The calcretes from the Cretaceous Gyeongsang Supergroup in the vicinity of Ulan city have been examined at five sites (Daedong, Seodong, Ansachon, Daogha, and Mangyangri). Im these calcretes, evidences indicating pedogenic origin are recognized. Included are calcite aureoles around detrital grains, pedotubular pores, microstromatactis, circumgranular cracks, fitted structure of adjacent peloids, calcrete ooids, rhizocretions, and calcrete intraclasts. On the basis of calcrete development together with lithofacies, the depositional environments of those deposits are intepreted as lake margin (Daedong deposits), braided to low-sinuosity river (Seodong deposits), braid plain (Ansachon deposits), and meandering river (Daegha and Mangyangri). Stratigraphically, the fluvial deposits of study area show paleoenvironmental change from braided to low-sinuosity river plain under arid climatic condition to meandering river plain under seasonally wet an dry climatic condition. The stratigraphic successions of the gyeongsang Supergroup of the study area (lacustrine-fluvial-lacustrine) together with paleoenvironmental change of fluvial deposits suggest that those deposits can be correlated with the Banyaweol-Songnaedong-Geoncheonri formations of the Gyeongsang Supergroup in the western part of the Yangsan Fault.
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