Geological Insights & Event News

Dr. Stephen Cossey will present the "Gulf of Mexico drawdown hypothesis" based on his research on Mexico’s Chicontepec Fm. He postulates an early Eocene isolation of the Gulf of Mexico, due to the Cuban arc colliding with the Bahamas, closing the Florida Straits and resulting in a rapid ≥200 m drawdown of water level after 55.8 Ma. Lower water levels resulted in canyon cutting and exposed bathyal beds for up to 850 kyr before refill. Bitumen bearing outcrops, rooting features, and Paleocene–Eocene salt/gypsum support this hypothesis. The resulting methane release is possibly linked to PETM.

Dr. Marsha W. French’s abstract explains how advanced SEM CL, EBSD WDS, and SIMS analyses reveal complex quartz overgrowth histories and trace element controls that help predict porosity preservation in deep, hot sandstones. In her Prez Sez column, Rebecca Helms highlights strong fall programming, praises the Tocito–El Vado–Gallup Sands field trip, and notes plans for future trips. Regional news includes NMGS, RMAG, GSA, PTTC, and university seminar events.

The June issue highlights the successful San Juan Basin Fieldtrip led by Dr. Lesli J. Wood, which visited the Tocito, El Vado and Gallup Sands near Shiprock, El Vado Reservoir and Cabezon Peak, NM. In his Prez Sez column, President John Youle reflects on strong member turnout and ongoing interest in regional stratigraphy. Matthew Huels, recent FLC graduate, is requesting support from members to attend AAPG (please see his abstract. Several officer positions are still open and elections have been postponed while we identify candidates.

Dr. Lesli J. Wood’s talk explores dynamic Cretaceous Western Interior Seaway shelf processes, showing that low net:gross sands such as the Frontier, Mancos B and Gallup were widely dispersed, with unusually large and pervasive hummocky cross stratification driven by powerful waves and plumes. This talk precedes her field trip, “The Tocito, El Vado and Gallup Sands of the San Juan Basin,” which departs tomorrow. In his Prez Sez column, President John Youle thanks officers for their work and urges members to volunteer for vacant officer positions in the Society and Foundation.

Four FLC students present their Senior Theses projects. Adam Robert Parker shows that sand depositional porosity varies mainly with sorting, but grain source also drives ~10% differences, with St. Peter sands lowest and Animas River sands highest. Rachel E. Kinney identifies freeze thaw–formed involution structures in Mesa Verde, indicating past periglacial conditions as low as 2,400 m. Joshua D. Mudge links volcanic clasts in the Telluride Conglomerate to an eroded Laramide volcanic center. Elizabeth Anastasia Hedrick digitizes Camp Bird Mine data to build 3D models for future studies.

Tim Rynott highlights renewed interest in Upper Cretaceous sandstones in the onshore Gulf of Mexico driven by large, deep, high porosity Tuscaloosa discoveries such as the Highlander well, where subsalt imaging and improved completions suggest multi TCF potential. These results are linked to the earlier Davey Jones well and to basin scale sediment pathways that may open 1,000–3,000 sq mi of new exploration. In his column, President John Youle urges members to contribute to the upcoming Oil and Gas Fields of the Four Corners, 1983–2017 volume. A San Juan Basin field trip is announced.