A REVIEW AND REASSESSMENT OF TRAVERTINE CLASSIFICATION

This paper provides a review of the classification of travertines with emphasis on their morphology. Three criteria are used to describe the m: geochemistry, microfabric and morphology. Geochemically, travertine s may be divided into two groups, the meteogene travertines, where the carrier carbon dioxide originates in the soil and epigean atmosphere, and the thermal (thermogene travertines where the carbon dioxide come s from thermally generated sources. Many travertine fabrics are influe nced by bacteria and plants. These include 'stromatolitic' forms, many oncoids, shrubs, tufts, mats and moss travertines. Morphologically, t ravertines are conveniently divided into autochthonous (spring mounds and ridges, cascades, barrages, fluvial and lacustrine crusts, paludal deposits and cemented rudites) and the allochthonous or clastic trave rtines (valley-fills, back-barrage deposits, alluvial cones). Traverti ne deposits often include a wide range of fabrics and morphologies in one system. They are influenced locally by discharge, slope, vegetatio n, climate and human activity. Intergradations occur, both within trav ertine types but also with other freshwater deposits, e.g. calcrete an d lake chalk. The influence of travertine deposition on the local hydr ology and geomorphology is also discussed. The review emphasises the s ignificance of scale and hydrology and aims to provide a unified schem e of travertine classification.