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Middle Permian (Capitanian) seawater 87 Sr/ 86 Sr minimum coincided with disappearance of tropical biota and reef collapse in NE Japan and Primorye (Far East Russia)
... The coeval 87 Sr/ 86 Sr values measured for whole-rock samples of fine-grained limestone (micrite) generally agree with those of brachiopods. Figure 2 (upper) displays the 87 Sr/ 86 Sr curve compiled from previous data ( Supplementary Table S1; references in Korte and Ullman 2016;Kani et al., 2008;Kani et al., 2013;Song et al., 2015;Kani et al., 2018;Wang et al., 2018;Li et al., 2020;Shen et al., 2020) from samples of biostratigraphically dated and well-preserved (diagenetically screened) brachiopod shells, conodonts and micrite samples. When Burke et al. (1982) first reported the Phanerozoic Sr isotope curve as a global seawater signal, nonmetamorphosed micrite samples were regarded to be promising for high-resolution Sr isotope stratigraphic correlation because a good correlation was confirmed between the brachiopod shell and associated micrites. ...
... The Capitanian minimum (∼0.7069) marks the termination of the decrease, and the extremely low value lasted the entire Capitanian (ca. 5 m.y.) (Kani et al., 2008;Kani et al., 2013). The average of reliable brachiopods was 0.70684 ± 0.00015 [standard deviation (SD), n 6] (data from Korte et al., 2006) and the average of all types of carbonates was 0.70694 ± 0.00012 (SD, n 147; data from Denison et al., 1994;Martin and Macdougall, 1995;Morante, 1996;Korte et al., 2006;Wang et al., 2018;Kani et al., 2008;Kani et al., 2013;Kani et al., 2018) in the Capitanian, equal to the minimum values in the Mesozoic curve (0.70683, the earlymiddle Oxfordian transition, Late Jurassic) (Wierzbowski et al., 2017) as the lowest 87 Sr/ 86 Sr ratios in the Phanerozoic. ...
... A negative shift in δ 13 C immediately before the GLB indicates that a major perturbation has occurred in the global carbon cycle (e.g., Wang et al., 2004;Kaiho et al., 2005;Isozaki et al., 2007;Saitoh et al., 2013). Several possible mechanisms for causing this perturbation were proposed; e.g., sea-level change (Wang et al., 2004), ocean stratification and anoxia (Isozaki et al., 2007;Tierney, 2010), methane release (Kani et al., 2018), Australia (Morante, 1996), Akasaka (Kani et al., 2013), Kamura (Kani et al., 2008), New Mexico (Denison et al., 1994), Texas (Denison et al., 1994;Martin and Macdougall, 1995;Korte et al., 2006), Utah (Denison et al., 1994), South China block (Denison et al., 1994;Korte et al., 2003;Korte et al., 2004;Korte et al., 2006;Song et al., 2015;Wang et al., 2018;Li et al., 2020;Li et al., 2021), Iran (Denison et al., 1994;Korte et al., 2003;Korte et al., 2004;Korte et al., 2006;Sedlacek et al., 2014), and European Zechstein (Korte et al., 2006). All data were adjusted to NIST SRM 987 0.710248 (McArthur et al., 2001) and recalculated according to the Geologic Time Scale 2012 . ...
The long-term trend in the Paleozoic seawater ⁸⁷Sr/⁸⁶Sr was punctuated by a unique episode called the “Capitanian minimum” at the end of the Guadalupian (Permian; ca. 260 Ma). This article reviews the nature and timing of this major turning point in seawater Sr isotope composition (⁸⁷Sr/⁸⁶Sr, δ⁸⁸Sr) immediately before the Paleozoic-Mesozoic boundary (ca. 252 Ma). The lowest value of seawater ⁸⁷Sr/⁸⁶Sr (0.7068) in the Capitanian and the subsequent rapid increase at an unusually high rate likely originated from a significant change in continental flux with highly radiogenic Sr. The assembly of the supercontinent Pangea and its subsequent mantle plume-induced breakup were responsible for the overall secular change throughout the Phanerozoic; nonetheless, short-term fluctuations were superimposed by global climate changes. Regarding the unidirectional decrease in Sr isotope values during the early-middle Permian and the Capitanian minimum, the suppression of continental flux was driven by the assembly of Pangea and by climate change with glaciation. In contrast, the extremely rapid increase in Sr isotope values during the Lopingian-early Triassic was induced by global warming. The unique trend change in seawater Sr isotope signatures across the Guadalupian-Lopingian Boundary (GLB) needs to be explained in relation to the unusual climate change associated with a major extinction around the GLB.
... 1: GSC 141726, axial section, 51F7-18-22; r Polytaxis cf. linea (Ozawa, 1925) Kani et al. (2018) suggest that the position of the Sen'kina Shapka and Iwaizaki areas would be located on the uppermost part of the Greater South China Block genus Neoendothyranella also are known from a limestone block in Kampuchea (Cambodia), at the locality Sampou where it was identified as Neoendothyra (Nguyen Duc Tien 1986: pl. 4, fig. 2). ...
... On the Asian side of the Paleo-Pacific, a Middle Permian paleobiogeographic fusulinid faunal connection of the South Primorye, Northeast China, and the South Kitakami Terrane of NE Japan with the so-called Northern Transitional Zone of Shi et al. (1995) was proposed by Ueno (2006) in his study of the distribution of the fusulinid genus Monodiexodina. A slightly different Wordian-Capitanian (Middle Permian) paleobiogeographic connection between the Sen'kina Shapka section of the South Primorye and the Iwaizaki section of the South Kitakami Belt of NE Japan, and northern part of Greater South China has recently been suggested by Kani et al. (2018). ...
... ellipsoidalis Sosnina, and Lepidolina shiraiwensis (Ozawa), Russian Far East forms, from a slump block (sample 10VD98) of a locality in southwestern Japan. Their proposed position of the Primorye area is to the east of the areas suggested by Ueno (2006) and Kani et al. (2018). ...
New foraminiferal assemblages consisting of fusulinids and smaller foraminifers have been described from a basalt/carbonate rock block (locality 51F7) and small outcrop of thin-bedded limestone (locality 51F6) located near the entrance to Marble Canyon west–southwest of the town of Cache Creek in southern British Columbia, Canada. The locality 51F7 contains diverse fusulinid and smaller foraminiferal faunas, whereas the locality 51F6 contains only fusulinids. The studied fusulinid assemblage is totally devoid of neoschwagerinids or verbeekinids, and contains genera such as Sichotenella and Wutuella that have never been reported from the Western Hemisphere. The studied foraminiferal fauna contains a group of taxa very similar to several species described from the Primorye area of the Russian Far East and Japan. Some fusulinids present, Reichelina and Codonofusiella, and smaller foraminifers are also similar to Capitanian age species of the Delaware Basin area of West Texas. The age of the British Columbia fauna appears to be Middle Permian, Guadalupian, earliest Capitanian, but a latest Wordian age cannot be excluded. Four new species are described: Reichelina cachecreekensis sp. nov., Sichotenella danneri sp. nov., Codonofusiella marblensis sp. nov., and Parafusulina turquoisensis sp. nov.
... The sharp drop from the earliest Permian to the Middle Permian is recognized as the largest continuous decline in marine 87 Sr/ 86 Sr ratios of the Phanerozoic (Korte and Ullmann, 2016;McArthur et al., 2020). The 87 Sr/ 86 Sr ratios in the late-Guadalupian registered the lowest values in the Paleozoic (Kani et al., 2008(Kani et al., , 2013(Kani et al., , 2018. A number of hypotheses have been put forward to explain the decline in seawater 87 Sr/ 86 Sr from the Early to Middle Permian. ...
... A significant number of studies have focused on geologically short intervals surrounding the Guadalupian-Lopingian boundary (GLB, ~ 259.1 Ma; Kani et al., 2008Kani et al., , 2013Kani et al., , 2018Liu et al., 2013) and the PTB (~ 251.9 Ma; Brand et al., 2012b;Cao et al., 2009;Dudás et al., 2017;Garbelli et al., 2016;Huang et al., 2008;Martin and Macdougall, 1995;Sedlacek et al., 2014;Song et al., 2015), but interpretations remain controversial. Some of the debates center around (i) the stratigraphic position of the lowest 87 Sr/ 86 Sr ratios (Kani et al., 2008(Kani et al., , 2013(Kani et al., , 2018 and (ii) the rates of change in 87 Sr/ 86 Sr ratios at different Permian substages (Cao et al., 2009;Dudás et al., 2017;Huang et al., 2008;Song et al., 2015). ...
... A significant number of studies have focused on geologically short intervals surrounding the Guadalupian-Lopingian boundary (GLB, ~ 259.1 Ma; Kani et al., 2008Kani et al., , 2013Kani et al., , 2018Liu et al., 2013) and the PTB (~ 251.9 Ma; Brand et al., 2012b;Cao et al., 2009;Dudás et al., 2017;Garbelli et al., 2016;Huang et al., 2008;Martin and Macdougall, 1995;Sedlacek et al., 2014;Song et al., 2015), but interpretations remain controversial. Some of the debates center around (i) the stratigraphic position of the lowest 87 Sr/ 86 Sr ratios (Kani et al., 2008(Kani et al., , 2013(Kani et al., , 2018 and (ii) the rates of change in 87 Sr/ 86 Sr ratios at different Permian substages (Cao et al., 2009;Dudás et al., 2017;Huang et al., 2008;Song et al., 2015). These differences potentially result in diverging interpretations of geologic events and inaccurate stratigraphic correlations. ...
The Permian Period is punctuated by Earth system changes unlike any other in geological history. The start of the Permian witnessed the termination of the Late Paleozoic Ice Age, followed by the climatic transition from icehouse to greenhouse conditions. The Guadalupian-Lopingian (Middle-Late Permian) was characterized by two biocrises associated to volcanisms: (i) the end-Guadalupian crisis and (ii) the end-Permian mass extinction. Seawater Sr isotope (⁸⁷Sr/⁸⁶Sr) records can shed light on the evolution of the Permian Earth system. The Permian ⁸⁷Sr/⁸⁶Sr record suffers from a number of issues including low resolution and potential diagenetic alteration. In this paper, we summarize the existing Permian ⁸⁷Sr/⁸⁶Sr records and focus on the current challenges. We also present a new, high-resolution Permian ⁸⁷Sr/⁸⁶Sr curve derived from pristine brachiopod shells based on data resulting from careful diagenetic screening. Our new record shows that the ⁸⁷Sr/⁸⁶Sr of seawater decreased continuously from the earliest Permian to the middle Capitanian (late Guadalupian), with the lowest ratio of 0.706832 registered in the Colania douvillei-Kahlerina pachiytheca Zone. Subsequently, ⁸⁷Sr/⁸⁶Sr ratios increased from the late Capitanian to the latest Permian and reached a ratio of 0.707167 just 0.8 m below the first occurrence of the Hindeodus parvus. We employed a stochastic oceanic box model to explore the potential drivers of the Permian seawater Sr isotope record. Our results support that changes in the hydrothermal input, rather than changes in continental weathering intensity, are the most likely controlling factor for the observed variations in Permian seawater ⁸⁷Sr/⁸⁶Sr. Therefore, we suggest that the marine hydrothermal system (and hence ocean basin dynamics and deep-sea temperatures) may have been the driver of the pronounced decreasing ⁸⁷Sr/⁸⁶Sr trend across the Permian.
... In recent years, however, evidence has accumulated for a 'sixth' major mass extinction event in the geologic past at the end of the Guadalupian Stage 259.8 Ma) at the midlate Permian boundary (Jin et al. 2006;Stanley 2007Stanley , 2016McGhee et al. 2013;Zhong et al. 2014;Kani et al. 2018). For a long time, this Guadalupian-Lopingian boundary event (also called the pre-Lopingian crisis) (Jin 1993;Jin et al. 1994) was largely overlooked, but work beginning in the 1990s led to a re-evaluation of the significance of that mass-extinction event (Jin 1993;Stanley and Yang 1994;Jin et al. 1994Jin et al. , 1995Shen and Shi 1996;Stanley 2016). ...
... The end-Guadalupian marine mass extinction affected shallow-water, nektonic and pelagic species (Jin et al. 1994;Shen and Shi 1996;Wang and Sugiyama 2000;Lai et al. 2008;Kani et al. 2018) and was ranked third in taxonomic severity using fossil range data by Sepkoski (1996), with an estimated 47% loss of marine genera, and also third most severe by Bambach et al. (2004) with an estimated 36% loss of marine genera (Table 1(a)). Stanley (2007) listed the end-Guadalupian extinction event with 45.7% of extinction of 'Modern-type' marine genera, and 62.1% of 'Paleozoic-type' marine genera, as the third most severe out of the eight mass-extinction events that he considered (Table 1(b)). ...
... Large volumes of greenhouse gases (CO 2 and CH 4 ) derived from the volcanism may have led to an episode of extremely warm global temperatures affecting marine and non-marine taxa, surface-ocean acidification (Rampino et al. 2019) and to warm and poorly oxygenated oceans, culminating in widespread ocean anoxia (Clapham and Payne 2011;Bond et al. 2015). By contrast, Isozaki et al. (2007aIsozaki et al. ( ), 2007bIsozaki et al. ( , 2011 suggested a brief cooling and drop in sea level (the Kamura Event) just prior to the Guadalupian-Lopingian boundary as a cause of the extinction event (Kani et al. 2018). ...
The modern loss of species diversity has been labelled the ‘sixth extinction’ subsequent to the five major mass extinctions widely recognised in the Phanerozoic geologic record – the end-Ordovician (443.8 Ma), the Late Devonian (372.2 Ma), end-Permian (251.9 Ma), end-Triassic (201.4 Ma) and end-Cretaceous (66 Ma) events. Rankings in terms of numbers of genera suffering extinction, and especially in terms of ecological impact, however, put the end-Guadalupian (end-Capitanian) (259.8 Ma) extinction event in the same category with the other major mass extinctions. Thus, there were apparently six major Phanerozoic mass extinctions, and the current loss of species should perhaps be called the ‘seventh extinction’.
... gian was a period of reef recovery (Huang et al., 2017;Wang et al., 2019). Long-term marine acidification (Beauchamp and Grasby, 2012) or climate cooling (Kani et al., 2018) were suggested as the cause of the decline of carbonate production. However, the process of the reduction in carbonate extent, as well as its implications for the coeval biotic and environmental evolution remains unclear. ...
... The subtropical to tropical paleo-Tethys is another region with thriving Guadalupian carbonate platforms (Fig. 1A). In the Arabian isolated platform and southern Primorye in Far East Russia (Fig. 1A, locations 5 and 9), the retreat of carbonate platform margins is evidenced by a facies shift from bioclastic limestone to mudstone or cherts in the upper part of the Guadalupian succession (Weidlich and Bernecker, 2007;Kani et al., 2018). Similar changes occur in Transcaucasia, the Abadeh area and the Pha Nok Khao platform (Fig. 1A, locations 6-8), where light grey, thick-bedded limestone becomes increasingly blackish and thinner, and contains a higher chert proportion upwards both in the middle and upper parts of the Capitanian succession, reflecting platform contraction during the T2 and T3 transgressions, respectively (Leven, 1998;Hada et al., 2015, Fig. 4;Arefifard and Payne, 2020, Fig. 10b). ...
In comparison with the amount of study undertaken on the end-Permian mass extinction, the preceding Guadalupian mass extinction has received little investigation, even though it marks a significant biotic turnover associated with global environmental changes. During the earlier event, reef carbonate production shut down and was replaced by siliceous, mud-rich deposits (SRDs) in South China. However, changes in carbonate platform productivity during this epoch remain to be clarified. This paper presents sedimentological and conodont biostratigraphic investigations on the Guadalupian SRDs developed on the Yangtze Carbonate Platform (YCP) in central Guizhou. The findings are viewed in the context of Guadalupian sequence correlation of South China successions, which shows that the integrity of the YCP failed to match the platform tectonic evolution. The platform evolution saw the onset of major intra-platform depressions and the gradual onlap by SRDs along the platform margin. Stratigraphic correlation reveals that the platform experienced three phases of onlap by SRDs during the early Roadian, the late Wordian and the late Capitanian upwards. Platform carbonates re-expanded their extent following the first two phases, but not during the final phase. An evolutionary model is proposed for the Guadalupian carbonate platform, which follows the contemporaneous eustatic sea-level fluctuations. The partial drowning observed within the platform interior and increasing retreat along the platform margin could suggest an insufficient carbonate sediment supply shedding from the platform top during the Guadalupian. The variation in carbonate productivity raises our attention to the change in shallow-water carbonate factories, which is closely related to the fortunes of carbonate-secreting biota and environmental factors impacting the carbonate platform producers during the Guadalupian.
... The paleotemperature curve reconstructed from δ 18 O of conodonts or shells of brachiopods may have been influenced by changes in biological habitat depth (Chen et al., 2013;Wang et al., 2020), and the accuracy may be limited by the inability to continuously sample. It is difficult to distinguish whether the Capitanian minimum of seawater Sr isotope ratios resulted from mid-ocean ridge spreading due to the convergence to the Pangea or suppression of weathering/erosion of continental crust related to cool climate (Kani et al., 2018). ...
The Late Paleozoic Ice Age (LPIA) represents the most recent ice-house state on Earth, attracting significant interest from those studying recent climate change and contemporary global warming. But the duration and evolutionary pattern of LPIA are still controversial, especially when it comes to the Middle-Late Permian. A series of weathering indices on detrital sediment built from a carbonate-dominated succession in central China provides an opportunity to reveal the Capitanian to Wuchiapingian climatic fluctuations in the low latitudes and their far-field responses to the Permian glacial evolution. The weathering indices exhibit consistent trends and divide the Capitanian to Wuchiapingian interval into four phases. The first and third phases are characterized by relatively lower values in weathering indices of logarithmic parameters, CIAcor, CIXcor, CIW, αAlNa, and relatively higher values of τNa and WIPcor, which suggest a relatively cold climate occurring in the early Capitanian and late Capitanian to early Wuchiapingian. These two cold phases were relevant to the Permian glacial epochs of P3 and P4. While the second and fourth phases show opposite features in those weathering indices, which indicate the middle Capitanian and late Wuchiapingian were under a relatively warm climate. The third phase was superimposed by several cooling-warming cycles, which keep consistent in tune with sea-level fluctuations. Both of them have an average duration of about 1.0 Ma, possibly suggesting an astronomical (obliquity)-forced glacioeustatic controlling mechanism for the unstable P4 epoch. The end of co-variation of climate and sea-level fluctuation and the increase of weathering indices happened in the middle Wuchiapingian, which suggests the demise of Permian glaciation. Additionally, the latest Capitanian warming period that happened during the P4 glaciation interval corresponds to the increasing strength of the eruption of the Emeishan Large Igneous Province (ELIP), which possibly indicates the interruption of P4 was mainly controlled by the active ELIP. The limited diversity loss at the end-Guadalupian was suggested as a result of climate warming to a restricted degree, due to a limited rate and magnitude of ELIP volcanism that happened in a cold period.
... This results in a δ 13 C negative excursion throughout the exogenic carbon reservoir, which is then recorded in marine carbonate rocks. In addition, the Capitanian minimum of 87 Sr/ 86 Sr ratios may have been related to enhanced igneous activity (main peak of the ELIP) ( Fig. 8E; McArthur et al., 2012;Kani et al., 2013Kani et al., , 2018Kani and Isozaki, 2021;Wang et al., 2018;. ...
The Guadalupian-Lopingian boundary (GLB) transition was regarded as a gradual warming period with the termination of the Late Paleozoic Ice Age (LPIA). However, the glacial-nonglacial cycles from Eastern Australia imply that the period was also influenced by climatic fluctuations. We here report on a GLB section of the South China Block confined by the conodont biostratigraphy to constrain weathering intensity and the associated climatic fluctuations during this critical interval. The chemical weathering indices were estimated by analyses of acid-insoluble residues extracted from carbonate rocks. Two weak weathering units (Unit 1 and 3, Early Capitanian and Early Wuchiapingian) and two strong weathering units (Unit 2 and 4, Late Capitanian and Middle Wuchiapingian) are identified. δ13Ccarb generally follow well the variation tracks of weathering indices. Two weak weathering units (Unit 1 and 3) correspond to the P3 glacial and the P4 glacial in high-latitude region of Australia. The CIA-converted land surface temperature and reported seawater temperature reflect the synchronous response of continental climate and marine conditions. The strong weathering duration (Unit 2) is closely related to the eruption of the Emeishan Large Igneous Province (ELIP) which promoted the temperature raising and induced the waning of high-latitude ice sheet accordingly. The climatic fluctuations paced with the onset, surge, and weakening of the ELIP should be responsible for the remarkable continent-ocean-biodiversity system changes and GLB extinction.
... Since the discovery of the Emeishan LIP (ELIP) in southwestern China, its significant influence on paleoclimate and global ecosystems has attracted the attention of a number of scholars (e.g., Wignall 2001;Zhou et al. 2002;Xu et al. 2010;Tian et al. 2016). Previous work on quantifying the variations in paleoclimate during the ELIP period has mostly focused on the C and Sr isotopic compositions, clay mineral assemblage types, and paleobiology in marine strata during this period (Kani et al. 2018;Cheng et al. 2019). There has been a lack of quantitative studies of the paleoclimate that are conducive to comparison on larger spatial and temporal scales. ...
... The problem with this scenario is that it is a bit like 'having your cake and eating it' such that the traps cause both warming and cooling. Kani et al., (2018) in Russia and Arefifard (2018) ...
Latest version that removes previous errors and adds new data
... Many improvements in this curve have been proposed by Denison et al. (1994), Veizer et al. (1999) Several papers have been published discussing the Sr seawater evolution related to specific ages in distinct seawater masses around the world (e.g. Ordovician and Silurian of Laurentia, Qing et al., 1998;Middle Devonian in Germany, Ebneth et al., 1997; Middle to Upper Cambrian in the USA, Montanez et al., 1996; middle Permian in Japan-Russia, Kani et al., 2018). Concerning Sr isotopic studies of the Tapajós Group, there are a few publications only in Itaituba and Nova Olinda formations. ...
Isotopic signatures presented in carbonates and fossils herein are one of the first attempts.
to obtain Sr and Nd data for the Early – Middle Pennsylvanian of the Itaituba epeiric sea and to evaluate the paleoseawater and paleotectonic of the Amazonas Basin. ⁸⁷Sr/⁸⁶Sr data range from 0.708330 ± 0.000018 to 0.708850 ± 0.000046, with ΔSW varying from −60 to −87 reflecting the marine sedimentation, while ΔSW varying from −33 to −51 suggest a post-depositional alteration. These values are in general agreement with the ⁸⁷Sr/⁸⁶Sr global seawater curve evolution for this time. The increasing influx of Sr from landmasses in a restricted marine basin, the Itaituba Epicontinental Sea, reflecting enhanced continental weathering during low stand sea level is a potential explanation for the Amazonas Basin during this time. Plotted in the εNd(t = 310 Ma) isotopic global seawater curve evolution data for the Itaituba and the Nova Olinda formations shift to lower values of εNd(t = 310 Ma), when compared to the Panthalassa Ocean. Nd isotopic signature suggests an incoming of seawater masses also from other oceans (e.g. Paleo-Tethys), instead of a unique Panthalassa Ocean provenance of water during the Pennsylvanian in the Amazonas Basin. ¹⁴³Nd/¹⁴⁴Nd isotopic values showed scattered 0.511608 ± 0.000077 to 0.512270 ± 0.000012. Nd-TDM around 1.5 Ga and εNd present-day values around −15 support an old continental Nd provenance to the ancient seawater, similar to those present in the rocks from Amazonian Craton.
... The rapid eruption of the Emeishan basalts in the late Capitanian would release a large amount of acidic gas (CO 2 , SO 2 , HF, etc.) in a short time and cause sudden seawater acidification (Bond et al., 2010;Wu et al., 2020). The assumption of ocean acidification is consistent with the recession of carbonate production in both the tropical and boreal latitudes (Beauchamp & Grasby, 2012;Bond et al., 2015;Flügel & Kiessling, 2002;Kani, Isozaki, Hayashi, Zakharov, & Popov, 2018). ...
The end‐Guadalupian extinction is an important biotic event in the Phanerozoic with an ecological impact comparable to the ‘big five’ extinctions. However, the age, pattern, and mechanism of this extinction are all under debate. The bivalves of the Alatoconchidae family attained body volumes up to 10,000 cm³ and had a wide distribution in the low latitude Palaeotethys and Panthalassa. These giant clams originated in the early Kungurian and went extinct in the Late Guadalupian. Therefore, they are the typical victims of the end‐Guadalupian extinction and are major index fossils for the understanding of this event. Although extraction of these giant bivalves from the host‐resistant limestone is hard, plenty of new‐found transverse sections on outcrops are available for morphological reconstruction and volume estimation. The measurement from the representative fossil localities in South China indicates the clams achieved a substantial volume increase during the Wordian and sustained the giant size to the late Capitanian, till their abrupt disappearance. The giant clams originated under atmospheric hyperoxia and warm climate after the Late Palaeozoic Ice Age. Their body volume increase was roughly parallel to the seawater warming. The accompanied high seawater carbonate saturation and Mg/Ca ratio are beneficial to their biomineralization of the large shells with aragonite or high‐Mg calcite components. On the contrary, these giant bivalves were probably killed by the major or rapid changes of those environmental factors that once facilitated their success, such as drastic fluctuation of seawater temperature, sudden ocean acidification, and marine anoxia.
... Finally, we use data from Wang et al. (2018) after correcting to SRM 987 of 0.710248: their data were supposedly reported after normalization to that value but normalizing (subtraction of a further 0.000031) brings them into agreement with other data, so we assume that the reported data were not normalized as stated. Compared to previous LOESS fits, the Capitanian minimum in 87 Sr/ 86 Sr is revised downward by 0.000022 to a value of 0.706835 on the basis of data in Kani et al. (2018) and Garbelli et al. (2019). For an alternative view of this interval, see Wang et al. (2018) and also Korte and Ullmann (2018). ...
The ⁸⁷Sr/⁸⁶Sr value of Sr dissolved in the world’s oceans has varied through time in a known way. When minerals, such as biogenic calcite, precipitate from seawater, they incorporate Sr from seawater and capture the ⁸⁷Sr/⁸⁶Sr value for marine-Sr at the time of precipitation. Measurement of the ⁸⁷Sr/⁸⁶Sr value in fossil precipitates, such as belemnites or foraminifera, can therefore be used to date and to correlate worldwide the marine sedimentary rocks in which the precipitates occur. Here, the theory and practice of the methodology is outlined.
The variation of marine-⁸⁷Sr/⁸⁶Sr through time is usually ascribed to changing fluxes of Sr from mid-ocean-ridge volcanism (⁸⁷Sr/⁸⁶Sr≈0.703) coupled with changing ⁸⁷Sr/⁸⁶Sr and flux through time of riverine inputs to the ocean of Sr with a high ratio (≈0.711).
... Finally, we use data from Wang et al. (2018) after correcting to SRM 987 of 0.710248: their data were supposedly reported after normalization to that value but normalizing (subtraction of a further 0.000031) brings them into agreement with other data, so we assume that the reported data were not normalized as stated. Compared to previous LOESS fits, the Capitanian minimum in 87 Sr/ 86 Sr is revised downward by 0.000022 to a value of 0.706835 on the basis of data in Kani et al. (2018) and Garbelli et al. (2019). For an alternative view of this interval, see Wang et al. (2018) and also Korte and Ullmann (2018). ...
Paleomagnetic data have been obtained from heterogeneous, shallow-water, miogeoclinal carbonate rocks of the Pogonip Group (Early Ordovician) in the Desert Range of southern Nevada, the Egan Range of east-central Nevada, and the southern House Range of western Utah. These rocks locally contain abundant replacive chert that preserves relict textures from the host limestones as well as clearly detrital grains (e.g., blue-luminescing feldspars). Stylolites are abundant and are interpreted as late diagenetic features, as they cut late cements and truncate bedding lamination. Differential compaction along stylolites wrapping around the chert masses has resulted in macroscopic deformation, as evidenced by tilting of bedding of over 25° about chert masses in some cases. We have used the differential compaction fabrics in these rocks to test for the age of acquisition of a generally well-grouped and well-defined characteristic magnetization.
All three carbonate sections give a low-inclination, southerly to southeasterly magnetization residing in magnetite (e.g., Decl. = 152°, Incl. = −21°, α95 = 3°, kl = −61, k2 = −21, N = 48 independent samples, site 12; Pogonip Group, Sawmill Canyon, Egan Range). The magnetization is interpreted to be secondary and acquired after local compaction because directions of magnetizations from different samples are not dispersed by the compaction deformation. The uniform reversed polarity in addition to the direction of the magnetization, moreover, is interpreted to suggest a late Paleozoic age of remagnetization. In the Desert Range, the remagnetization had been previously attributed to a viscous partial thermoremanent magnetization (VPTRM) from deep burial. Based on several observations, we now argue for a chemical origin from late diagenetic magnetite, such as is now well-documented in the Appalachians and mid-continent. The cherts are almost nonmagnetic, as would be expected from their impermeability if the magnetite were precipitated from late fluids. Abundant authigenic alkali feldspar in the Desert Range is also consistent with late metasomatism. Finally, in the Egan Range, the remagnetization extends through a section exceeding 3 km in thickness, into rocks as young as Mississippian, which were never buried as deeply and thus not heated to the same degree as lower Paleozoic strata.
These results underscore the utility of integrating observations based on paleomagnetic data with carbonate textures. “Micro”-field tests can constrain both the timing of magnetization acquisition and of diagenetic events. The micro-fold tests discussed apply to features that are not formed by tectonic deformation. The availability of field tests from early formed textures in sedimentary rocks is especially important given the recent recognition of widespread remagnetization in ancient rocks.
... Finally, we use data from Wang et al. (2018) after correcting to SRM 987 of 0.710248: their data were supposedly reported after normalization to that value but normalizing (subtraction of a further 0.000031) brings them into agreement with other data, so we assume that the reported data were not normalized as stated. Compared to previous LOESS fits, the Capitanian minimum in 87 Sr/ 86 Sr is revised downward by 0.000022 to a value of 0.706835 on the basis of data in Kani et al. (2018) and Garbelli et al. (2019). For an alternative view of this interval, see Wang et al. (2018) and also Korte and Ullmann (2018). ...
The 87 Sr/ 86 Sr value of Sr dissolved in the world's oceans varied though time in a known way, facts that allow 87 Sr/ 86 Sr to be used to date and to correlate marine sedimentary rocks worldwide. In this work, the variation in 87 Sr/ 86 Sr is displayed graphically and the theory and practice of the methodology is discussed. Chapter Outline 7.
Located in the eastern Paleo-Tethys Ocean and near the equator, carbonate sedimentation widely developed in the Sichuan Basin in the Permian Guadalupian period. Although the growth and decline of carbonate particles are closely related to the surrounding sedimentary environment, the relationships between the grain composition and distribution of the northwest Sichuan Basin and the sedimentary environment are not clear. This study explored the particle type, particle content, and sedimentary structure of 300 thin sections from 19 wells and seven field profiles of the Guadalupian period in the northwest Sichuan Basin, identified seven microfacies and four microfacies associations, analyzed the sedimentary environment, and established a sedimentary evolution model. The results show that there was a warm-water Dasycladaceae-dominated and foraminifera-dominated open platform developed in the early Roadian era in the research area. As the climate cooled during the late Roadian era, the warm-water carbonate sedimentary environment was replaced by a cold-water bryozoan-dominated and echinoid-dominated marginal sedimentary environment. As the climate continued to cool and the sea level dropped, the platform margin grain beach sediment underwent further development in the early Wordian era. In the late Wordian era stage, the sedimentary environment was influenced by the Dongwu movement, resulting in sea level changes and acidification caused by hydrothermal activities, which reduced the degree of grain beach development. During the Capitanian era, the climate became warmer due to the eruption of the ELIP. The uplift caused by the Dongwu movement resulted in a relative shallowing of the platform margin region, and hence, the grain beach sediment only developed in the southwest, while the northeast was dominated by deepwater basin sediments. The sudden transition from a warm-water, autotroph-dominated carbonate open platform to a cold-water, heterozoan-dominated carbonate platform margin resulted from a combination of tectonic movements, rapid sea level changes, and sedimentary environment changes during the Guadalupian era.
The Permian–Triassic sedimentary succession in the Julfa region is lithostratigraphically composed of limestones and shales of the Julfa Formation, the Zal Member shales, and the Paratirolites Limestone of the Ali-Bashi Formation, as well as shales and carbonate beds of the Elikah Formation. The Lower Julfa Beds are rich in benthic organisms such as brachiopods and corals, while the Upper Julfa Beds and Ali-Bashi Formation contain pelagic assemblages including ammonoids, fishes, and conodonts. These rocks have already been studied from different palaeontological and geochemical perspectives, but most have focused on the strata near the Permian–Triassic boundary. In the present study, ammonoids from older intervals around the Wuchiapingin–Changhsingian boundary in the four stratigraphic sections Aras Valley, Ali-Bashi 1, Ali-Bashi 4, and Zal are outlined. Fourteen genera and 22 species of ammonoids were identified and assigned to five successive biozones. The Araxocers latissimum Zone in the Lower Julfa Beds and the Vedioceras ventrosulcatum Zone in the Upper Julfa Beds document the Wuchiapingian. Following upwards, the Iranites transcaucasius-Phisonites triangulus Zone, Dzhulfites nodosus Zone and Shevyrevites shevyrevi Zone in the Zal Member confirm an early Changhsingian age. This follows the previously presented ages based on conodonts.
Keywords: Permian, Julfa, Ammonoid, Wuchiapingian, Changhsingian.
Introduction
The northwestern region of Iran along the Permian was a part of the Cimmerian blocks, separated from the Gondwana margin, and migrated northward parallel to the opening of the Neo-Tethys Ocean. At the Permian–Triassic boundary, this region was located near the equator, surrounded by the Neo-Tethys in the south and Paleo-Tethys in the north (Stampfli and Borel 2002; Kent and Muttoni 2020). Northwestern Iran contains valuable Lopingian successions and holds evidence of the largest extinction event in Earth's history at the end of Permian. The classical stratigraphic sections in the Caucasus and Julfa have been of interest to geologists since the 19th century. (e.g., Abich 1878; Rieben 1934; Stepanov et al. 1969; Kozur 2007; Richoz et al. 2010; Ghaderi et al. 2014a, b; Korn et al. 2016; Gliwa et al. 2020). The Permian–Triassic sequences of Julfa and Ali-Bashi mountains have been studied by Stepanov et al. (1969). They have categorized the whole succession into eight major rock units, including Genishik Beds (A), Khachik Beds (B), Lower Julfa beds (C), Upper Julfa beds (D), Permian-Triassic Transition Beds (E), Paratirolites Limestone (F), Lower Elika Formation (G) and Upper Elika Formation (H). After Stepanov et al. (1969), Teichert et al. (1973) also reviewed the Ali-Bashi Mountains region, especially the units E and F in Stepanov et al. (1969) during four parallel stratigraphic sections (sections 1 to 4). They have combined E and F units and introduced a new formation called Ali-Bashi Formation. In the following years, the rock sequences in the Ali-Bashi Mountains have been of great importance for studying molluscan fossils and conodonts. Based on conodonts, brachiopods, and ammonoids, the biostratigraphic information and chemical stratigraphy of these stratigraphic sections have been studied in various papers over the last two decades (e.g., Kozur 2007; Shen and Mei 2010; Ghaderi et al. 2014a, b; Schobben et al. 2015, 2017; Korn et al. 2016) and have greatly improved our knowledge about this lesser-known area in Central Tethys. However, there are still deficiencies in some aspects. In the present paper, ammonoid fauna of the Wuchiapingian–Changhsingian boundary in four different stratigraphic sections of Aras valley, Ali-Bashi 1 and 4, and Zal has been identified, and the biostratigraphy of the sections is presented accordingly.
Material & Methods
142 different ammonoid specimens were taken in situ from the Julfa and Zal Beds, of which 84 belong to the Aras Valley section, 11 belong to Ali-Bashi 1, 18 belong to Ali-Bashi 4, and 29 belong to the Zal. Morphological characteristics of the specimens such as conch geometry and measurements of conch diameter, whorl height and width, apertural height, umbilical width, shape of the venter, arrangement and the shape of flanks, umbilical margin and the umbilical wall, shell ornaments such as growth lines, ribs, constrictions, and suture line were investigated according to Korn (2010) method. Cross-sections and suture lines of most of the ammonoids were drawn in Corel Draw 2019 software. Systematic paleontological studies have also been performed using various references (e.g., Ruzhencev and Shevyrev 1965; Zhao et al. 1978; Bando 1979; Kotlyar et al. 1983; Korn 2003; Leonova 2011; Ghaderi et al. 2014a; Korn et al. 2016; Korn and Ghaderi 2019). The ammonoid specimens discussed in this study are stored in the museum of the Geology Department of the Ferdowsi University of Mashhad, and some in the repository of the Museum fur Naturkundeh in Berlin, Germany.
Discussion of Results & Conclusions
The Lopingian ammonoid assemblages of the Julfa area have a different distribution in different parts of the sections in terms of abundance and species diversity; most of them are of late Changhsingian age in these successions (Ghaderi et al. 2014a; Korn et al. 2016). Older specimens of Lopingian have less variety and abundance. The fauna in this study includes 14 genera and 22 species of ammonoids of Julfa Beds and Ali-Bashi Formation Zal Member. Fourteen genera and 18 species have been identified in the Aras Valley section, eight genera and eight species in Ali-Bashi 1, 9 genera and 11 species in Ali-Bashi 4, and eight genera and 10 species in the Zal section. Based on the Korn and Ghaderi (2019) for the Aras Valley section and what has been obtained in the present study, the classic ammonoid biostratigraphy proposed for the Wuchiapingian–Changhsingian boundary interval in the Transcaucasia (Ruzhencev and Shevyrev 1965) revised and used for the Julfa region with some modifications.
The following biozones are described here and presented in ascending order:
Araxoceras latissimum Range Zone: Due to the partial outcrop of the Lower Julfa Beds in the Aras Valley section and the absence of their basal parts, the constituent interval of this biozone in the mentioned section is incomplete, and its thickness is small compared to other sections. The ammonoid assemblage accompanying this biozone in different sections includes Pseudogastrioceras relicuum, Araxoceras insolens, Prototoceras discoidale, Vescotoceras sp. and Araxoceras truncatum, which well confirms the age of early Wuchiapingin for this biozone.
Vedioceras ventrosulcatum Range Zone: This biozone has extended into the Upper Julfa Beds; however, the zonal maker species Vedioceras ventrosulcatum was not observed in the studied sections in this study. Korn and Ghaderi (2019) have described other species of the genus Vedioceras, such as Vedioceras fusiforme, as a respectable alternative to the species Vedioceras ventrosulcatum and the definition of this biozone. The ammonoid fauna associated with this biozone in different sections, including Pseudogastrioceras relicuum, Pseudotoceras armenorum, Dzhulfoceras sp., and Vedioceras sp.
Iranites transcaucasius - Phisonites triangulus Assemblage Zone: Korn et al. (2019) in the Aras Valley section and the authors of the present study in the other three sections, Ali-Bashi 1, 4, and Zal introduce the Iranites transcaucasius - Phisonites triangulus Assemblage Zone at the Changhsingianin base. This biozone begins with the unveiling of the Zal Member in the lowest part of the Ali-Bashi Formation. Disappearance of Dzhulfoceras and Vedioceras and the emergence of the first Iranites are the most distinctive feature of this biozone. Phisonites triangulus is also present in the platy marly limestone near the member’s base, associated with Xenodiscus dorashamensis and Pseudogastrioceras relicuum. With the onset of this biozone in the basal part of the Zal Member, there is a significant reduction in benthic versus pelagic fauna, indicating a deepening of the basin, minimization of benthos organisms such as brachiopods, and the predominance of pelagic animals like ammonoids, conodonts, and fishes.
Dzhulfites nodosus Range Zone: This range zone begins with the appearance of Dzhulfites as well as the newly introduced genus Araxoceltites (Korn et al. 2019) and is located approximately in the middle of the Zal Member. The best record of this biozone in northwestern Iran is related to the Aras Valley section, where Araxoceltites sanestapanus, Dzhulfites nodosus, and Dzhulfites spinosus have been found together at -9.5 meters below the extinction horizon of the section. The ammonoids Araxoceltites laterocostatus, Araxoceltites cristatus, and Pseudogastrioceras relicuum are also present as the accompanying fauna in this biozone.
Shevyrevites shevyrevi Interval Zone: This biozone with a very limited stratigraphic range at the top of the Zal Member is just located below the Paratirolites limestone and begins with the appearance of Shevyrevites shevyrevi. Arexoceltites cristatus is one of the most common species of this biozone, which is found alongside Shevyrevites and rare species belonging to Dzhulfites. The other ammonoids identified in this biozone in different sections include Araxoceltites laterocostatus, Araxoceltites sanestepanus, Dzhulfites nodosus, Dzhulfites spinosus, Pseudogastrioceras relicuum, and Shevyrevites nodosus.
It should be noted that all Lopingian ammonoids found in the Julfa region, except for Pseudogastrioceras and Timorites, which are belonging to Goniatitida, are ceratitic types. The predominance of ceratitids in the studied ammonoid assemblages indicates the effect of habitat on end Guadalupian extinction. So that nectobenthic and benthopelagic taxa with less lateral compaction, living in shallower tropics, are more damaged and more severely deformed. In contrast, those with high lateral compression have the most preservation. This confirms the selective effect of extinction on the mentioned fauna, indicating in unfavorable conditions, the ceratitids migrated to deeper areas due to their ability to live in the deep-water column and even survived from the end Permian great extinction event
For the first time very low values (up to 0.706707) of the ratio 87 Sr/ 86 Sr were recorded in the bio-genic carbonates of the Omolon massif (Northeast Asia) of the Capitanian age. These results are in good agreement with previously obtained data on limestones in Japan (Kani et al., 2013; 2018). In general, the strontium ratio curve constructed by us repeats the well-known world trend, differing by its somewhat underestimated (by an average of 0.0005-0.0008) values. The Capitanian strontium minimum can be associated with the entry into the ocean of significant amounts of lightweight femic strontium due to a sharp increase in paleospreading. The maximum values of the strontium ratio, obtained from the middle part of the Intomodesma evenicum bivalve Subzone are 0.706986, which corresponds to the lower part of the Changhsingian stage.
To clarify environmental and biological responses to the extinction-related global change that occurred during the Late Guadalupian (Permian), high-resolution lithostratigraphy is analyzed of the uppermost part of the Capitanian (Upper Guadalupian) shallow-marine Iwaizaki Limestone in the South Kitakami Belt, NE Japan, deposited as a patch reef on a continental shelf at the northeastern extension of South China, with various shallow marine fossils, e.g., rugose corals, fusulines, brachiopods, crinoids, and calcareous algae. The topmost ca. 40 m-thick interval of the limestone (Unit 8) is composed of interbedded limestone and mudstone, which are subdivided into the following four distinct subunits: Subunit 8-A of limestone-dominated alternation with nodular limestone, Subunit 8-B of mudstone-dominated alternation of limestone and mudstone, Subunit 8-C of thickly bedded limestone, and Subunit 8-D of calcareous mudstone, in ascending order. Subunit 8-D is covered directly with a thick black mudstone unit mostly of the Lopingian age. A clear pattern of step-wise disappearance of shallow-marine, tropically-adapted fossil biota, e.g., large bivalves (Alatoconchidae), rugose corals (Waagenophyllum), and large-tested fusulines (Lepidolina), is detected in the topmost Unit 7 and Unit 8 (8A to 8B), regardless of significant fluctuations of water-depth within this interval. The overall stratigraphic change in lithofacies within Unit 8 indicates a deepening trend, which was probably controlled by subsidence of the basement. Nonetheless, tectonic-driven subsidence led to the preservation of continuous stratigraphic records of the topmost Iwaizaki Limestone with the collapsing history of a patch reef, despite a global sea-level drop across the G-L boundary. The appearance of global cooling probably led to the extinction of warm water-adapted benthic tropical biota and the collapse of a reef complex during the Capitanian.
http://kse.wnoz.us.edu.pl/iascp.htm-FC&P42.pdf - newsletter of current publications on fossil corals, sponges and reefs
The Sikhote–Alin orogenic belt, Russian South East, consists of folded terranes made up of Jurassic and Early Cretaceous accretionary prisms, turbidite basins, and island arc terranes that are overlapped unconformably by undeformed upper Cenomanian to Cenozoic volcanic deposits. The Jurassic and Early Cretaceous accretionary prisms, together with the Early Cretaceous island arc, are related to subduction of the Paleo-Pacific plate. The turbidite basin, which began to form at the beginning of the Early Cretaceous, is related to left-lateral movement of the Paleo-Pacific plate along the Paleo-Asian continental margin. The collage of terranes that make up the Sikhote–Alin orogenic belt was amalgamated in two stages. The first began after Jurassic subduction beneath the Asian continent was terminated, and the second took place in the late Albian, when the Early Cretaceous island arc collided with the continental margin. Intense deformation of the terranes took place along the continental margin in the form of large-scale translations from south to north, together with oroclinal folding. The deformation resulted in rapid thickening of sediments in the upper crust, resulting in turn in the formation of granitic–metamorphic material in the continental lithosphere. In the southwestern part of the Sikhote–Alin orogen, granites were intruded during the Hauterivian–Aptian, while the entire orogenic belt was affected by intrusions in the late Albian–early Cenomanian. Synorogenic intraplate volcanic rocks and alkaline ultramafic–mafic intrusions also testify to the fact that the orogenic processes in the Sikhote–Alin were related to a transform continental margin, and not to subduction. Geochemical and Nd isotopic data indicate, the primary continental crust of the Sikhote-Alin was of a “hybrid” nature, consisting of juvenile basic components accreted from an oceanic plate and recycled sedimentary material derived from the erosion of ancient blocks.
The Permian large gastropod “Pleurotomaria” yokoyamai Hayasaka was found for the first time from the Capitanian (upper Guadalupian) Iwaizaki Limestone in the South Kitakami Belt, Northeast Japan. A smaller planispiral gastropod Porcellia sp. was found in association with it. These taxa have been scarcely reported, except from the coeval Permian limestones at Akasaka in Southwest Japan and in the Balya Maden area, western Turkey. The Akasaka Limestone was deposited as a low-latitude atoll on a mid-Panthalassan seamount, whereas the Iwaizaki Limestone was laid down as a patch reef within a terrigenous clastics-dominated facies on a shallow marine continental shelf. The occurrence of this unique assemblage suggests that the Iwaizaki Limestone originated also in a Permian low-latitude domain, and that the South Kitakami Belt likely formed a part of the continental margin of South China, representing its eastern extension to Northeast Japan.
The Maizuru Belt in southwest Japan and the Khanka Massif in Far East Russia include both Siluro-Devonian and Permo-Triassic granitoids. In order to elucidate the simultaneity of granitoid magmatism in the Maizuru Belt and the Khanka Massif, we investigated zircon U-Pb ages using LA-ICP-MS for granitoid samples from the Maizuru area in the northern zone of the Maizuru Belt and from the Vladivostok area in the southernmost part of the Khanka Massif. Five granitoid samples from the Vladivostok area yielded ages of 422.2±2.5 Ma, 260.7±3.1 Ma, 301.7±2.4 Ma, 249.7±3.5 Ma, and 431.9±2.7 Ma. Additionally, a porphyry sample yielded an age of 423.7±3.2 Ma. Four granitoid samples from the Maizuru area yielded ages of 291.6±4.3 Ma, 443.8±4.1 Ma, 279.7±2.4 Ma, and 259.0±3.0 Ma. In reference to the coexistence of the Triassic sedimentary sequence and Siluro-Devonian and Permo-Triassic granitoids across the Sea of Japan, it seems that there were strong relationships between the northern zone of the Maizuru Belt and the southernmost part of the Khanka Massif. Our data provide additional evidence to support a geological connection between southwest Japan and the Vladivostok area before the Miocene opening of the Sea of Japan.
The Upper Carboniferous to Upper Permian deposits of the Sverdrup Basin (Arctic Canada) record a transition from carbonate to silica dominated shallow shelf ecosystems. Chert expansion started during the latest Carboniferous in distal deep-water slope environments when prolific warm-water, photozoan carbonate factories developed on the adjacent shallow shelves. A shift to heterozoan factories during the Sakmarian–Artinskian was caused by the introduction of cooler water in response to paleoceanographic changes along NW Pangea. By Kungurian time, heterozoan carbonate factories narrowed substantially while hyalosponge factories had expanded well into the mid shelves. A brief return to widespread heterozoan carbonate sedimentation occurred during the Wordian, followed by further encroachment of shallow shelves by biosiliceous factories during the Capitanian and Wuchiapingian. A major drop in relative rates of carbonate sediment accumulation with time suggests both carbonate and biosiliceous factories were under considerable stress prior to the Late Permian Extinction event. It is proposed that Sverdrup Basin waters became progressively more acidic in response to build up of atmospheric CO2 throughout the Permian which led to a gradual shoaling of the lysocline and the calcite compensation depth, which was amplified by upwelling along the northwestern margin of Pangea. Ocean acidification initiated in response to amalgamation of the Pangea supercontinent. This inhibited the silicate weathering-response through development of thick protective soil blankets. A temperature shock associated with the extinction event led to a major fall of the lysocline allowing carbonates to resume accumulation in spite of low pH conditions. The subsequent die off of terrestrial vegetation, stripping of soil cover, widespread continental erosion and repeated exposures of fresh rock surfaces associated with a major base level shift allowed silicate weathering to restart and drive oceans back to carbonate saturation.
Permian Rugosa of southern Primorye (Russian Far East) occur in a series of terranes
of different tectonic origin. The taxonomical composition of Guadalupian (Wordian–Capitanian)
rugose corals distributed in southern Primorye changed progressively in an ecological succession,
starting with primitive persistent cosmopolitan taxa (assemblage I). This was replaced by assemblage
II with a marked invasion of Peri-Gondwanian genera such as Timorphyllum and Verbeekiella,
and, in the Late Capitanian, by typical Cathyasian colonial waagenophyllids (assemblage
III). Subsequent communities have nearly no transitional forms. The latter assemblage was
abruptly replaced by small fasciculate and solitary primitive forms (assemblage IV). Species
peculiarities of assemblages of the Parafusulina stricta Zone and the specific lithological features
of coral-bearing deposits indicate a palaeogeographical differentiation of terrane positions. The
terranes are of various origins: oceanic arcs, passive margin and guyot. The extinction of massive
colonial Rugosa in southern Primorye (western Palaeo-Pacific) is identified as a biotic event that
is recognizable in Japan, and probably in Inner Mongolia. It also coincides with a general
reduction in coral diversity at the end of the Capitanian in China. The present study of the taxonomical
distribution of corals has enabled the level of massive waagenophyllid extinction to be
defined precisely and to correlate it to a similar pattern in adjacent territories of the Palaeo-
Pacific below the Lopingian boundary. The diversity decrease coincides with the last phase of
the Kamura event, and the effects of the Emeishan volcanism is correlated with a second positive
shift in d13C (South China). The assumed cooling impacted on the fauna in the western Palaeo-
Pacific. The stepwise elimination of massive colonial waagenophyllids and large fusulinids
documented in the southern Primorye at the end of the Capitanian is considered to be the first
step in the Permian–Triassic extinction, about 8 Myr prior to the final Permian–Triassic
(P–T) global event.
Despite their utility for bio- and chemostratigraphy, many carbonate platform sequences have been difficult to analyze using paleomagnetic techniques due to their extraordinarily weak natural remanent magnetizations (NRMs). However, the physical processes of magnetization imply that stable NRMs can be preserved that are many orders of magnitude below our present measurement abilities. Recent advances in reducing the noise level of superconducting magnetometer systems, particularly the introduction of DC-SQUID sensors and development of a low-noise sample handling system using thin-walled quartz-glass vacuum tubes, have solved many of these instrumentation problems, increasing the effective sensitivity by a factor of nearly 50 over the previous techniques of SQUID moment magnetometry.
Here we report the successful isolation of a two-polarity characteristic remanent magnetization from Middle–Late Permian limestone formed in the atoll of a mid-oceanic paleo-seamount, now preserved in the Jurassic accretionary complex in Japan, which had proved difficult to analyze in past studies. Paleothermometric indicators including Conodont Alteration Indices, carbonate petrology, and clumped isotope paleothermometry are consistent with peak burial temperatures close to 130 °C, consistent with rock magnetic indicators suggesting fine-grained magnetite and hematite holds the NRM. The magnetic polarity pattern is in broad agreement with previous global magnetostratigraphic summaries from the interval of the Early–Middle Permian Kiaman Reversed Superchron and the Permian–Triassic mixed interval, and ties the Tethyan–Panthalassan fusuline zones to it. Elevated levels of hematite associated with the positive δ^(13)C_(carb) of the Kamura event argue for a brief spike in environmental oxygen. The results also place the paleo-seamount at a paleolatitude of ~ 12° S, in the middle of the Panthalassan Ocean, and imply a N/NW transport toward the Asian margin of Pangea during Triassic and Jurassic times, in accordance with the predicted trajectory from its tectono-sedimentary background. These developments should expand the applicability of magnetostratigraphic techniques to many additional portions of the Geological time scale.
The 87Sr/86Sr value of Sr dissolved in the world's oceans has varied though time, which allows one to date and correlate sediments. This variation and its stratigraphic resolution is discussed and graphically displayed. INTRODUCTION The ability to date and correlate sediments using Sr isotopes relies on the fact that the 87Sr/86Sr value of Sr dissolved in the world's oceans has varied though time. In Fig. 7.1, we show this variation, plotted according to the time scale presented in this volume. More detail is given in Fig. 7.2, on which we plot both the curve of 87Sr/86Sr through time and the data used to derive it. Comparison of the measured 87Sr/86Sr of Sr in a marine mineral with a detailed curve of 87Sr/86Sr through time can yield a numerical age for the mineral. Alternatively, 87Sr/86Sr can be used to correlate between stratigraphic sections and sequences by comparison of the 87Sr/86Sr values in minerals from each (Fig. 7.3). Such correlation does not require a detailed knowledge of the trend through time of 87Sr/86Sr, but it is useful to know the general trend in order to avoid possible confusion in correlation near turning points on the Sr curve. Strontium isotope stratigraphy (SIS) can be used to estimate the duration of stratigraphic gaps (Miller et al., 1988), estimate the duration of biozones (McArthur et al., 1993, 2000, 2004) and stages (Weedon and Jenkyns, 1999), and to distinguish marine from non-marine environments (Schmitz et al., 1991; Poyato-Ariza et al., 1998).
The Abadeh section, well-exposed in the Hambast Valley in central Iran, has long been one of the most extensively studied sections because of its continuous carbonate-dominated strata from Lower Permian to Lower Triassic. However, biostratigraphy and correlation with the equivalent sequences in other regions remain controversial. In this paper both carbon isotope excursion (δ13Ccarb) and strontium isotope ratio (87Sr/86Sr) based on bulk carbonate samples have been measured to serve as chemostratigraphical proxies to estimate the three different chronostratigraphical boundaries in the Lopingian at the Abadeh section, including the Permian–Triassic Event (PTEB), the Guadalupian–Lopingian (GLB), and the Wuchiapingian–Changhsingian boundaries (WCB). These three boundaries are important for understanding the marine biological evolution around this critical interval. Based on the δ13C excursions, the rising trend of 87Sr/86Sr and the value around 0.7073, and the occurrence of microbialite beds, the Permian–Triassic event boundary (= Bed 25 at the Meishan section) is suggested at − 0.5 m below the base of the main microbialite bed. The GLB is suggested at − 46.5 m based on the position of the minor δ13Ccarb negative depletion, coupled with the values between 0.7069 and 0.7070 of 87Sr/86Sr and its beginning point of the rising trend, which is above the lowest value 0.7068 of 87Sr/86Sr ratio in the Paleozoic. The relationship between section thickness and their high-resolution depositional age (projecting age) is interpolated for the whole Lopingian using locally weighted regression scatter plot smoother (LOWESS) of strontium isotopic ratio. Based on the negative δ13C excursion and the value 0.7072 of 87Sr/86Sr ratio, the WCB is estimated at 1 m above the lithologic boundary between Unit 6 and Unit 7, much lower than the boundary defined by previous conodont biostratigraphy, but similar to other index fossils. This boundary is projected as ca. 254.6 Ma in 87Sr/86Sr-age projecting model and is close to zircon U/Pb dating age from South China.
U-Pb analyses of more than 1,000 single detrital zircons from 16 formations of the Silurian–Lower Cretaceous continuous succession of the South Kitakami Belt (SKB), Northeast Japan, provide a detrital zircon reference for the complex continental-margin orogen of Japan. As a result, three tectonic phases were discriminated. Siluro–Devonian sandstone samples contain many syn-sedimentary zircons and 36.5‒48.0% of Precambrian zircons scattering between 700 Ma and 3,000 Ma, suggesting that they were deposited along an active continental margin of East Gondwana. Permian–Early Jurassic sandstone samples contain virtually no Precambrian zircons, suggesting that they were deposited along the active margin of an oceanic island arc. Middle Jurassic–Early Cretaceous sandstone samples contain many 300‒170 Ma zircons and up to 28% of Paleoproterozoic (around 1,850 Ma) zircons but no Neoproterozoic zircons. Moreover, the zircons during the magmatic hiatus in Korea (158‒110 Ma) were detected only in one Lower Cretaceous sandstone sample. The age distribution suggests that the Paleoproterozoic zircons in the Middle Jurassic–Lower Cretaceous sandstone of the SKB were most likely supplied from a Paleoproterozoic orogen in the North China Block. Thus, the South Kitakami Paleoland, which accumulated the continuous succession of the SKB was born along a margin of Gondwana in the Silurian–Devonian, rifted from the continent and drifted in the Tethys ocean as an oceanic island arc in the Permian–Early Jurassic, and finally amalgamated along an active continental margin where detrital zircons of the North China Block were supplied in the Middle Jurassic.
The aftermath of the great end-Permian period mass extinction 252 Myr
ago shows how life can recover from the loss of >90% species
globally. The crisis was triggered by a number of physical environmental
shocks (global warming, acid rain, ocean acidification and ocean
anoxia), and some of these were repeated over the next 5-6 Myr.
Ammonoids and some other groups diversified rapidly, within 1-3 Myr, but
extinctions continued through the Early Triassic period. Triassic
ecosystems were rebuilt stepwise from low to high trophic levels through
the Early to Middle Triassic, and a stable, complex ecosystem did not
re-emerge until the beginning of the Middle Triassic, 8-9 Myr after the
crisis. A positive aspect of the recovery was the emergence of entirely
new groups, such as marine reptiles and decapod crustaceans, as well as
new tetrapods on land, including -- eventually -- dinosaurs. The
stepwise recovery of life in the Triassic could have been delayed either
by biotic drivers (complex multispecies interactions) or physical
perturbations, or a combination of both. This is an example of the wider
debate about the relative roles of intrinsic and extrinsic drivers of
large-scale evolution.
Fusulinoideans from the Metadoliolina dutkevitchi-Monodiexodina sutchanica Zone of the lower part of the Chandalaz Formation in the Senkina Shapka section in South Primorye, Far East Russia, are described. The fusulinoidean zone is assigned to the early Midian (=Capitanian: late Middle Permian) based mainly on the morphologie and biostratigraphic characteristics of Metadoliolina dutkevitchi. Previously, a Midian age has been established for the Metadoliolina dutkevitchi-Monodiexodina sutchanica Zone by the coexistence of Lepidolina species. However, the occurrence of Lepidolina with the two zonal species in this area has not been verified by the illustration of Lepidolina specimens. We examined a fusulinoidean-bearing sample from the Metadoliolina dutkevitchi-Monodiexodina sutchanica Zone, and three fusulinoidean species, Monodiexodina sutchanica, Pseudofusulina sp. and Metadoliolina dutkevitchi, are de-scribed and illustrated.
The Middle Permian (Guadalupian) strata in South Primorye, Russian Far East and Northeast China are well developed and characterized by the fusulinid Monodiexodina fauna, transitional brachiopod, coral and bryozoan faunas, but little has been done for the correlation between the areas in the two countries. This paper provides a review of the faunas in and around the Monodiexodina-bearing beds in all the key sections in the South Primorye area and a correlation with their equivalents in Northeast China. The Monodiexodina-bearing beds are of Wordian (Early Midian) age based on the associated conodont Jinogondolella cf. aserrata and the brachiopod Substriatifera vladivostokensis zones. These beds are commonly overlain by the Early Capitanian (Middle Midian) fusulinid Parafusulina stricta Zone, brachiopod Leptodus nobilis-Spiriferella Zone and coral Paracaninia columbina-Lophocarinophyllum chandalasicum Zone. The Monodiexodina-bearing beds are also found from the Hugete and Jisu Honguer formations in the Zhesi area, the Sijiashan Formation in the southern Daxinganling Range and the Daheshen Formation in Jilin Province in Northeast China. These Monodiexodina-bearing beds mostly occur in calcarenite and sandy limestone and are largely the same age in the northern temperate transitional zone.
Palaeozoological, palaeobotanical and geochemical analyses of Lower Permian to the lowermost Cretaceous sediments exposed in the southern Russian Far East (Bureya–Jiamusi–Khanka superterrane and the Sergeevka terrane), and higher latitude areas (northern Russian Far East and Spitsbergen) suggest a direct relationship with global climatic events defined by the data from oxygen-isotopic palaeotemperatures. Several positive carbon-isotopic anomalies discovered within the uppermost Cisuralian, Guadalupian, early Lopingian and Aalenian–Bajocian intervals are possibly connected to strong hydrological intermixing of oceanic waters under the influence of considerable thermal gradients.
Strontium isotope systematics are introduced and the various components contributing to strontium in seawater are outlined. Residence time of Sr in seawater and present day variations in ⁸⁷Sr/⁸⁶Sr are discussed. Changes in this ratio with time are considered on the basis of ⁸⁷Sr/⁸⁶Sr ratios measured from authigenic minerals in marine sediments. Diagenetic factors are considered followed by discussion of stratigraphical resolution and analytical problems. Detailed analysis of fluctuations and oscillations with time, on various scales from 10⁹ years to 10⁴ years are graphically presented and interpreted. Practical applications of the knowledge of ⁸⁷Sr/⁸⁶Sr variations conclude the chapter. -A.J.Barker
Spatial and temporal variations in biological diversity are critical in understanding the role of biogeographical regulation (if any) on mass extinctions. An analysis based on a latest database of the stratigraphic ranges of 89 Permian brachiopod families, 422 genera, and 2059 species within the Boreal, Paleoequatorial, and Gondwanan Realms in the Asian-western Pacific region suggests two discrete mass extinctions, each possibly with different causes. Using species/family rarefaction analysis, we constructed diversity curves for late Artinskian-Kungurian, Roadian-Wordian, Capitanian, and Wuchiapingian intervals for filtering out uneven sampling intensities. The end-Changhsingian (latest Permian) extinction eliminated 87-90% of genera and 94-96% of species of Brachiopoda. The timing of the end-Changhsingian extinction of brachiopods in the carbonate settings of South China and southern Tibet indicates that brachiopods suffered a rapid extinction within a short interval just below the Permian/Triassic boundary. In comparison, the end-Guadalupian/late Guadalupian extinction is less profound and varies temporally in different realms. Brachiopods in the western Pacific sector of the Boreal Realm nearly disappeared by the end-Guadalupian but experienced a relatively long-term press extinction spanning the entire Guadalupian in the Gondwanan Realm. The end-Guadalupian brachiopod diversity fall is not well reflected at the timescale used here in the Paleoequatorial Realm because the life-depleted early Wuchiapingian was overlapped by a rapid radiation phase in the late Wuchiapingian. The Guadalupian fall appears to be related to the dramatic reduction of habitat area for the brachiopods, which itself is associated with the withdrawal of seawater from continental Pangea and the closure of the Sino-Mongolian seaway by the end-Guadalupian.
The end-Guadalupian extinction, at the end of the Middle Permian, is thought to have been one of the largest biotic crises in the Phanerozoic. Previous estimates suggest that the crisis eliminated 58% of marine invertebrate genera during the Capitanian stage and that its selectivity helped the Modern evolutionary fauna become more diverse than the Paleozoic fauna before the end-Permian mass extinction. However, a new sampling-standardized analysis of Permian diver-sity trends, based on 53731 marine invertebrate fossil occurrences from 9790 collections, indicates that the end-Guadalupian ''extinction'' was actually a prolonged but gradual decrease in diversity from the Wordian to the end of the Permian. There was no peak in extinction rates; reduced genus richness exhibited by all studied invertebrate groups and ecological guilds, and in different lati-tudinal belts, was instead driven by a sharp decrease in origination rates during the Capitanian and Wuchiapingian. The global diversity decrease was exacerbated by changes in beta diversity, most notably a reduction in provinciality due to the loss of marine habitat area and a pronounced decrease in geographic disparity over small distances. Disparity over moderate to large distances was unchanged, suggesting that small-scale beta diversity changes may have resulted from com-pression of bathymetric ranges and homogenization of onshore-offshore faunal gradients stem-ming from the spread of deep-water anoxia around the Guadalupian/Lopingian boundary. Al-though tropical invertebrate genera were no more likely than extratropical ones to become extinct, the marked reduction in origination rates during the Capitanian and Wuchiapingian is consistent with the effects of global cooling (the Kamura Event), but may also be consistent with other en-vironmental stresses such as anoxia. However, a gradual reduction in diversity, rather than a sharp end-Guadalupian extinction, precludes the need to invoke drastic extinction mechanisms and in-dicates that taxonomic loss at the end of the Paleozoic was concentrated in the traditional end-Permian (end-Changhsingian) extinction, which eliminated 78% of all marine invertebrate genera.
This paper briefly describes the geology of southern Sikhote-Alin of Russia and the Inner zone of Southwest Japan, and presents
a new correlation model in which the Samarka terrane (sensu stricto), Udeka Formation, Sebuchar Formation and Kalinovka ophiolite in Sikhote-Alin are considered as northern extensions of the
Mino-Tamba terrane, Hikami Formation, Kozuki Formation, and Yakuno ophiolite in Southwest Japan, respectively. This correlation
is based on the similarities in lithology, age, faunal assemblage, and structural relationship between them. The Samarka and
Mino-Tamba terranes consists of Jurassic accretionary complexes including Permian greenstone-limestone complex, Permian to
Lower Jurassic radiolarian bedded chert, Jurassic clastic rocks, and Jurassic melanges. The Udeka and Hikami formations are
composed mainly of greenish gray sandstone with minor shale intercalations yielding Permian radiolarians. The Sebuchar and
Kozuki formations are characterized by basalts accompanied with shale, limestone and chert. The limestone includes Carboniferous
fusulinaceans, while Permian radiolarians occur in the chert. The Kalinovka and Yakuno ophiolites consist of a series of ultramafic
to mafic igneous rocks with an ophiolitic succession. Since the ages of these ophiolites have not been clearly established,
we correlate them on the basis of their lithology and tectonic positions. These units form a stack of nappes from the lower
to upper horizons in the following order: Mino-Tamba terrane, Hikami Formation, Kozuki Formation, and Yakuno ophiolite in
Japan, and Samarka terrane (sensu stricto), Udeka Formation, Sebuchar Formation, and Kalinovka ophiolite in Russia. This correlation supports the reconstruction model
of Japan before the opening of the Sea of Japan proposed by Yamakita and Otoh (1999).
In order to examine paleogeographic link between Primorye and Japan with respect to other continental blocks in East Asia, middle-upper Paleozoic shallow marine sandstones of the Khanka block and Sergeevka belt were analyzed by LA-ICPMS U-Pb dating of detrital zircons. The age spectra of detrital zircons of the Devonian Lyutorgian Formation, Lower Carboniferous Shevelevka Formation, and Permian Lyudyanza Formation in the Vladivostok-Nakhodka area share more or less the same age range; the majority of detrital zircons are dated 500-400 Ma (Cambrian to Silurian). These ages are common in previously dated granitoids with arc signature in Primorye and also in Japan, thus suggest a probable derivation from a single subduction-related Paleozoic batholith belt along the Pacific rim. The zircon age spectra of the Devonian and Carboniferous sandstones show similarities to those of coeval sandstones in NE and SW Japan. The middle-late Paleozoic sedimentary basins in Primorye and Japan commonly had a provenance featuring early Paleozoic arc rocks. In addition, all of these Paleozoic terrigenous clastics in Primorye and Japan consistently contain Proterozoic zircons. Occurrence of Meso- to Neoproterozoic (ca. 1500 and 600 Ma) grains positively suggests a link to the South China block, as other blocks in East Asia lack crusts of this age of pan-African affinity. The common age spectra of detrital zircons of the Paleozoic sandstones in southern Primorye and NE-SW Japan support the concept of “Greater South China” that is comprised of conterminous South China to extend to Japan/Primorye, which is consistent with the mutual similarities recognized in Paleozoic marine fauna. Paleozoic South China was much larger than previously imagined, and this greater size, almost double the present conterminous South China, requires much larger area in the paleogeographical reconstruction of Rodinia.
High-resolution (930 samples) magnetic susceptibility (MS) and anhysteretic remanent magnetization (ARM) analyses were conducted on the ~ 49 m thick Middle Permian Maokou Formation at Dukou, South China. Spectral analysis of covariant MS and ARM series reveal Milankovitch cycles with eccentricity, obliquity, and precession. A 5.7 myr floating 405 kyr eccentricity cycle-calibrated astronomical time scale was constructed and used as a geochronometer for estimating the durations of the conodont zones. The results indicate that the durations of the Jinogondolella postserrata, J. altudaensis, J. prexuanhanensis, and J. xuanhanensis conodont zones were 490 kyr, 560 kyr, 820 kyr, and 750 kyr, respectively. The 405 kyr-calibrated MS and ARM series also show prominent ~ 1 myr cyclicity, which may correspond to the secular frequencies of Earth and Mars, s4–s3, in the Middle Permian. The early Capitanian time interval was synchronous with the Kamura cooling event, and the accentuated obliquity cycling may signal ice-sheet expansion. The modulations of the obliquity have a close relationship with third-order eustatic sequences of the Wordian and Capitanian stages, suggesting a glacioeustatic origin during the Middle Permian.
The strontium isotope ratio (87Sr/S6Sr) of seawater has changed significantly through time in response to variations in the input of Sr to the oceans from various crust and upper mantle sources with differing 87Sr /86Sr values. An important aspect of this temporal variation is the empirical finding that, while the 87Sr /86Sr of seawater may vary through time, at any given time the Sr isotope ratio of the oceans is everywhere the same. Isotopic uniformity is achieved because the marine residence time of Sr (~ 4 X 106 yr) is long (e.g., Veizer 1989) compared to the oceanic circulation time (~ 103 yr). The oceans, therefore, are well mixed with respect to both Sr and Sr isotope ratio, and all coeval, marine-derived, carbonates, sulfates, and phosphates will possess the same initial 87Sr/S6Sr value. Consequently, the temporal changes in the 87Sr/S6Sr of seawater can be used to correlate and date marine strata and can provide insight into the global processes that have shaped our world.
A facies model of the Permian Kapp Starostin Formation assigns various facies to specific depositional environments and thus shows the detailed spatial and temporal development of a temperate, mixed siliceous-carbonate ramp from the upper Cisuralian (Artinskian) into the Lopingian (Changhsingian). Calcareous, partly glauconitic and generally well-sorted sandstones are interpreted to represent shallow-marine sand flats within the most proximal, foreshore to shoreface areas of the inner ramp. These sediments indicate the uplift of a terrestrial, siliciclastic source area probably to the north or northeast of the study area. Highly diverse, commonly strongly silicified, skeletal limestones contain a typical heterozoan biotic assemblage, marked by a varying abundance of brachiopods, bryozoans and crinoids, as well as siliceous sponge spiculae. The carbonate-producing biota shows a specific distribution within the open-marine areas of the inner to mid ramp, where the bioclastic debris was reworked, redistributed and washed together by waves, tides and periodically occurring storms. While sandy brachiopod shell banks (coquinas) were mainly present within the inner ramp, bryozoan and crinoidal detritus accumulated within more distal areas, originating from scattered build-ups at the outer edge of the mid ramp. Spiculitic cherts, the most prominent facies of the Kapp Starostin Formation, are formed by the accumulation of abundant siliceous sponge spiculae, representing the major silica factory of the shelf. These deposits have the widest distribution, ranging from the inner ramp (light-coloured, massive to nodular cherts) around the fair-weather wave base to deeper-marine, outer ramp areas below the storm-weather wave base (dark-coloured, bedded to massive cherts). Finely laminated to massive black shales generally indicate the most distal, deep-marine, toe-of-slope and basinal areas of the outer ramp, below the storm-weather wave base. The sediments originate from the accumulation of fine-grained, terrigenous matter under quiet-water conditions. The local preservation of primary lamination points to oxygen-depleted conditions, while bioturbation at other levels indicates the presence of bottom-feeding organisms under well-oxygenated conditions. The various facies were deposited on a stable, shallow submarine ramp marked by a subdued relief, gently sloping towards the south. The strata are arranged into four stacked parasequences (shallowing-upward cycles), which are interpreted as the result of short-term, possibly glacio-eustatic sea-level fluctuations superimposed on a long-term sea-level fall.
Extensive and new marine geological and geophysical data of the Japan Sea have been compiled into geological maps. The tectonic evolution of the Japan Sea has been examined based on observation and interpretation of its geological structure. The ages of formation of the basins in the Japan Sea are estimated from sediment stratigraphy, basement depth, and heat flow data. Topographic highs in the Japan Sea are classified into four groups; continental fragments, rifted continental fragments, tectonic ridges, and volcanic seamounts. Two types of back-arc spreading are proposed; a single rift type and multi rift type. The tectonic evolution of the Japan Sea is summarized in two significant tectonic stages. 1) Divergent tectonics over the Japanese island arcs caused back-arc spreading of the Japan Sea from 30 to 10 Ma. Overprinting of arc volcanism on the back-arc basin resulted in an abundance of volcanic seamounts and a thick accumulation of volcaniclastics in the basins. 2) Lithospheric convergence along the eastern margin of the Japan Sea since latest Pliocene time produced the uplifted and thrust faulted Okushiri and Sado Ridges. -from Japanese Geomorphological Union
The original stable isotopic composition of Paleozoic marine carbonate rocks is important to establish a baseline for evaluating diagenetic alteration and providing a reliable data-base for modeling exogenic geochemical cycles of the elements. We have compared the delta 18O and delta 13C values in the nonluminescent portions of brachiopods wih similar published data of whole brachiopods, other whole fossils, and estimates of original isotopic composition of marine cements. The carbon and oxygen isotopic compositions of all components decrease in delta 18O and delta 13C in geologically older material. Neither temporal trend is monotonic, however. Oxygen isotopic results suggest an important positive shift in delta 18O of about 2per mille during the early Carboniferous, whereas the carbon isotope trend shows a major positive shift (approx 2%n3per mille) during the mid-Carboniferous. -from Authors
In order to clarify the early history of Japan, particularly during the Early Paleozoic, pre-Devonian granitoids in the South Kitakami Belt (SKB), NE Japan were dated by U–Pb zircon age by laser-ablation inductively coupled plasma-mass spectrometry (LA-ICP-MS). Two samples of diorite/tonalite from the Nagasaka area (Shoboji Diorite) and two of mylonitic tonalite from the Isawa area (Isawagawa Tonalite) yielded late Cambrian ages (500–490 Ma) for the primary magmatism. These ages newly identify a ca. 500 Ma (late Cambrian) arc plutonism in central NE Japan, which has not been recognized previously and has the following geological significance. The Cambrian granitoids are the oldest felsic plutonic rocks in NE Japan, which are independent of the previously known ca. 450 Ma (latest Ordovician) Hikami Granite in SKB. The Cambrian granitoids are extremely small in size at present but likely had a much larger distribution primarily, at least 30 km wide and potentially up to 80 km wide in a cross-arc direction. Their southerly extension was recognized in the Hitachi area (ca. 200 km to the south) and in central Kyushu (ca. 1500 km to SW). They likely represent remnants of the same mature arc plutonic belt in Early Paleozoic Japan, which developed in western Panthalassan (paleo-Pacific) margin, as well as the Khanka block in Far East Russia. The extremely small size of the Cambrian granitoids at present can be best explained by intermittent, severe tectonic erosion since the Paleozoic. This Cambrian arc granitoid belt likely developed from Primorye possibly to eastern Cathaysia (South China) via Japan.
The South Kitakami belt is unique in exposing a thick, well-preserved Paleozoic shelf sequence in Japan in which Phanerozoic accretionary complexes dominate. Its origin with respect to continental blocks has been debated in regard of two options, i.e., as belonging to the margin of North China or South China. Present work on U–Pb detrital zircon dating has identified Neoproterozoic mineral grains from the Silurian and Carboniferous sandstones in the S. Kitakami belt, and proved the link between Paleozoic Japan and South China with dominant Proterozoic basements. South China likely extended further to the east from the mainland China.
The Capitanian minimum in the Permian represents one of the most significant features in the Phanerozoic seawater 87Sr/86Sr history. In order to establish the detailed Sr chemostratigraphy around the Guadalupian minimum, 87Sr/86Sr ratios were measured for the Capitanian (upper Middle Permian) paleo-atoll limestones at Akasaka in Japan. The limestone was primarily deposited on a paleo-seamount in the low-latitude mid-Panthalassa, and was secondarily accreted to Japan (South China block) margin in the Jurassic. As being free from local continental influences, the Akasaka limestone recorded well-mixed seawater isotope composition of the Permian low-latitude mid-superocean. We detected extremely low 87Sr/86Sr ratios (ca. 0.7068–0.7069) in the 70 m-thick Capitanian interval, immediately below the Guadalupian–Lopingian (Middle-Late Permian) boundary (G–LB), of the Akasaka limestone. This Sr isotopic profile at Akasaka suggests that the global seawater was least affected by radiogenic continental flux throughout the Capitanian. As these values correspond to the lowest in the Paleozoic, this interval with low 87Sr/86Sr ratios, lasted for at least some milllion years, represents the Capitanian minimum, which marks the significant turning point from the Late Paleozoic decrease to Early Mesozoic increase in seawater 87Sr/86Sr ratio. The geological lines of evidence indicate that the Capitanian minimum was caused likely by the mid-Permian cooling that may have driven extensive ice-cover over continental crusts to suppress continental flux enriched in radiogenic Sr into the superocean. The rapid increase in 87Sr/86Sr values after the minimum can be explained either by the deglaciation or by the Pangean rifting.
We have applied UPb, trace element, and Sr isotopic analyses to subsamples of a single specimen of the Capitan Formation from the Permian Reef Complex of New Mexico with the goal of calibrating the Late Permian time scale and understanding the factors that set and later alter the initial U/Pb ratio and Pb isotopic composition of the limestone. The data indicate a limestone UPb isochron age of 249.8 ± 4.7 Ma (2σ) and a PbPb age of 249 ± 18 Ma. In addition, with μ values (≜238U/204Pb) ranging up to 4200, among the highest ever recorded for a limestone, we also obtain precise single sample 206Pb*/238U, 207Pb*/235U and 207Pb*/206Pb* ages indicating averages of 250.2 ± 3.2 Ma, 250.0 ± 2.8 Ma, and 256.3 ± 3.5 Ma, respectively. Comparison of the average Pb*/U age of 250 ± 3 Ma for the latest Guadalupian with published radiometric constraints for the Late Permian suggests preservation of essentially the depositional age.
Precise measurements of 786 marine carbonate, evaporite, and phosphate
samples of known age provide a curve of seawater
87Sr/86Sr versus geologic time through the
Phanerozoic. Many episodes of increasing and decreasing values of
87Sr/86Sr of seawater have occurred through the
Phanerozoic. The Late Cambrian Early Ordovician seawater ratios are
approximately equal to the modern ratio of 0.70907. The lowest ratios,
˜0.7068, occurred during the Jurassic and Late Permian. The
configuration of the curve appears to be strongly influenced by the
history of both plate interactions and seafloor spreading throughout the
Phanerozoic. The curve provides a basis for dating many marine
carbonate, evaporite, and phosphate samples. Furthermore, diagenetic
modifications of original marine 87Sr/86Sr values
are often interpretable. Analysis of 87Sr/86Sr
data, therefore, may provide useful information on regional diagenetic
patterns and processes. All of the Cenozoic samples and some of the
Cretaceous samples are from Deep Sea Drilling Project (DSDP) cores. With
the exception of the DSDP samples, the curve was constructed only from
samples containing at least 200 ppm Sr and not more than 10% dilute acid
insoluble material. All measurements are made by comparison with
standard SrCO3 (NBS SRM 987) for which a
87Sr/86Sr of 0.71014 is assumed. Precision is
estimated to be ± 0.00005 at the 95% confidence level. Measured
ratios of 42 modern marine samples average 0.70907, with a standard
deviation of 0.00004. *Present addresses: (Denison) Suite 616, One
Energy Square. 4925 Greenville Avenue, Dallas, Texas 75206; (Nelson)
2516 West Five Mile Parkway, Dallas, Texas 75233
The geotectonic framework and the evolutionary history of the Japanese Islands need revision in accordance with the various geophysical/geological evidence gathered by new methodologies in the recent years including seismic tomography, vibroseis/ground-breaking seismic experiments, and detrital zircon chronology. These investigations have addressed various themes such as: 1) seismic profile of the crust and mantle beneath the Japanese Islands, 2) high-precision ages of the protoliths of high-P/T metamorphic rocks, and 3) provenance of terrigenous clastics. The results have led to a number of important findings including: 1) detection of a large mass of slab around the mantle boundary layer suggesting the long-term oceanic subduction beneath Japan, 2) confirmation of the subhorizontal piled-nappe structure for the entire crust of Japan, 3) finding a new high-P/T metamorphosed accretionary complex unit that represents the youngest blueschist in Japan, 4) finding of the oldest (Early Cambrian) arc batholith and cover sediments, and 5) the identification of plural arc batholiths which have already been erased from the surface. Based on a synthesis of these new data, this article presents a re-evaluation of the conventional geotectonic subdivision of the subduction-related orogen in Japan, re-definition of the elements and their mutual boundaries, and re-consideration of the geotectonic evolution of the Japanese Islands. In particular, the historical change in provenance suggests that proto-Japan has experienced large-scale tectonic erosion in multiple stages, and the corresponding large amounts of continental crust materials were subducted. For understanding the orogenic growth of Japan during the last ca. 500million years, the significance of tectonic erosion coupled with continental contraction, as well as the oceanward accretionary growth, requires further attention.
The estimated path of seawater during the Mississippian, Pennsylvanian and Permian is based on 228 analyses. The samples are largely from the southern interior of the U.S.A., where rocks of this age are widely exposed. Multiple analyses from single rock units are used to define the seawater ratio for different time-periods.The seawater declines from ∼0.70812 (Δsw − 95) Mississippian to an estimated low in the early Meramecian of near 0.70755 (Δsw − 152). The value rises to near 0.70812 (Δsw − 95) in latest Mississippian. The ratio rises to 0.70830 (Δsw − 77) in Mid-Pennsylvanian and decreases to near 0.70809 (Δsw − 98) during Virgilian time. The earliest Permian value is near 0.70793 (Δsw − 114). After rising to 0.70804 (Δsw − 103) in the early Leonardian the seawater falls sharply to reach a low of 0.70672 (Δsw − 235) in Ochoan time. The end of the Paleozoic is estimated to be near 0.70707 (Δsw − 200) based on samples from China.Analysis of the Paleozoic curve shape shows an alternating dominance of oceanic and continental Sr contributions. The extended and precipitous decline in the during mid-Permian is unmatched during the Phanerozoic. The contrast of the Paleozoic seawater Sr curve shape to that in the Mesozoic and Cenozoic indicates a potentially fundamental change in the balance of oceanic and continental Sr contributions at the end of the Permian.
A population of 169 Permian articulate brachiopod shells was analysed for their 87Sr/86Sr ratios. 51 of these, characterised as well preserved and stratigraphically well defined, are utilized for delineation of the Permian seawater strontium isotope trend. The 87Sr/86Sr curve shows values of about 0.7080 in the lowermost Permian (Asselian), followed by a gradual decline to 0.70685 in the Capitanian and a minor rise in the Dzhulfian and lower Dorashamian to values of 0.70715 just below the Permian-Triassic boundary.The Early Permian decrease in the strontium isotope curve that commences in the early Sakmarian is coincident with the advancing deglaciation of the Gondwana and with the increased aridity in large parts of the Pangaea. These factors may have led to a reduced continental weathering of Rb-rich silicate rocks, and thus to the decline in seawater 87Sr/86Sr. Starting with the Artinskian, the opening of the Neotethys and the associated widespread basaltic volcanism supplied low radiogenic strontium to seawater from an enhanced hydrothermal flux. In the Capitanian, basaltic volcanism in the entire Palaeotethys ceased and this may have been the reason for a slightly more radiogenic seawater isotopic composition during the Lopingian. Higher input of riverine Sr due to expansion of humid areas may have been a contributory factor.
A dropstone-bearing, Middle Permian to Early Triassic peri-glacial sedimentary unit was first discovered from the Khangai–Khentei Belt in Mongolia, Central Asian Orogenic Belt. The unit, Urmegtei Formation, is assumed to cover the early Carboniferous Khangai–Khentei accretionary complex, and is an upward-fining sequence, consisting of conglomerates, sandstones, and varved sandstone and mudstone beds with granite dropstones in ascending order. The formation was cut by a felsic dike, and was deformed and metamorphosed together with the felsic dike. An undeformed porphyritic granite batholith finally cut all the deformed and metamorphosed rocks. LA-ICP-MS, U–Pb zircon dating has revealed the following 206Pb/238U weighted mean igneous ages: (i) a granite dropstone in the Urmegtei Formation is 273 +/- 5 Ma (Kungurian of Early Permian); (ii) the deformed felsic dike is 247 +/- 4 Ma (Olenekian of Early Triassic); and (iii) the undeformed granite batholith is 218 +/- 9 Ma (Carnian of Late Triassic). From these data, the age of sedimentation of the Urmegtei Formation is constrained between the Kungurian and the Olenekian (273–247 Ma), and the age of deformation and metamorphism is constrained between the Olenekian and the Carnian (247–218 Ma). In Permian and Triassic times, the global climate was in a warming trend from the Serpukhovian (early Late Carboniferous) to the Kungurian long and severe cool mode (328–271 Ma) to the Roadian to Bajocian (Middle Jurassic) warm mode (271–168 Ma), with an interruption with the Capitanian Kamura cooling event (266–260 Ma). The dropstone-bearing strata of the Urmegtei Formation, together with the glacier-related deposits in the Verkhoyansk, Kolyma, and Omolon areas of northeastern Siberia (said to be of Middle to Late Permian age), must be products of the Capitanian cooling event. Although further study is needed, the dropstone-bearing strata we found can be explained in two ways: (i) the Urmegtei Formation is an autochthonous formation indicating a short-term expansion of land glacier to the central part of Siberia in Capitanian age; or (ii) the Urmegtei Formation was deposited in or around a limited ice-covered continent in northeast Siberia in the Capitanian and was displaced to the present position by the Carnian.
Nearly 10 million years before the Permo-Triassic boundary (PTB; ca. 251 Ma) characterized by the greatest mass extinction in the Phanerozoic, the Middle-Upper Permian boundary marked another big biotic decline almost comparable in magnitude to the PTB event. Two stratigraphic sections spanning across the Maokouan (Middle Permian)-Wuchiapingian (Upper Permian) boundary (MWB) were newly found in paleo-atoll limestone within the Jurassic accretionary complex in Kamura and Akasaka, Japan. These two sections share almost identical litho- and biostratigraphy that records a remarkable biotic extinction of large-shelled fusulinids and a sharp lithologic change exactly across the MWB. These new data, as the first evidence from the shallow-water mid-oceanic realm, suggest that a quick environmental change occurred in a global scale across the MWB. A thin, acidic tuff recognized at the MWB horizon in the paleoatoll limestone has a potential utility as a key bed for global correlation and suggests a possible link between the end-Permian biosphere crisis and the explosive acidic volcanism.
A Middle Permian mass extinction, first discovered in 1994, has become known as the “end-Guadalupian event” in the literature. However, recent studies of foraminifera- and brachiopod-range truncations in conodont-dated sections on the South China Block have shown that the losses occur below this level, in the middle of the Capitanian Stage. Extinctions were suffered by several other groups, notably the corals, whilst the mollusc record is more enigmatic. A major bivalve crisis has been reported in some studies, the giant alatoconchids being notable victims, but not others. Gastropods were unaffected by the crisis whilst a roughly contemporaneous ammonoid mass extinction may have occurred in the Early Wuchiapingian, a few million years after the main marine losses. Compilation of data from plant species in South China reveals a significant 24% loss, suggesting that the Capitanian crisis also occurred on land. An intra-Capitanian extinction of 56% of plant species in North China Block sequences may also have coincided with these losses. Correlation of these marine and terrestrial extinction events, using the palaeomagnetic record, provides two alternatives: either turnover amongst plant species is contemporaneous with the marine extinction (and the eruption of the Emeishan flood basalt province in southwest China); or plant losses post-date the marine extinction and instead coincide with the waning phase of the igneous province. Current understanding of the major dinocephalian extinction suggests this event occurred during the preceding stage (the Wordian), but future improvements in both sampling and dating this tetrapod crisis may reveal a synchronicity of plant, animal and marine invertebrate extinctions. The clear temporal link of the Capitanian marine extinction with Emeishan volcanism suggests that these flood basalt eruptions triggered the crisis. A contemporaneous, major negative C isotope excursion suggests that, like many other mass extinction events, methane release from hydrates may also be implicated. However, in the best-dated Chinese sections the main excursion is found to slightly post-date the extinction which occurs at the end of an unusual (and unexplained) interval of exceptionally heavy δ13C values. Other “usual suspects” for mass extinctions either lack geological and palaeontological evidence (e.g. marine anoxia and global cooling) or do not precisely correlate with the extinction (e.g. major, eustatic regression).
Conodont, C isotope and fossil and facies data are presented for the Capitanian (Middle Permian) mass extinction record seen in platform carbonates (Maokou and Wuchiaping formations) of South China, where limestones interdigitate with the volcanic succession of the Emeishan large igneous province. The Maokou Formation provides an extinction record marked by the loss of keriothecal-walled fusulinaceans and a turnover in calcareous algae. In sections within the Emeishan province this crisis occurs at the base of the oldest record of volcanism from the Jinogondolella altudaensis conodont zone (of mid-Capitanian age). Around the periphery of the Emeishan province this extinction level lies within the upper part of the Maokou Formation at a level where platform carbonate deposition was frequently interrupted by thick volcanic ash depositional events. The assemblages of the uppermost Maokou Formation are characterised by typical “Late Permian” taxa although these levels still lie within the Middle Permian (Guadalupian Series). “Disaster” taxa, such as Earlandia and Diplosphaerina are locally prolifically abundant in the aftermath of the mass extinction. The crisis is particularly noteworthy amongst photosynthetic taxa such as calcareous algae and fusulinaceans that probably harboured photosymbionts. Therefore, a kill mechanism involving cooling from explosive volcanism and potentially acid rain from sulphate aerosols appears appropriate. A composite δ13Ccarb curve, calibrated against a high-resolution conodont biostratigraphy reveals a major intra-Capitanian negative excursion (of > 5‰) superimposed on typically heavy (4–5‰) Middle Permian values. This curve can also be recognised in Panthalassan seamount carbonates of Japan although this requires reassignment of apparently Upper Permian limestones to the Middle Permian. In both China and Japan the Capitanian mass extinction occurs during the early stage of this major, intra-Capitanian negative excursion. Assuming typical platform carbonate accumulation rates, the records of the Maokou Formation suggest δ13Ccarb values fell at ∼ 0.01‰/kyr suggesting a catastrophic origin (such as gas hydrate destabilisation) is unlikely, although a volcanic source is possible.
Significant differences between faunal and floral associations existing in different paleogeographic realms in the Kungurian–Late Permian interval make it difficult to correlate the Permian deposits of the world. Resolving this problem is one of the main tasks of Permian stratigraphy. The global significance of Permian strata of the Primorye region of Far East Russia is enhanced by the specific Middle Permian mixed Tethyan, Boreal and Gondwanan-type brachiopod fauna, mixed Angara-Euromerican-Cathaysian flora, and their close spatial and stratigraphical association with fusulinids, bryozoans, ammonoids, conodonts. These facts permit tracing of global correlational levels of some Permian sequences within the different paleobiogeographical realms: for example, the Monodiexodina sutschanica-Metadoliolina dutkevichi fusulinid zone of the Wordian age and Parafusulina stricta fusulinid zone of the Capitanian age. The Late Permian fauna of the Primorye is mainly Tethyan in origin and provides correlation with similar aged sequences from South China.
Detailed observations and mass angular measurements in relicts of the host protoskeleton, their foliation, the shadow banding,
the contacts between granite and aplite varieties, and taxitic texture served as the basis for the graphical and statistical
analyses of the structural patterns in the Ordovician Tafuinsky granite intrusion. They revealed pre- and syn-granite types
of structural patterns that were formed under the external longitudinal compression. The first of them is characteristic of
the trajectories of structural elements constituting the protoskeleton hosting the massif and the shadow banding in the granites
oriented transversely to the compression. The second type corresponds to the two main phases of the massif formation: the
granite and the aplite. It is formed by combinations of conjugate counter-dipping thrusts and shears that control the distribution
of the granite and aplite substances. In addition, these combinations frequently produce pseudofolded structures distinctly
reflected in the control over the aplite bodies. Such a structural style of syngranite deformations suggests that, by their
formation dynamics, they are similar to their pregranite counterparts. Both the pre- and syn-granite structural patterns demonstrate
that the activation of the external compression was of different-order and pulsed mode with a certain periodicity. Moreover,
the long compression pulses distinctly correspond to the stages and phases in the massif formation, when the compression twice
changed its orientation at their transitions in the clockwise manner with an angular step of 10°. The geodynamics of the main
longitudinal compression and its structural derivatives are regarded as a principal factor that determined the position and
architecture of the massif.
Key wordsintrusion structures-structural patterns-strain fields-longitudinal compression-geodynamics-Tafuinsky granite massif-southern Primorye region-Far East
Middle to Upper Permian shallow marine carbonates in the Kamura area, Kyushu (SW Japan), were derived from a paleo-atoll complex developed on an ancient seamount in mid-Panthalassa. The Capitanian (Upper Guadalupian) Iwato Formation (19 m-thick dark gray limestone) and the conformably overlying Wuchiapingian (Lower Lopingian) Mitai Formation (17 m-thick light gray dolomitic limestone) are composed of bioclastic limestone of subtidal facies, yielding abundant fusulines. A secular change in stable carbon isotope ratio of carbonate carbon (δ13Ccarb) was analyzed in the Kamura section in order to document the oceanographic change in the superocean Panthalassa with respect to the mass extinction across the Guadalupian–Lopingian boundary (G–LB). The Iwato Formation is characterized mostly by unusually high positive δ13Ccarb values of + 4.9 to + 6.2‰, whereas the Mitai Formation by low positive values from + 1.9 to + 3.5‰. The negative excursion occurred in three steps around the G–LB and the total amount of the negative shifts reached over 4‰. A remarkably sharp drop in δ13Ccarb values, for 2.4‰ from 5.3 down to 2.9‰, occurs in a 2 m-thick interval of the topmost Iwato Formation, after all large-shelled fusulines and bivalves disappeared abruptly. Such a prominent high positive δ13Ccarb plateau interval in the end-Guadalupian followed by a large negative shift across the G–LB was detected for the first time, and this trend in the mid-superoceanic sequence is correlated chemostratigraphically in part with the GSSP (Global Stratotype Section and Point) candidate for the G–LB in S. China. The present results prove that the end-Guadalupian event was doubtlessly global in context, affecting circum-Pangean basins, Tethys, and Panthalassa. The end-Guadalupian interval of a high positive plateau in δ13Ccarb values over + 5‰ is particularly noteworthy because it recorded an unusually high bio-productivity period that has not been known in the Permian. This end-Guadalupian high-productivity event, newly named “Kamura event”, suggests burial of a huge amount of organic carbon, draw-down of atmospheric CO2 and resultant global cooling at the end of Guadalupian, considerably after the Gondwana glaciation. The low temperatures during the Kamura event may have caused the end-Guadalupian extinction of large-shelled Tethyan fusulines and bivalves adapted to warm climate. On the other hand, the following event of ca. 4‰ negative shift in δ13Ccarb values across the G–LB indicates a global warming in the early Lopingian. This may have allowed radiation of the new Wuchiapingian fauna, and this trend appears to have continued into the Mesozoic. These observations are in good agreement with the global sea-level curve in the Middle–Late Permian. The smooth and gradual pattern of the negative shift suggests that the causal mechanism was not of catastrophic nature (e.g. bolide impact, sudden melting of methane hydrate) but was long and continuous.
The 87Sr/86Sr values based on brachiopods and conodonts define a nearly continuous record for the Late Permian and Triassic intervals. Minor gaps in measurements exist only for the uppermost Brahmanian, lower part of the Upper Olenekian, and Middle Norian, and only sparse data are available for the Late Permian. These 219 measurements include 67 brachiopods and 114 conodont samples from the Tethyan realm as well as 37 brachiopods and one conodont sample from the mid-European Middle Triassic Muschelkalk Sea. The Late Permian/Lower Triassic interval is characterized by a steep 1.3 × 10−3 rise, from 0.7070 at the base of the Dzhulfian to 0.7082 in the late Olenekian, a rate of change comparable to that in the Cenozoic. In the mid-Triassic (Anisian and Ladinian), the isotope values fall to 0.7075, followed again by a rise to 0.7081 in the Middle/Late Norian. The 87Sr/86Sr values decline again in the Late Norian (Sevatian) and Rhaetian to 0.7076.