A geochemical view into continental palaeotemperatures of the end-Permian using oxygen and hydrogen isotope composition of secondary silica in chert rubble breccia: Kaibab Formation, Grand Canyon (USA)

Ray Kenny

doi:10.1186/s12932-017-0047-y

Abstract

The upper carbonate member of the Kaibab Formation in northern Arizona (USA) was subaerially exposed during the end Permian and contains fractured and zoned chert rubble lag deposits typical of karst topography. The karst chert rubble has secondary (authigenic) silica precipitates suitable for estimating continental weathering temperatures during the end Permian karst event. New oxygen and hydrogen isotope ratios of secondary silica precipitates in the residual rubble breccia: (1) yield continental palaeotemperature estimates between 17 and 22 °C; and, (2) indicate that meteoric water played a role in the crystallization history of the secondary silica. The continental palaeotemperatures presented herein are broadly consistent with a global mean temperature estimate of 18.2 °C for the latest Permian derived from published climate system models. Few data sets are presently available that allow even approximate quantitative estimates of regional continental palaeotemperatures. These data provide a basis for better understanding the end Permian palaeoclimate at a seasonally-tropical latitude along the western shoreline of Pangaea.

Highlights

The end Permian subaerial erosion surface exposed at the top of the Kaibab Formation (KF) is important because it occupies a time in Earth history that represents the largest and most severe mass extinction in the Phanerozoic [1,2,3] resulting in a substantial loss of terrestrial and marine life [4, 5]
All data are reported relative to V-SMOW in standard δ-notation. δ18O values represent total oxygen of chert and silica; δD values are derived from non-surface hydroxyl groups of chert and silica
The prominence of drusy and botryoidal silica phases in KF chert rubble vugs suggest that quartz precipitated directly without opaline percursors, and stable isotopic data show clearly that the microquartz sampled from the paleokarst horizons precipitated from waters that had a meteoric water component

Summary

Introduction

The end Permian subaerial erosion surface exposed at the top of the Kaibab Formation (KF) is important because it occupies a time in Earth history that represents the largest and most severe mass extinction in the Phanerozoic [1,2,3] resulting in a substantial loss of terrestrial and marine life [4, 5]. Kidder and Worsley [16] have suggested that a significant increase in atmospheric CO2 was present across the Permian–Triassic Boundary (PTB) resulting in global, tundra-free, “warmhouse” climate conditions [17, 18]. Kiehl and Shields [26] used reconstructed palaeogeographical data to produce a comprehensive climate model which showed that the Earth was warmer than

Results

Discussion

Conclusion