How Hot Is Too Hot? Disentangling Mid-Cretaceous Hothouse Paleoclimate from Diagenesis Journal Article uri icon

Overview

abstract

  • The North American Newark Canyon Formation (~113–98 Ma); presents an opportunity to examine how various terrestrial carbonate; facies reflect different aspects of paleoclimate during one of the; hottest periods of Earth’s history. We combined carbonate facies; analysis with δ13C, δ18O, and Δ47 datasets to assess which palustrine; and lacustrine facies preserve stable isotope signals that are most; representative of climatic conditions. Type section palustrine facies; record the heterogeneity of the original palustrine environment in which; they formed. Using the pelmicrite facies that formed in deeper wetlands,; we interpret a lower temperature zone (35–40°C) to reflect warm season; water temperatures. In contrast, the mottled micrite facies reflects; hotter temperatures (36–68°C). These hotter temperatures preserve; radiatively heated “bare-skin” temperatures that occurred in a shallow; depositional setting. The lower lacustrine unit has been secondarily; altered by hydrothermal fluids while the upper lacustrine unit likely; preserves primary temperatures and δ18Owater of catchment-integrated; precipitation. Based on this investigation, the palustrine pelmicrite; and lacustrine micrite are the facies most likely to reflect ambient; climate conditions, and therefore, are the best facies to use for; paleoclimate interpretations. Average warm season water temperatures of; 41.1±3.6°C and 37.8±2.5°C are preserved by the palustrine pelmicrite; (~113–112 Ma) and lacustrine micrite; (~112–103 Ma), respectively. These data support; previous interpretations of the mid-Cretaceous as a hothouse climate.; Our study demonstrates the importance of characterizing facies for; identifying the data most representative of past climates.

publication date

  • July 22, 2022

has restriction

  • hybrid

Date in CU Experts

  • August 2, 2022 1:22 AM

Full Author List

  • Fetrow AC; Snell K; Fiori RVD; Long SP; Bonde JW

author count

  • 5

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