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High-precision geochronology confirms voluminous magmatism before, during, and after Earth's most severe extinction.

Burgess SD, Bowring SA - Sci Adv (2015)

Bottom Line: Magmatism is hypothesized to have caused rapid injection of massive amounts of greenhouse gases into the atmosphere, driving climate change and subsequent destabilization of the biosphere.Establishing a causal connection between magmatism and mass extinction is critically dependent on accurately and precisely knowing the relative timing of the two events and the flux of magma.New U/Pb dates on Siberian Traps LIP lava flows, sills, and explosively erupted rocks indicate that (i) about two-thirds of the total lava/pyroclastic volume was erupted over ~300 ky, before and concurrent with the end-Permian mass extinction; (ii) eruption of the balance of lavas continued for at least 500 ky after extinction cessation; and (iii) massive emplacement of sills into the shallow crust began concomitant with the mass extinction and continued for at least 500 ky into the early Triassic.

View Article: PubMed Central - PubMed

Affiliation: Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.

ABSTRACT
The end-Permian mass extinction was the most severe in the Phanerozoic, extinguishing more than 90% of marine and 75% of terrestrial species in a maximum of 61 ± 48 ky. Because of broad temporal coincidence between the biotic crisis and one of the most voluminous continental volcanic eruptions since the origin of animals, the Siberian Traps large igneous province (LIP), a causal connection has long been suggested. Magmatism is hypothesized to have caused rapid injection of massive amounts of greenhouse gases into the atmosphere, driving climate change and subsequent destabilization of the biosphere. Establishing a causal connection between magmatism and mass extinction is critically dependent on accurately and precisely knowing the relative timing of the two events and the flux of magma. New U/Pb dates on Siberian Traps LIP lava flows, sills, and explosively erupted rocks indicate that (i) about two-thirds of the total lava/pyroclastic volume was erupted over ~300 ky, before and concurrent with the end-Permian mass extinction; (ii) eruption of the balance of lavas continued for at least 500 ky after extinction cessation; and (iii) massive emplacement of sills into the shallow crust began concomitant with the mass extinction and continued for at least 500 ky into the early Triassic. This age model is consistent with Siberian Traps LIP magmatism as a trigger for the end-Permian mass extinction and suggests a role for magmatism in suppression of post-extinction biotic recovery.

No MeSH data available.


Related in: MedlinePlus

Generalized map of the current extent of Siberian Traps LIP rocks.Overlain on the map are sample names and locations, which are keyed by color to rock type. Base map and outcrop extent modified from (9). Stratigraphic sections for the Noril’sk and Maymecha-Kotuy sections showing lava stratigraphy and sample location. Stratigraphy modified from (11).
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Figure 1: Generalized map of the current extent of Siberian Traps LIP rocks.Overlain on the map are sample names and locations, which are keyed by color to rock type. Base map and outcrop extent modified from (9). Stratigraphic sections for the Noril’sk and Maymecha-Kotuy sections showing lava stratigraphy and sample location. Stratigraphy modified from (11).

Mentions: Pyroclastic and epiclastic breccias, likely the product of volatile-rich explosive phreatomagmatic volcanism (18), are found primarily in the southern third of the magmatic province (Fig. 1). In this area, pyroclastic breccia is found as thick (up to 1 km), massive, unsorted, and matrix-supported mixtures of primary volcanic clasts incorporated with sedimentary clasts, likely incorporated upon eruption or during subsequent deposition. When found in stratigraphic association, pyroclastic rocks are found underlying the base of lava stratigraphy, as is the case in the Maymecha-Kotuy section (13). In addition, pyroclastic rocks are also interspersed with the basal lava stratigraphy in both the Noril’sk and Maymecha-Kotuy sections (12, 14). We have sampled pyroclastic/epiclastic rocks from throughout the magmatic province (Fig. 1) and have isolated zircon crystals from 26 such samples. Because of the predominance of exotic clasts in all but two of these rocks, the zircon population represents multiple age populations. Thus, to relatively rapidly bin these zircons into age populations in hopes of finding grains indicative of eruption age, grains from these rocks were first dated by the LA-ICPMS technique. Following this analysis, the youngest grains, which are most likely to be representative of eruption age, were dated by the CA-TIMS technique. The two true pyroclastic rocks sampled, both welded tuffs, were sampled at a stratigraphic height of ~2 km above the base of the Maymecha-Kotuy lava stratigraphy (Fig. 1).


High-precision geochronology confirms voluminous magmatism before, during, and after Earth's most severe extinction.

Burgess SD, Bowring SA - Sci Adv (2015)

Generalized map of the current extent of Siberian Traps LIP rocks.Overlain on the map are sample names and locations, which are keyed by color to rock type. Base map and outcrop extent modified from (9). Stratigraphic sections for the Noril’sk and Maymecha-Kotuy sections showing lava stratigraphy and sample location. Stratigraphy modified from (11).
© Copyright Policy - open-access
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4643808&req=5

Figure 1: Generalized map of the current extent of Siberian Traps LIP rocks.Overlain on the map are sample names and locations, which are keyed by color to rock type. Base map and outcrop extent modified from (9). Stratigraphic sections for the Noril’sk and Maymecha-Kotuy sections showing lava stratigraphy and sample location. Stratigraphy modified from (11).
Mentions: Pyroclastic and epiclastic breccias, likely the product of volatile-rich explosive phreatomagmatic volcanism (18), are found primarily in the southern third of the magmatic province (Fig. 1). In this area, pyroclastic breccia is found as thick (up to 1 km), massive, unsorted, and matrix-supported mixtures of primary volcanic clasts incorporated with sedimentary clasts, likely incorporated upon eruption or during subsequent deposition. When found in stratigraphic association, pyroclastic rocks are found underlying the base of lava stratigraphy, as is the case in the Maymecha-Kotuy section (13). In addition, pyroclastic rocks are also interspersed with the basal lava stratigraphy in both the Noril’sk and Maymecha-Kotuy sections (12, 14). We have sampled pyroclastic/epiclastic rocks from throughout the magmatic province (Fig. 1) and have isolated zircon crystals from 26 such samples. Because of the predominance of exotic clasts in all but two of these rocks, the zircon population represents multiple age populations. Thus, to relatively rapidly bin these zircons into age populations in hopes of finding grains indicative of eruption age, grains from these rocks were first dated by the LA-ICPMS technique. Following this analysis, the youngest grains, which are most likely to be representative of eruption age, were dated by the CA-TIMS technique. The two true pyroclastic rocks sampled, both welded tuffs, were sampled at a stratigraphic height of ~2 km above the base of the Maymecha-Kotuy lava stratigraphy (Fig. 1).

Bottom Line: Magmatism is hypothesized to have caused rapid injection of massive amounts of greenhouse gases into the atmosphere, driving climate change and subsequent destabilization of the biosphere.Establishing a causal connection between magmatism and mass extinction is critically dependent on accurately and precisely knowing the relative timing of the two events and the flux of magma.New U/Pb dates on Siberian Traps LIP lava flows, sills, and explosively erupted rocks indicate that (i) about two-thirds of the total lava/pyroclastic volume was erupted over ~300 ky, before and concurrent with the end-Permian mass extinction; (ii) eruption of the balance of lavas continued for at least 500 ky after extinction cessation; and (iii) massive emplacement of sills into the shallow crust began concomitant with the mass extinction and continued for at least 500 ky into the early Triassic.

View Article: PubMed Central - PubMed

Affiliation: Massachusetts Institute of Technology, 77 Massachusetts Avenue, Cambridge, MA 02139, USA.

ABSTRACT
The end-Permian mass extinction was the most severe in the Phanerozoic, extinguishing more than 90% of marine and 75% of terrestrial species in a maximum of 61 ± 48 ky. Because of broad temporal coincidence between the biotic crisis and one of the most voluminous continental volcanic eruptions since the origin of animals, the Siberian Traps large igneous province (LIP), a causal connection has long been suggested. Magmatism is hypothesized to have caused rapid injection of massive amounts of greenhouse gases into the atmosphere, driving climate change and subsequent destabilization of the biosphere. Establishing a causal connection between magmatism and mass extinction is critically dependent on accurately and precisely knowing the relative timing of the two events and the flux of magma. New U/Pb dates on Siberian Traps LIP lava flows, sills, and explosively erupted rocks indicate that (i) about two-thirds of the total lava/pyroclastic volume was erupted over ~300 ky, before and concurrent with the end-Permian mass extinction; (ii) eruption of the balance of lavas continued for at least 500 ky after extinction cessation; and (iii) massive emplacement of sills into the shallow crust began concomitant with the mass extinction and continued for at least 500 ky into the early Triassic. This age model is consistent with Siberian Traps LIP magmatism as a trigger for the end-Permian mass extinction and suggests a role for magmatism in suppression of post-extinction biotic recovery.

No MeSH data available.


Related in: MedlinePlus