Y. Kolodny David Z. Piper 1987 <p><span>The stable isotopes of carbon and sulfur in a major marine sedimentary phosphate deposit from the northwestern United States (the Phosphoria Formation of Permian age) characterize the chemical properties of the depositional environment. The δ</span>³⁴<span>S and δ</span>¹³<span>C analyses suggest deposition under conditions of variable redox from a solution the acidity of which was controlled by reaction with carbonate rocks and exchange with seawater. The δ</span>¹⁸<span>O concentration of apetite indicates phosphatization in a shallow sea, during three glacial and intervening interglacial stages. These data tend to corroborate the interpretation of field studies by others, that the apatite formed on a continental shelf in an area of intense oceanic upwelling during several episodes of sea level change.</span></p> application/pdf 10.1016/0198-0149(87)90044-6 en Elsevier The stable isotopic composition of a phosphorite deposit: δ13C, δ34S, and δ18O article