Detrital Zircon Geochronology: A Novel Approach for Stratigraphic Correlation of Late Mississippian-Early Pennsylvanian Strata in Southwestern Kansas and Northwestern Arkansas

Abstract

The Late Mississippian to Early Pennsylvanian is a dynamic time interval across the globe, with major changes in tectonics, climate, and eustacy. In the U.S. midcontinent, these changes are reflected in pulses of clastic sediment delivered to the Hugoton Embayment and Arkoma Shelf, during a time of widespread carbonate platform deposition. The resulting carbonate-siliciclastic successions are notoriously difficult to correlate in the subsurface due to similarities in log and core characteristics and a dearth of diagnostic fauna. Here we evaluate if the detrital zircon provenance of upper Mississippian to middle Pennsylvanian sandstones can be used to confidently correlate intervals in two study areas. (1) In southwestern Kansas, we focus on the Hugoton Embayment, where sandstones, deposited in two valley-filling intervals, the Chester and Morrow, are important reservoirs. However, differentiation between these intervals and time-equivalent carbonates is difficult. More than 1700 detrital zircon U-Pb ages have been acquired from 15 samples from 10 boreholes in six oil and gas fields. Detrital zircon age spectra show that Chester sandstones are characterized by zircon U-Pb age clusters of 900-1295 Ma (Grenville) and 390-475 Ma, consistent with sediment delivery from the central Appalachian orogen. Age spectra for Morrow sandstones record a change in provenance, with the presence of two additional age groups, 1300-1500 Ma and 1600-1800 Ma, that match the age of basement in the Granite-Rhyolite and Yavapai-Maztzal provinces, respectively. We ascribe changes in the zircon age spectra and introduction of these grains to the development of uplifts linked with the ancestral Rockies in the early Pennsylvanian. The introduction of these grains in the Morrow may be a diagnostic characteristic of the unit and age-equivalent carbonates that can be used for stratigraphic correlations in the region. (2) For the Arkoma shelf, 1200 new detrital zircon U-Pb ages were obtained from 11 samples, collected from outcrops in northwestern Arkansas, covering 9 clastic intervals that capture the transition from the Late Mississippian stable shelf to the Middle Pennsylvanian foreland basin. The detrital zircon U-Pb age spectra suggest little difference in provenance between the Chesterian and Morrowan age units; however, a strong 1600-1800 Ma age peak may be a diagnostic feature of the Atokan age strata, reflecting sediment contributions from Ouachita orogen and accretionary complex.

AAPG Datapages/Search and Discovery Article #90323 ©2018 AAPG Annual Convention and Exhibition, Salt Lake City, Utah, May 20-23, 2018