Abstract

An oxygen and carbon isotopic stratigraphy generated from benthic foraminifera is presented for the Naples Beach section of the Monterey Formation. These data improve correlation of this important section to middle Miocene climate changes. Oxygen isotopic correlation to the deep-sea record suggests that enhanced organic carbon-rich deposition within the Monterey Formation closely coincided with deep water cooling and East Antarctic ice growth from 14.5–14.1 Ma, and with a maximum in deep-sea δ¹³C. To the extent that the Naples Beach section reflects regional sedimentation patterns within the Miocene Monterey Formation, organic carbon-rich deposition in this interval contributed to deep-sea δ¹³C maxima and to synchronous middle Miocene global cooling, through ocean/climate positive feedback mechanisms involving drawdown of atmospheric pCO₂. The carbon isotopic data from Naples Beach indicate that maxima in the marine δ¹³C record coincided with especially organic carbon-rich micro-environments within the Monterey Formation.