Collaborative Research: Unlocking secrets of Earth's largest sand sea: Paleoenvironmental records of the Lower Jurassic Navajo Sandstone, Colorado Plateau, USA Grant uri icon



  • Study of ancient (paleo-) ecosystems preserved in the Navajo Sandstone, the largest sand sea (eolian) system ever known that was deposited between 190 and 175 million years ago (Lower Jurassic), will provide crucial information to understanding biotic, water (hydrology), and landscape (environments) during a greenhouse period of global climate. Results will reveal how biotic community structure responded to climate changes during the transition from wetter to drier eolian landscape successions. This study will transform how biodiversity, hydrology, and environmental factors of the largest eolian systems are interpreted for understanding Earth history. This study will be a model for evaluating climate sensitivities in eolian systems, and provide guidance on future hydrologic, ecologic, and climatic studies in global warming cycles. Research will have broad impacts to interpret the links between biological, chemical, and physical sediment records in a paleoclimate context. Our collaboration has a firm commitment to increase involvement of undergraduate and graduate students of underrepresented groups in research and training, and training of Earth/Space Science education majors and teachers. Each Investigator is involved with outreach or geologic education efforts. Study results will have high visibility to the public because of the prominence of the Navajo Sandstone in so many of the Colorado Plateau's National Parks, Monuments, public lands, and wilderness areas. Partnerships with government agencies will ensure broad dissemination of scientific results to the general public and secondary geoscience teachers via video modules, pictures, and science content for websites, publications or brochures.

    This interdisciplinary study will examine the sedimentology, hydrology, and biology recorded within paleoecosystems of the Lower Jurassic Navajo Sandstone (Ss) on the Colorado Plateau, USA. The Navajo Ss represents the largest erg system ever known, deposited during the: (1) disintegration of the megamonsoonal climate system after the breakup of Pangea; (2) early diversification of mammals; and (3) increased diversity and dominance of dinosaurs in continental ecosystems. Two hypotheses to understand the response of terrestrial and aquatic ecosystems to high-frequency climatic changes that affected paleohydrologic and paleoenvironmental settings in a variably arid landscape will be integrated into one generalized model: (H1) The climatic and paleohydrologic status of the Navajo Ss evolved from relatively moist in the lower part to relatively dry in the upper part, as well as regionally moist to dry from east to west. (H2) Groundwater evolved from fresh to saline from east to west across the basin, and biota was strongly influenced by its distribution and the change in water chemistry, such that animal body size, based on burrow diameters, decreases up-section and regionally towards the west. Field and laboratory studies will include: (1) stratigraphic and sedimentologic analyses in a stratigraphic framework to systematically document vertical changes, with the objective to subdivide the Navajo Ss: (2) C and O stable isotopic and petrographic analyses of tufas to provide data on paleoclimate and changes in the water budget; and (3) ichnological and paleontological analyses integrated with sedimentologic, stratigraphic, petrographic, and geochemical analyses of clastic and carbonate facies that represent a variety of paleoenvironments. Efforts will focus in the area northwest of Moab, UT, which is the highest priority target area with a high concentration of burrowed zones, plant fossils, and tufa and lacustrine deposits to address H1 and H2. Outcrop exposure is exceptionally good, which will facilitate establishing reliable timelines. As we establish these timelines, we may focus the study further to concentrate on the variability along those timelines.

date/time interval

  • January 20, 2015 - January 31, 2018

total award amount

  • $65,551.00