Pulsed Volcanic Combustion Events Coincident with the End- Permian Terrestrial Disturbance and the Following Global Crisis Kunio Kaiho1*, Md
Total Page：16
File Type：pdf, Size：1020Kb
https://doi.org/10.1130/G48022.1 Manuscript received 13 June 2020 Revised manuscript received 3 September 2020 Manuscript accepted 6 September 2020 © 2020 The Authors. Gold Open Access: This paper is published under the terms of the CC-BY license. Published online 4 November 2020 Pulsed volcanic combustion events coincident with the end- Permian terrestrial disturbance and the following global crisis Kunio Kaiho1*, Md. Aftabuzzaman1, David S. Jones2 and Li Tian3 1 Department of Earth Science, Tohoku University, Sendai 980-8578, Japan 2 Department of Geology, Amherst College, 11 Barrett Hill Road, Amherst, Massachusetts 01002, USA 3 State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China ABSTRACT boundary; 31°04′47.28′′N, 119°42′20.88′′E), Eruption of the Siberian Traps large igneous province (LIP) is thought to have triggered Zhejiang Province, southern China; and Bul- the Permian-Triassic biological crisis, the largest of the Phanerozoic mass extinctions. Mer- la (46°33′52.16″N, 11°38′07.02″E), between cury concentration enrichments have been widely used as a proxy for volcanic inputs to the towns of Castelrotto and Ortisei, northern sediments, especially for ancient LIP eruptions. However, detailed correlations of magmatic Italy (Fig. 1). These sections are correlated by pulses with extinction events in the terrestrial and marine realms are not fully resolved. Here conodont zones and carbonate carbon isotopes we use paired coronene (a six-ring polycyclic aromatic hydrocarbon, a high-temperature (Chen et al., 2016; Kaiho et al., 2016a), and for combustion proxy) and mercury spikes as a refined proxy for LIP emplacement. In records Meishan, high-precision isotope dilution–ther- from stratigraphic sections in south China and Italy, we identify two sets of paired coronene- mal ionization mass spectrometry (ID-TIMS) mercury spikes accompanied by land plant biomarker spikes, followed by a rapid decrease U-Pb dating provides a highly-resolved age coinciding with terrestrial ecological disturbance and extinction of marine metazoans. Each model (Burgess et al., 2014; Yin et al., 2014). short-term episode is likely caused by high-temperature combustion of sedimentary hydro- Each studied sample covers 1–3 cm in height, carbons during initial sill emplacement of the Siberian Traps LIP. These data indicate that with no gaps between samples for the critical discrete volcanic eruptions could have caused the terrestrial ecosystem crisis followed by horizons (each bed was cut into several samples; the marine ecosystem crisis in ∼60 k.y., and that the terrestrial ecosystem was disrupted by see Tables S1–S3 in the Supplemental Material1). smaller global environmental changes than the marine ecosystem. We used five- to six-ring PAHs as (benzo[e] pyrene + benzo[ghi]perylene + coronene) / phen- INTRODUCTION centration in many marine and nonmarine set- anthrene (egc/phe), the coronene/phe ratio, and The Permian-Triassic (P-Tr) mass extinction tings (e.g., Wang et al., 2018; Shen et al., 2019b; the coronene index (coronene/egc) to estimate is composed of two separate global events: (1) Chu et al., 2020). Further, elevated mercury can combustion events, high-temperature combustion the end-Permian terrestrial ecological distur- be sourced from either direct atmospheric depo- events, and combustion temperature, respectively bance (EPTD); and (2) the sudden global end- sition from volcanic emissions or riverine inputs (Kaiho et al., 2016b; Fig. S1 in the Supplemen- Permian extinction (EPE), accompanied by soil from terrestrial organic-matter oxidation (Gras- tal Material); and the terrestrial plant index [n- erosion and surface-water anoxia (Song et al., by et al., 2013, 2017, 2019; Wang et al., 2018; alkane ratio (n-C27+29+31)/(n-C17+19+21+27+29+31)] to 2013; Kaiho et al., 2016a). The EPTD predated Shen et al., 2019a; Dal Corso et al., 2020). Thus, investigate soil erosion and vegetation collapse the EPE by tens of thousands to hundreds of we use the concentration of coronene (a six- (long chain n-alkanes are widely used terrestrial thousands of years (Fielding et al., 2019). These ring polyaromatic hydrocarbon [PAH] formed plant biomarkers; Bush and McInerney, 2013). events are hypothesized outcomes of Siberian by high-temperature combustion) in conjunction Although total PAHs are usually used as combus- Traps volcanism (Shen et al., 2011; Bond and with mercury to identify P-Tr volcanic events. tion proxy, we used egc/phe and coronene/phe be- Grasby, 2017; Burgess et al., 2017). cause phenanthrene (a three-ring PAH, the most Sedimentary mercury enrichments, proxies GEOLOGIC SETTING AND METHODS common PAH) is also formed by diagenesis, and for massive volcanic events, have been detected We analyzed abundances of combustion- five- to six-ring PAHs are enriched in combustion in dozens of P-Tr boundary sections across the related and terrestrial plant–related biomark- materials. More detailed methods are provided in globe (e.g., Sanei et al., 2012; Wang et al., 2018; ers, mercury abundance, and total organic car- the Supplemental Material. Grasby et al., 2019; Shen et al., 2019a), but un- bon (TOC) in sedimentary rock samples from certainty remains in their interpretation. First, three low-latitude shallow marine sections: Li- RESULTS the EPE lagged the initial spike of mercury con- angfengya (29°30′29.65″N, 106°52′58.26″E), We measured biomarker concentrations 13 km west of the city of Chongqing, south- well above detection limits and blank sample western China; Meishan (the Global Strato- values. The 22S/(22S + 22R) ratio of C31 ho- *E-mail: [email protected] type Section and Point [GSSP] for the P-Tr mohopanes and computed vitrinite reflectance 1Supplemental Material. Methods, geochemical data, and supplemental figures. Please visithttps://doi.org/10.1130/GEOL.S.13076138 to access the supplemental material, and contact [email protected] with any questions. CITATION: Kaiho, K., et al., 2021, Pulsed volcanic combustion events coincident with the end-Permian terrestrial disturbance and the following global crisis: Geology, v. 49, p. 289–293, https://doi.org/10.1130/G48022.1 Geological Society of America | GEOLOGY | Volume 49 | Number 3 | www.gsapubs.org 289 Downloaded from http://pubs.geoscienceworld.org/gsa/geology/article-pdf/49/3/289/5236761/289.pdf by guest on 29 September 2021 ter coincident with volcanism and extinction. Coronene is a highly condensed six-ring PAH Figure 1. Global paleo- and a stable molecule in Earth surface environ- geographic map showing ments and can be preserved across geological location of sections stud- time. It requires abnormally high energy to ied (stars) and referenced form coronene from hydrocarbons compared to (squares), as well as the related Siberian Traps smaller PAHs, as evidenced by heating experi- large igneous province. ments and thermodynamic simulations (Nori- Base map is after Ziegler naga et al., 2009). Wildfire combustion occurs et al. (1998). at 700–1000 °C (Pyne et al., 1996) and produces coronene indices ∼0.1, which correspond to the background values for mass extinctions (Kaiho et al., 2016b). The ∼0.1 value is also formed by (Rc) ( methylphenanthrene ratio, MPR) values High correlation between Hg and Hg/TOC 900–1000 °C in shorter-duration (a few seconds) in the three sections studied indicate that all the beginning below the events and continuing to heating, and the high coronene indices (>0.3) samples are “mature” at the stage of early to Event 2 (r = +0.83; Fig. 3D) indicates that there observed in Events 1 and 2, and the third spike peak oil generation, indicating no contamina- is little influence of the low TOC on the spikes of coronene, require combustion temperatures tion by modern hydrocarbon (Tables S1–S3). in Hg/TOC during the events in Liangfengya. >∼1200 °C (estimated from data of Norinaga Ten TOC measurements of a limestone from Here, low TOC (<0.2%) does not produce ar- et al. [2009]). Such high-temperature combus- Liangfengya with very low TOC yield a mean of tificial spikes in Hg/TOC for the two events. tion of organic matter to form coronene can oc- 0.03577% with standard deviation of 0.00053%, The correlation coefficient between Hg/TOC cur with large-scale volcanic activity or aster- with measured mass of carbon in all studied rock and coronene/phe and between Hg and coro- oid or comet impacts causing high-temperature samples more than five times the lowest detec- nene/phe is high during the pre-events to Event combustion of sedimentary hydrocarbon and ter- tion limit; the results indicate the reliability of 2 (r = +0.47 and +0.32, respectively) and low restrial plants in the emplacement or target ar- the TOC data despite their low concentrations after the Event 2 (r = –0.16 and –0.32, respec- eas. Five- to six-ring PAHs, including coronene (Tables S4–S6). tively; Figs. 3B and 3C). These correlation varia- enrichment, have been found associated with This study identifies coincidental high values tions imply that the sources of Hg subsequent to three mass extinctions (Late Devonian, end- of coronene/phe and Hg/TOC as volcanic events Event 2 differed from those for the lower beds. Permian, and Cretaceous-Paleogene boundary) because terrestrial biomass oxidation does not The relatively high TOC in samples predating but are absent from strata immediately below cause enrichment of the five- to six-ring PAHs. Event 1 at Bulla causes low correlation between and above the mass-extinction horizons (Kaiho At Liangfengya, the first volcanic event (Event Hg and the other proxies (Figs. 3H–3J) because et al., 2013, 2016b; this study). 1) occurred in the upper part of bed 14 to basal the main host of the Hg is TOC. We normalized The coronene indices of the two events bed 17, from the uppermost part of the Clarkina Hg by TOC, resulting in high correlation be- identified here are indicative of temperatures changxingensis to the basal C.