prevailed at the beginning of the Quaternary and braided rivers carried gravel and sand southeast towards the Yellow Sea. Cooler and drier conditions in Q2 times reconcentrated diamonds from the underlying Q1 gravels. Post-Q2 faulting deflected the drainage to the south and subsequent erosion left only small remnants of diamondiferous Q2 gravel. A study of diamond shape characteristics suggests that the diamonds in the Quaternary sediments were derived from the known kimberlites to the north, although the possibility of undiscovered kimberlites occurring beneath the Quaternary sediments cannot be ruled out.