Sediment provenance studies utilizing detrital geochronology are often limited by source‐rock non‐uniqueness with respect to mineral age. Thus, the development of integrated techniques which permit identification of source rock age and lithology are highly desirable. In this case study from the southern Massif Central, France, we target modern‐river sediment from the river Tarn to assess the utility of combined U‐Pb and multiple trace‐element geochemical analysis of detrital apatite as a provenance tool. The study area was chosen because the sediment source areas chiefly comprise a relatively simple mix of medium‐ to low‐grade Variscan metasediments and late Variscan granitoids, which should yield detrital apatite readily distinguishable by age, trace‐element chemistry, or both. Based on comparison with previously published apatite trace‐element data from metasedimentary rocks and granitoids, pelitic apatite in the river Tarn detritus is primarily distinguished by high Sr/Mn, light rare‐earth element depletion (LREE) and low actinide contents, whereas granitic apatite is characterized by much lower Sr/Mn, and high LREE and actinide abundances. These source rock determinations are highly consistent with apatite trace‐element data from Tarn tributaries that drain either predominantly metapelitic or granitoid catchments. U‐Pb analysis of detrital rutile was also undertaken on those catchments for comparative purposes. As pelitic and granitic apatite can be readily distinguished, samples that have experienced downstream sediment mixing can then be comprehensively characterized. Using this method we identify a source lithology for nearly every analyzed apatite grain in the river sediment, even though 59% of the analyzed grains do not yield reliable U‐Pb ages.

Hosting up to 3.3 billion barrels of oil in place, the upfaulted Precambrian crystalline rocks of the Lancaster field, offshore west of Shetland, give key insights into how fractured hydrocarbon reservoirs can form in such old rocks. The Neoarchean ( c. 2700–2740 Ma) charnockitic basement is cut by deeply penetrating oil-, mineral- and sediment-filled fissure systems seen in geophysical and production logs and thin sections of core. Mineral textures and fluid inclusion geothermometry suggest that a low-temperature (<200°C) near-surface hydrothermal system is associated with these fissures. The fills help to permanently prop open fissures in the basement, permitting the ingress of hydrocarbons into extensive well-connected oil-saturated fracture networks. U–Pb dating of calcite mineral fills constrains the onset of mineralization and contemporaneous oil charge to the mid-Cretaceous and later from Jurassic source rocks flanking the upfaulted ridge. Late Cretaceous subsidence and deposition of mudstones sealed the ridge, and was followed by buoyancy-driven migration of oil into the pre-existing propped fracture systems. These new observations provide an explanation for the preservation of intra-reservoir fractures (‘joints’) with effective apertures of 2 m or more, thereby highlighting a new mechanism for generating and preserving fracture permeability in sub-unconformity fractured basement reservoirs worldwide. Supplementary material: Analytical methods and isotopic compositions and ages are available at https://doi.org/10.6084/m9.figshare.c.4763237 Thematic Collection: This article is part of the Geology of Fractured Reservoirs collection available at: https://www.lyellcollection.org/cc/the-geology-of-fractured-reservoirs

The development of laser ablation techniques using inductively coupled plasma mass spectrometry has enabled the routine and fast acquisition of in situ U–Pb and Pb–Pb isotope ratio data from single detrital grains or parts of grains. Detrital zircon dating is a technique that is increasingly applied to sedimentary provenance studies. However, sand routing information using zircon analysis alone may be obscured by repeated sedimentary reworking cycles and mineral fertility variations. These biases are illustrated by two clear case studies from the Triassic–Jurassic of the Barents Shelf where the use of U–Pb geochronology on apatite and rutile and Pb–Pb isotopic data from K-feldspar is highly beneficial for provenance interpretations. In the first case study, U–Pb apatite ages from the (Induan – Norian) Havert, Kobbe and Snadd formations indicate an evolving provenance and identify possible episodes of storage within foreland basins prior to delivery onto the Barents Shelf. In the second case study, U–Pb rutile and Pb isotopic analyses of K-feldspar from the Norian–Pliensbachian Realgrunnen Subgroup provide a clear distinction between north Norwegian Caledonides and Fennoscandian Shield sources and suggest that a similar approach may be used to test competing models for sand dispersal for this Subgroup in regions farther north than this study.

An integrated heavy-mineral, mineral-chemical and zircon-dating study of the Triassic succession exposed on the south Devon coast, in the western part of the Wessex Basin, indicates derivation from a combination of granitic and metasedimentary lithologies of ages of mostly over 550 Ma. These sources were probably located at a relatively proximal location near the southern margin of the basin. Derivation from more distal sources in the Armorican Massif or local Variscan sources to the west appears unlikely in view of the scarcity of Permo-Carboniferous (Variscan-age) zircons. The Budleigh Salterton Pebble Bed Formation was derived from a different combination of source lithologies than the Otter Sandstone Formation, the former including staurolite-grade metasediments that were absent in the catchment area of the Otter Sandstone. The Devon coast succession has provenance characteristics that differ from equivalent sandstones further east in the Wessex Basin, and from sandstones in the East Irish Sea Basin to the north. These differences indicate that sediment supply patterns to the linked Triassic basin systems in southern Britain are complex, involving multiple distinct sub-catchment areas, and that heavy-mineral studies have considerable potential for unravelling these sub- -catchment area sources