by John W. Geissmann, Paul E. Olsen, Jingeng Sha, Roberto Stanley Molina-Garza, Wolfram Michael Kürschner, Gerhard H. Bachmann

Partial support is requested from ICDP for the drilling and core/downhole logging costs for a continuous ~460 m core through nearly the entire Triassic section (Chinle and Moenkopi formations) at Petrified Forest National Park (PFNP), Arizona, USA. This area exposes one of the most famous and well-studied successions of the continental Triassic in the World. A continuous core will place this spectacular record in a reliable quantitative and globally exportable time scale, uncorrupted by ambiguities in correlation, which has proved to be impractical to achieve in outcrop. The Petrified Forest core will provide a sound reference section for registering magnetostratigraphic, geochronologic, environmental, and paleontologic data to a common thickness with unquestioned superposition. With such a reference section in hand the entire massive assemblage of outcrop data from the PFNP and the surrounding region can be integrated. The hole will deviate 30° from vertical, providing core-bedding intersections as an azimuthal guide. The core orientation will be registered to the hole wall using whole-core-scans, compass-oriented acoustic and optical televiewer images, and dipmeter surveys. Core orientation will allow recovery of a high resolution magnetic polarity stratigraphy for correlation to fossil-rich outcrop sections. High-precision U-Pb zircon dates from discrete levels in the core will calibrate the polarity sequence and provide critical data to fill the geochronologic gap in global time scales for the Late Triassic. The Petrified Forest core has considerable relation to anthropogenic effects on climate, as the profound environmental and biotic changes recorded in the Late Triassic stratigraphy can be viewed as natural experiments bearing on understanding origins of aridification; global change due to changes in atmospheric composition; and effects of and recovery from biodiversity loss. The PFNP averages 600,000 visitors a year, and we will leverage the educational effect of the project by developing, with the park staff, a permanent exhibit on the Petrified Forest core that will illustrate concepts behind understanding deep time and Earth history. The coring site itself will become a unique interpretive opportunity, displaying “science in action”. The scientific research related to the project is being partly funded by the US NSF; broadly speaking all phases of research will serve as opportunities to involve postdoctoral scientists, and graduate and undergraduate students from several institutions. Projects by PIs outside the US involving research on the Petrified Forest core are being developed. This experiment will be a catalyst for deep understanding of this critical time in Earth History.

• The Triassic Period (~252-202 Ma) witnessed the evolutionary appearance of modern terrestrial biota, the origin and rise to ecological dominance of dinosaurs, and dramatic climate changes on the continents. The complex of epicontinental basins in western Pangea, now exposed on the Colorado Plateau, preserves a rich low-paleolatitude biotic and paleoenvironmental terrestrial record from the Triassic. Despite a long and distinguished history of study of the Colorado Plateau region, particularly of the Chinle and Moenkopi formations, striking ambiguities in temporal duration and resolution, major uncertainties in global correlations, and significant doubts about paleolatitudinal position hamper incorporation of the huge amount of information from the region into larger tests of major competing climatic, biotic, and tectonic hypotheses of global importance for Earth system processes. The age-calibrated chronostratigraphy of the proposed Petrified Forest core will address major issues of early Mesozoic biotic and environmental change and will allow answers to, among others, critical questions: Were marine and continental biotic turnover events in the Late Triassic coupled? Was the largest faunal turnover event on land during the Late Triassic synchronous with the giant Manicouagan bolide impact? Do major marine biotic transitions in the Tethyian realm have continental counterparts? Does the Newark basin astronomically-calibrated time scale fit independent radioisotopic dates from the Chinle Formation? The project involves several co-PIs from international institutions; several from ICDP members. The proposed funding duration of 24 months will include drilling and the initial acquisition of basic stratigraphic, logging, magnetics, and geochronologic data for utilization by the scientific community.

Chinle, Climate Change, CPCP, Geochronology, ICDP-2010/05, Magneto Stratigraphy, North America, Stratigraphy, Triassic

Latitude: 35.08593, Longitude: -109.76548