T62 Recent Advances in Soil and Paleosol Science

Sunday, 15 October 2023
1:30 PM - 5:30 PM
320

EARLY CRETACEOUS ICE AGES FROM WEATHERING AND BIOMASS OF MIGRATING ANGIOSPERMS

Paper number: T62-5
Program: Technical Sessions
Time: 2:20 PM – 2:35 PM

Authors

Abstract

The Early Cretaceous, Wonthaggi and Eumeralla Formations of Victoria, Australia, include frigid paleosols (Gelisols) with clastic dikes (ice wedges), load casts of mud (periglacial convolutions), and coal-mantled stone-rolls (aapamires), at the same early Hauterivian and late Barremian levels as dropped pebbles and glendonites in marine rocks of South Australia, New South Wales, Svalbard, Nunavut, and Barents Sea. These permafrost paleosols represent fern-lycopsid tundra and coniferous taiga vegetation, but alternate with non-calcareous Histosols and Ultisols, indicative of humid temperate ecosystems at times of Early Cretaceous greenhouse spikes, revealed by stomatal index of fossil ginkgo leaves, by black shales of oceanic anoxic events, marine transgressions, and both marine and non-marine carbon isotopic anomalies. The greenhouse spikes are widely attributed to massive volcanic eruptions, causing volatility in global carbon dioxide levels, rather than a protracted supergreenhouse, but what caused the ice ages? A key biological innovation of early angiosperms enabling their spread to high latitudes, including Victoria during the Early Cretaceous, was their abbreviated life cycle without extended megagametophyte development within the seed, thus enabling rapid colonization of coastal regions disturbed by large sea level changes and greenhouse warm spikes. Silicate substrates more quickly colonized by plants than before, especially in polar regions with abundant fresh minerals, rapidly built biomass and consumed atmospheric carbon dioxide during weathering from feldspathic sandstone to clay and coal seen in Early Cretaceous paleosols of Victoria.

Geological Society of America Abstracts with Programs. Vol. 55, No. 6

doi: 10.1130/abs/2023AM-388579

© Copyright 2023 The Geological Society of America (GSA), all rights reserved. Permission is hereby granted to the author(s) of this abstract to reproduce and distribute it freely, for noncommercial purposes. Permission is hereby granted to any individual scientist to download a single copy of this electronic file and reproduce up to 20 paper copies for noncommercial purposes advancing science and education, including classroom use, providing all reproductions include the complete content shown here, including the author information. All other forms of reproduction and/or transmittal are prohibited without written permission from GSA Copyright Permissions.