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The ideal goal of biostratigraphic studies is to make stratigraphic ranges of all species clear and to fix globally synchronous biohorizons as age controls. However, it is difficult to achieve this goal in simple, traditional ways, and so a new solution is proposed for Permian radiolarian biostratigraphy. To achieve this goal (including to establish a globally applicable biostratigraphy, to estimate the numerical age of biohorizons, and to determine stratigraphic ranges at species level), all 400 known Permian radiolarian species, approximately 70 stratigraphic sections, and 1560 samples from 350 previously published papers about the low-latitude Tethys and Panthalassa oceans were analyzed. Issues of Permian studies are summarized and a solution is proposed from the Cenozoic point of view. Considering traditional methods, as well as successful methods in Cenozoic radiolarian studies, here we implement newly proposed methods that have never been used for Permian radiolarian studies: Unitary Association Method (UAM), “Minimum Disordered Biohorizon Algorithm” (MDBA), Graphic Correlation (GC), and ‘Reiteration Estimation Rounds’ (RER). Of these, our proposed RER is a new method to predict the probability of the estimated age for a sample by Bayesian inference and joint probability (both statistical methods). As these four methods are applicable to any biostratigraphic study, the principals and practical applications of these methods are carefully explained so non-specialists can understand the logical procedure. As a result, 15 Unitary Association Zones (UAZs) are established for the entire Permian biostratigraphic scheme by UAM, the numerical ages of 42 first occurrences (FOs) are estimated from non-parametric data from the middle Guadalupian (middle Permian) to the uppermost Lopingian (uppermost Permian) by MDBA and GC, and the statistical likelihood UAZ ranges of 165 species in the entire Permian were obtained using the RER procedure. A usability test of our UAZs shows that 97.96% of the 933 tested samples from previously published papers are well correlated and without contradiction. Within the statistical error of Cenozoic synchronous biohorizons at 1.4 Myr, 23 of 42 FOs are potentially regarded as synchronous events. As the statistical likelihoods of UAZ ranges are estimated by Bayesian inference, these ranges can be updated by anyone. [ABSTRACT FROM AUTHOR]

The lower Middle Cambrian of Scandinavia is reviewed and subjected to sequence stratigraphical analysis. Sequences are defined as transgressive–regressive depositional units bounded by maximum regressive surfaces and their correlative conformities. The lower Middle Cambrian forms part of a 2nd order sequence, labelled Cambrian Supersequence 3 (CS-3). It is bounded at the base by a regional unconformity ascribed to the so-called Hawke Bay Event, the focus of this paper. CS-3 comprises at least four 3rd order sequences, but the upper part above the Triplagnostus gibbus Zone has not been analysed as yet and the upper supersequence boundary remains undefined for the time being. The oldest sequence of CS-3 is seemingly of Early Cambrian age. There are numerous T/R cycles in the Acadoparadoxides oelandicus Superzone, here ranked as subsequences (4th order sequences), but a classification as 3rd order cycles of some of these is possible, thereby increasing the number of prospective sequences in CS-3. The high frequency sea-level fluctuations are reminiscent of glacioeustasy and the early Mid Cambrian possibly represents a c. 5 Ma long glacial interval with overall low global sea-level and frequent sea-level changes. The Hawke Bay Event, as identified in Scandinavia, primarily reflects an extensive and long-lasting epeirogenic uplift of western Baltica, and using the term event is a misnomer. The uplift is informally referred to as the Hawke Bay uplift. However, the initial rapid uplift in the latest Early Cambrian coincided with ≥ 100 m eustatic lowering of the sea-level, leading to simultaneous regression in the East Baltic area and elsewhere. This forced regression is assumed representing the Hawke Bay Event s.str. In Estonia–Latvia–Lithuania, the unconformity separating the Kibartian and Deimenian regional stages signals the Hawke Bay regression. The Hawke Bay uplift gradually and differentially subsided during the early Mid Cambrian, starting in the Öland–Gotland area, and the collapse then slowly progressed westwards and southwestwards. Subsidence also advanced from western Norway and eastwards whereas the western margin of Baltica apparently remained uplifted throughout the late Mid Cambrian to earliest Ordovician. In central Scandinavia, the last traces of the Hawke Bay uplift eventually disappeared during the Acidusus atavus Chron. As a result the Hawke Bay unconformity represents a greater hiatus in central and southernmost Scandinavia where the uplift persisted for a longer time (locally up to c. 6 Ma), causing long-lasting non-deposition associated with minor erosion. The epeirogenic uplift is inferred to have been triggered by stress-induced isostasy linked to major plate-tectonic adjustments, possibly the onset of subduction in the adjacent Iapetus Ocean or cessation of the Timanide collision, or both. A series of palaeogeographical maps is constructed for the Middle Cambrian of Scandinavia and adjacent countries. Subcrop and onlap maps of the Hawke Bay unconformity, as well as isopach maps for Middle Cambrian formations are also shown. The elongate land area that straddled the axis of the Scandinavian Peninsula during the Early Cambrian disappeared after subsidence of the Hawke Bay uplift and a new basin configuration was established. This had an overall gentle westwardly sloping sea floor delimited by a broad uplift along the western Baltica margin that formed a submarine sill from the medial Mid Cambrian and onwards. The sill, which eventually disappeared in the later part of the Tremadocian, restricted exchange of water masses and the deeper parts of the epicontinental sea became characterized by dysoxic and anoxic conditions. The resulting organic-rich deposit is referred to as Alum Shale. The sea-level rose eustatically after the terminal Early Cambrian Hawke Bay lowstand (in a strict sense) to reach a temporary highstand during the later part of the A. oelandicus Superchron. It then fell abruptly again at the end of the A. oelandicus Superchron and remained low in the earliest part of the Paradoxides paradoxissimus Superchron. Overall, on a 2nd order scale, the sea-level remained low during the early Mid Cambrian and as a result, the clastic supply was relatively high. The principal sediment supply was from the east; initially minor amounts of clastics were also supplied from the uplifted parts of Scandinavia but overall erosion of the uplifted area was limited, probably due to the extremely flat topography. The high clastic influx from the east resulted in progradation, progressively shifting the coastline westwards. Eventually it reached a position roughly corresponding to the present-day east coast of mainland Sweden. In addition to the initial Hawke Bay regression (s.str,) in the latest Early Cambrian significant forced regressions occurred at the end of the Acadoparadoxides pinus – Pentagnostus praecurrens Chron (here named the Faludden Lowstand) and in the T. gibbus Chron (the Mid-gibbus Lowstand). Several unnamed sea-level lowerings also occurred in the A. pinus – P. praecurrens Chron. A rapid, major sea-level rise at the beginning of the A. pinus – P. praecurrens Chron, estimated at c. 60–70 m, is named the Oelandicus Drowning. Fast sea-level rises at the start and in the middle of the T. gibbus Chron are referred to as the Forsemölla and Exsulans drownings, respectively. From the middle of the T. gibbus Chron onwards into the A. atavus Chron there was a major sea-level rise (Atavus Highstand). This latter rise is estimated at c. 100 m and for the first time the sea-level became as high or higher than it was just prior to the Hawke Bay regression. The associated transgression shifted the coastline some 500–700 km eastwards and from then onwards, extreme clastic starvation prevailed in the epicontinental sea covering Scandinavia. Simultaneously, the mid-shelf became a net sedimentary bypass zone, either due to regular outboard transport of sediment during storms or due to recurrent erosive events associated with sea-level lowstands. Two Mid Cambrian depositional phases are recognized, termed Depositional Phases 3 and 4. Depositional Phase 3 encompasses the transient increase in sedimentary supply during the early Mid Cambrian sea-level lowstand, whereas DP4 covers the strongly starved conditions and widespread dysoxia from the A. atavus Chron onwards associated with high sea-level. A gradual expansion of the oxygen minimum zone during the Mid Cambrian developed independently of the rising sea-level and is suggestive of a stratified water column, presumably created by silled basin conditions. It is likely, however, that the general ‘background’ oxygen level in the oceans also was low, perhaps due to sluggish global circulation in a greenhouse world. Two new regional stages, the Bödan and Almbackenian, are introduced for the Middle Cambrian A. oelandicus and P. paradoxissimus superzones of Scandinavia, respectively. The base of the Middle Cambrian Timofeevia lancare acritarch assemblage zone is located within the upper part of the A. pinus – P. praecurrens trilobite Zone. The T. gibbus trilobite Zone is informally subdivided into a lower Paradoxides jemtlandicus subzone and an upper Bailiaspis dalmani subzone. [ABSTRACT FROM AUTHOR]

With a depositional history spanning the early Aptian to early Albian (~19 mys), the Lower Cretaceous Xinminpu Group in Jiuquan, NW China provides detailed record of an inland ecosystem responding to global climatic and environmental changes. The Xinminpu Group exhibits the most typical elements of the Jehol Biota found outside NE China, a highly diverse avifauna and a mid-Cretaceous angiosperm flora. The absence of a comprehensive stratigraphical framework for this area however limits the degree to which the unit can be interpreted relative to coeval sections and the geological records in genera. Recent fossil discoveries and radio-isotopic age data can provide a more detailed biostratigraphical and chronostratigraphical framework for Lower Cretaceous units around Jiuquan. The data complied here indicate that the Chijinpu Formation correlates with the middle-upper Yixian and lower Jiufotang formations of NE China making it early Aptian in age, and the Xiagou Formation correlates with the upper Jiufotang and Shahai formations making it late early Aptian-early Albian in age. This research further reports a novel zircon U-Pb age constraint of 112.4 ± 0.3 Ma for a basalt sample from the lowermost Zhonggou Formation, which is supported to be correlated with the Fuxin Formation of early Albian age. The Chijinpu Formation contains typical elements of the Jehol Biota, i.e. the Eosestheria - Lycoptera - Ephemeropsis trisetalis assemblage, confirming the interpretation that the Jehol Biota had reached Jiuquan during its second evolutionary stage. The Xiagou Formation contains the amphibious avifauna appearing just above OAE1a, indicating a close link between the early Ornithuromorpha evolution and early Aptian global climate changes. The Zhonggou Formation in Jiuquan records the first appearance of an angiosperm flora above OAE1b. Depositional indicators suggest a humid climate with a gradual shift to arid conditions during this time. This review paper laid foundation for the systematic study of the well-preserved Early Cretaceous ecosystem in Jiuquan, allowing to understand correlations between inland and marine environments as recorded in sediments from this critical period. • We establish the stratigraphy and time scales for the Lower Cretaceous in Jiuquan. • We review how a Cretaceous inland ecosystem responded to global climatic change. • This study summarizes the detailed fossil records for the Jehol Biota in NW China. • Robust age for the less-studied outcrops allows to test the Jehol radiations. • A close link existed between early Ornithuromorpha evolution and OAE1a. [ABSTRACT FROM AUTHOR]

Planktonic foraminifera are widely used for biostratigraphy and correlation of Mediterranean Neogene marine sediments, and are a fundamental component in the astronomical tuning of the Neogene Time Scale. Recent developments in high-resolution studies, focused on the astronomical calibration of cyclically marine sediments cropping out in land-based sections and recovered from deep-sea successions, increased the accuracy of stratigraphic ranges of planktonic foraminiferal species improving the biostratigraphic resolution and biochronology. The large amount of data on planktonic foraminifera obtained through quantitative/semiquantitative analyses, published in the recent years, allowed the revision of many biohorizons and their calibrations. We incorporate these developments and emendments into the existing Mediterranean planktonic foraminiferal biozonation. Therefore, in this paper, we present an emended Standard Mediterranean planktonic foraminiferal biozonation with a detailed description of zones and subzones within the framework of the Astronomical Tuned Neogene Time Scale 2004 and 2012 (ATNTS2004, ATNTS2012) and we provide the range chart of the most common planktonic foraminiferal taxa and the quantitative distribution pattern of selected marker species. Twenty-two biozones and thirty-one subzones that span the past 23 million years have been identified. We distinguished them using the following code system: MMi1 to MMi13, and NDZ (for the time interval related to the Messinian Salinity Crisis): Mediterranean Miocene biozones, MPl1 to MPl6: Mediterranean Pliocene biozones (according to the Gelasian as the uppermost stage of the Pliocene Series/Epoch), and MPle1 to MPle2: Mediterranean Pleistocene biozones (according to the Calabrian as the lowermost stage of the Pleistocene Series/Epoch). We assembled 118 Neogene planktonic foraminiferal biohorizons from multiple datasets, and incorporated the calibration of these bioevents into a revised Neogene planktonic foraminiferal biochronology. The revised and recalibrated data provide a major progress in biostratigraphic and biochronologic resolution and a template for future progress of the Neogene time scale. Unfortunately, two main gaps of planktonic foraminiferal quantitative data occur in the late Burdigalian, between 16.12 Ma and 17.23 Ma, and at Aquitanian/Burdigalian boundary, between 19.74 Ma and 20.66 Ma, due to the absence of high-resolution studies of these time intervals in the Mediterranean. [ABSTRACT FROM AUTHOR]