“All things . . . are in flux like a river,” wrote the ancient Greek philosopher Heraclitus. As many geologists know, it is not only rivers that change, but indeed many types of flow are in flux. In this contribution, Hovikoski and others explore density flow deposits, and the nature and dynamics of hybrid deposits, in a lacustrine setting. Focusing specifically on the origin of potentially flow-transforming mud, the paper describes a 500-m-long core, offshore Vietnam, from a Paleogene, freshwater rift-lake system. The results show that hybrid beds of various scales develop in freshwater lakes, in bed motifs very similar to marine deposits. The data also suggest that lake-bottom mud commonly was assimilated into density flows, which in turn played an important role in changing flow concentration. Given the common density stratification of lakes, conditions favorable to development and preservation of these facies may be more common than anticipated.
Density-flow deposition in a freshwater lacustrine rift basin, Paleogene Bach Long Vi Graben, Vietnam by Jussi Hovikoski, Jens Therkelsen, Lars H. Nielsen, Jørgen A. Bojesen-Koefoed, Hans P. Nytoft, Henrik I. Petersen, Ioannis Abatzis, Hoang A. Tuan, Bui Thi Ngoc Phuong, Cao Van Dao, and Michael B.W. Fyhn