Boreskov

PP‐45(Ketris and Judovich, 2009), and phosphorite (Altshuler, 1960). The range of some elementconcentrations in analyzed samples (in ppm) is shown in the table.The comparing of these values with average concentration of elements in black shaleshows that Karatau shale is enriched only in Sr and Y, being depleted in all other elements.The Maardu shale is enriched in Mo, U, Pb, V, and according to preliminarydetermination, also in Hg, which is unusial in ordinary sedimentary deposits.The concentration of microelements in Maikop clays underlying the ore breccia isrelatively near to values typical for black shales and even higher for Mo.The Recent organic‐rich oozes with phosphatic inclusions from both Peruvian andNamibian shelves are enriched relative to black shales in Cd and Mo, but equal in Ni, Sr, U,slightly depleted in Ag, As, Ba, Cu, Pb, V, Zn, and essentially depleted in La, Sb, as well as in Biand Re.The data concerning average concentrations of microelements in phosphorite are notcomplete and need some reconsideration but still valid in the present case.When compared with average values offered by Altschuler (1960) the Karatauphosphorite is enriched in As and Sr and depleted in other minor elements. The Maarduphosphorite is highly enriched in Hg and Mo, to lesser extent in Sr and Pb, along withnegligible fluctuation of other elements. The Maikop breccia is exceedingly rich in Mo andenriched in U, Ni, Se, Cu, Zn, Sr, La, Y, and Sc. The Recent and Late‐Quaternary phosphoritesare enriched in Sr and Mo.Average concentration of elements (ppm) in carbonaceous‐phosphatic depositsElementKaratau Maardu Maikop Peru shelf Namibian shelfShale Phos. Shale Phos. Shale Phos. Sedim. Phos. Sedim. Phos.Ag 0.13 0.28 2.7 0.27 0.40 0.75 0.50 0.35 0.60 0.19As 14 62 35 49 43 72 21 10 19 14Ba 264 240 380 170 336 215 365 190 235 115Cd 0.13 0.10 1.9 0.17 1.4 5.7 31 8.4 40 13.5Cu 12 10 65 30 78 300 43 25 49 19La 23 150 32 200 40 600 17 10 10 85Mo 5.5 10.7 200 19 122 214 37 6.5 85 36Ni 12 70 85 18 110 470 63 43 98 48Pb 23 29 94 180 30 64 18 9.5 6 8Sb 0.9 4.0 8.8 30 11 30 2.8 1.4 0.65 3.55Tl 0.06 0.05 6.6 1.4 1.5 13 1.5 2.3 1.3 11.0U 18 21 98 50 34 1480 10 46 23 84V 35 50 680 25 185 75 120 97 130 33Zn 19 50 57 14 152 786 97 50 93 38215