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Metcalfe, Ian
- PublicationLower Permian (Late Kungurian) conodonts from the Sibumasu Terrane, Malaysia: paleoecological, paleobiogeographical and tectonic implications
Late Kungurian (Lower Permian) conodonts are described from the Kanthan Limestone, Perak, Peninsular Malaysia and for the first time from the Sibumasu Terrane of the Malay Peninsula. The co-occurrence of Gullodus duani, Gullodus hemicircularis, Gullodus sicilianus, Mesogondolella lamberti and Mesogondolella siciliensis represent the Mesogondolella lamberti International Conodont Zone and the broadly equivalent Mesogondolella siciliensis Regional Conodont Zone. A small fault-bounded basal Pennsylvanian (basal Bashkirian) conodont fauna including Gnathodus girtyi simplex and Declinognathodus inaequalis is also reported. The late Kungurian conodonts from the Kanthan Limestone were deposited in a relatively deep-water environment on the northern passive margin of the Sibumasu Terrane of the eastern Cimmerian Continent located at c. 35o S latitude. Biogeographically, the fauna represents the southern peri-Gondwana Cool Water Province which is consistent with its palaeogeographic location. A new scheme, utilizing characteristics of P1 elements, including position of the 1st denticle, location of 2nd and 3rd denticles, platform shape, platform cross-section, denticle shape in cross-section, and lateral denticle development is proposed for distinguishing between species of the hindeodid genera Gullodus, Hindeodus and Isarcicella. The late Kungurian fauna from the Kanthan Limestone represents the southern peri-Gondwana Cool Water Province supporting palaeogeographic reconstructions placing the Sibumasu Terrane in moderate southern palaeolatitudes in the Kungurian.
- PublicationMarine invertebrate fossils from the Permian–Triassic boundary beds of two core sections in the northern Perth Basin, Western Australia(Taylor & Francis, 2022)
;Shi, G R; ;Lee, Sangmin ;Chu, Daoliang ;Wu, Huiting ;Yang, TingluZakharov, Yuri DMarine macroinvertebrate fossils from two petroleum exploration cores, Apium-1 and Redback-2, are described, and found to contain two separate assemblages. The assemblage from the Apium-1 core was recovered from an ca 5-m-thick interval (2756.35–2751.28 m) in the basal Hovea Member (‘inertinitic interval’) of the Kockatea Shale and includes the following forms: ?Spinomarginifera sp., Cimmeriella sp., ?Etherilosia sp., Elivina sp., Cleiothyridina sp., and Paeckelmanelloidea gen. et. sp. indet. (all brachiopods). The age of this assemblage is interpreted as Changhsingian, as constrained by its association with the palynofloral Dulhuntyispora parvithola Zone. The assemblage from the Redback-2 core was recovered from the ‘sapropelic interval’ of the Hovea Member of the Kockatea Shale between 3806 m and 3786 m and comprises the following forms: Lingulidae gen. et sp. indet. (brachiopod), Claraia perthensis Dickins & McTavish, Crittendenia cf. australasiatica (Krumbeck), ?Paralledon,/i> sp. (bivalves), ?Otoceras sp. (ammonoid), Microconchus utahensis Zaton, Taylor & Vinn (microconchid) and Magniestheria mangaliensis (Jones) (spinicaudatan). Among these, the first local appearances of the lingulid species, ?Otoceras sp. and M. mangaliensis are associated with the palynofloral Protohaploxypinus microcorpus Zone and are interpreted as latest Changhsingian in age. Other occurrences of the Redback-2 fossil assemblage overlap with the palynofloral Kraeuselisporites saeptatus Zone and are considered to be of earliest Triassic (Griesbachian) age.
- PublicationPulses in silicic arc magmatism initiate end-Permian climate instability and extinction(Nature Publishing Group, 2022-05)
; ; ; ;Blevin, Phil LCrowley, JimBrief pulses of intense volcanic eruptions along convergent margins emit substantial volatiles that drive climatic excursions that can lead to major extinction events. However, correlating volcanic outpouring to environmental crises in the geological past is often difficult due to poor preservation of volcanic sequences and the need for precise dating methods. Here we present a high-fidelity CA-TIMS U–Pb zircon record of an end-Permian flare-up event in eastern Australia, which involved the eruption of >39,000–150,000 km3 of silicic magma in circa 4.21 ± 0.5 million years. A correlated high-resolution tephra record (circa 260–249 Ma) in the proximal sedimentary basins suggests recurrence of eruptions from the volcanic field in intervals of ~51,000–145,000 years. Peak eruption activity at 253 ± 0.5 million years ago is chronologically associated with intervals of pronounced species decline and the demise of the Glossopteris forests in the initial stages of the end-Permian mass extinction event (~1–2 Myr). Simultaneous eruptions along multiple arcs around the globe occurred at the same time as eastern Australia. In conjunction, these global eruptions are considered as a trigger of greenhouse crises and ecosystem stress that preceded the catastrophic eruption of the Siberian Traps.
- PublicationMultiple Tethyan ocean basins and orogenic belts in AsiaFour Tethyan ocean basins are recognised in Asia, the Proto-Tethys (Late Proterozoic - Silurian), Palaeo-Tethys (Middle Devonian - Late Triassic), Meso-Tethys (Middle Permian - Late Cretaceous) and Ceno-Tethys (late Middle Triassic - Eocene). Multi-disciplinary data, including ages of pelagic sediments, ocean plate stratigraphy, seamounts, ophiolites, blueschists, eclogites in accretionary complexes, volcanic arc and magmatic rocks found along suture zones of the Tethyan oceans are described and used to date the opening and closure of these oceans. The evolution of the Tethyan ocean basins in Asia illustrates that Asia has been a giant convergent zone for more than 500 million years and the Phanerozoic construction and evolution of Asia involved the opening and closure of Tethyan ocean basins and the collision and accretion of Gondwana-derived continental blocks and the Indian Craton. Subduction processes, arc and back-arc basin generation, and continent-continent and arc-continent collisions led to the principal orogenic events, basin development and related mineral and energy resource deposits recorded in Asia. Three major orogenic belts are recognised in Asia, the Central Asian Orogenic Belt, that relates to the evolution of the Palaeo-Asia Ocean, and the Tethyan (Tethysides) Orogenic Belt and the Alpine-Himalayan Orogenic Belt which relate to the evolution of Tethyan ocean basins. The principal Tethyan basin related orogenies in Asia are the Bhimphedian Orogeny (Ordovician-Silurian) that reflects the collision of major Asian continental blocks ("Asian-Hun Superterrane") with Gondwana, the Indosinian (Cimmerian) Orogeny (Permian-Triassic) resulting from Palaeo-Tethyan subduction processes, collisions of Asian blocks and collision of the Cimmerian continent with Asia, and the Himalayan-Tibetan Orogeny (Cretaceous-Palaeogene) caused by subduction of the Meso- and Ceno-Tethys oceans and the Lhasa-Asia and India-Asia collisions.
- PublicationUpper Permian and Lower Triassic conodonts, high-precision U-Pb zircon ages and the Permian-Triassic boundary in the Malay PeninsulaConodont biostratigraphic and high-precision U-Pb isotope data are presented for the Permian-Triassic transition in three limestone hills, Gua Bama, Gua Panjang and Gua Sei, in the Malay Peninsula. Gua Bama yielded conodonts representating the Clarkina orientalis, Clarkina wangi and Clarkina subcarinata zones and the Wuchiapingian-Changhsingian stage boundary is identified for the first time in Malaysia. The Wuchiapingian subspecies Hindeodus julfensis wardlawi Kozur is elevated to species level, H. wardlawi, and evolved to the Changhsingian species Hindeodus julfensis Sweet and then Hindeodus changxingensis Wang. Distinguishing features and a new phylogeny of species of the genera Hindeodus and Isarcicella in the Late Permian-Early Triassic are presented. A new CA-TIMS high-precision U-Pb age of 253.70 ± 0.06 Ma for zircon from a tuff layer 6.5 m above the Wuchiapingian-Changhsingian boundary and in the lower part of the Clarkina subcarinata zone is reported. Conodont faunas from Gua Panjang represent the Clarkina changxingensis-Hindeodus praeparvus, Clarkina yini-Clarkina zhangi, and Hindeodus parvus zones and the PTB is placed at approximately 12 m in the studied 19 m thick sequence. Three tuff layers in the lower part of Gua Panjang contain zircon grains with CA-TIMS U-Pb ages of 252.23 ± 0.07 Ma, 252.47 ± 0.12 Ma and 252.16 ± 0.16 Ma (maximum age), respectively. Conodont faunas from Gua Sei represent the Upper Permian (Changhsingian) Clarkina hauschei - Hindeodus latidentatus Zone and the basal Triassic lower Induan (Griesbachian) Hindeodus parvus and Isarcicella staeschei zones. The PTB is placed at 30 m above the base of the Gua Sei sequence.
- PublicationQuantitative stratigraphic correlation of the Lower Triassic in South China based on conodont unitary associationsUnitary Association Method (UAM) analyses of conodont faunas from 28 sections spanning the biggest Phanerozoic end-Permian mass extinction and significant global environmental and ecosystem perturbations during the succeeding Early Triassic are presented. Based on 72 conodont species, 26 Unitary Association Zones (UAZs) are established for the latest Permian to earliest Middle Triassic of South China. These UAZs provide quantitative high-resolution tools to correlate sequences in the Early Triassic of South China and to compare and test high-resolution conodont biostratigraphy based on interval conodont zones developed over the past three decades. Our quantitative analyses provide insights on ongoing debates relating to the First Appearance Datum (FAD) of the conodont Hindeodus parvus which is used to place and subsequently correlate the "Golden Spike" defining the base of the Triassic (Permian-Triassic Boundary) at the base of Bed 27c at the GSSP Meishan D Section. Previous proposals that suggested potential earlier occurrences of H. parvus below its FAD at Meishan section are not supported by our results. In deep water sections, the First Occurrence (FO) of H. parvus lies at the base of UAZ 5 at the Bianyang section while it lies within UAZ 6 at the Meishan section. This indicates that the earliest occurrence of H. parvus in South China is in the Bianyang section but this conclusion needs further testing due to the reliance on "spot" data by the UAM. Anomalously high occurrences of Hindeodus in the Mingtang section (close to the Bianyang section) further suggests that the Bianyang-Mingtang area may have provided a temporally extended habitable zone for anchignathodontid conodonts. Stage boundaries currently proposed or established using interval conodont zones locate within or between UAZs and are difficult to correlate with carbon isotope curves. UAZs are useful in helping to define GSSPs by recognizing which correlations are most robust and in the selection of the most appropriate species and level for GSSPs.