The geological record following the c. 2.3 billion years old Great Oxidation Event includes evidence for anomalously high burial of organic carbon and the emergence of widespread mountain building. Both carbon burial and orogeny occurred globally over the period 2.1 to 1.8 billion years ago. Prolific cyanobacteria were preserved as peak black shale sedimentation and abundant graphite. In numerous orogens, the exceptionally carbonaceous sediments were strongly deformed by thrusting, folding, and shearing. Here an assessment of the timing of Palaeoproterozoic carbon burial and peak deformation/metamorphism in 20 orogens shows that orogeny consistently occurred less than 200 million years after sedimentation, in a time frame comparable to that of orogens through the Phanerozoic. This implies that the high carbon burial played a critical role in reducing frictional strength and lubricating compressive deformation, which allowed crustal thickening to build Palaeoproterozoic mountain belts. Further, this episode left a legacy of weakening and deformation in 2 billion year-old crust which has supported subsequent orogenies up to the building of the Himalayas today. The link between Palaeoproterozoic biomass and long-term deformation of the Earth’s crust demonstrates the integral relationship between biosphere and lithosphere.
|Number of pages||9|
|Journal||Communications Earth & Environment|
|Publication status||Published - 26 Nov 2021|
Bibliographical noteThe work was partially supported by NERC grant NE/M010953/1. The manuscript benefitted by advice from Michael Brown and Ross Mitchell.
Data Availability StatementThe data tables used to produce the results of this article can be accessed at the National Geoscience Data Centre (https://doi.org/10.5285/d10a1c96-55ff-4a35-be6b-92a4eb766b38), entitled ‘Data tables for global Palaeoproterozoic black shales’, linked to NERC grant NE/M010953/1.
- Structural geology