Inter-laboratory comparison of oxygen isotope compositions from biogenic silica by Chapligin, B, Leng, M, Webb, E, Alexandre, A, Dodd, J, Ijiri, A, Lücke, A, Shemesh, A, Abelmann, A, Herzschuh, U, Longstaffe, F, Meyer, H, Moschen, R, Okazaki, Y, Rees, N, Sharp, Z, Sloane, H, Sonzogni, C, Swann, G, Sylvestre, F, Tyler, J, Yam, R