Cool-Climate or Warm-Spike Lateritic Bauxites at High Latitudes?

Laterites and bauxites and their associated Ultisols and Oxisols are widespread in warm-wet climates today, and their spread to high latitudes has been attributed to episodes of past global warming. Bauxitic paleosols from the Early Eocene Monaro Volcanics of southeastern Australia have been claimed as exceptions formed in a cool-wet climate. Reexamination and chemical analysis of a sequence of intrabasaltic paleosols in the Bega no. 7 core of radiometrically dated Monaro Volcanics now show highly variable paleotemperature and precipitation. The core includes 53 successive paleosols, mostly nonbauxitic, but bauxitic paleosols reveal local spikes in warmth and precipitation coincident with early Eocene (55-, 52-, 51-, and 48-Ma) global spikes of warmth, precipitation, and high atmospheric CO. These bauxitic paleosols thus formed in warm-wet, not cool-dry, climates, and their poleward spread coincided with global greenhouse spikes.