A Multidisciplinary Approach to Sediment Provenance Analysis of the Late Silurian-Devonian Lower Old Red Sandstone succession, Northern Midland Valley Basin, Scotland

We would like to thank the British Geological Survey for access to petrographical samples and additional data and Dr Emrys Phillips for discussion.Peer reviewedPostprin

Heavy-Mineral Assemblages In Sandstone Intrusions : Panoche Giant Injection Complex, California, U.S.A.

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New methods in provenance studies based on heavy minerals: an example from Miocene sands in Jylland, Denmark

New techniques using Computer Controlled Scanning Electron Microscopy (CCSEM) and Laser Ablation – Inductively Coupled Plasma – Mass Spectroscopy (LA-ICP-MS) have recently been developed at the Geological Survey of Denmark and Greenland (GEUS) to determine source, compositional variation and sedimentary pathways of sandstones. These new time- and cost-efficient methods are highly applicable in petroleum and mineral exploration. This paper illustrates how the provenance and variability of Miocene titanium-rich sands in western and central Jylland have been investigated, but the methods are presently also used offshore the Faroe Islands and in East and West Greenland. CCSEM and LA-ICP-MS utilise simple sample preparation methods, are relatively rapid and less expensive than conventional methods and yield more information

Contemporaneous opening of the Alpine Tethys in the Eastern and Western Alps: Constraints from a Late Jurassic gabbro intrusion age in the Glockner Nappe, Tauern Window, Austria

Metabasic rocks of the ophiolitic sequences of the Glockner Nappe and Eclogite Zone in the south-central Tauern Window, Austria, reveal important insights into rifting and spreading of the Alpine Tethys. U–Pb dating of magmatic zircons yields a concordant 157±2 Ma crystallization age for the precursor of a coarse-grained metagabbro from the Glockner Nappe. The Late Jurassic intrusion age is coeval with mafc plutonic activity in the Western and Central Alps. Although Penninic ophiolitic sequences in tectonic windows of the Eastern Alps are usually disrupted, an ocean–continent transition setting can be reconstructed for the Glockner Nappe, similar to many ophiolites in the Liguria–Piemont domain in the Western and Central Alps. Together, these observations strongly suggest a formation in the Liguria–Piemont branch of the Alpine Tethys and are inconsistent with a formation in the Valais domain. This fnding has important implications for paleogeographic reconstructions of the Penninic realm in the Eastern Alps. Whereas the Glockner Nappe metagabbro and metabasalts clearly reveal their depleted mantle origin, the metabasic rocks of the Eclogite Zone record a more complex formation history involving depleted mantle melting and crustal assimilation in a continental margin setting

Defining regional and local sediment sources in the ancestral Colorado River system: A heavy mineral study of a mixed provenance unit in the Fish creek-vallecito basin, Southern California

The Colorado River has flowed across the dextral strike-slip plate boundary between the North American and Pacific plates since the latest Miocene or earliest Pliocene. The Fish Creek- Vallecito Basin (FCVB) lies on the Pacific Plate in southern California, dextrally offset from the point where the modern Colorado river enters the Salton Trough; it contains a record of ancestral Colorado River sedimentation from 5.3–2.5 Ma. The basin stratigraphy exhibits a changing balance between locally derived (L-Suite) and Colorado River (C-Suite) sediments. This paper focuses on the Palm Springs Group (PSG), a thick fluvial and alluvial sequence deposited on the upper delta plain (between 4.2–2.5 Ma) when the Colorado was active in the area, allowing the detailed examination of the processes of sediment mixing from two distinct provenance areas. The PSG consists of three coeval formations: 1) Canebrake Conglomerate, a basin margin that has coarse alluvial fan deposits derived from surrounding igneous basement; 2) Olla Formation, fan-fringe sandstones containing L-Suite, C-Suite, and mixed units; and 3) Arroyo Diablo Formation, mineralogically mature C-Suite sandstones. Stratigraphic analysis demonstrates that the river flowed through a landscape with relief up to 2000 m

A multi-proxy provenance study of late carboniferous to middle Jurassic sandstones in the Eastern Sverdrup basin and its bearing on arctic palaeogeographic reconstructions

A multi-proxy provenance study of Late Carboniferous to Middle Jurassic sandstones from the eastern Sverdrup Basin was undertaken employing optical petrography and heavy mineral analysis, chemical analysis of apatite, garnet and rutile grains, as well as detrital zircon U–Pb geochronology and Hf isotope analysis. Late Carboniferous to Middle Jurassic strata on the southern basin margin are inferred as being predominantly reworked from Silurian to Devonian strata within the adjacent Franklinian Basin succession. Higher-grade metamorphic detritus appeared during Middle to Late Triassic times and indicates exhumation and erosion of lower (Neoproterozoic to Cambrian) levels within the Franklinian Basin succession and/or a direct detrital input from the Canadian-Greenland Shield

The timing and tectonic context of Pan-African gem bearing pegmatites in Malawi: Evidence from Rb–Sr and U–Pb geochronology

The Pan-African belts of Malawi contain a largely unexplored endowment of gem bearing pegmatites. We present U–Pb in zircon (LA-ICPMS) and Rb–Sr mineral isochron geochronological and isotope data from pegmatites across Malawi. The pegmatites contain tourmaline, beryl, aquamarine, zircon, amethyst and sunstone as gemstone species. Two zircon bearing pegmatites in southern Malawi intruded early in the Pan-African orogenic cycle at 719 ± 5 Ma and 729 ± 4 Ma and are associated with the emplacement of alkaline rocks that formed during an intra-continental rifting episode in the eastern part of former Rodinia. One further zircon pegmatite containing inherited zircon of a similar age (746 ± 44 Ma) was emplaced at 598 ± 15 Ma, after the assembly of Western and Eastern Gondwana and the formation of the East African Orogen (EAO). The majority of the analysed pegmatites, however, are significantly younger

Reconstructing drainage pathways in the North Atlantic during the Triassic utilizing heavy minerals, mineral chemistry, and detrital zircon geochronology

In this study, single-grain mineral geochemistry, detrital zircon geochronology, and conventional heavy-mineral analysis are used to elucidate sediment transport pathways that existed in the North Atlantic region during the Triassic. The presence of lateral and axial drainage systems is identified and their source regions are constrained. Axial systems are suggested to have likely delivered sediment sourced in East Greenland (Milne Land–Renland) as far south as the south Viking Graben (>800 km). Furthermore, the data highlight the existence of lateral systems issuing from Western Norway and the Shetland Platform as well as a major east-west–aligned drainage divide positioned adjacent to the Milne Land–Renland region. This divide separated the catchments that flowed north to the Boreal Ocean from those that flowed south into a series of endoreic basins and, ultimately, the Tethys Sea. A further potential drainage divide is identified to the west of Shetland. The data presented and the conclusions reached have major implications for reservoir prediction, as well as correlation, throughout the region. Furthermore, understanding the drainage networks that existed during the Triassic can help constrain paleogeographic reconstructions and provides an important framework for the construction of facies models in the region