PALAIOS, 2013, v. 28, p. 661–663 Research Article DOI: 10.2110/palo.2012.p12-102r
ORGANISM-ENVIRONMENT INTERACTIONS DURING THE PERMIAN-TRIASSIC MASS EXTINCTION AND ITS AFTERMATH ZHONG-QIANG CHEN,1 THOMAS J. ALGEO,2,3 and MARGARET L. FRAISER 4 1State
Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan, 430074, China,
[email protected]; 2Department of Geology, University of Cincinnati, Cincinnati, Ohio 45221, USA,
[email protected]; 3State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, 430074, China; 4Department of Geosciences, University of Wisconsin-Milwaukee, Milwaukee, Wisconsin 53211, USA,
[email protected]
Multicellar life came closest to complete annihilation during the ca. 252 Ma Permian–Triassic mass extinction (PTME), which resulted in the largest crash in global biodiversity since the Cambrian explosion (Alroy et al., 2008). This largest biocrisis in the Phanerozoic has also dramatically redirected the course of biotic evolution during the Mesozoic and Cenozoic, and is responsible for much of the structure of marine and terrestrial ecosystems today (Chen and Benton, 2012). However, many aspects of the biotic recovery following the PTME have been puzzling, including its tempo and mechanism (Erwin, 1994, 2001; Benton and Twitchett, 2003). Growing evidence shows that stressed environments and multiple disaster events that further devastated terrestrial and marine ecosystems during the Early Triassic may have accounted for the prolonged delay in biotic recovery following the PTME (Algeo et al., 2011). Three decades of paleontological effort have made late Permian to Early Triassic marine ecosystems among the most thoroughly studied fossil communities in Earth history (Chen and Benton, 2012). Changes in biodiversity of all fossil groups through this critical interval are well known today. Among the clades most severely affected were corals, brachiopods, foraminifera, radiolarians, bryozoans, echinoderms, gastropods, bivalves, and ammonoids (Erwin, 1994). Individual clades exhibited dramatically different diversity changes during the crisis, however. For example, brachiopods were among the commonest animals in Permian oceans but experienced a sharp decline in diversity during the Early Triassic, and their diversity did not rebound significantly until the early Middle Triassic (Chen et al., 2005). Corals suffered a major diversity loss in the PTME and did not reappear until the middle Anisian (Sepkoski, 1984). This is also true for radiolarians, a clade that suffered a large depletion in diversity during the Early Triassic and early Anisian (O’Dogherty et al., 2010). In contrast, ammonoid faunas underwent a rapid albeit punctuated diversity rebound in the Early Triassic, reaching a higher diversity by the Smithian than prior to the PTME (Brayard et al., 2009; Stanley, 2009). Foraminifera also show a strong recovery during the Early Triassic, passing their precrisis diversity by the Smithian (Song et al., 2011). The PTME had a lesser effect on conodonts, which showed a stepwise increase in diversity throughout the Early Triassic (Orchard, 2007). Among echinoderms, crinoids disappeared for most of the Early Triassic and rebounded during the end-Spathian (Erwin, 2001), while ophiuroids experienced a diversity increase and geographic expansion immediately after the PTME (Chen and McNamara, 2006). As a result, the recovery of some animal clades (e.g., ammonoids, foraminifera) and trace fossils occurred during the Olenekian, i.e., within 2–3 myr of the PTME, whereas that of others was delayed by 5–10 myr, lasting until the late Anisian stage of the Middle Triassic (Chen and Benton, 2012). The tempo of biotic recovery in the Triassic remains disputed because of these differences among individual clades. Since its inception in 2008, the goal of IGCP Project 572 (with .130 members worldwide) has been to document the rebuilding of marine ecosystems following the PTME in different environmental settings Published Online: November 2013
worldwide. The IGCP572 community published a thematic issue on Permian–Triassic ecosystems in 2011 (Algeo et al., 2011). The present thematic issue follows up on this earlier work, focusing on organismenvironment interactions during the biocrisis and the postextinction recovery. The overall goal of this thematic issue is to provide a better understanding of the causes of the prolonged devastation of marine ecosystems following the PTME and its significance in terms of the long-term coevolution of life and the physical environment in the Earth system. The studies contributed to this special issue provide stratigraphic, sedimentologic, paleontological, paleoecologic, and geochemical insights from diverse locations around the world. In particular, these studies address the role of protracted environmental devastation on the recovery of Early Triassic marine ecosystems. Analysis of the PTME at a global scale depends heavily on development of detailed biozonation schemes that are based largely on the fossil record of conodonts (Mei et al., 1998; Henderson and Mei, 2007; Orchard, 2007). High-resolution biostratigraphic frameworks have been developed for the Meishan GSSP (Yin et al., 2001; Jiang et al., 2007; Zhang et al., 2009) as well as other sections in South China (e.g., Nicoll et al., 2002; Zhao et al., 2007; Metcalfe and Nicoll, 2007; Jiang et al., 2011) and globally (e.g., Perri and Farabegoli, 2003; Kozur, 2004, 2005). In this volume, two studies contribute to this effort by providing detailed analyses of conodont biostratigraphy through the uppermost Permian to Lower Triassic from sections in Guizhou Province (Yan et al., 2013) and Hubei Province (Zhao et al., 2013). The studied sections represent two very different environmental settings. Yan et al. (2013) examine the flanks of the Permian–Triassic Great Bank of Guizhou, an isolated carbonate platform in the Nanpanjiang Basin, southwest China. This isolated platform has yielded detailed biotic and geochemical records that have provided insights into marine ecosystem perturbations and climatic extremes during the PTME and its aftermath (Payne et al., 2004; Song et al., 2011; Sun et al., 2012). Zhao et al.’s (2013) fine conodont biostratigraphic study of Lower Triassic strata in the Three Gorges area helps not only to define precisely the PTB and Lower Triassic stages and their boundaries, but also to detect a much thicker PTB succession than that of the Meishan GSSP. The Lower Triassic succession studied by Zhao et al. (2013) has the potential to yield high-resolution geochemical records of environmental and climatic change following the end-Permian crisis. The other studies of the present thematic issue offer additional insights regarding organic-environment interactions and protracted or recurrent environmental stresses during the PTB interval and Early Triassic. The paper by Brookfield et al. (2013) explores environmental changes through the Permian–Triassic transition at Guryul Ravine, Kashmir, a classic PTB site that has received detailed sedimentologic and isotopic study in the past (Brookfield et al., 2003; Algeo et al., 2007). The authors present a new interpretation of this section as a record of possible extreme storm and/or earthquake and tsunami deposits around the PTB. They propose that at least two large earthquakes and several tsunamis coincided with and/or rapidly followed the PTME, although it is unclear whether these events were triggered by the forces that caused the end-Permian crisis (e.g., the
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Siberian Traps flood basalt eruptions; Wignall, 2007; Korte et al., 2010). Although additional evidence from other PTB sites is needed to document the full scale of these earthquake and tsunami events, this study provides a clue that additional catastrophic processes may have contributed to the devastation and delayed recovery of marine ecosystems during the latest Permian to Earliest Triassic. The paper by Korngreen et al. (2013) documents sedimentologic and paleontological changes within a 40-m-interval spanning the PTB from a borehole in Israel. The study site was situated on the northern margin of Gondwana during the Permian–Triassic transition, an area that has received little detailed study to date. This paper provides paleontologic, sedimentologic, cyclostratigraphic, and isotopic data that reveal the demise of the latest Permian marine ecosystem in the western Tethyan Ocean region and its renewal during the Early Triassic. Compared with shallow marine environments, the nature of ecosystem changes in deep-shelf environments during the Permian– Triassic transition are more poorly known. Two papers in the present thematic issue document organism-environment interactions in such deep-shelf environments in South China. The paper by Shen et al. (2013) reports results of a study of two deepwater sections composed mainly of radiolarian cherts and cherty mudstones, Shangsi in Sichuan Province and Xinmin in Guizhou Province. It explores the effects of volcanism on open-marine microplankton communities represented by acritarchs and radiolarians, two microplankton clades that reacted differently to volcanic eruptions. Acritarchs were found in peak abundance in the mudstones overlying each volcanic ash layer but were otherwise present in only low concentrations in the background sediment. In contrast, radiolarians were rare in the layers of sediment laid down by volcanic eruptions but were frequently abundant in the background intervals. Radiolarians underwent a major regional extinction near the PTB, nearly at the same time as acritarchs reached their peak abundance. The authors infer that Permian–Triassic volcanic eruptions may have had both positive effects (e.g., through increased nutrient supply) and negative effects (e.g., through metal toxicity, lowered seawater pH, and increased turbidity) on marine microplankton communities. The paper by Liu et al. (2013) examines changes in the abundance, morphotype (form) diversity, and size of sponge spicules across the PTB in two deep-shelf sections, Dongpan in Guangxi Province and Maanying in Guizhou Province. It shows that the PTME was accompanied by not only strong reductions in spicule abundance and diversity but also a pronounced miniaturization stage in spicule size. The authors infer that a decline in nutrient availability and a shift toward more reducing conditions were the most likely causes of the observed changes in sponge spicule assemblages, although they note that other factors (e.g., extreme warming; Sun et al., 2012) cannot be ruled out. One key observation of this study is that the two study sections exhibit differences in the timing and intensity of the sponge biocrisis. The deeper-water section (Dongpan) is characterized by an earlier onset of spicule miniaturization and by a complete disappearance of sponges prior to the PTB, whereas the shallower-water section (Maanying) documents survival of at least some sponge forms into the Early Triassic, possibly because the shallow setting was a less hostile environment for sponges to inhabit during the crisis. This observation may be of relevance to the nearshore refugium hypothesis (Beatty et al., 2008; Zonneveld et al., 2010). Although some marine faunal clades rebounded during the Early Triassic, a complete, healthy marine ecosystem trophic structure was not reestablished until the middle to late Anisian (early Middle Triassic) (Chen and Benton, 2012). Evidence for ecosystem recovery comes from fossil Lagersta¨tten such as the Luoping Biota, a diverse marine reptile fauna from the early Middle Triassic of Yunnan Province in southwestern China (Hu et al., 2011). One factor that may have contributed to the exceptional preservation of this biota is widespread development of microbial mats during the Early Triassic (Pruss et al.,
2004; Baud et al., 2007). In their contribution to this thematic issue, Luo et al. (2013) describe a new type of microbial mat found in association with the Luoping Biota. These mats exhibit well-formed reticulated ridge structures in dolomite that are morphologically similar to wrinkle structures preserved in the other Lower Triassic siliciclastic settings (Pruss et al., 2004; Mata and Bottjer, 2009). The authors infer that these structures are of biogenic origin, and that they played a crucial role in fossil preservation through rapid sealing and prevention of oxidative degradation. More generally, matground ecosystems may have provided habitable environments for metazoans at various trophic levels during the Early-Middle Triassic marine ecosystem recovery. Most of the papers in this thematic issue were presented at the IGCP 572 Symposium that was held jointly with the XVII International Congress on the Carboniferous and Permian, 3–8 July 2011, in Perth, Australia. This special publication is timely because IGCP Project 572 members have made great efforts to gain new insights concerning the Permian–Triassic mass extinction and its aftermath since 2008. We hope that the new studies included in this special issue will further our understanding of biota-environment coevolution during this critical period of Earth history. ACKNOWLEDGMENTS We are grateful to journal coeditors Stephen Hasiotis and John-Paul Zonneveld and to the reviewers, Benoit Beauchamp, Zhong-Qiang Chen, Matthew Clapham, Margaret Fraiser, Charles Henderson, Tea Kolar-Jurkovsek, Pedro Marenco, Sara Pruss, Adam Woods, Jiaxin Yan, and Hongfu Yin for their critical reviews of the papers collected in this thematic issue. ZQC’s work is supported by the 973 Program of China (2011CB808800 to SCX) and the 111 Program of China (B08030 to SCX), and an aid grant (GPMR201302 to ZQC). This thematic issue is a contribution to the IGCP 572 ‘‘Permian–Triassic ecosystems.’’ REFERENCES ALGEO, T.J., HANNIGAN, R., ROWE, H., BROOKFIELD, M., BAUD, A., KRYSTYN, L., and ELLWOOD, B.B., 2007, Sequencing events across the Permian–Triassic boundary, Guryul Ravine (Kashmir, India): Palaeogeography, Palaeoclimatology, Palaeoecology, v. 252, p. 328–346. ALGEO, T.J., CHEN, Z.Q., FRAISER, M.L., and TWITCHETT, R.J., 2011, Terrestrialmarine teleconnections in the collapse and rebuilding of Early Triassic marine ecosystems: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 308, p. 1–11. ALROY, J., ABERHAN, M., BOTTJER, D.J., FOOTE, M., FURSICH, F.T., HARRIES, P.J., HENDY, A.J.W., HOLLAND, S.M., IVANY, L.C., KIESSLING, W., KOSNIK, M.A., MARSHALL, C.R., MCGOWAN, A.J., MILLER, A.I., OLSZEWSKI, T.D., PATZKOWSKY, M.E., PETERS, S.E., VILLIER, L., WAGNER, P.J., BONUSO, N., BORKOW, P.S., BRENNEIS, B., CLAPHAM, M.E., FALL, L.M., FERGUSON, C.A., HANSON, V.L., KRUG, A.Z., LAYOU, K.M., LECKEY, E.H., NURNBERG, S., POWERS, C.M., SESSA, J.A., SIMPSON, C., TOMASOVYCH, A., and VISAGGI, C.C., 2008, Phanerozoic trends in the global diversity of marine invertebrates: Science, v. 321, p. 97–100. BAUD, A., RICHOZ, S., and PRUSS, S., 2007, The Lower Triassic anachronistic carbonate facies in space and time: Global and Planetary Change, v. 55, p. 81–89. BEATTY, T.W., ZONNEVELD, J.-P., and HENDERSON, C.M., 2008, Anomalously diverse Early Triassic ichnofossil assemblages in northwest Pangea: A case for a shallowmarine habitable zone: Geology, v. 36, p. 771–774. BENTON, M.J., and TWITCHETT, R.J., 2003, How to kill (almost) all life: The endPermian extinction event: Trends in Ecology and Evolution, v. 18, p. 358–365. BRAYARD, A., ESCARGUEL, G., BUCHER, H., MONNET, C., BRU¨HWILER, T., GOUDEMAND, N., GALFETTI, T., and GUEX, J., 2009, Good genes and good luck: Ammonoid diversity and the end-Permian mass extinction: Science, v. 325, p. 1118–1121. BROOKFIELD, M.E., TWITCHETT, R.J., and GOODINGS, C., 2003, Palaeoenvironments of the Permian-Triassic transition sections in Kashmir, India: Palaeogeography, Palaeoclimatology, Palaeoecology, v. 198, p. 353–371. BROOKFIELD, M.E., ALGEO, T.J., HANNIGAN, R., WILLIAMS, J., and BHAT, G.M., 2013, Shaken and stirred: Seismites and tsunamites at the Permian–Triassic boundary, Guryul Ravine, Kashmir, India: PALAIOS, v. 28, p. 568–582, doi: 10.2110/ palo.2012.p12-070r. CHEN, Z.Q., and BENTON, M.J., 2012, The timing and pattern of biotic recovery following the end-Permian mass extinction: Nature-Geoscience, v. 5, p. 375–383.
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