Limits...
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

Stratigraphy, geochronology, and magnetic polarity for Siberian Traps LIP rocks and the Permian-Triassic GSSP at Meishan, China.Placement of the Permian-Triassic boundary on the lava stratigraphy is based on magnetic polarity, geochemistry, and geochronology. Polarity for the Noril’sk and Maymecha-Kotuy sections from (30–32). Paleopolarity for the GSSP section from (33). The Permian-Triassic boundary shown is defined by the first appearance datum of the conodont Hindeodus parvus and is shown as the solid red line. Placement of the P-T boundary from (4).
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Figure 3: Stratigraphy, geochronology, and magnetic polarity for Siberian Traps LIP rocks and the Permian-Triassic GSSP at Meishan, China.Placement of the Permian-Triassic boundary on the lava stratigraphy is based on magnetic polarity, geochemistry, and geochronology. Polarity for the Noril’sk and Maymecha-Kotuy sections from (30–32). Paleopolarity for the GSSP section from (33). The Permian-Triassic boundary shown is defined by the first appearance datum of the conodont Hindeodus parvus and is shown as the solid red line. Placement of the P-T boundary from (4).

Mentions: Because only two “young” grains were isolated from a population of more than 800 zircons sourced from pyroclastic rocks collected throughout the province, we believe that these dates are not representative of the timing of eruption. If zircon crystallized during or just before eruption in any of these samples, one would expect to identify a population of young grains rather than a solitary grain that crystallized ~3 Ma before initial lava eruption. Thus, we favor the interpretation that the youngest dated zircon from pyroclastic rocks (255.58 ± 0.38 Ma) is the youngest age in a detrital spectrum and thus the maximum age for pyroclastic magmatism. The minimum age for these rocks and the maximum age of lavas at the base of the Maymecha-Kotuy section is 252.24 ± 0.12 Ma (Fig. 3). The lower ~1800 m of lava in this section erupted before 251.904 ± 0.061 Ma, over a maximum duration of 336 ± 126 ky. Paleomagnetic secular variation constraints measured from the lowest ~600 m (~30 flows) of this section suggest that the eruption of these rocks occurred over 10 to 100 ky (29). Tripling this value to accommodate the section thickness below the dated tuff bed yields a duration on the order of 30 to 300 ky, consistent with our new geochronology. About 135 m stratigraphically above sample M09-11-1, sample M09-12-1 yields a date of 251.483 ± 0.088 Ma, suggesting a hiatus in magmatism/deposition somewhere between the two samples with a maximum duration of 420 ± 149 ky. In this region, lava accumulation resumed by 251.483 ± 0.088 Ma, denoting a maximum age of the upper ~2 km of the Maymecha-Kotuy lava stratigraphy, which includes the Maymechites and Guli intrusive suite (Fig. 3).


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

Burgess SD, Bowring SA - Sci Adv (2015)

Stratigraphy, geochronology, and magnetic polarity for Siberian Traps LIP rocks and the Permian-Triassic GSSP at Meishan, China.Placement of the Permian-Triassic boundary on the lava stratigraphy is based on magnetic polarity, geochemistry, and geochronology. Polarity for the Noril’sk and Maymecha-Kotuy sections from (30–32). Paleopolarity for the GSSP section from (33). The Permian-Triassic boundary shown is defined by the first appearance datum of the conodont Hindeodus parvus and is shown as the solid red line. Placement of the P-T boundary from (4).
© Copyright Policy - open-access
Related In: Results  -  Collection

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

Figure 3: Stratigraphy, geochronology, and magnetic polarity for Siberian Traps LIP rocks and the Permian-Triassic GSSP at Meishan, China.Placement of the Permian-Triassic boundary on the lava stratigraphy is based on magnetic polarity, geochemistry, and geochronology. Polarity for the Noril’sk and Maymecha-Kotuy sections from (30–32). Paleopolarity for the GSSP section from (33). The Permian-Triassic boundary shown is defined by the first appearance datum of the conodont Hindeodus parvus and is shown as the solid red line. Placement of the P-T boundary from (4).
Mentions: Because only two “young” grains were isolated from a population of more than 800 zircons sourced from pyroclastic rocks collected throughout the province, we believe that these dates are not representative of the timing of eruption. If zircon crystallized during or just before eruption in any of these samples, one would expect to identify a population of young grains rather than a solitary grain that crystallized ~3 Ma before initial lava eruption. Thus, we favor the interpretation that the youngest dated zircon from pyroclastic rocks (255.58 ± 0.38 Ma) is the youngest age in a detrital spectrum and thus the maximum age for pyroclastic magmatism. The minimum age for these rocks and the maximum age of lavas at the base of the Maymecha-Kotuy section is 252.24 ± 0.12 Ma (Fig. 3). The lower ~1800 m of lava in this section erupted before 251.904 ± 0.061 Ma, over a maximum duration of 336 ± 126 ky. Paleomagnetic secular variation constraints measured from the lowest ~600 m (~30 flows) of this section suggest that the eruption of these rocks occurred over 10 to 100 ky (29). Tripling this value to accommodate the section thickness below the dated tuff bed yields a duration on the order of 30 to 300 ky, consistent with our new geochronology. About 135 m stratigraphically above sample M09-11-1, sample M09-12-1 yields a date of 251.483 ± 0.088 Ma, suggesting a hiatus in magmatism/deposition somewhere between the two samples with a maximum duration of 420 ± 149 ky. In this region, lava accumulation resumed by 251.483 ± 0.088 Ma, denoting a maximum age of the upper ~2 km of the Maymecha-Kotuy lava stratigraphy, which includes the Maymechites and Guli intrusive suite (Fig. 3).

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