Sedimentary noise modeling of lake-level change in the Late Triassic Newark Basin of North America

Two different hypotheses, glacioeustasy and groundwater aquifer eustasy, have been proposed to explain shortterm, high-amplitude sea-level oscillations during past greenhouse-dominated intervals. However, the veracity of aquifer eustasy on long-term, high amplitude sea level has never been rigorously tested. We evaluate these competing hypotheses using the objective approach of sedimentary noise modeling for lake-level reconstruction. Statistical tuning and astronomical calibration of paleoclimate and paleoenvironment proxies (depth rank, rock color, gamma ray, and sonic velocity) from the lacustrine Newark Basin enable the construction of a 31.55-Myr long astronomical time scale (ATS) for the Late Triassic that is comparable to the classic Newark ATS previously presented. Using this timescale, sedimentary noise modeling in the lacustrine Newark Basin is carried out through the Late Triassic. Lake level fluctuations reconstructed by sedimentary noise modeling and principal component analysis reveal that million-year scale lake-level variations were linked to astronomical forcing with periods of-3.3 Myr,-1.8 Myr, and-1.2 Myr. Our results demonstrate that astronomical forcing, as a driver of groundwater dynamics, may have had an impact on global sea-level changes during the Late Triassic. This study thus emphasizes the importance of high-resolution, objective reconstruction of sea-and lake-levels for further testing the hypotheses of glacioeustasy and aquifer eustasy under warm conditions.

Automated summary

Two competing hypotheses, glacioeustasy and groundwater aquifer eustasy, were evaluated for their impact on global sea-level changes during the Late Triassic. Sedimentary noise modeling and principal component analysis were used to reconstruct lake level fluctuations, revealing a link between million-year scale lake-level variations and astronomical forcing. This study highlights the importance of high-resolution, objective reconstructions of sea- and lake-levels for further testing these hypotheses under warm conditions.