Deep- versus shallow-marine sandstone provenance in the mid-Carboniferous Clare Basin, western Ireland

2021 ◽  
pp. jgs2020-216
Author(s):  
Martin Nauton-Fourteu ◽  
Shane Tyrrell ◽  
David M. Chew ◽  
Foteini Drakou ◽  
Katharina Pfaff ◽  
...  
Keyword(s):  
Deep Water ◽  
Temporal Variations ◽  
Heavy Mineral ◽  
The South ◽  
Deep Basin ◽  
Content Type ◽  
Shallow Marine ◽  
Red Sandstone ◽  
Source To Sink ◽  
Supplementary Material

In a ‘source to sink’ sedimentary system, multiple processes have the potential to modify the sediment composition during sediment generation at the source, through transport, deposition and burial. To investigate these issues, a multi-proxy provenance study of deep-water and shallow-marine sandstones from the mid-Carboniferous Clare Basin was undertaken, utilising zircon and apatite U-Pb geochronology, heavy mineral analysis (including apatite trace element data) and petrography. Data from the deep-water submarine fans show a similar provenance signal to the shallow marine sandstones. Data, from across the Clare Basin stratigraphy indicate sands were likely and consistently derived from the south and SW, with a portion of the detritus being recycled from Old Red Sandstone basins to the south. The provenance signal, however, shows spatial and temporal variations across the basin that are explained by fluctuations in the amount of recycled sediments and are linked with the evolving Variscan Orogenic Belt. Heavy mineral data from both shallow marine and deep-water sandstones suggest a basin configuration with a delta system feeding directly into the deep basin.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5446739

scholarly journals Suitability of surficial media for Ni-Cu-PGE exploration in an established mining camp: a case study from the South Range of the Sudbury Igneous Complex, Canada

2021 ◽  
pp. geochem2021-051
Author(s):  
Sarah Hashmi ◽  
Matthew I. Leybourne ◽  
Stewart Hamilton ◽  
Daniel Layton-Matthews ◽  
M. Beth McClenaghan
Keyword(s):  
Anthropogenic Contamination ◽  
The South ◽  
Aqua Regia ◽  
Content Type ◽  
Igneous Complex ◽  
Sudbury Igneous Complex ◽  
Geochemical Study ◽  
Pge Mineralization ◽  
Supplementary Material

A geochemical study over the southwestern part of the South Range of the Sudbury Igneous Complex (SIC) was completed to assess the suitability of surficial media (humus, B-horizon soil and C-horizon soil) for delineating geochemical anomalies associated with Ni-Cu-PGE mineralization. Another objective was to test whether Na pyrophosphate can eliminate the effects of anthropogenic contamination in humus. Results of this study suggest that the natural geochemical signature of humus is strongly overprinted by anthropogenic contamination. Despite no indication of underlying or nearby mineralization, metal concentrations in humus samples by aqua regia collected downwind from smelting operations are higher compared to background, including up to 13 times higher for Pt, 12 times higher for Cu and 9 times higher for Ni. The high anthropogenic background masks the geogenic signal such that it is only apparent in humus samples collected in the vicinity of known Ni-Cu-PGE deposits. Results of this study also demonstrate that anthropogenically-derived atmospheric fallout also influences the upper B-horizon soil; however, lower B-horizon soil (at > 20 cm depth) and C-horizon soil (both developed in till) are not affected. Glacial dispersal from Ni-Cu-PGE mineralization is apparent in C-horizon till samples analyzed in this study. Compared to the background concentrations, the unaffected C-horizon till samples collected immediately down-ice of the low-sulfide, high precious metal (LSHPM) Vermilion Cu-Ni-PGE deposit are enriched over 20 times in Pt (203 ppb), Au (81 ppm) and Cu (963 ppm), and over 30 times in Ni (1283 ppm).Supplementary material:https://doi.org/10.6084/m9.figshare.c.5691080

scholarly journals The naming of the Permian System

2021 ◽  
pp. jgs2021-037
Author(s):  
Michael J. Benton ◽  
Andrey G. Sennikov
Keyword(s):  
System Level ◽  
Naming Time ◽  
Content Type ◽  
Red Sandstone ◽  
Link Type ◽  
Permian System ◽  
Urgent Task ◽  
Great Leader ◽  
Supplementary Material ◽  
Access To Documents

The naming of the Permian by Roderick Murchison in 1841 is well known. This is partly because he ‘completed’ the stratigraphic column at system level, but also because of the exotic aspects of his extended fieldwork in remote parts of Russia and Murchison's reputed character. Here, we explore several debated and controversial aspects of this act, benefiting from access to documents and reports notably from Russian sources. Murchison or Sedgwick could have provided a name for the unnamed lower New Red Sandstone in 1835 based on British successions or those in Germany, so perhaps the Imperial aim of naming time from British geology was not the urgent task some have assumed. Murchison has been painted as arrogant and Imperialistic, which was doubtless true, but at the time many saw him as a great leader, even an attractive individual. Others suggest he succeeded because he stood on the shoulders of local geologists; however, his abilities at brilliant and rapid geological synthesis are undoubted. Two unexpected consequences of his work are that this arch conservative is revered in Russia as a hero of geological endeavours, and, for all his bombast, his ‘Permian’ was not widely accepted until 100 years after its naming.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5412079

Terreneuvian bio- and chemostratigraphy of the South Sichuan Region (South China)

2021 ◽  
pp. jgs2020-167
Author(s):  
Ben Yang ◽  
Michael Steiner
Keyword(s):  
Carbon Isotope ◽  
South China ◽  
Cambrian Explosion ◽  
The South ◽  
Yangtze Craton ◽  
Content Type ◽  
Link Type ◽  
Small Shelly Fossils ◽  
Assemblage Zone ◽  
Supplementary Material

Classical sections, such as the Maidiping and Daqiao Mine sections of South Sichuan (China), expose early Cambrian deposits that are crucial for understanding the biological and environmental evolution of Yangtze Craton. These sequences are rich in Terreneuvian small shelly fossils, which can be assigned to assemblages I and III from South China. The Anabarites trisulcatus– Protohertzina anabarica Assemblage Zone (Assemblage I) is recognized at the lower Maidiping Formation. The second assemblage (Paragloborilus subglobosus – Purella squamulosa Assemblage Zone) cannot be verified in South Sichuan, although previous reports claimed its existence based on the occurrence of Paragloborilus subglobosus. The third assemblage (Watsonella crosbyi Assemblage Zone) is confirmed in the upper Maidiping Formation. The abundant bioclasts in this interval indicate abrasions and bioerosions by winnowing or starved sedimentation. Carbon isotope values from the Maidiping section present no negative excursion at the presumed Ediacaran–Cambrian transition. A positive carbon isotope excursion is observed in the upper Maidiping Formation (Assemblage III) which is correlated to the ZHUCE excursion in the Dahai Member of eastern Yunnan. The shallow water deposits of South Sichuan can be correlated with the South China, western Mongolia and Siberia successions based on biozonations and carbon isotope trends.Thematic collection: This article is part of the Advances in the Cambrian Explosion collection available at: https://www.lyellcollection.org/cc/advances-cambrian-explosionSupplementary material:https://doi.org/10.6084/m9.figshare.c.5326834

How well is the deep Tore seamount basin ventilated?

2020 ◽  
Author(s):  
Laura Antón ◽  
Susana Lebreiro ◽  
Silvia Nave ◽  
Luke Skinner ◽  
Elizabeth Michel ◽  
...  
Keyword(s):  
Ocean Circulation ◽  
Water Depth ◽  
Deep Water ◽  
Planktonic Foraminifera ◽  
Deep Ocean ◽  
South Atlantic ◽  
Age Difference ◽  
The South ◽  
Deep Basin ◽  
Iberian Margin

<p>The Last Glacial Maximum (LGM) was characterized by increased carbon storage in the deep ocean, as well as extremely poorly ventilated southern-sourced deep water (AABW) compared to northern-sourced deep water (NADW).</p><p>Here we analyse benthic (Cibicidoides wellerstorfi) d<sup>13</sup>C, and compare 3 sites sitting on the deep floor at 5 km water depth: MD13-3473 in the Tore inside basin; MD03-2698 in the Iberian margin; and TN057-21 in the South Atlantic. The Tore Seamount is a geological structure 300 km off the West Iberian margin at 40°N latitude. It has a crater-like morphology with a 5500 m deep basin in its middle, where calypso core MD13-3473 was collected, confined from the open ocean by a summit rim at 2200 m water depth (wd). The only connection between the deepest Tore Seamount basin and the Atlantic circulation is a NE gateway down to 4300 mwd.</p><p>The results for the LGM show similar values around -1.0 ‰ for the South Atlantic and the Iberian margin, in other words these sites were both bathed by AABW. However, the Tore basin record exhibits values around 0 ‰, similarly to open sites in the Iberian margin at 3.5 km depth. This seems to indicate a remarkable isolation of the Tore inside basin from the Atlantic deep bottom waters influence.</p><p>Among other things, we plan to examine the residence time of the Tore basin bottom water by measuring the radiocarbon age difference between benthic and planktonic foraminifera. </p><p>Our results confer to this enclosed environment the status of an in-situ deep ocean laboratory where to test hypotheses of past ocean circulation changes like the role of deep waters in sequestering glacial CO<sub>2</sub>. Core MD13-3473 covers 430 thousands of years, therefore 5 deglacial cycles (Spanish project “TORE5deglaciations”, CTM2017-84113-R, 2018-2020).</p>

Structure of the Dingle Peninsula, SW Ireland: evidence for the nature and timing of Caledonian, Acadian and Variscan tectonics

2014 ◽  
Vol 152 (2) ◽  
pp. 242-268 ◽  
Author(s):  
S.P. Todd
Keyword(s):  
Deep Water ◽  
Volcanic Rocks ◽  
Fault Zones ◽  
Early Devonian ◽  
Shallow Marine ◽  
Red Sandstone ◽  
Early Ordovician ◽  
The North ◽  
Tectonic History ◽  
Extensional Structures

AbstractThe Palaeozoic rocks of the Dingle Peninsula provide a record of the evolution of the Caledonides, Acadides and Variscides. The succession ranges from Early Ordovician deep-water sediments, through Silurian shallow marine to non-marine sediments and volcanic rocks to an Old Red Sandstone (ORS) succession topped by Carboniferous marine shales. Comparison of structural styles in the unconformity-bounded groups, together with a detailed analysis of fault zones, allows the tectonic history to be deduced. The older rocks record Caledonian processes on the margin of Avalonia during Early Ordovician time and convergence then soft collision with Laurentia during Silurian time. The Dingle Basin was developed during the late Silurian – Early Devonian transtension in the Iapetus suture zone and was inverted in the latest Emsian Acadian orogenic episode. Post-Dingle Group ORS groups in the north of the peninsula were deposited in a syn-rift footwall block to the main Munster Basin. The Acadian transpressional and Munster Basin extensional structures were reactivated or overprinted in the Variscan deformation such that Acadian folds are transected by Variscan cleavage in both plan and vertical views. After Iapetus closure, changes in the tectonic regime are believed to be a result of adjustments in the geometry of subduction of the Rheic Ocean.

scholarly journals Rift-related magmatism influences petroleum system development in the NE Irish Rockall Basin, offshore Ireland

2020 ◽  
Vol 26 (4) ◽  
pp. 511-524
Author(s):  
Christopher A.-L. Jackson ◽  
Craig Magee ◽  
Carl Jacquemyn
Keyword(s):  
Deep Water ◽  
System Development ◽  
Source Area ◽  
Sedimentary Basins ◽  
Reservoir Quality ◽  
Content Type ◽  
The Poor ◽  
Supplementary Material ◽  
Break Up ◽  
Upper Paleocene

Large volumes of hydrocarbons reside in volcanically influenced sedimentary basins. Despite having a good conceptual understanding of how magmatism impacts the petroleum systems of such basins, we still lack detailed case studies documenting precisely how intrusive magmatism influences, for example, trap development and reservoir quality. Here we combine 3D seismic reflection, borehole, petrographical and palaeothermometric data to document the geology of borehole 5/22-1, NE Irish Rockall Basin, offshore western Ireland. This borehole (Errigal) tested a four-way dip closure that formed to accommodate emplacement of a Paleocene–Eocene igneous sill-complex during continental break-up in the North Atlantic. Two water-bearing turbidite-sandstone-bearing intervals occur in the Upper Paleocene; the lowermost contains thin (c. 5 m), quartzose-feldspathic sandstones of good reservoir quality, whereas the upper is dominated by poor-quality volcaniclastic sandstones. Palaeothermometric data provide evidence of anomalously high temperatures in the Paleocene–Eocene succession, suggesting the poor reservoir quality within the target interval is likely to reflect sill-induced heating, fluid flow, and related diagenesis. The poor reservoir quality is also probably the result of the primary composition of the reservoir, which is dominated by volcanic grains and related clays derived from an igneous-rock-dominated, sediment source area. Errigal appeared to fail due to a lack of hydrocarbon charge: that is, the low bulk permeability of the heavily intruded Cretaceous mudstone succession may have impeded the vertical migration of sub-Cretaceous-sourced hydrocarbons into supra-Cretaceous reservoirs. Break-up-related magmatism did, however, drive the formation of a large structural closure, with data from Errigal at least proving high-quality, Upper Paleocene deep-water reservoirs. Future exploration targets in the NE Irish Rockall Basin include: (i) stratigraphically trapped Paleocene–Eocene deep-water sandstones that onlap the flanks of intrusion-induced forced folds; (ii) structurally trapped, intra-Cretaceous, deep-water sandstones incorporated within intrusion-induced forced folds; and (iii) more conventional, Mesozoic fault-block traps underlying the heavily intruded Cretaceous succession (e.g. Dooish). Similar plays may exist on other continental margins influenced by break-up magmatism.Supplementary material: Borehole-related reports, and litho- and composite logs are available at https://doi.org/10.6084/m9.figshare.c.4803267

Georgian port project falters but should survive

2019 ◽  
Keyword(s):  
Black Sea ◽  
Deep Water ◽  
Investment Climate ◽  
The South ◽  
South Caucasus ◽  
Content Type ◽  
Water Port ◽  
Black Sea Coast ◽  
East West ◽  
Sea Coast

Subject The Anaklia port project. Significance An ambitious plan to build a new deep-water port on the eastern Black Sea coast has been delayed after one partner in the project consortium left and a possible substitute declined to join. Although uncertainty is hampering the project, external interest in the strategically located port, coupled with domestic pressure not to abandon the project, should keep it alive. Impacts Success would reinforce east-west connections in the South Caucasus as opposed to Russia-sponsored north-south initiatives. Failure to find large investors for Anaklia is likely to undermine the overall investment climate. Any progress at Anaklia will be a catalyst for Russia to ramp up efforts to build its own deep-water port.

Evidence from the U-Pb-Hf signatures of detrital zircons for a Baltican provenance for basal Old Red Sandstone successions, northern Scottish Caledonides

2021 ◽  
pp. jgs2020-241
Author(s):  
Rob A. Strachan ◽  
Hugo K. H. Olierook ◽  
Christopher L. Kirkland
Keyword(s):  
Detrital Zircon ◽  
Detrital Zircons ◽  
Early Devonian ◽  
Content Type ◽  
Red Sandstone ◽  
Isotopic Signatures ◽  
Supplementary Material ◽  
Detrital Zircon Ages ◽  
Subduction System ◽  
Isotope Analyses

The provenance of Devonian Old Red Sandstone (ORS) continental successions in the northern Scottish Caledonides is poorly known: were they derived locally or from more distal sources? The integration of U-Pb and Hf isotope analyses in detrital zircon crystals reduces potential ambiguities arising from non-unique age populations and yields information on the crustal evolution of source terranes. Samples of basal ORS successions yield zircon U-Pb age groupings of c. 1800–1500 and c. 1200–900 Ma, with minor Neoarchaean, Tonian, Ediacaran and Ordovician contributions. SW Baltica provides the best match for detrital zircon ages and Hf isotopic signatures, and much of the >900 Ma zircon population was probably recycled from Neoproterozoic successions. εHf(t) values in c. 1800–1000 Ma grains reflect the assembly of Nuna, development of a long-lived retreating subduction system along its margin, and Grenville collisional orogenesis. These basal ORS successions were likely deposited within the same regional fluvial system as coeval sedimentary rocks in the Midland Valley, draining an area of positive relief in SW Baltica where continental convergence continued through the Early Devonian.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5301780

Timing of slip across the South Tibetan detachment system and Yadong–Gulu graben, Eastern Himalaya

2020 ◽  
Vol 178 (1) ◽  
pp. jgs2019-197
Author(s):  
Hanwen Dong ◽  
Kyle P. Larson ◽  
Dawn A. Kellett ◽  
Zhiqin Xu ◽  
Guangwei Li ◽  
...  
Keyword(s):  
Late Miocene ◽  
Analytical Data ◽  
Eastern Himalaya ◽  
Model Parameters ◽  
The South ◽  
Southern Tibet ◽  
Content Type ◽  
The North ◽  
Extensional Strain ◽  
Supplementary Material

The Yadong–Gulu graben preserves the kinematic and temporal relationships between east–west-directed extension in southern Tibet and north–south extensional strain in the Himalaya. In the Yadong region, distinct outer and inner top-down-to-the-north segments of the South Tibetan detachment system (STDS) are recognized. Herein, we combine high- to medium-T (U–Pb, 40Ar/39Ar) and low-T (apatite fission-track, apatite (U–Th)/He and zircon (U–Th)/He) thermochronometry to investigate the timing of slip across the STDS and Yadong–Gulu structures. These data demonstrate that the cessation of the Yadong shear zone, the structurally outer ductile segment of the STDS, occurred c. 20 Ma and that motion along the inner brittle–ductile Zherger La detachment continued after c. 16.6 Ma, ending by 11 Ma. The cooling history in the immediate STDS footwall is characterized by two main episodes of relatively rapid cooling and exhumation. The first occurred in the middle Miocene (c. 15–11 Ma), and is common along-strike of the innermost STDS footwall, related to cooling of the STDS. The second occurred in the late Miocene–Pliocene (c. 7–3 Ma), and is local to the Yadong–Gulu graben footwall in NW Bhutan, indicating that late Miocene–Pliocene slip along the graben system contributed to exhumation of the STDS east of the graben rift.Supplementary material: Tables of analytical data, dating results, and input data and model parameters of HeFTy are available at https://doi.org/10.6084/m9.figshare.c.5132941

Serpukhovian in Britain: use of foraminiferal assemblages for dating and correlating

2020 ◽  
pp. jgs2020-170
Author(s):  
P. Cózar ◽  
I. D. Somerville
Keyword(s):  
Shallow Water ◽  
Deep Water ◽  
Content Type ◽  
South Wales ◽  
First Occurrence ◽  
Supplementary Material ◽  
First Time ◽  
Early Late ◽  
Basinal Facies ◽  
Serpukhovian Stage

Analysis of foraminiferal assemblages from the Viséan-Serpukhovian boundary interval in Britain has led to the recognition that levels correlated with the first occurrence of Lochriea ziegleri at the base of the Serpukhovian Stage can be established by the foraminifer Neoarchaediscus gregorii in England and Scotland, which first occurs from the Single Post and Cockleshell limestones in northern England and laterally equivalent levels, as well as Asteroarchaediscus bashkiricus, and A. rugosus (except for South Wales). Contrary to some previous studies, the base of the Serpukhovian does not equate with the base of the Namurian (Pendleian Substage), but lies approximately at the early-late Brigantian boundary, based on the first occurrence of Neoarchaediscus postrugosus. Four foraminiferal assemblages are distinguished in the early Serpukhovian (7-10) and four assemblages in the late Serpukhovian (11-14). Despite the contrast in facies, it is now recognised for the first time that throughout the Midland Valley of Scotland, northern England and South Wales. the foraminiferal assemblages from shallow-water platform facies are completely compatible with the ammonoid subzones from deep-water basinal facies, with no apparent mismatches. There appears to be close comparability of foraminiferal assemblages and first appearance datums of marker species with most of the international foraminiferal zonal schemes in Russia.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5240408

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