Studies in diagenesis

Abstract

U.S. GEOLOGICAL SURVEY BULLETIN 1578Cover shows scanning electron micrograph of late-stage smectite (lower left) coating earlier chabazite crystals formed on early-stage smectite, in altered Pliocene vitric tuff, Durkee, Oregon. See article by A.j . Gude 3rd, and R. A. Sheppard, (this volume, PREFACEThe collection of research papers in this volume evolved from a workshop on diagenesis in sedimentary rocks sponsored by the U.S. Geological Survey. The workshop was held March 16--18, 1982, in Golden, Colorado, and was attended by 248 participants from the Survey's Geologic and Water Resources Divisions.The idea for the workshop came to four of us-Walt Dean, Phoebe Hauff, Harry Tourtelot, and me-during a series of informal discussions in late 1980. The complexity and interdisciplinary nature of the broad range of diagenetic processes were clearly recognized, as was their importance in the genesis, transport, emplacement, and mode of occurrence of a wide variety of organic fuels and mineral resources. The advantages of bringing together scientists who were actively engaged in diagenesis studies from several branches in two divisions of the Survey were readily apparent, and so a proposal for such a multidisciplinary and interdivisional workshop was formulated. The proposal was accepted and approved by the Survey in early 1981 .The workshop comprised two days of technical sessions consisting of oral papers and concurrent poster displays. A third day was set aside so that participants could schedule one-on-one conferences with any of the invited guest speakers or arrange small group discussions on topics of mutual interest. Each of the four half-day technical sessions represented a different aspect of diagenesis---<=hemical, carbonate, fine clastic, and coarse clastic-and began with an invited review paper on the theme of that session. The program opened with an overview "keynote" paper by Robert M. Garrels on the role of diagenesis in the geochemical cycle. In the first session, Robert A. Berner reviewed advances in several aspects of sediment-fluid interaction accompanying early diagenesis, and Lynton Land surveyed diagenesis in carbonate rocks to lead off the second session. In the third session John Hower reviewed the advancements in clay mineral diagensis, and in the final session Raymond Siever discussed thermal and burial relationships during the history of sedimentary basins.During these sessions 50 Survey authors presented 22 talks and 9 poster displays on topics ranging from diagenesis in limestones to uranium deposits to zeolitic tuffs. The authors reported findings of field, laboratory, and theoretical investigations dealing with such disparate approaches as organic geochemistry of hydrocarbon maturation, stable isotope fractionation, petrographic analysis, mineral equilibria and dissolution kinetics, mapping and field relations, and trace element geochemistry. The concurrent poster sessions presented results of more intensely focused studies.The workshop's flavor and organization have been retained in this...