The provenance of the Devonian Old Red Sandstone of the Dingle Peninsula, SW Ireland; the earliest record of Laurentian and peri-Gondwanan sediment mixing in Ireland

The Lower Old Red Sandstone in southern Ireland is hosted in the Early Devonian Dingle Basin, which lies immediately south of the Iapetus Suture on the Dingle Peninsula, County Kerry. The basin developed as a post-Caledonian pullapart structure prior to Acadian deformation, which in turn was followed by end-Carboniferous Variscan deformation. Detrital zircon U–Th–Pb geochronology is complemented by mica Ar–Ar and apatite U–Pb geochronology to gain a comprehensive understanding of the provenance of the Lower Devonian Lower Old Red Sandstone of the Dingle Basin and assess contributions of major tectonic components (e.g. Laurentia, Ganderia). Sedimentary rocks in the Lower Old Red Sandstone have similar detrital zircon age distributions, which are dominated by c. 1.2 Ga zircons as well as late Neoproterozoic grains. This indicates a dominant contribution of detritus of Laurentian affinity as well as contributions from westerly and southerly derived Ganderian detritus. Caledonian uplift of the area north of the Iapetus Suture would have facilitated a large contribution of (peri-)Laurentian material. The Upper Old Red Sandstone on the Dingle Peninsula has a distinctly different detrital zircon character including few late Neoproterozoic zircons and abundant zircons of c. 1.05 Ga age, indicating sediment derivation only from Laurentia and no recycling from the Lower Old Red Sandstone

Spatial-temporal-compositional evolution of syn-orogenic magmatism in the northern New England Orogen: Implications for the Permo-Triassic eastern Gondwanan margin

This project investigated the evolution of igneous activity in eastern Australia during the Permian and Triassic. In Queensland, this Permo-Triassic igneous activity was previously thought to be synchronous with an Andean-scale mountain building event. This study utilised uranium-lead dating, whole rock and mineral isotopic geochemistry to test this hypothesis. The resulting dates and geochemical compositions demonstrate discrete pulses of igneous activity before, during, and following mountain building, providing updated tectonic models for the Permian and Triassic in eastern Australia

Multiple post-depositional thermal events in the Drummond Basin, Australia:Evidence from apatite and zircon (U[sbnd]Th)/He thermochronology

Multiple phases of extension and contraction in orogens can produce relatively complicated thermal histories for sedimentary basins as recorded by thermochronological datasets. This makes it difficult to determine which tectonic events had the most impact on the thermal state, and were drivers of exhumation, of the upper crust. In this study, apatite and zircon (U[sbnd]Th)/He data obtained from five drill core samples (Campaspe DDH-1) from the Drummond Basin are used to construct a continuous, post-depositional thermal history of this Late Devonian-Early Carboniferous rift basin. Detrital zircon U/Pb ages indicate a maximum depositional age of ~340 Ma for the sampled formations, however, most apatite (U[sbnd]Th)/He (AHe) analyses yielded apparent ages of 30–100 Ma (n = 35) and zircon (U[sbnd]Th)/He (ZHe) analyses gave ages of 200–340 Ma (n = 67). Zircon (U[sbnd]Th)/(He[sbnd]Pb) double dating yielded no correlation between U/Pb and ZHe ages, with all the ZHe ages younger than depositional age. These data indicate disturbance of the ZHe and AHe systems after deposition. Inverse thermal history modeling using the QTQt and HeFTy codes suggests the samples experienced two post-depositional heating-cooling cycles: (1) rapid heating to ~150–195 °C at ~300 Ma was followed by rapid cooling to near-surface temperatures of ~50 +50/−30 °C between 270 and 240 Ma, and (2) gradual heating until the Early Cretaceous, when temperatures increased to ~105 +15/−10 °C followed by rapid cooling beginning ~90 Ma. We relate the ~300 Ma heating to the Kennedy-Connors-Auburn silicic large igneous province, revealing that major regional igneous events can significantly perturb a basin thermal history. In contrast, the slow temperature increase between ~270 and 100 Ma is related to progressive burial by overlying sediments of the Galilee and Great Australian basins. Finally, rapid cooling beginning ~90 Ma was synchronous with rift margin exhumation.</p

The Provenance of Middle Jurassic to Cretaceous sediments in the Irish and Celtic Sea Basins: tectonic and environmental controls on sediment sourcing

The Jurassic and Cretaceous sedimentary infill of the Irish and Celtic Sea basins is intimately associated with the breakup of the supercontinent Pangea, and the opening of the Atlantic margin. Previous basin studies have constrained tectonism, basin uplift and sediment composition, but sediment provenance and routing have not received detailed consideration. Current hypotheses for basin infill suggest localised sediment sourcing throughout the Jurassic and Cretaceous, despite a dynamic tectonic and paleoenvironmental history spanning more than 100 million years. We present detrital zircon, white mica and apatite geochronology alongside heavy mineral data from five basins. Findings reveal that basin infill derived predominantly from distal sources with lesser periods of local sourcing. We deduce that tectonically induced marine transgression and regression events had a first-order control on distal versus proximal sedimentary sourcing. Additionally, tectonism which uplifted the Fastnet Basin region during the Middle–Late Jurassic recycled basin sediments into the connected Celtic and Irish Sea Basins. Detrital geochronology and heavy mineral evidence support three distinct provenance switches throughout the Jurassic and Cretaceous in these basins. Overall an integrated multi-proxy provenance approach provides novel insights to tectonic and environmental controls on basin infill as demonstrated in the Irish and Celtic Sea Basins

Erratum for 'The provenance of the Devonian Old Red Sandstone of the Dingle Peninsula, SW Ireland; the earliest record of Laurentian and peri-Gondwanan sediment mixing in Ireland,' Journal of the Geological Society, London, 175, 411-424

Samples in this paper have been assigned formations based on the Geological Survey of Ireland shapefile released prior to the commencement of the study. However, the authors were not aware that, since obtaining the samples, an updated shapefile had been released. This update affects three of the four apatite samples assigned to the Lower Devonian Ballymore Formation. The location of samples Mb-1, Mb-4 and Mb-5 now places them well within the undifferentiated, Upper Devonian Slieve Mish Group. As outlined in our paper, the apatite ages were originally produced concurrently with apatite fission track analysis and were later used in our study to provide additional provenance information in support of the detrital zircon geochronological data. In the second paragraph of the discussion section we say the following: "Williams et al. (1999) obtained an age of 411 Ma for the Cooscrawn Tuff Bed in the Ballymore Formation, which is older than 22 of the 70 detrital apatites analysed in this formation". The reassignment of the three samples to the Upper Devonian Slieve Mish Group nullifies the above statement. However, our interpretation that the depositional age of the Ballymore Formation is younger than the 411 Ma age given by Williams et al. (1999) is predominantly based upon the evidence given by the six youngest detrital zircons from the formation which underlies the Ballymore Formation (i.e. the Slea Head Formation). These zircons give a concordia age of 405 ± 4 Ma. This suggests that the Ballymore Formation was more than likely deposited after 409 Ma. We do not believe that the reassignment of the three samples has any major impact on our provenance interpretations. The ∼420 Ma age of the majority of the apatites in samples Mb-1, Mb-4 and Mb-5 actually fits with the range of Palaeozoic detrital zircons in sample AK-17 which was taken from the Slieve Mish Group, thereby supporting minor input of rocks affected by end-Scandian metamorphism

Full detrital U–Pb zircon dataset. The provenance of the Devonian Old Red Sandstone of the Dingle Peninsula, SW Ireland; the earliest record of Laurentian and peri-Gondwanan sediment mixing in Ireland

Full detrital U–Pb zircon datase