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Ice Volume and Paleoclimate History of the Late Paleozoic Ice Age from Conodont Apatite Oxygen Isotopes from Naqing (Guizhou, China)

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Ice Volume and Paleoclimate History of the Late Paleozoic Ice Age from Conodont Apatite Oxygen Isotopes from Naqing (Guizhou, China) PALAEO-07632; No of Pages 11 Palaeogeography, Palaeoclimatology, Palaeoecology xxx (2016) xxx–xxx Contents lists available at ScienceDirect Palaeogeography, Palaeoclimatology, Palaeoecology journal homepage: www.elsevier.com/locate/palaeo Ice volume and paleoclimate history of the Late Paleozoic Ice Age from conodont apatite oxygen isotopes from Naqing (Guizhou, China) Bo Chen a,⁎, Michael M. Joachimski b, Xiang-dong Wang c, Shu-zhong Shen a,Yu-pingQic, Wen-kun Qie c a State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, PR China b GeoZentrum Nordbayern, Universität Erlangen-Nürnberg, Schlossgarten 5, 91054 Erlangen, Germany c Key Laboratory of Economic Stratigraphy and Paleogeography, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, 39 East Beijing Road, Nanjing 210008, PR China article info abstract Article history: A high-resolution and continuous conodont apatite oxygen isotope record spanning the late Viséan to Middle Received 5 August 2015 Permian is reported from South China, which is interpreted with respect to the ice volume and/or tropical seawa- Received in revised form 21 December 2015 ter temperature history of the Late Paleozoic Ice Age (LPIA). The presented δ18O record shows significant fluctu- Accepted 1 January 2016 ations in δ18O from the late Viséan to Middle Permian with highest values observed in the Bashkirian (Early Available online xxxx Pennsylvanian). The δ18O maximum coincides with a major eustatic sea level fall recorded in low-latitude succes- sions and postdates the significant increases in 87Sr/86Sr and δ13C measured on well-preserved brachiopod Keywords: carb fl fi Oxygen isotopes calcite, which can be interpreted as re ecting intensi ed weathering as consequence of the closure of Rheic Conodont apatite Ocean as well as enhanced carbon burial. Both processes may have contributed to lower greenhouse gas levels Late Palaeozoic Ice Age and cooled down the Earth's surface, triggering the maximum glaciation. The high Bashkirian δ18O values are Bashkirian interpreted to represent the glacial maximum of the LPIA. A coeval change in faunal composition and a decreasing Maximum glaciation diversity in climate-sensitive marine invertebrates can be ascribed to icehouse cooling and/or loss of habitat. De- Naqing section spite inconsistencies with earlier interpretations that the Early Permian represented the glacial maximum of the LPIA as inferred from Gondwanan glacial sediments records, the suggested Bashkirian glacial maximum agrees well with ice extent estimates based on the regional tectonic history in Gondwana, which suggests that the Bashkirian glaciation occurred during Gondwana interior uplift promoting maximum ice cover of the entire LPIA. However, maximum glaciation is only poorly represented in the depositional record because large parts of the glacial deposits were possibly removed by erosion as outlined by a major regional unconformity. © 2016 Elsevier B.V. All rights reserved. 1. Introduction of Gondwana (Crowell and Frakes 1970; Caputo and Crowell 1985; Dickins 1997; López-Gamundí 1997; Isbell et al. 2003a; Fielding et al. The Late Palaeozoic Ice Age (LPIA) has been widely recognized as the 2008a, 2008b, 2008c; Gulbranson et al. 2010). Ice volume changes in longest ice age during the Phanerozoic, which occurred at a time while this dynamic LPIA model are critical for assessing the LPIA's extent, the Earth's physical, chemical, and biological systems experienced pace as well as its climatic influences. major changes (Heckel 1994, 2008; Falcon-Lang 2004; Joachimski Based on the palaeogeographic distribution of glacial sediments, the et al. 2006; Clapham and James 2008; Grossman et al. 2008; Isbell ice volume of the LPIA was generally thought to reach its first peak dur- et al. 2008a; Falcon-Lang and DiMichele 2010). Early studies considered ing the Bashkirian, followed by a contraction in the Late Pennsylvanian. the LPIA glaciation as a single massive ice sheet that waxed and waned Maximum ice volume was suggested to occur in the Early Permian, be- continuously across Gondwana for more than 100 million years fore the demise in the middle Sakmarian (Isbell et al. 2003a, 2003b, (Veevers and Powell 1987; Frakes and Francis 1988; Frakes et al. 2012) or the end of the Capitanian and early Wuchiapingian (Fielding 1992; Ziegler et al. 1997; Hyde et al. 1999; Blakey 2008; Buggisch et al. 2008a, 2008b, 2008c; Mory et al. 2008; Waterhouse and Shi et al. 2011). However, this concept was challenged recently due to in- 2010; Frank et al. 2015). Besides the sedimentary record, indirect prox- creasing evidence that indicated a more dynamic LPIA characterized ies, such as eustatic sea level changes inferred from low-latitude sedi- by multiple, short-lived glaciations of 1–8 million years duration alter- mentary sequences, are considered as alternative and potentially more nating with non-glacial or warm periods having approximately identi- reliable proxy to reconstruct the ice volume history during the LPIA. Sig- cal duration (Fielding et al. 2008a, 2008b). Further, onset and demise nificant eustatic sea level changes in low-latitude successions are gener- of these glaciations were found to be asynchronous in various parts ally coincident with variations in continental ice volume (Rygel et al. 2008), but many uncertainties remain in estimating both magnitude ⁎ Corresponding author. of sea level and ice volume change (Fielding et al. 2008b; Rygel et al. E-mail address: [email protected] (B. Chen). 2008). As a consequence, disparities are usually found while comparing http://dx.doi.org/10.1016/j.palaeo.2016.01.002 0031-0182/© 2016 Elsevier B.V. All rights reserved. Please cite this article as: Chen, B., et al., Ice volume and paleoclimate history of the Late Paleozoic Ice Age from conodont apatite oxygen isotopes from Naqing (Guizhou, Chin..., Palaeogeogr. Palaeoclimatol. Palaeoecol. (2016), http://dx.doi.org/10.1016/j.palaeo.2016.01.002 2 B. Chen et al. / Palaeogeography, Palaeoclimatology, Palaeoecology xxx (2016) xxx–xxx glacial records from higher latitudes and sea level records from tropical of secular changes in the oxygen isotope ratio of seawater and/or successions. For example, cyclothems documented to dominate late palaeotemperature may be complicated by compiling oxygen isotope Middle through Late Pennsylvanian strata in Midcontinent of North data from different areas or palaeocontinents (e.g., Korte et al. 2005; America, the Moscow Basin in Russia, the Donets Basin in Ukraine, and Frank et al. 2008). In contrast, continuous oxygen isotope records other low-latitude areas are interpreted as far-field effects of waxing from a specific area may provide more straightforward and reliable and waning of Gondwanan ice sheets (Alekseev et al. 1996; Heckel data for reconstructing the palaeoclimate history. 2008; Eros et al. 2012). However, sedimentary records from Gondwana In this paper, we present a continuous oxygen isotope record indicate the absence of coeval glacial deposits (Isbell et al. 2003a). from the late Viséan to Middle Permian (Middle Mississippian to The oxygen isotope composition of biogenic apatite or calcite can re- Guadalupian) based on the analysis of conodont apatite from the cord ice volume changes as well as changes in seawater temperature. Naqing section in the Guizhou Province, South China. The δ18O record Oxygen isotope studies using well-preserved brachiopod shell calcite comprises almost the entire LPIA and thus provides a continuous ice or conodont apatite have demonstrated a significant increase/decrease volume and/or tropical sea surface temperature history. In addition, in δ18O coinciding with major ice buildup/melting phases as indicated we discuss how the tropical biosphere responded to the transitions by glacial deposits (e.g., Mii and Grossman 1999; Mii et al. 2001; between interglacial and maximum glacial conditions during the LPIA. Grossman et al. 2008; Buggisch et al. 2008; Frank et al. 2008) but also showed that some isotope oscillations are not compatible with glacia- 2. Geological setting tion/deglaciation events (Frank et al. 2008; Isbell et al. 2012; Chen et al. 2013). Potential diagenetic alteration, local environmental effects, Conodont samples were collected from the Naqing section located and the lack of temporal and spatial coverage of the isotope records about 44 km southwest of Luodian City in southern Guizhou Province, were suggested as potential reasons for the disagreement (Grossman South China (Fig. 1). The section is characterized by a continuous Car- et al. 2008; Frank et al. 2008). For instance, large differences in oxygen boniferous to Permian carbonate sequence with abundant conodont el- isotope ratios measured on Permian brachiopods and conodonts from ements and fusulinids. Lithologically, the section is dominated by dark different palaeocontinents suggest that local climate conditions grey and grey limestones with frequent silicified or cherty limestones (e.g., evaporation/precipitation ratio) might have significantly influ- horizons (Mei et al. 1999; Henderson and Mei 2003) deposited in a enced δ18O values of brachiopods and conodonts. Most importantly, slope setting of the Luodian basin in the Dian–Qian–Gui platform no general trend is visible if Permian brachiopod or conodont δ18O (Fig. 1), located near the palaeoequator in the eastern Tethys during data from different areas are plotted together (Grossman et
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