Geological, geophysical, and geochemical data support a theory that Earth experienced several intervals of intense, global glaciation ("snowball Earth" conditions) during Precambrian time. This snowball model predicts that postglacial, greenhouse-induced warming would lead to the deposition of banded iron formations and cap carbonates. Although global glaciation would have drastically curtailed biological productivity, melting of the oceanic ice would also have induced a cyanobacterial bloom, leading to an oxygen spike in the euphotic zone and to the oxidative precipitation of iron and manganese. A Paleoproterozoic snowball Earth at 2.4 Giga-annum before present (Ga) immediately precedes the Kalahari Manganese Field in southern Africa, suggesting that this rapid and massive change in global climate was responsible for its deposition. As large quantities of O(2) are needed to precipitate this Mn, photosystem II and oxygen radical protection mechanisms must have evolved before 2.4 Ga. This geochemical event may have triggered a compensatory evolutionary branching in the Fe/Mn superoxide dismutase enzyme, providing a Paleoproterozoic calibration point for studies of molecular evolution.
Download full-text PDF |
Source |
|---|---|
| http://www.ncbi.nlm.nih.gov/pmc/articles/PMC26445 | PMC |
| http://dx.doi.org/10.1073/pnas.97.4.1400 | DOI Listing |
Publication Analysis
Top Keywords
Similar Publications
Impact-induced initiation of Snowball Earth: A model study.
Sci Adv
February 2024
Department of Earth and Planetary Sciences, Yale University, 210 Whitney Ave., New Haven, CT 06511, USA.
During the Neoproterozoic and Paleoproterozoic eras, geological evidence points to several "Snowball Earth" episodes when most of Earth's surface was covered in ice. These global-scale glaciations represent the most marked climate changes in Earth's history. We show that the impact winter following an asteroid impact comparable in size to the Chicxulub impact could have led to a runaway ice-albedo feedback and global glaciation.
View Article and Find Full Text PDFCryogenian Origins of Multicellularity in Archaeplastida.
Genome Biol Evol
February 2024
Bristol Palaeobiology Group, School of Biological Sciences and School of Earth Sciences, Life Sciences Building, University of Bristol, Bristol BS8 1TQ, UK.
Earth was impacted by global glaciations during the Cryogenian (720 to 635 million years ago; Ma), events invoked to explain both the origins of multicellularity in Archaeplastida and radiation of the first land plants. However, the temporal relationship between these environmental and biological events is poorly established, due to a paucity of molecular and fossil data, precluding resolution of the phylogeny and timescale of archaeplastid evolution. We infer a time-calibrated phylogeny of early archaeplastid evolution based on a revised molecular dataset and reappraisal of the fossil record.
View Article and Find Full Text PDFBiogeochemical transformations after the emergence of oxygenic photosynthesis and conditions for the first rise of atmospheric oxygen.
Geobiology
September 2023
Department of Earth and Planetary Sciences, Tokyo Institute of Technology, Tokyo, Japan.
The advent of oxygenic photosynthesis represents the most prominent biological innovation in the evolutionary history of the Earth. The exact timing of the evolution of oxygenic photoautotrophic bacteria remains elusive, yet these bacteria profoundly altered the redox state of the ocean-atmosphere-biosphere system, ultimately causing the first major rise in atmospheric oxygen (O )-the so-called Great Oxidation Event (GOE)-during the Paleoproterozoic (~2.5-2.
View Article and Find Full Text PDFPervasive Hydrothermal Events Associated with Large Igneous Provinces Documented by the Columbia River Basaltic Province.
Sci Rep
June 2020
Earth Sciences, University of Oregon, Eugene, OR, USA.
The degree and extent of crustal hydrothermal alteration related to the eruption of large igneous provinces is poorly known and not easily recognizable in the field. We here report a new δO dataset for dikes and lavas from the Columbia River Basalt Group (16-15 Ma) in the western USA, and document that dikes on average are 1-2‰ more depleted in δO than basalt flows. We show that this observation is best explained with the involvement of heated meteoric waters during their cooling in the crust.
View Article and Find Full Text PDFThe Great Oxidation Event preceded a Paleoproterozoic "snowball Earth".
Proc Natl Acad Sci U S A
June 2020
School of Earth and Environmental Sciences, University of St Andrews, St Andrews KY16 9AL, Scotland, United Kingdom.
The inability to resolve the exact temporal relationship between two pivotal events in Earth history, the Paleoproterozoic Great Oxidation Event (GOE) and the first "snowball Earth" global glaciation, has precluded assessing causality between changing atmospheric composition and ancient climate change. Here we present temporally resolved quadruple sulfur isotope measurements (δS, ∆S, and ∆S) from the Paleoproterozoic Seidorechka and Polisarka Sedimentary Formations on the Fennoscandian Shield, northwest Russia, that address this issue. Sulfides in the former preserve evidence of mass-independent fractionation of sulfur isotopes (S-MIF) falling within uncertainty of the Archean reference array with a ∆S/∆S slope of -1.
View Article and Find Full Text PDFWant AI Summaries of new PubMed Abstracts delivered to your In-box?
Enter search terms and have AI summaries delivered each week - change queries or unsubscribe any time!