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  • 1. Betts, Marissa, J.
    et al.
    Paterson, John, R.
    Jacquet, Sarah, M.
    Andrew, Anita S.
    Hall, Philip A.
    Jago, James, B.
    Jagodzinski, Elisabeth A.
    Preiss, Wolfgang V.
    Crowley, James L.
    Brougham, Tom
    Mathewson, Ciaran P.
    Garcia-Bellido, Diego C.
    Topper, Timothy, P.
    Skovsted, Christian
    Swedish Museum of Natural History, Department of Paleobiology.
    Brock, Glenn, A.
    Early Cambrian chronostratigraphy and geochronology of South Australia2018In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 185, p. 498-543Article in journal (Refereed)
    Abstract [en]

    The most successful chronostratigraphic correlation methods enlist multiple proxies such as biostratigraphy and chemostratigraphy to constrain the timing of globally important bio- and geo-events. Here we present the first regional, high-resolution shelly fossil biostratigraphy integrated with δ13C chemostratigraphy (and corresponding δ18O data) from the traditional lower Cambrian (Terreneuvian and provisional Cambrian Series 2) of South Australia. The global ZHUCE, SHICE, positive excursions II and III and the CARE are captured in lower Cambrian successions from the Arrowie and Stansbury basins. The South Australian shelly fossil biostratigraphy has a consistent relationship with the δ13C results, bolstering interpretation, identification and correlation of the excursions. Positive excursion II straddles the boundary between the Kulparina rostrata and Micrina etheridgei zones, and the CARE straddles the boundary between the M. etheridgei and Dailyatia odyssei zones, peaking in the lower parts of the latter zone. New CA-TIMS zircon dates from the upper Hawker Group and Billy Creek Formation provide geochronologic calibration points for the upper D. odyssei Zone and corresponding chemostratigraphic curve, embedding the lower Cambrian successions from South Australia into a global chronostratigraphic context. This multi-proxy investigation demonstrates the power of integrated methods for developing regional biostratigraphic schemes and facilitating robust global correlation of lower Cambrian successions from South Australia (part of East Gondwana) with coeval terranes on other Cambrian palaeocontinents, including South and North China, Siberia, Laurentia, Avalonia and West Gondwana.

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  • 2.
    Johansson, Åke
    Swedish Museum of Natural History, Department of Geology.
    Comment on Li et al. (2023): A dynamic 2000—540 Ma Earth history: From cratonic amalgamation to the age of supercontinent cycle2023In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 241, p. 1-3, article id 104457Article in journal (Other (popular science, discussion, etc.))
    Abstract [en]

    The paper “A dynamic 2000—540 Ma Earth history: From cratonic amalgamation to the age of supercontinentcycle” that was recently published in Earth-Science Reviews by Li et al. (2023) is an impressive piece of work, putting together data for the Proterozoic supercontinent cycle into a coherent model including both maps and animations. Nevertheless, as they write themselves, there will no doubt be room for improvements of their model, some of which I hope to contribute with in this comment from my Baltica perspective, in particular when it comes to the relations between Baltica, Amazonia and West Africa.

  • 3. Luo, Qingyong
    et al.
    Fariborz, Goodarzi
    Zhong, Ningning
    Wang, Ye
    Qiu, Nansheng
    Skovsted, Christian
    Swedish Museum of Natural History, Department of Paleobiology.
    Suchy, Vaclav
    Schovsbo, Niels Hemmingsen
    Morga, Rafal
    Xu, Yaohui
    Hao, Jingyue
    Liu, Anji
    Wu, Jin
    Cao, Weixun
    Min, Xu
    Wu, Jia
    Graptolites as fossil geo-thermometers and source material of hydrocarbons: An overview of four decades of progress2020In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 200, article id 103000Article in journal (Refereed)
    Abstract [en]

    The thermal maturity of lower Paleozoic graptolite-bearing marine sediments, which host many hydrocarbon deposits worldwide, has long been difficult to determine due to the absence of wood-derived vitrinite particles for conventional vitrinite reflectance. In 1976, graptolite reflectance was introduced as a new indicator for organic maturity of these deposits and has been used since in many regional studies. The majority of these studies, however, were done on a limited sample set and a limited range of thermal maturity, which resulted in a number of controversial views concerning the usefulness of graptolite reflectance as an alternative paleothermal indicator and its correlation with vitrinite reflectance through various proxies. In this paper, we review previous studies and combine those analyses with new data to assess the physical and chemical characteristics of graptolite periderm with increasing thermal maturity. We conclude that graptolite random reflectance (GRor) is a better parameter for the thermal maturity assessment than graptolite maximum reflectance (GRomax) due to the better quality of available data. Combining published data with results of our study of both natural and heat-treated graptolites and vitrinite, we present a new correlation between GRor and equivalent vitrinite reflectance (EqVRo), as EqVRo = 0.99GRor + 0.08. Chemical composition of graptolite periderm is similar to vitrinite; graptolites are mainly kerogen Type II-III, are gas prone and have a substantial hydrocarbon potential. Lower Paleozoic graptolite-bearing organic-rich sediments are important shale gas source rocks and reservoirs globally and make a significant contribution to worldwide petroleum reserves

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  • 4.
    Mays, Chris
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Vajda, Vivi
    Swedish Museum of Natural History, Department of Paleobiology. Department of Geology, Lund University, Sweden.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Permian–Triassic non-marine algae of Gondwana—distributions, natural affinities and ecological implications2021In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 212, p. 1-29, article id 103382Article in journal (Refereed)
    Abstract [en]

    The abundance, diversity and extinction of non-marine algae are controlled by changes in the physical and chemical environment and community structure of continental ecosystems. We review a range of non-marine algae commonly found within the Permian and Triassic strata of Gondwana and highlight and discuss the non-marine algal abundance anomalies recorded in the immediate aftermath of the end-Permian extinction interval (EPE; 252 Ma). We further review and contrast the marine and continental algal records of the global biotic crises within the Permian–Triassic interval. Specifically, we provide a case study of 17 species (in 13 genera) from the succession spanning the EPE in the Sydney Basin, eastern Australia. The affinities and ecological implications of these fossil-genera are summarised, and their global Permian–Triassic palaeogeographic and stratigraphic distributions are collated. Most of these fossil taxa have close extant algal relatives that are most common in freshwater, brackish or terrestrial conditions, and all have recognizable affinities to groups known to produce chemically stable biopolymers that favour their preservation over long geological intervals. However, these compounds (e.g., sporopollenin and algaenan) are not universal, so the fossil record is sparse for most algal groups, which hinders our understanding of their evolutionary histories. Owing partly to the high preservational potential of Zygnematophyceae, a clade of freshwater charophyte algae and sister group to land plants, this group has a particularly diverse and abundant Permian–Triassic fossil record in Gondwana. Finally, we review and contrast the marine and continental algal records of the global biotic crises within the Permian–Triassic interval. In continental settings, Permian algal assemblages were broadly uniform across most of southern and eastern Gondwana until the EPE; here, we propose the Peltacystia Microalgal Province to collectively describe these distinct and prolonged freshwater algal assemblages. In the immediate aftermath of the EPE, relative increases in non-marine algae have been consistently recorded, but the distributions of prominent taxa of Permian freshwater algae became severely contracted across Gondwana by the Early Triassic. We highlight the paucity of quantitative, high-resolution fossil evidence for this key group of primary producers during all biotic crises of the Permian and Triassic periods. This review provides a solid platform for further work interpreting abundance and diversity changes in non-marine algae across this pivotal interval in evolutionary history.

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  • 5. Olierook, Hugo K.H.
    et al.
    Jourdan, Fred
    Merle, Renaud
    Swedish Museum of Natural History, Department of Geology.
    Age of the Barremian–Aptian boundary and onset of the Cretaceous Normal Superchron2019In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 197Article in journal (Refereed)
    Abstract [en]

    The age assigned to the boundary of the Barremian and Aptian stages remains one of the most poorly constrained post-Pangean stratigraphic boundaries. The lack of a Global Boundary Stratotype Section and Point (GSSP) for the stage boundary has hampered efforts to calibrate the absolute age of the Cretaceous period in the geological time scale. The current definition of the Barremian–Aptian boundary also approximates the onset of magnetic polarity chron M0r; the end of this chron denotes the start of the Cretaceous Normal polarity Superchron that is of fundamental importance for plate reconstructions. Currently, there is up to 5% discrepancy in the age estimates of the Barremian–Aptian boundary (ca. 126–121 Ma) and the start of the Cretaceous Normal Superchron. Here, we review available geochronological information from the late Barremian and early Aptian stages collected from the Pacific Ocean, China, California, the Ontong Java Nui large igneous province and the High Arctic large igneous province. By utilizing only robust geochronological data including U-Pb and recalibrated 40Ar/39Ar ages from sites with magnetic polarity information and/or paleontological constraints, we calculate a best estimate of between 123.8 and 121.8 Ma for the Barremian–Aptian boundary and the onset of chron M0r at 2σ confidence. Using estimates of the duration of chron M0r (0.49 ± 0.10 Myr, 2σ), we conservatively compute the start of the Cretaceous Normal Superchron to between 123.4 and 121.2 Ma (2σ). Using an age of 83.07 ± 0.15 Ma (2σ) for the end of the Cretaceous Normal Superchron, the duration of the superchron is also constrained to between 38.0 and 40.5 Myr (2σ). These age ranges for the Barremian–Aptian boundary, the onset of the Cretaceous Normal Superchron and the duration of the superchron currently provide the best estimates until a GSSP is formally ratified.

  • 6. O'Sullivan, Gary
    et al.
    Chew, David
    Kenny, Gavin
    Swedish Museum of Natural History, Department of Geology.
    Henrichs, Isadora
    Mulligan, Donal
    The trace element composition of apatite and its application to detrital provenance studies2020In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 201, article id 103044Article in journal (Refereed)
    Abstract [en]

    Apatite's ubiquity in crystalline rocks, variable trace element contents (particularly with regard to the REE, actinides and Sr), and amenability to various datingtechniques based on the decay of the radioisotopes U and Th, permit specific provenance determinations. In this study, we first present a comprehensive descriptionof the trace element behaviour of apatite in various kinds of bedrocks (igneous rocks from felsic through to ultramafic compositions, metamorphic rocks from low tohigh grades and of diverse protolith composition, and authigenic apatite) in which we explain why apatite is so highly diverse in terms of its trace elementcomposition. Next, we present a synthesis of bedrock apatite trace-element compositional data from previous work, assembling a library of apatite compositions thatincludes the most abundant apatite-bearing lithologies in the Earth's crust, and many other less abundant rock types. Compositional statistics, classification, and amachine learning classifier are then applied to this dataset to generate biplots that can be used to determine the broad source lithology of detrital apatite, withmisclassification averaging 15%. This methodology is tested in three case studies to demonstrate its utility. In these examples, detrital apatite can be convincinglylinked to different lithology types, and combined apatite trace-element and UePb data can determine the terranes from which individual apatites were likely derived.The addition of apatite trace-element information therefore enables the determination of the source lithology, making the extraction of novel information and morespecific provenance determinations possible, and opening up new avenues in source-to-sink modelling.

  • 7. Riley, Teal R.
    et al.
    Burton-Johnson, Alex
    Flowerdew, Michael J.
    Poblete, Fernando
    Castillo, Paula
    Hervé, Francisco
    Leat, Philip T.
    Millar, Ian L.
    Bastias, Joaquin
    Whitehouse, Martin J.
    Swedish Museum of Natural History, Department of Geology.
    Palaeozoic – Early Mesozoic geological history of the Antarctic Peninsula and correlations with Patagonia: Kinematic reconstructions of the proto-Pacific margin of Gondwana2023In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 236, p. 104265-104265, article id 104265Article in journal (Refereed)
  • 8.
    Tewari, Rajni
    et al.
    Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, India.
    Ram- Awatar, Ram-
    Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, India.
    Pandita, Sundeep
    Department of Geology, University of Jammu, Jammu-180006, India.
    McLoughlin, Stephen
    Swedish Museum of Natural History, Department of Paleobiology.
    Agnihotri, Deepa
    Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, India.
    Pillai, Suresh
    Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, India.
    Singh, Vartika
    Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, India.
    Kumar, Kamlesh
    Birbal Sahni Institute of Palaeobotany, 53 University Road, Lucknow-226007, India.
    Bhat, Ghulam
    Directorate of Geology and Mining, Jammu and Kashmir Government, Srinagar, India.
    The Permian-Triassic palynological transition in the Guryul Ravine section, Kashmir, India: implications for Tethyan – Gondwanan correlations2015In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 149, p. 53-66Article in journal (Refereed)
    Abstract [en]

    This first palynological study of the Permian–Triassic succession in the Guryul Ravine, Kashmir, India, reveals impoverished latest Permian spore-pollen assemblages in the uppermost Zewan Formation, a rich palynoassemblage from the basal Khunamuh Formation characteristic of the Permian–Triassic transition zone and depleted Triassic assemblages from higher in the Khunamuh Formation. The collective assemblages can be broadly correlated to the Densipollenites magnicorpus and Klausipollenites decipiens palynozones of peninsular India and to palynofloras spanning the Permian–Triassic boundary elsewhere in Gondwana. Generally, low spore-pollen yields and poor preservational quality of the studied assemblages hinder more precise correlations and are inferred to be a function of an offshore marine depositional setting on the margin of the Neotethys Ocean, and thermal alteration associated with Cenozoic collisional tectonism between India and Asia.

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  • 9.
    Topper, Timothy
    et al.
    Swedish Museum of Natural History, Department of Paleobiology.
    Betts, Marissa J.
    Palaeoscience Research Centre, School of Environmental and Rural Science, University of New England, Armidale, New South Wales 2351, Australia.
    Dorjnamjaa, Dorj
    Institute of Paleontology, Mongolian Academy of Sciences, 15160, Ulaanbaatar, Mongolia.
    Li, Guoxiang
    State Key Laboratory of Palaeobiology and Stratigraphy, Nanjing Institute of Geology and Palaeontology, Chinese Academy of Sciences, Nanjing 210008, China.
    Li, Luoyang
    Swedish Museum of Natural History, Department of Paleobiology. Key Lab of Submarine Geosciences and Prospecting Techniques, Ministry of Education, and College of Marine Geosciences, Ocean University of China, Qingdao 266100, PR China.
    Altanshagai, Gundsambuu
    Institute of Paleontology, Mongolian Academy of Sciences, 15160, Ulaanbaatar, Mongolia, School of Arts and Sciences, National University of Mongolia, Ulaanbaatar, 14200, Mongolia.
    Enkhbaatar, Batkhuyag
    Institute of Paleontology, Mongolian Academy of Sciences, 15160, Ulaanbaatar, Mongolia, School of Arts and Sciences, National University of Mongolia, Ulaanbaatar, 14200, Mongolia.
    Skovsted, Christian
    Swedish Museum of Natural History, Department of Paleobiology.
    Locating the BACE of the Cambrian: Bayan Gol in southwestern Mongolia and global correlation of the Ediacaran–Cambrian boundary2022In: Earth-Science Reviews, ISSN 0012-8252, E-ISSN 1872-6828, Vol. 229, p. 104017-104017, article id 104017Article in journal (Refereed)
    Abstract [en]

    The diversification of animals during the Cambrian Period is one of the most significant evolutionary events inEarth’s history. However, the sequence of events leading to the origin of ‘modern’ ecosystems and the exacttemporal relationship between Ediacaran and Cambrian faunas are uncertain, as identification of the Ediacaran–Cambrian boundary and global correlation through this interval remains problematic. Here we review thecontroversies surrounding global correlation of the base of the Cambrian and present new high-resolutionbiostratigraphic, lithostratigraphic and δ13C chemostratigraphic data for terminal Ediacaran to basal Cambrianstrata in the Zavkhan Basin of Mongolia. This predominantly carbonate sequence, through the Zuun-Arts andBayangol formations in southwestern Mongolia, captures a distinct, negative δ13C excursion close to the top ofthe Zuun-Arts Formation recognized as the BAsal Cambrian carbon isotope Excursion (BACE). In this location,the nadir of the BACE closely coincides with first occurrence of the characteristic early Cambrian protoconodontProtohertzina anabarica. Despite recent suggestions that there is an evolutionary continuum of biomineralizinganimals across the Ediacaran–Cambrian transition, we suggest that this continuum is restricted to tubular forms,and that skeletal taxa such as Protohertzina depict ‘true’ Cambrian representatives that are restricted entirely tothe Cambrian. Employing the first appearance of the trace fossil Treptichnus pedum to define the base of theCambrian suffers significant drawbacks, particularly in carbonate settings where it is not commonly preserved.As T. pedum is the only proxy available to correlate the Cambrian Global boundary Stratotype Section and Point(GSSP) defined at Fortune Head, Newfoundland, we suggest that the GSSP be redefined elsewhere, in a newstratigraphic section that contains secondary markers that permit global correlation. We propose the nadir of theBACE as the favored candidate to define the base of the Cambrian. However, it is essential that the BACE becomplemented with secondary markers. In many global sections the nadir of the BACE and the first occurrence ofthe genus Protohertzina are closely juxtaposed, as are the BACE and T. pedum. Hence these taxa provide essentialbiostratigraphic control on the BACE and increase potential for effective global correlation. We also recommendthat an Auxiliary boundary Stratotype Section and Point (ASSP) be simultaneously established in order toincorporate additional markers that will aid global correlation of the Ediacaran–Cambrian boundary. The BAY4/5 section through the upper Zuun-Arts and Bayangol formations yields key shelly fossils and δ13C values and istherefore an ideal candidate for consideration as the GSSP for the Ediacaran–Cambrian boundary.

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