Dataset Information

Volcanic ash as a driver of enhanced organic carbon burial in the Cretaceous.

ABSTRACT: On greater than million year timescales, carbon in the ocean-atmosphere-biosphere system is controlled by geologic inputs of CO2 through volcanic and metamorphic degassing. High atmospheric CO2 and warm climates in the Cretaceous have been attributed to enhanced volcanic emissions of CO2 through more rapid spreading at mid-ocean ridges and, in particular, to a global flare-up in continental arc volcanism. Here, we show that global flare-ups in continental arc magmatism also enhance the global flux of nutrients into the ocean through production of windblown ash. We show that up to 75% of Si, Fe and P is leached from windblown ash during and shortly after deposition, with soluble Si, Fe and P inputs from ash alone in the Cretaceous being higher than the combined input of dust and rivers today. Ash-derived nutrient inputs may have increased the efficiency of biological productivity and organic carbon preservation in the Cretaceous, possibly explaining why the carbon isotopic signature of Cretaceous seawater was high. Variations in volcanic activity, particularly continental arcs, have the potential of profoundly altering carbon cycling at the Earth's surface by increasing inputs of CO2 and ash-borne nutrients, which together enhance biological productivity and burial of organic carbon, generating an abundance of hydrocarbon source rocks.

SUBMITTER: Lee CA

PROVIDER: S-EPMC5843639 | biostudies-literature | 2018 Mar

REPOSITORIES: biostudies-literature

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Volcanic ash as a driver of enhanced organic carbon burial in the Cretaceous.

Lee Cin-Ty A CA Jiang Hehe H Ronay Elli E Minisini Daniel D Stiles Jackson J Neal Matthew M

Scientific reports 20180308 1

On greater than million year timescales, carbon in the ocean-atmosphere-biosphere system is controlled by geologic inputs of CO2 through volcanic and metamorphic degassing. High atmospheric CO2 and warm climates in the Cretaceous have been attributed to enhanced volcanic emissions of CO2 through more rapid spreading at mid-ocean ridges and, in particular, to a global flare-up in continental arc volcanism. Here, we show that global flare-ups in continental arc mag ...[more]

PMID: 29520023

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Project description:Abstract The Paleocene‐Eocene Thermal Maximum (PETM) is recognized globally by a negative excursion in stable carbon isotope ratios (δ13C) in sedimentary records, termed the carbon isotope excursion (CIE). Based on the CIE, the cause, duration, and mechanisms of recovery of the event have been assessed. Here, we focus on the role of increased organic carbon burial on continental margins as a key driver of CO2 drawdown and global exogenic δ13C during the recovery phase. Using new and previously published sediment proxy data, we show evidence for widespread enhanced primary production, low oxygen waters, and high organic carbon (Corg) burial in marginal and restricted environments throughout the δ13C excursion. With a new biogeochemical box model for deep and marginal environments, we show that increased phosphorus availability and water column stratification on continental margins can explain the increased Corg burial during the PETM. Deoxygenation and recycling of phosphorus relative to Corg were relatively mild, compared to modern day anoxic marine systems. Our model reproduces the conditions reconstructed by field data, resulting in a burial of 6,000 Pg across the PETM, in excess of late Paleocene burial, and ∼3,300 Pg C for the critical first 40 kyr of the recovery, primarily located on continental margins. This value is consistent with prior data and model estimates (∼2,000–3,000 Pg C). To reproduce global exogenic δ13C patterns, this Corg burial implies an injection of 5,000–10,000 Pg C during the first ∼100–150 kyr of the PETM, depending on the source's δ13C (−11‰ to −55‰). Key Points Data and modeling show increased productivity, deoxygenation, and organic C burial in marginal and restricted environments during the PETM Excess burial of ∼3,300 Pg organic C burial at the early stages of the PETM recovery Excess organic C burial during recovery requires several thousands of Pg of 13C‐depleted carbon input to match global exogenic δ13C trends

Dataset Information

Volcanic ash as a driver of enhanced organic carbon burial in the Cretaceous.

Publications

Volcanic ash as a driver of enhanced organic carbon burial in the Cretaceous.

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