Nonmarine time-stratigraphy in a rift setting: An example from the Mid-Permian lower Quanzijie low-order cycle Bogda Mountains, NW China
Panorama view of the Quanzijie Formation, NW China.
Implications of loess and fluvial deposits on paleoclimatic conditions during an icehouse–hothouse transition, Capitanian upper Quanzijie low-order cycle, Bogda Mountains, NW China
Panorama view of the Hongyanchi and Quanzijie formations, NW China.
Provenance and depositional conditions of fluvial conglomerates and sandstones and their controlling processes in a rift setting, mid-Permian lower and upper Quanzijie low order cycles, Bogda Mountains, NW China
Outcrop exposing the Quanzijie sandstones, NW China.
A prograding margin during global sea‐level maxima: an example from Mahajanga Basin, northwest Madagascar
The Mesozoic shelf margin in the Mahajanga Basin, northwest Madagascar, provides an example where inherited palaeobathymetry, coupled with sea‐level changes, high sediment supply and fluctuations in accommodation influenced the stacking patterns and geometry of clinoforms that accreted onto a passive rifted margin. This work highlights the importance of sediment supply and inherited palaeobathymetry as controls on the evolution of shelf margins and it provides a new understanding of the evolution of the Mahajanga Basin during the Mesozoic.
Sedimentary architecture, structural setting, and Late Cenozoic depocentre migration of an asymmetric transtensional basin: Lake Izabal, eastern Guatemala
View of Lake Izabal from the Mico Mountains, eastern Guatemala.
The role of flexural slip during the development of multilayer chevron folds
This study uses 2D finite element analysis to provide a thorough quantitative evaluation of flexural slip based on buckling of effective single layers1 and true multilayers1. The results show that effective single layer buckle folds amplifying the dominant wavelength, λd, do not result in chevron folds in any of the situations considered - varying initial perturbation, viscosity contrast and friction coefficient.
The LIBRE [Lake Izabal Basin Research Endeavor] Scientific Drilling Workshop: Drilling and coring the Lake Izabal Basin
September 1, 2019 - August 31, 2021
Sponsor: NSF, National Science Foundation
LIBRE-Lake Izabal Basin Research Endeavor
March 30, 2020 - May 31, 2022
Sponsor: Intl Continental Sci Drilling Program
The Lake Izabal Basin in eastern Guatemala developed along the Polochic Fault, the northern fault of the Polochic-Motagua Fault System (PMFS), the onland extension of the North American and Caribbean plate boundary. In 1976, the plate boundary ruptured in a 7.5 Mw earthquake, killing >23,000 people and causing catastrophic damage to homes and other infrastructure in Guatemala.
Despite sharing characteristics with the North Anatolian, San Andreas, and Dead Sea faults, relatively little is known about this plate boundary. The Izabal Basin developed ~12 My ago and has accumulated >4 km of sediment because of continuous sinistral movement along the Polochic Fault. Presence of the northern strand of the Polochic Fault along the north shore of Lake Izabal, along with the thick sediment cover, make the site ideal for multidisciplinary study of past tectonic, climatic, volcanic, and biological changes in the area.
Our research project has two main objectives. First, we will drill, log, and core the Polochic Fault to investigate the loading state of the fault and assess seismic risk. Second, we will target the progradational infill of the Lake Izabal Basin along the depocenter migration axis, with the goal of recovering overlapping cores that contain a record spanning at least 1, and possibly as much as 5-10 My. Data from the cores will provide information about climate in the Neotropics over multiple glacial-interglacial cycles, the origin, extinction and migration of species in the area, and volcanic activity along the Central American volcanic arc.
Nixtun-Ch'ich' and its environmental impact: Sedimentological and archaeological correlates in a core from Lake Petén Itzá in the southern Maya lowlands, Guatemala
View of Lake Petén Itzá from the Nixtun-Ch'ich' archeological site, northern Guatemala.
Recent onset of eutrophication in Lake Izabal, the largest water body in Guatemala
Field photos of coring operations in shallow waters of Lake Izabal near the Polochic Delta, eastern Guatemala.
The role of the Polochic Fault as part of the North American and Caribbean Plate boundary: Insights from the infill of the Lake Izabal Basin
Outcrop photo exposing the initial infill of the Lake Izabal Basin, eastern Guatemala.
Natural and anthropogenic sources of lead, zinc, and nickel in sediments of Lake Izabal, Guatemala
View of nickel processing plant near the northern shore of Lake Izabal, eastern Guatemala.
Timing of deformation along the Iron Springs thrust, southern Sevier fold-and-thrust belt, Utah: Evidence for an extensive thrusting event in the mid-Cretaceous
Ph.D students Daniel Quick and William Chandonia measuring a stratigraphic sections near Three Peaks, Utah.
Dr. Obrist's current research interests include the understanding of sedimentary processes controlling basin fill and evolution. One of his goals is to decipher the signals in the sedimentary record to interpret past climate and tectonic processes and paleoenvironmental conditions at a variety of timescales.
He utilizes diverse tools, including field, sedimentological, geophysical, and laboratory techniques, that provide unique perspectives to interpret the geological record. He has been involved in projects attempting to understand deep-time paleoclimate changes during the Permo-Triassic mass extinction and during the Late Paleozoic Ice Age, Holocene climate and tectonic changes in Guatemala, and in hydrocarbon exploration projects in western Africa and Madagascar.
Phone: (573) 341-7879
332 McNutt Hall, Rolla MO 65409