The Phytoclast Group as a tracer of palaeoenvironmental changes in the early Toarcian

2021 ◽  
pp. SP514-2020-271
Author(s):  
Bruno Rodrigues ◽  
Ricardo L. Silva ◽  
João Graciano Mendonça Filho ◽  
Matías Reolid ◽  
Driss Sadki ◽  
...  
Keyword(s):  
Hydrological Cycle ◽  
Temperate Climate ◽  
Northern Spain ◽  
The West ◽  
Content Type ◽  
Climate Gradients ◽  
Water Column Stratification ◽  
Supplementary Material ◽  
Marine Areas ◽  
Palaeoenvironmental Changes

AbstractIn this paper, we present a detailed review of upper Pliensbachian-lower Toarcian kerogen assemblages from the southern areas of the West Tethys shelf (between Morocco and northern Spain) and demonstrate the use of the Phytoclast Group as a tracer of palaeoenvironmental changes in the early Toarcian.The kerogen assemblages in the studied sections from the southern areas of the West Tethys shelf are dominated by the Phytoclast Group and terrestrial palynomorphs, although punctual increases in amorphous organic matter (AOM), freshwater (Botryococcus) and marine microplankton (dinoflagellate cysts, acritarchs, and prasinophyte algae) were observed at specific stratigraphic intervals. The opaque/non-opaque phytoclasts (OP/NOP) ratio was used to trace changes in palaeoclimate and other palaeoenvironmental parameters and reflect climate gradients associated with water availability during early Toarcian. During the Pliensbachian-Toarcian and Jenkyns events, changes in kerogen assemblages in the southern areas of the West Tethys shelf correlated with changes in the northern Tethys and Panthalassa shelf.The acceleration of the hydrological cycle associated with the aforementioned events was less intense in the northern Gondwana, southern and western Iberian basins, a reflection of the palaeogeographic position of these basins within the semi-arid climate belt when compared with the northern Iberian region and other northern areas of the West Tethys and Panthalassa shelf, inserted in winter-wet and warm temperate climate belts. AOM enrichment associated with the Pliensbachian-Toarcian and Jenkyns events reflects an increase in primary productivity linked with increased continental weathering, fluvial runoff and riverine OM, and nutrient input into marine areas, inducing water column stratification and promoting the preservation of OM.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5421485

Metamorphism of the Buchan type-area, NE Scotland, and its relation to the adjacent Barrovian domain

2021 ◽  
pp. jgs2021-040
Author(s):  
David R.M. Pattison ◽  
Shantal A. Goldsmith
Keyword(s):  
Field Gradient ◽  
Shear Zone ◽  
Low Grade ◽  
The West ◽  
Geological Evidence ◽  
Content Type ◽  
Type Area ◽  
Igneous Intrusions ◽  
Supplementary Material ◽  
Lower Temperature

The metamorphism of the Buchan block in northeast Scotland, and its relation to the Barrovian domain to its west, have been reassessed from consideration of mineral assemblages, microstructures, phase equilibrium modelling and monazite U-Pb geochronology. Zones of increasing metamorphic grade surround a central low grade domain (biotite zone) and define a northward-opening, U-shaped metamorphic map pattern ascribed to post-metamorphic folding. The eastern and southern Buchan domain show the classic Buchan-type prograde sequence cordierite – andalusite – sillimanite – migmatite/gneiss, representing a metamorphic field gradient of gently increasing pressure between 2.5-3.0 kbar, ∼550 °C and 3.5-4.0 kbar, ∼750 °C. A lower pressure metamorphic field gradient (by less than ∼0.5 kbar) is interpreted for the northeastern Buchan domain. The west Buchan domain shows a prograde sequence of staurolite+andalusite – sillimanite – gneiss/migmatite, representing a metamorphic field gradient higher by ∼1 kbar or less than the classic sequence. Uniquely in the northwestern Buchan domain is a staurolite-cordierite-andalusite domain in which staurolite-bearing schists are interpreted to have been overprinted by cordierite+andalusite assemblages. Monazite U-Pb geochronology of schists and gneisses from the Buchan block, including the Cowhythe and Ellon gneisses, yields ages in the range 470 ±5 Ma, supporting geological evidence that the gneisses are metamorphosed Dalradian strata rather than older basement gneisses. The metamorphic ages are similar to the ages of mafic igneous intrusions in the Buchan block, even though many of the exposed intrusions post-date the regional metamorphic zones. The Buchan metamorphic zones are truncated to the west by the Portsoy-Duchray Hill lineament (PDHL), a ductile shear zone that juxtaposes the Buchan rocks against higher-pressure, lower-temperature (kyanite-bearing) Barrovian schists to the west. A 2-15 km wide corridor of andalusite pseudomorphed by kyanite occurs between the PDHL and the Keith shear zone to its west. Monazite geochronology of the Barrovian rocks west of Portsoy shows little evidence of the c. 470 Ma signature of the Buchan block, instead yielding a dominant cluster of ages at c. 450 Ma and a more poorly defined grouping at c. 490 Ma.Supplementary materials: Analytical methods, thermodynamic modelling; tables S1-S13; figures S1-S5 are available at https://doi.org/10.6084/m9.figshare.c.5536745

A Late Triassic vegetation record from the Huangshanjie Formation, Junggar Basin, China: possible evidence for the Carnian Pluvial Episode

2021 ◽  
pp. SP521-2021-151
Author(s):  
Jungang Peng ◽  
Sam M. Slater ◽  
Vivi Vajda
Keyword(s):  
Climate Changes ◽  
Hydrological Cycle ◽  
Junggar Basin ◽  
Forest Community ◽  
Late Triassic ◽  
Spores And Pollen ◽  
Content Type ◽  
Supplementary Material ◽  
Vegetation And Climate ◽  
Climax Forest

AbstractThe Carnian Pluvial Episode (CPE; ∼234‒232 million years ago) is characterized by an accelerated hydrological cycle, global warming and a period of elevated biotic turnover. Using spores and pollen, we reconstruct vegetation and climate changes through a Carnian‒Norian (Upper Triassic) interval of the Huangshanjie Formation from the Junggar Basin, China. Four palynofloras were identified, representing distinct vegetation communities. Among these palynofloras, we observed a prominent shift from a conifer-dominated climax forest community, with common ginkgophytes and bennettites, to a fern-dominated community, suggestive of an environmental perturbation. We interpret this change as a regional shift in vegetation, likely caused by increased humidity, consistent with the CPE. Our records represent the first indication of a possible CPE-induced vegetation response in the Junggar Basin and highlight how this event likely affected floral communities of inland Laurasia.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5738637

Provenance of Carboniferous sandstones in the central and southern parts of the Pennine Basin, UK: evidence from detrital zircon ages

2020 ◽  
pp. pygs2020-010
Author(s):  
A.C. Morton ◽  
J.I. Chisholm ◽  
D. Frei
Keyword(s):  
Detrital Zircon ◽  
Local Source ◽  
The West ◽  
Content Type ◽  
North West ◽  
Source Areas ◽  
The North ◽  
Isotopic Analyses ◽  
Supplementary Material ◽  
Detrital Zircon Ages

New U-Pb isotopic analyses of detrital zircon grains from Namurian and Westphalian sandstones in the central and south parts of the Pennine Basin are combined with published analyses from the same region, to assess existing views on the nature and location of the source areas that supplied the clastic sediment. The study confirms that most sandstones were derived from distant areas to the north, west and south, and that a local source, in the Wales-Brabant High, also supplied sediment at times. The northern sources are thought to lie mainly in Laurentia (East Greenland), with some input from Baltica (Norway). Most sandstones entering from the west are thought to have been supplied from areas of Avalonian basement, with some components recycled from sediments that were themselves derived from the Caledonian belt that lay to the north. An exception is the Clifton Rock: its source is thought to lie entirely in the Irish Caledonides or in southern Scotland. Sandstones supplied from the south contain significant numbers of late Devonian and Carboniferous grains, indicating the inclusion of material eroded from the active Variscan orogenic belt in Europe. Northern provenance prevailed during Namurian and early Langsettian times, then alternated with western supply until the late Langsettian. Western input then dominated through most of Duckmantian times, until superseded in the late Duckmantian by supply from the Variscan orogen. The Woolley Edge Rock, now shown to be an isolated member of the northern group, entered the area just before the earliest sandstone of Variscan origin.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5174702

Cenozoic volcanism along Dahongliutan fault in the West Kunlun Mountains, China: Implication from distribution of volcanic rocks, volcanic geology, and geochemistry

2021 ◽  
pp. SP510-2020-132
Author(s):  
Bo Zhao ◽  
Feixiang Wei ◽  
Wenjian Yang ◽  
Jiandong Xu ◽  
Xiaoge Cui
Keyword(s):  
Volcanic Field ◽  
Magma Source ◽  
Geophysical Research ◽  
The West ◽  
Content Type ◽  
Kunlun Mountains ◽  
Volcanic Fields ◽  
Supplementary Material ◽  
West Kunlun ◽  
Volcanic Activities

AbstractIn the West Kunlun Mountains, four volcanic fields (i.e., Kangxiwa, Dahongliutan, Qitaidaban, and Quanshuigou) are distributed along the Dahongliutan fault, which is approximately 180 km long. Based on field investigations, chronological measurements, and geochemical analysis of some volcanic fields, the results of geological, geochemical, and geophysical research by the predecessors in the corresponding study areas are summarised. The volcanic activities in these areas were mainly effusive eruptions, explosive eruptions, and phreatomagmatic eruptions. In this study, we discovered the Qitaiyanhu volcanic field for the first time and determined that the 14C age of the lacustrine strata underlying the Qitaiyanhu lava flows are 13110 ± 40 a B.P., indicating that there may still have been volcanic activities in the late Pleistocene and even the Holocene in the Dahongliutan fault area. The base surge deposits, which are the products of the interaction between magma and water, were found in the Kangxiwa volcanic field. The four shoshonitic rock fields of Kangxiwa, Dahongliutan, Qitaidaban, and Quanshuigou are likely to be products of different evolution stages from the same magma source area. The magmatic origin of these volcanic fields may be related to the upwelling of the asthenosphere, triggered by the collision between the Indian and Tarim plates.Supplementary material at https://doi.org/10.6084/m9.figshare.c.5353446

‘Block and basin’ style rift basins: sedimentological insights from the Mississippian Fell Sandstone Formation

2021 ◽  
pp. jgs2021-083
Author(s):  
Louis P. Howell ◽  
Charlotte Priddy ◽  
Andrew J. Mitten ◽  
Adam J. Jeffery ◽  
Stuart S. Egan ◽  
...  
Keyword(s):  
Major Element ◽  
Normal Fault ◽  
Rift Basin ◽  
Rift Basins ◽  
The West ◽  
Content Type ◽  
Stratigraphic Framework ◽  
Supplementary Material ◽  
Sandstone Formation ◽  
Depositional Models

The block and basin tectono-stratigraphic framework for the northern Pennine (rift) Basin, within which buoyant granite intrusions core intra-basin fault-bound blocks, has long held traction. However, many of the elements of this framework are rooted in primitive tectonic models and, perhaps unsurprisingly, corresponding depositional models often reflect this. Using sedimentological and sedimentary provenance approaches, the syn-rift (Mississippian) fluvio-deltaic Fell Sandstone Formation and age-equivalent strata within the northern Pennine Basin are examined. Highlighted divergences from classically depicted models relate to occurrences of pre-Carboniferous basement domes or monoclines, which are unbound by major vertically displacing (>100 m) fault systems. Such structures in the northern Pennine Basin are all granite-cored and their origins are associated with their buoyancy and flexural isostatic processes. One such basement dome, the Cheviot Block, confined and deflected the Fell Sandstone fluvio-deltaic system from the west, causing locally elevated net sand content and variations in dominant palaeodrainage direction. Central parts of the Alston Block, which forms a regional monocline along an E-W axis, were comparatively uplifted because of flexural isostatic responses to granite intrusions. The findings presented are not just at variance with classically depicted depositional models for the region, but also with more general depictions of dominantly normal fault-driven rift basin systems.Supplementary material: [table of data locations with derivation, trace element data, and major element (oxide) data] is available at https://doi.org/10.6084/m9.figshare.c.5733257

Why are companies still struggling to reach higher continuous improvement maturity levels? Empirical evidence from high performance companies

2015 ◽  
Vol 27 (3) ◽  
pp. 316-327 ◽  
Author(s):  
Daniel Jurburg ◽  
Elisabeth Viles ◽  
Carmen Jaca ◽  
Martin Tanco
Keyword(s):  
Continuous Improvement ◽  
Measurement System ◽  
High Performance ◽  
Basque Country ◽  
Holistic Approach ◽  
Special Focus ◽  
Structured Interviews ◽  
Northern Spain ◽  
Content Type ◽  
High Performing

Purpose – Continuous improvement (CI) is regarded as a powerful approach to achieve business excellence. However, the implementation is not simple as it involves managing a considerable amount of tangible and intangible factors throughout the whole organization. The purpose of this paper is to fill the gap by presenting first-hand information about how companies really implement and organize their CI processes. Design/methodology/approach – The study was based on semi-structured interviews in ten high performing companies in the Basque Country, a region in northern Spain well known for its business quality. The objective was to analyze the state of their CI processes, putting special focus on how the organizational structure integrates with the CI processes and what are the characteristics of the corresponding measurement system. Findings – The study shows a lack of company-wide focus on CI, little written evidence of previous improvement activities, unclear improvement process owner, and poor use of adequate measurement systems to monitor CI. Practical implications – Managers should understand that is not enough to guarantee their own commitment and provide the structure, since in order to become learning organization, a different holistic approach towards the CI process must be adopted. Originality/value – While most previous work on this field have focused primarily on how to implement different techniques in order to achieve better productive performance, this study presents empirical research from a more holistic approach, assessing the characteristics affecting CI by considering strategy, structure, and the measurement system.

Disinformation is a rising security threat to the West

2021 ◽  
Keyword(s):  
Artificial Intelligence ◽  
Social Media ◽  
The United States ◽  
Step Change ◽  
Media Discourse ◽  
Security Threat ◽  
The West ◽  
Content Type ◽  
Synthetic Media ◽  
Victims Of Bullying

Significance Articles containing the bogus quotes were shared across social media globally. The case illustrates how disinformation is created and spread for malign influence, and its ease of entry into social media discourse, which makes it so difficult to untangle and counter. Impacts Political polarisation within the United States is impeding a 'whole of society' response. Russian and Chinese disinformation campaigns will claim the two nations are falsely accused victims of bullying by envious foes. Artificial intelligence-created synthetic media such as deepfakes will enable a step-change in the sophistication of 'infowars'.

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

Entry barriers could easily thwart China’s tech plans

2021 ◽  
Keyword(s):  
Artificial Intelligence ◽  
Quantum Computing ◽  
Import Substitution ◽  
Entry Barriers ◽  
The West ◽  
Content Type ◽  
Technological Competition ◽  
Efficiency And Productivity

Significance These are: artificial intelligence, semiconductors, quantum computing, genetics, biotechnology, neuroscience and aerospace. Impacts It is not always useful to view technological competition between China and the West as a ‘race’. China will likely burn significant capital just to achieve parity with advanced countries, and may never achieve it. Low margins will encourage protectionism and import substitution, with an impact on efficiency and productivity.

Jurassic–Cretaceous arc magmatism along the Shyok–Bangong Suture from NW Himalaya: Formation of the peri-Gondwana basement to the Ladakh Arc

2021 ◽  
pp. jgs2021-035
Author(s):  
Wanchese M. Saktura ◽  
Solomon Buckman ◽  
Allen P. Nutman ◽  
Renjie Zhou
Keyword(s):  
Late Cretaceous ◽  
Nw Himalaya ◽  
Content Type ◽  
Magmatic Arc ◽  
Basement Rocks ◽  
Ladakh Himalaya ◽  
Accreted Terranes ◽  
Volcaniclastic Rocks ◽  
Supplementary Material ◽  
Depositional Age

The Jurassic–Cretaceous Tsoltak Formation from the eastern borderlands of Ladakh Himalaya consists of conglomerates, sandstones and shales, and is intruded by norite sills. It is the oldest sequence of continent-derived sedimentary rocks within the Shyok Suture. It also represents a rare outcrop of the basement rocks to the voluminous Late Cretaceous–Eocene Ladakh Batholith. The Shyok Formation is a younger sequence of volcaniclastic rocks that overlie the Tsoltak Formation and record the Late Cretaceous closure of the Mesotethys Ocean. The petrogenesis of these formations, ophiolite-related harzburgites and norite sill is investigated through petrography, whole-rock geochemistry and U–Pb zircon geochronology. The youngest detrital zircon grains from the Tsoltak Formation indicate Early Cretaceous maximum depositional age and distinctly Gondwanan, Lhasa microcontinent-related provenance with no Eurasian input. The Shyok Formation has Late Cretaceous maximum depositional age and displays a distinct change in provenance to igneous detritus characteristic of the Jurassic–Cretaceous magmatic arc along the southern margin of Eurasia. This is interpreted as a sign of collision of the Lhasa microcontinent and the Shyok ophiolite with Eurasia along the once continuous Shyok–Bangong Suture. The accreted terranes became the new southernmost margin of Eurasia and the basement to the Trans-Himalayan Batholith associated with the India-Eurasia convergence.Supplementary material:https://doi.org/10.6084/m9.figshare.c.5633162

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