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Recent studies on the stratigraphy of Paleozoic successions belonging to key sectors of the inner Northern Apennines provide data that can be used to propose new hypotheses about the palaeogeography of the western Mediterranean domain during post-Hercynian times. We report here the first evidence of mid- to late Permian (Guadalupian–Lopingian) palynomorphs in the chronostratigraphically highly debated metamorphic units of the Northern Apennines (the Rio Marina Formation, the Mt Calamita Formation and the Le Cetine Formation) and consider the stratigraphic implications for the Tuscan ‘basement’ to which the study rocks belong and their palaeogeographical attribution considering their Gondwana affinity. These results agree with the interpretation that the Alpine Tethyan sedimentary cycle was already active during the mid- to late Permian. Thematic collection: This article is part of the ‘Apennines and Tyrrhenian system’ collection available at: https://www.lyellcollection.org/cc/the-apennines-tyrrhenian-system

In this paper we reply to the criticisms advanced by Narkiewicz (2017) on the paper by Schito et al. (2017). We clarify the issues related to the stratigraphic and thermal maturity constraints used for reconstructing burial and thermal models of the two blocks of the Holy Cross Mountains. We also show how geological evidences brought by Narkiewicz (2017) as a proof of elevated Variscan heat flow are not conclusive or at least suggest the occurence of a localized thermal anomaly only along the area of the Holy Cross Fault. In the end, we performed new burial and thermal models in the Kielce region demonstrating that stratigraphic thickness variations between Schito et al. (2017) and Narkiewicz et al. (2010) produce only negligible differences in levels of thermal maturity of Paleozoic rocks. In addition, we outline that levels of thermal maturity for Silurian rocks can be matched only by using constant heat flow values through the Paleozoic and point to a decisive role for the absence of regional high Variscan heat flow in the area.

Thermal maturity of six organic rich samples from Jurassic continental successions cropping out in the Holy Cross Mountains in Central Poland, has been characterized by classic thermal maturity indicators, micro-Raman spectroscopy and Palynomorph Darkness Index, in order to create a multi-method workflow for complex palynofacies thermal maturity assessment. Transmitted light observations on dispersed organic matter define a Hettangian lacustrine depositional environment, characterized by periods of reducing/oxidizing conditions and variable sedimentation rates. Thermal maturity detected by classical maturity indicators and PDI indicates an early maturation stage of hydrocarbon generation and is in agreement with spectroscopic analyses performed on phytoclast groups. Moreover, Raman parameters in the sporomorph group indicate a systematic shift toward a lower degree of aromatization compared to the phytoclast group. Finally, the multivariate statistical analysis performed on Raman spectra is found to be a promising tool to define and predict the heterogeneity of dispersed organic matter in sediments.

Poland is considered the most prospective country for shale gas production in Europe. Hydrocarbon generation/expulsion scenarios, drawn in the latest intensive exploration phases, tend to overestimate maturation levels when compared with brand new data acquired after recent drillings. We tested an integrated workflow to correlate published and original thermal maturity datasets for the Paleozoic to Jurassic successions cropping out in the Holy Cross Mountains. These successions, when preserved in subsurface, host the major source rocks in the area. The application of the workflow allowed us to highlight the burial and thermal evolutionary scenarios of the two tectono-stratigraphic blocks of the Holy Cross Mountains (Łysogory and Kielce blocks) and to propose this approach as a tool for reducing levels of uncertainty in thermal maturity assessment of Paleozoic successions worldwide. In particular, published datasets including colour alteration indexes of Paleozoic microfossils (conodont, acritarchs) and vitrinite and graptolite reflectance data, show differences in levels of thermal maturity for the Łysogory (mid mature to overmature) and Kielce (immature to late mature) blocks. Original data, derived from optical analysis, pyrolysis, and Raman spectroscopy on kerogen, and X-Ray diffraction on fine-grained sediments, mostly confirm and integrate published data distribution. 1D thermal models, constrained by these data, show burial and exhumation events of different magnitude, during the Late Cretaceous, for the Łysogory (maximum burial depths of 9 km) and Kielce (burial depths of 6 km) blocks that have been related to the Holy Cross Fault polyphase activity. In the end, Palynomorph Darkness Index and Raman spectroscopy on kerogen, for Llandoverian and Cambrian rocks, turned out to be promising tools for assessing thermal maturity of Paleozoic organic facies devoid of vitrinite macerals.

International audience; New major and trace element data and (40)Ar/(39)Ar plateau ages constrain the timing, duration and time-related geochemical evolution of the Central Atlantic magmatic province in the U.S.A. (Newark and Culpeper basins) and refine correlations with basaltic lava flows from other Late Triassic-Early Jurassic circum-Atlantic basins. The precise, statistically robust (40)Ar/(39)Ar plateau ages were obtained on biotite and on fresh plagioclase and calculated using the latest (40)K decay constants. These ages are supported by a general consistency of the Ca/K calculated from (37)Ar/(39)Ar of the plateau steps and the Ca/K obtained by detailed electron microprobe analyses on plagioclase phenocrysts. The ages of five analyzed basalt lava flows, from all three lava flow units in the Newark basins, and the ages of two sill samples are indistinguishable, indicating a brief magmatic peak phase at 201.8 +/- 0.7 Ma. Recalibrated (40)Ar/(39)Ar plateau ages from the entire province indicate a near-synchronous onset and peak volcanic activity at the Triassic-Jurassic boundary within the circum-Atlantic basins from the U.S.A., Canada and Morocco. The early erupted magmas (Moroccan Lower to Upper basalts, the Fundy basin North Mountain Basalt, and Orange Mountain and equivalent U.S.A. flows) yield an enriched geochemical signature (e.g., with relatively high La/Yb), whereas late magmas in the U.S.A. (Hook Mountain and Hampden basalts) and Morocco (Recurrent basalt) yield relatively depleted geochemical compositions (low La/Yb). A slight, but significant age difference for eruption of Hook Mountain and Hampden basalts (200.3 +/- 0.9 Ma) and Recurrent basalts (198.2 +/- 1.1 Ma) is interpreted as evidence of a diachronous northward rift-drift transition during break-up of Pangea. Our data indicate also a prolonged intrusive sequence that continued until about 195 Ma at the Palisades sill and is consistent with sporadic late CAMP magmatism for dykes from the south-eastern U.S.A. and for intrusions from Guinea.

A sedimentological, palynological and microfaunal integrated analysis was carried out across the Permian-Triassic transition in a 35 m thick section near Seres (Badia Valley, northern Italy). This section includes the uppermost part of the Bellerophon Formation and the base of the Werfen Formation (Tesero Horizon and the lowermost Mazzin Member). The Bellerophon Formation (”badiota facies”) displays a general shallowing-upward trend. It has been subdivided into three intervals on the basis of facies, microfacies, biofacies and palynofacies associations. The Bellerophon-Werfen Formation boundary was located at the boundary between a thin black organic-rich layer and a 50 cm thick limestone bed, containing in the upper part the first oolitic beds. The palynological assemblages show throughout the Bellerophon Formation a gradual decrease of exclusive Permian palynomorphs and a concomitant increase of Triassic ranging forms. Triassic palynomorphs were found in the lower part of the Tesero Oolitic Horizon (TOH), where the Permian-Triassic transition can be recognized. Foraminifers with Triassic affinity appear just above the proposed Permian Triassic transition. This multidisciplinary approach led to evidence the palaeoenvironmental evolution which was characterized by variations in the water column oxygenation from dysoxic to oxic conditions related to climatic and/or physiographic changes influencing the water layering. Palynofacies studies show a shift from relatively distal to more proximal conditions which reached the maximum during the deposition of the black organic-rich level at the upper boundary of the Bellerophon Formation. The overlying shallowing upward cycle at the base of the TOH starts with an anoxic transgressive layer and ends with the oolitic beds.

AThe aims of this study are to reconstruct the geological setting of the Punta Bassano series (Marettimo Island, Egadi Archipelago, western Sicily) and its palaeogeographic evolution. The reference section for the Upper Triassic of Marettimo shows an alternation of marl and limestone beds together with brecciated levels. The limestones are both homogeneous mudstones with evaporite pseudomorphs and laminated with fenestrae. Foraminiferal, palynomorph, and ostracod associations constrain the Punta Bassano sequence to the Carnian-Rhaetian interval. The Punta Bassano succession represents a shallow inner ramp, ranging from open-marine environment with good water circulation to lagoonal and peritidal protected environments. Freshwater input from rivers or groundwater on the carbonate ramp is indicated by the ostracod microfauna. The comparison of facies and microfauna with those from other sequences of the Mediterranean Upper Triassic (Pyrenees, Corsica, Sardinia, and Tunisia) allows us to confine the Punta Bassano sedimentation to the northern margin of the Tethys, between the Corsican and the Pyrenean depositional setting. These new results indicate that Marettimo Island, which is considered a single structural element being formed by four tectonic units, is a piece of the southern margin of the European Plate, displaced over a longer distance to become part of the other Egadi Islands, when the Corso-Sarde block made its rotation and successive collision with the North African Margin. palynomorph, and ostracod associations constrain the Punta Bassano sequence to the Carnian-Rhaetian interval. The Punta Bassano succession represents a shallow inner ramp, ranging from open-marine environment with good water circulation to lagoonal and peritidal protected environments. Freshwater input from rivers or groundwater on the carbonate ramp is indicated by the ostracod microfauna. The comparison of facies and microfauna with those from other sequences of the Mediterranean Upper Triassic (Pyrenees, Corsica, Sardinia, and Tunisia) allows us to conWne the Punta Bassano sedimentation to the northern margin of the Tethys, between the Corsican and the Pyrenean depositional setting. These new results indicate that Marettimo Island, which is considered a single structural element being formed by four tectonic units, is a piece of the southern margin of the European Plate, displaced over a longer distance to become part of the other Egadi Islands, when the Corso-Sarde block made its rotation and successive collision with the North African Margin.

Paleomagnetic and biostratigraphic data from the Al Azizia Formation of northwestern Libya, consisting of uppermost Middle Triassic/lowermost Upper Triassic limestones, shed new light on the latitudinal drift of Africa and Adria and related climatic changes. A characteristic component of magnetization carried by magnetite delineates paleomagnetic poles which are coincident with coeval poles from the Southern Alps. Data from this study and the literature are integrated, showing that relatively unrotated remnants of the Adria. margin like the Southern Alps (e.g., the Dolomites), Istria, Gargano, Apulia and Iblei moved in close conjunction with Africa since at least Permian times. A Permian-Cenozoic apparent polar wander (APW) curve for Africa/Adria is constructed. The paleolatitude trend for northern Libya calculated from this APW superposed to the zonal latitudinal bands of relative aridity and humidity typical of modern-day climate predicts that northern Libya drifted northwards from the equatorial belt to the and tropic during the Triassic, and crossed the humid subequatorial/arid subtropical boundary zone at Late Triassic times. This inference is fully supported by Permo-Triassic palynological and facies analysis from this study and the literature. We conclude that a zonal climate model coupled with paleomagnetically constrained paleogeographic reconstructions provides a powerful null hypothesis for understanding past climatic conditions. (C) 2001 Elsevier Science BN. All rights reserved.