Abstract

Using quantitative proxy models of peat and bauxite formation, based upon modern analogues, predictions of the distribution of peats (coals) and bauxites for both the Late Jurassic (Kimmeridgian) and mid-Cretaceous (Cenomanian) have been made using a General Circulation Model (GCM). The predictions have been compared with the known distribution of these deposits. Such an approach provides a means of identifying and isolating which components of the GCM accurately reflect palaeoclimate. The prediction of peats and bauxites for the Jurassic and Cretaceous show good correspondence with known coals and bauxites and provides otherwise elusive quantitative estimates of high latitude climate. The GCM is thus successfully replicating precipitation and mean annual temperatures for both the Kimmeridgian and Cenomanian.

Investigations of Mesozoic palaeoclimate using General Circulation Models (GCMs) have often focused on qualitative evaluation of results (e.g. Barron & Washington 1982; Valdes et al. 1995; Chandler et al. 1992). A number of recent studies have, however, highlighted the need for GCM predictions to be quantitatively validated against the sedimentological and palaeobiological record (e.g. Poore & Chandler 1994; Pollard & Schulz 1994; Price et al. 1995). Quantitative estimates of terrestrial climate have been produced by physiognomic analysis of floras (e.g. Herman & Spicer 1996; Wolfe & Upchurch 1987), and have also been derived from organisms such as crocodiles (e.g. Markwick 1994). Comparable results have been used effectively for validating GCM predictions (e.g. Sloan & Barron 1992), but data tend to be restricted to North America and are often Latest Cretaceous, or younger, in age.

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