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

Utilization of continental transforms in break-up: observations, models, and a potential link to magmatism

2021 ◽  
pp. SP524-2021-119
Author(s):  
E. R. Lundin ◽  
A. G. Doré ◽  
J. Naliboff ◽  
J. Van Wijk
Keyword(s):  
Stress Field ◽  
Numerical Modelling ◽  
Thermal Gradients ◽  
Transform Faults ◽  
Content Type ◽  
Lithospheric Thinning ◽  
Potential Link ◽  
Supplementary Material ◽  
Break Up ◽  
Lower Crustal

AbstractReactivation of continental transform faults (hereafter; transforms) is identified herein as a significant factor in continental break-up, based on a global review of divergent margins and numerical modelling. Divergent margins that have reactivated transforms are characterized by linear and abrupt terminations of thick continental crust. Transforms represent some of the largest structures on Earth, and these megastructures represent major lithospheric weaknesses and are therefore prone to reactivation upon changes in the stress field, which typically occur during plate break-up. The blunt termination of the margins is consistent with observations of very limited pre-breakup lithospheric thinning of such margins. This mode of break-up appears to occur abruptly, and contrasts notably with highly tapered and slowly extended divergent margins. Magma leakage along transforms is well-known worldwide where divergence occurs across such features. This leakage may evolve to dike injections, further reducing the plate strength. We observe that many of the blunt margins we attribute to transform reactivation have been prone to above-normal magmatism and are marked by seaward dipping reflectors underlain by high-velocity lower crustal intrusions. The magmatism may be directly related to the separation of abruptly terminated margins, whereby the large resulting lateral thermal gradients trigger edge-driven convection and melt addition.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5756724

The Origin of Carbonatites from the eastern Armutlu Peninsula (NW Turkey)

2021 ◽  
pp. jgs2020-171
Author(s):  
Mutlu Özkan ◽  
Ömer Faruk Çelik ◽  
Andrea Marzoli ◽  
Rahmi Melih Çörtük ◽  
Mehmet Zeki Billor
Keyword(s):  
Continental Crust ◽  
Source Area ◽  
Field Studies ◽  
Mineral Chemistry ◽  
Geochemical Characteristics ◽  
Content Type ◽  
Neodymium Isotopes ◽  
Nw Turkey ◽  
Supplementary Material ◽  
Opaque Minerals

Unusual carbonate dykes, which have a thickness of up to 4 meters, crosscut the amphibolites from the high-grade metamorphic rocks in the Armutlu Peninsula (NW Turkey). They are described as carbonatites based on their petrographic, geochemical, and isotope-geochemical characteristics. The carbonatites, which show commonly equigranular texture, are composed of calcite and clinopyroxene with other minor phases of plagioclase, mica, garnet, K-feldspar, quartz, epidote, titanite, and opaque minerals. They contain abundant xenoliths of pyroxenite and amphibolite. Geochemical characteristics of the carbonatites are significantly different from those of mantle-derived carbonatites. They have remarkably low incompatible elements (e.g. Ba, Th, Nb) and total REE contents (11-91 ppm) compared to mantle-derived carbonatites. The high 87Sr/86Sr(i) (0.70797-0.70924) and low εNd(t) (-8.08 to -9.57) of the carbonatites confirm that they were derived from the continental crust rather than from a mantle source. Mica from carbonatite was dated by the 40Ar/39Ar method and yielded Late Jurassic – Early Cretaceous (148-137 Ma). This age is significantly younger from the age (Upper Triassic) of adjacent amphibolites. All data from field studies, as well as petrographic, geochemical and geochronological observations, suggest that these carbonatites were formed from the anatectic melting of a carbonated source area in the continental crust.Supplementary material: A complete description of the analytical methods (Whole rock chemistry, mineral chemistry, Strontium and Neodymium isotopes and 40Ar/39Ar measurements) and mineral chemistry and 40Ar-39Ar dating results are available at https://doi.org/ 10.6084/m9.figshare.12946955

Eruption history, petrogeochemistry, and geodynamic background of Tengchong volcanoes in Yunnan Province, SW China

2020 ◽  
pp. SP510-2020-45
Author(s):  
Hongmei Yu ◽  
Bo Zhao ◽  
Zhengquan Chen ◽  
Haiquan Wei ◽  
Wenjian Yang ◽  
...  
Keyword(s):  
Yunnan Province ◽  
Volcanic Rocks ◽  
Evolutionary Process ◽  
Source Area ◽  
Volcanic Field ◽  
Indian Plate ◽  
Eurasian Plate ◽  
Content Type ◽  
Supplementary Material ◽  
Eruption History

AbstractThe Tengchong Volcanic Field (TVF) is one of the youngest volcanic areas in China, and located in the southwestern part of Yunnan Province, China, adjacent to the collision zone between the Indian Plate and Eurasian Plate. This paper summarizes the results of previous research on the eruption history, petrochemistry, and geodynamic background of the TVF and presents a detailed analysis of the available data. Eruptions took place from the Pliocene to the Holocene and were divided into five stages. The composition of the magma went through two cycles: the N2-Q1 P-Q2 P volcanic rocks went through the evolutionary process from basalt to dacite and the Q3 P-Qh magma evolved from trachybasalt to trachyte. The evolution of magma is mainly related to the crystallisation and separation of pyroxene and ilmenite. The mantle source area of the TVF volcanic rocks was caused by the mixing between the MORB-source mantle and the eastern Indian continental margin sediments (EIS) to different degree. Geophysical data also showed that the Indian Plate has been subducted under the TVF area. There are also magma chambers in the crust within a depth of 25 km in the TVF that are replenished by mantle magma.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5227663

scholarly journals Transport of mafic magma through the crust and sedimentary basins: Jameson Land, East Greenland

2021 ◽  
pp. jgs2021-043
Author(s):  
Christian Haug Eide ◽  
Nick Schofield ◽  
John Howell ◽  
Dougal A Jerram
Keyword(s):  
Seismic Data ◽  
Mafic Magma ◽  
Sedimentary Basins ◽  
Skaergaard Intrusion ◽  
Content Type ◽  
East Greenland ◽  
Brittle Ductile Transition ◽  
Magma Transport ◽  
Supplementary Material ◽  
Crustal Magma

Igneous sheet-complexes transport magma through the crust, but most studies have focused on single segments of the magma-transport-system or have low resolution. In the Jameson Land Basin in East Greenland, reflection-seismic data and extensive outcrops give unparalleled constraints on mafic intrusions down to 15 km. This dataset shows how sill-complexes develop and how magma is transported from the mantle through sedimentary basins. The feeder zone of the sill-complex is a narrow zone below basin, where a magmatic underplate body impinges on thinned crust. Magma was transported through the crystalline crust through dykes. Seismic data and published geochemistry indicate magma was supplied from a magmatic underplate, without perceptible storage in crustal magma-chambers and crustal assimilation. As magma entered the sedimentary basin, it formed distributed, bowl-shaped sill-complexes throughout the basin. Large magma volumes in sills (4-20 times larger than the Skaergaard Intrusion), and few dykes highlight the importance of sills in crustal magma-transport. On scales smaller than 0.2 km, host-rock lithology, and particularly mudstone tensile strength-anisotropy, controls sill-architecture in the upper 10km of the basin, whereas sills are bowl-shaped below the brittle-ductile transition zone. On scales of kilometres and towards basin margins, tectonic stresses and lateral lithological changes dominate architecture of sills.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5670470

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

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

U-Pb isotopic ages and provenance of some far travelled exotic pebbles from glaciogenic sediments of the Polonez Cove Formation (Oligocene, King George Island)

2020 ◽  
pp. jgs2020-113
Author(s):  
Jerzy Nawrocki ◽  
Magdalena Pańczyk ◽  
Krystian Wójcik ◽  
Andrzej Tatur
Keyword(s):  
Source Area ◽  
Crystalline Rocks ◽  
Substantial Part ◽  
King George Island ◽  
Pb Isotope ◽  
Content Type ◽  
Isotope Data ◽  
Supplementary Material ◽  
Glaciogenic Sediments ◽  
The Antarctic

Zircon grains from nine erratic pebbles of granite, granodiorite/tonalite and quartzite from the Polonez Cove Formation (southern King George Island) were studied for their U-Pb isotope ages and provenance. The calculated concordia ages of the studied pebbles are 108.79 ± 0.89 Ma, 119.7 ± 2.2 Ma, 178.6 ± 2.8 Ma, 180.7 ± 1.9 Ma, 207.4 ± 3.1 Ma, 231.1 ± 1.9 Ma, 1087.5 ± 4 Ma and 1833 ± 4 Ma. The source area of individual pebbles was analyzed and defined. Pebbles of crystalline rocks were derived from the Antarctic Peninsula, as well as from the Antarctic mainland. The erratic made of quartzite was eroded from the southernmost part of the Ellsworth Mountains (Linder Pak Member of Howard Nunatak Formation). Our isotope data analytically supports the earlier thesis that the Oligocene ice-sheet covered a substantial part of Antarctica and its nucleus was located in its central part.Supplementary material: The U-Pb isotope data (Table S1) are available at https://doi.org/10.6084/m9.figshare.c.5233335

The role of subsidence and accommodation generation in controlling the nature of the aeolian stratigraphic record

2021 ◽  
pp. jgs2021-042
Author(s):  
Grace I.E. Cosgrove ◽  
Luca Colombera ◽  
Nigel P. Mountney
Keyword(s):  
Sedimentary Basins ◽  
Content Type ◽  
Stabilizing Agents ◽  
Basin Subsidence ◽  
Sedimentary Architecture ◽  
Stratigraphic Record ◽  
Supplementary Material ◽  
Stratal Architecture ◽  
Elevated Water

Despite a well-documented record of preserved aeolian successions from sedimentary basins characterised by widely variable subsidence rates, the relationship between aeolian architecture and subsidence-driven accommodation generation remains poorly constrained and largely unquantified. Basin subsidence as a control on aeolian sedimentary architecture is examined through analysis of 55 ancient case-studies categorised into settings of ‘slow’ (1–10 m/Myr), ‘moderate’ (10–100 m/Myr) and ‘rapid’ (>100 m/Myr) time-averaged subsidence rates. In rapidly subsiding basins, aeolian successions are thicker and associated with: (1) thicker and more laterally extensive dune-sets with increased foreset preservation; (2) greater proportions of wet-type interdunes and surface stabilization features; (3) more extensive interdune migration surfaces, bounding sets that climb more steeply. In slowly subsiding basins, aeolian successions are thinner, and associated with a greater proportion of (1) aeolian sandsheets; (2) supersurfaces indicative of deflation and bypass. Rapid subsidence promotes: (1) steeper bedform climb, resulting in increased preservation of the original dune foreset deposits; (2) relatively elevated water-tables, leading to sequestration of deposits beneath the erosional-baseline and encouraging development of stabilizing agents; both factors promote long-term preservation. Slow subsidence results in (1) lower angles-of-climb, associated with increased truncation of the original dune forms; (2) greater post-depositional reworking, where sediment is exposed above the erosional-baseline for protracted time. Quantitative analysis of sedimentary stratal architecture in relation to rates of basin subsidence helps demonstrate the mechanisms by which sedimentary successions are accumulated and preserved into the long-term stratigraphic record.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5515695

Assessing the Livelihood Empowerment Against Poverty (LEAP) program as a conditional income transfer: a search for a conceptual framework

2022 ◽  
Vol ahead-of-print (ahead-of-print) ◽  
Author(s):  
Alhassan Abdul-Wakeel Karakara ◽  
Ernest Amoabeng Ortsin
Keyword(s):  
Conceptual Framework ◽  
Poverty Reduction ◽  
Social Protection ◽  
Insurance Coverage ◽  
Implementation Strategies ◽  
Cash Transfer ◽  
Primary Data ◽  
Transfer Program ◽  
Content Type ◽  
The Poor

Purpose Ghana has implemented different kinds of pro-poor program and policies since its independence to reduce poverty. The Livelihood Empowerment Against Poverty (LEAP) is one of such program. LEAP is a social cash transfer program and its implementation has been under the auspices of the Ministry of Gender, Children and Social Protection since 2008. It provides direct cash and health insurance coverage for extremely poor households across the country to alleviate short-term poverty and encourage long-term human capital development. This paper examines the LEAP program in terms of how it has achieved its aim and the opportunities for improvement.Design/methodology/approach Primary data were obtained from interviews of 110 beneficiaries of the program. The study proposes a conceptual framework that links poverty reduction and social policies to assist researchers analyze pro-poor or social cash transfer program.Findings The findings show that the program is challenged with administrative bureaucracies, irregular inflow of funds, perceived political interferences, inconsistent implementation strategies and low value of the cash transfer (which results in little or no impact on consumption). However, the data also show that LEAP has positive impacts on nonconsumption spending like children's schooling. The program' exit strategy does not impact much on beneficiaries to allow them exit without the tendency of being poor.Practical implications This paper discussed the LEAP program as a social cash transfer to the poor in Ghana. The study constructed a conceptual framework to help researchers and practitioners analyze the implementation of pro-poor interventions. This conceptualization allows for cash transfer program to empower beneficiaries and exits them to allow for other beneficiaries to enroll, ensuring reduction in poverty over time. Generally, the beneficiaries have benefited from the LEAP in the areas of consumption, education and healthcare with few beneficiaries being able to accumulate some few assets. The LEAP program has no exit plan.Originality/value This study adds to literature by offering a conceptual framework to help researchers and policy makers in dealing with social assistance policies to the poor. The study also gave an insight into how pro-poor policy strategies could be crafted.

Volcano-sedimentary processes at Las Derrumbadas rhyolitic twin domes, Serdán-Oriental basin, Eastern Trans-Mexican Volcanic Belt

2021 ◽  
pp. SP520-2021-144
Author(s):  
Marie-Noëlle Guilbaud ◽  
Corentin Chédeville ◽  
Ángel Nahir Molina-Guadarrama ◽  
Julio Cesar Pineda-Serrano ◽  
Claus Siebe
Keyword(s):  
Volcanic Belt ◽  
Debris Avalanche ◽  
Density Currents ◽  
Content Type ◽  
Mexican Volcanic Belt ◽  
Wide Range ◽  
Eruptive Episode ◽  
Basin Floor ◽  
Supplementary Material ◽  
Trans Mexican Volcanic Belt

AbstractThe eruption of the ∼10 km3 rhyolitic Las Derrumbadas twin domes about 2000 yrs ago has generated a wide range of volcano-sedimentary deposits in the Serdán-Oriental lacustrine basin, Trans-Mexican Volcanic Belt. Some of these deposits have been quarried, creating excellent exposures. In this paper we describe the domes and related products and interpret their mode of formation, reconstructing the main phases of the eruption as well as syn-and-post eruptive erosional processes. After an initial phreatomagmatic phase that built a tuff ring, the domes grew as an upheaved plug lifting a thick sedimentary pile from the basin floor. During uplift, the domes collapsed repeatedly to form a first-generation of hetero-lithologic hummocky debris avalanche deposits. Subsequent dome growth produced a thick talus and pyroclastic density currents. Later, the hydrothermally-altered over-steepened dome peaks fell to generate 2nd generation, mono-lithologic avalanches. Subsequently, small domes grew in the collapse scars. From the end of the main eruptive episode onwards, heavy rains remobilized parts of the dome carapaces and talus, depositing lahar aprons. Las Derrumbadas domes are still an important source of sediments in the basin, and ongoing mass-wasting processes are associated with hazards that should be assessed, given their potential impact on nearby populations.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5752296

Sign in / Sign up

Export Citation Format

Share Document