• journal_title：Geology
• Contributor：Raymond M. Coveney ; Jr. ; Nelson R. Shaffer
• Publisher：Geological Society of America
• Date：1988-
• Format：text/html
• Language：en
• Identifier：10.1130/0091-7613(1988)016<0018:SIVIPS>2.3.CO;2
• journal_abbrev：Geology
• issn：0091-7613
• volume：16
• issue：1
• firstpage：18

Conditions of sedimentation have affected isotopes in coarse-grained sulfides from Pennsylvanian shales. For example, the Mecca Shale Member (Desmoinesian Series) contains highly variable values for δ³⁴S (≈;-10‰ ; σ, standard deviation, ≈9) near the ancient shoreline of the Illinois basin, whereas equivalent strata in Missouri and Kansas, farther from the ancient shoreline, have more negative and less variable values (-14.5‰; σ ≈ 5). Sulfides from younger beds in the Missourian Series contain still lighter and less variable sulfur (δ³⁴S ≈ -27‰; σ ≈ 3.1). Because low δ³⁴S values are typical of sediments deposited in anoxic deep waters, these results suggest that Missourian shales formed slowly in deep waters. The Desmoinesian shales may have been deposited more rapidly in shallower seas. Alternatively, secular shifts for δ³⁴S in sea-water SO₄ may have been stronger than previously realized.