scholarly journals Neoproterozoic (Torridonian) alluvial fan succession, northwest Scotland, and its tectonic setting and provenance

2001 ◽  
Vol 138 (2) ◽  
pp. 161-184 ◽  
Author(s):  
GEORGE E. WILLIAMS
Keyword(s):  
Tectonic Setting ◽  
Normal Fault ◽  
Source Area ◽  
Alluvial Fan ◽  
Normal Faults ◽  
Main Body ◽  
The West ◽  
The North ◽  
Divergent Flow ◽  
Laurentian Margin

The presence of alluvial fan deposits in the lower Neoproterozoic Torridon Group in northwest Scotland illuminates Torridonian basin development at the eastern Laurentian margin. The 450 m thick Cape Wrath Member of the Applecross Formation consists of alluvial fan conglomerate and arkose succeeded by more distal, braidplain feldspathic sandstone. Palaeocurrent data comprising >2650 measurements on trough cross-bedding are of low variability and show overall eastward flow. The projection upcurrent of regionally divergent flow directions for the lower part of the member indicates a fan of c. 50 km radius with its apex 30 km to the west near a basement (pre-Caledonian) normal fault with downthrow to the east beneath the north Minch Basin. Extensional tectonics controlled deposition of the Applecross Formation. Regional uplift, causing erosion of a youthful topography on the Lewisian Gneiss, was followed by the development of the Applecross extensional basin in two main stages. Uplift of a western source area by movement on basin-bounding normal faults occurred first in the north and caused pediplanation and alluvial fan deposition in the Cape Wrath area, with subsequent uplift of the source area for the main body of the Applecross Formation occurring further to the west and south along the line of the Minch Fault. The bulk of the Applecross Formation was derived from a weathered terrain of felsic crystalline and related supracrustal rocks reaching from the Outer Hebrides region westward for up to c. 250 km onto what are now the continental margins of the North Atlantic. The tectonic events may mark an early phase in the crustal extension that led ultimately to the opening of the Iapetus ocean.

scholarly journals Neoproterozoic (Torridonian) alluvial fan succession, northwest Scotland, and its tectonic setting and provenance

2001 ◽  
Vol 138 (4) ◽  
pp. 471-494 ◽  
Author(s):  
GEORGE E. WILLIAMS
Keyword(s):  
Tectonic Setting ◽  
Normal Fault ◽  
Source Area ◽  
Alluvial Fan ◽  
Normal Faults ◽  
Main Body ◽  
The West ◽  
North West ◽  
The North ◽  
Divergent Flow

The presence of alluvial fan deposits in the lower Neoproterozoic Torridon Group in north-west Scotland illuminates Torridonian basin development at the eastern Laurentian margin. The 450 m thick Cape Wrath Member of the Applecross Formation consists of alluvial fan conglomerate and arkose succeeded by more distal, braidplain feldspathic sandstone. Palaeocurrent data comprising > 2650 measurements on trough cross-bedding are of low variability and show overall eastward flow. The projection upcurrent of regionally divergent flow directions for the lower part of the member indicates a fan of c. 50 km radius with its apex 30 km to the west near a basement (pre-Caledonian) normal fault with downthrow to the east beneath the north Minch Basin. Extensional tectonics controlled deposition of the Applecross Formation. Regional uplift, causing erosion of a youthful topography on the Lewisian Gneiss, was followed by the development of the Applecross extensional basin in two main stages. Uplift of a western source area by movement on basin-bounding normal faults occurred first in the north and caused pediplanation and alluvial fan deposition in the Cape Wrath area, with subsequent uplift of the source area for the main body of the Applecross Formation occurring further to the west and south along the line of the Minch Fault. The bulk of the Applecross Formation was derived from a weathered terrain of felsic crystalline and related supracrustal rocks reaching from the Outer Hebrides region westward for up to c. 250 km onto what are now the continental margins of the North Atlantic. The tectonic events may mark an early phase in the crustal extension that led ultimately to the opening of the Iapetus ocean.

Subsidence discrepancy in the Valencia Trough revealed from reflection seismic observations and backstripping results

2020 ◽  
Author(s):  
Penggao Fang ◽  
Geoffroy Mohn ◽  
Julie Tugend ◽  
Nick Kusznir
Keyword(s):  
Tectonic Setting ◽  
Temporal Distribution ◽  
Drill Hole ◽  
Western Mediterranean ◽  
Normal Faults ◽  
Seismic Profiles ◽  
Gulf Of Lions ◽  
North West ◽  
The North ◽  
Valencia Trough

<p>    The Valencia Trough is commonly included as part of the set of western Mediterranean Cenozoic extensional basins that formed in relation with the Tethyan oceanic slab rollback during the latest Oligocene to early Miocene. It lies in a complex tectonic setting between the Gulf of Lions to the North-West, the Catalan Coastal Range and the Iberian chain to the West, the Balearic promontory to the East and the Betic orogenic system to the South. This rifting period is coeval with or directly followed by the development of the external Betics fold and thrust belts at the southern tip of the Valencia Trough. Recent investigations suggest that the Valencia Trough is segmented into two main domains exhibiting different geological and geophysical characteristics between its northeastern and southwestern parts. The presence of numerous Cenozoic normal faults and the well-studied subsidence pattern evolution of the NE part of the Valencia Trough suggest that it mainly formed coevally with the rifting of Gulf of Lion. However, if a significant post-Oligocene subsidence is also evidenced in its SW part; fewer Cenozoic rift structures are observed suggesting that the subsidence pattern likely results from the interference of different processes.</p><p>    In this presentation, we quantify the post-Oligocene subsidence history of the SW part of the Valencia Trough with the aim of evaluating the potential mechanisms explaining this apparent subsidence discrepancy. We analyzed the spatial and temporal distribution of the post-Oligocene subsidence using the interpretation of a dense grid of high-quality multi-channel seismic profiles, also integrating drill-hole results and velocity information from expanding spread profiles (ESP). We used the mapping of the main unconformities, especially the so-called Oligocene unconformity, to perform a 3D flexural backstripping, which permits the prediction of the post-Oligocene water-loaded subsidence. Our results confirm that the post-Oligocene subsidence of the SW part of the Valencia Trough cannot be explained by the rifting of the Gulf of Lions. Previous works already showed that the extreme crustal thinning observed to the SW is related to a previous Mesozoic rift event. Here, we further highlight that if few Cenozoic extensional structures are observed, they can be interpreted as gravitational features rooting at the regionally identified Upper Triassic evaporite level. Backstripping results combined with the mapping of the first sediments deposited on top of the Oligocene unconformity show that they are largely controlled by the shape of Betic front with a possible additional effect of preserved Mesozoic structures. At larger scale, we compare the mechanisms accounting for the origin and subsidence at the SW part of the Valencia Trough with those responsible for the subsidence of its NE part and the Gulf of Lions.</p>

The Late Cenozoic evolution of the Aksu basin (Isparta Angle; SW Turkey). New insights

2011 ◽  
Vol 182 (2) ◽  
pp. 133-148 ◽  
Author(s):  
André Poisson ◽  
Fabienne Orszag-Sperber ◽  
Erdal Kosun ◽  
Maria-Angella Bassetti ◽  
Carla Müller ◽  
...  
Keyword(s):  
Coral Reefs ◽  
Normal Faults ◽  
The West ◽  
Shallow Marine ◽  
Northern Margin ◽  
Sea Level Fluctuations ◽  
Marine Deposits ◽  
The North ◽  
Sw Turkey ◽  
Isparta Angle

Abstract The Mio-Pliocene basins around the Antalya gulf in SW Turkey developed above the Tauric Mesozoic platforms on which the Antalya nappes had been thrusted (in Late Cretaceous-Paleocene times). The closure of the initial Isparta Angle during these events (E-W compression) initiated the N-S orientation of the main structural lines, which persisted later and explains the orientation of the Aksu basin in contrast with the E-W orientation of the eastern Neo-gene Mediterranean basins. The area, and all southwestern Turkey, became emergent at the end of the Oligocene and were the site of shallow-marine carbonate deposits in the Chattian-Aquitanian, giving way to the wide Lycian basin in Burdigalian-Langhian times. The progressive emplacement of the Lycian nappes from the north over this basin provoked first its subsidence and then its emersion when the nappes attained their final position over the Bey Daglari platform in Langhian times. Coinciding, or in response to the Lycian nappes emplacement, the Aksu basin was initiated as an elongated N-S graben which was filled by thick accumulations of terrestrial and marine deposits(including coral reefs), which derived from the erosion of the Lycian allochton and its basement (Langhian?, Serravallian and Tortonian times). The syn-sedimentary tectonics : reactivation of the normal faults along the west margin of the basin, the continuous uplift of the neighbouring continental areas (beginning of the Aksu thrust), governed the geometry of the basin. As a result and due to the uplift of its northern margin, the Aksu basin migrated towards the south and in Messinian times it was reduced to a narrow gulf along the eastern margin of which the Gebiz limestones were deposited as fringing coral reefs. The age of these limestones has been debated. Our new data allow us to attribute them to the Messinian. The drastic retreat of the sea at the end of this period, provoked the erosion of large parts of the Messinian deposits and the formation of deep canyons on land and under the sea down to the Antalya abyssal plain, in which evaporites were deposited. During the Zanclean transgression, the Eskiköy-Kargi canyon was filled by coarse clastics of a Gilbert delta derived from the northern continental area following a model well known elsewhere in the Mediterranean basins. Southward, shallow-marine sands and marls unconformably cover the remnants of the Messinian deposits and the emergent areas of the southern Antalya gulf. After Zanclean times (end of Pliocene?), the Aksu basin was deformed, due to the west-directed Aksu compressional event (end of the Aksu thrust). Quaternary terraces of the Aksu river at various altitudes, as well as the terraces of the Antalya tufa can be related to sea level fluctuations.

Late Jurassic - Early Cretaceous paleoenvironmental evolution of the Transbaikal basins (SE Siberia): implications for the Mongol-Okhotsk orogeny

2017 ◽  
Vol 188 (1-2) ◽  
pp. 9 ◽  
Author(s):  
Marc Jolivet ◽  
Anastasia Arzhannikova ◽  
Andrei Frolov ◽  
Sergei Arzhannikov ◽  
Natalia Kulagina ◽  
...  
Keyword(s):  
Early Cretaceous ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Tectonic Setting ◽  
Alluvial Fan ◽  
Crustal Thickening ◽  
Compressive Deformation ◽  
Transbaikal Region ◽  
Meandering River ◽  
The North

The Late Jurassic - Early Cretaceous tectonic evolution of SE Siberia was marked by the closure of the Mongol-Okhotsk ocean. While this geodynamic event led to compressive deformation and denudation in a wide area encompassing the North-Altay, Sayan and Baikal Patom ranges, it was contemporaneous to widespread extension from the Transbaikal region situated immediately north of the suture zone to the Pacific plate, affecting eastern Mongolia and northeastern China. In this study we review the paleontological and sedimentological data available in the Russian literature and provide new macro-floral and palynological data from the Mesozoic sediments of three Transbaikal basins. These data are used to describe the paleoenvironmental and paleoclimatic evolution of the Transbaikal area in order to assess the topographic evolution of the region in relation with the closure of the Mongol-Okhotsk ocean. We establish that the Transbaikal basins evolved in a continuously extensional tectonic setting from at least the Early-Middle Jurassic to the Early Cretaceous. The associated sedimentary environments are characterized by retrogradation from alluvial fan–braided river dominated systems prevailing during the Early to Middle Jurassic initial opening of the basins to meandering river– lacustrine systems that developed during the Late Jurassic - Early Cretaceous interval. No evidence of high relief topography was found and we conclude that, while compression and denudation occurred in the North Altai, Sayan and Patom ranges, in the Transbaikal region, the docking of the Mongolia-North China continent to Siberia was a “soft collision” event, possibly involving a major strike-slip displacement that did not lead to an orogenic event implying strong compressive deformation, crustal thickening and topography building.

scholarly journals Multiple Lines of Evidence for a Potentially Seismogenic Fault Along the Central-Apennine (Italy) Active Extensional Belt–An Unexpected Outcome of the MW6.5 Norcia 2016 Earthquake

2021 ◽  
Vol 9 ◽  
Author(s):  
Federica Ferrarini ◽  
Rita de Nardis ◽  
Francesco Brozzetti ◽  
Daniele Cirillo ◽  
J Ramón Arrowsmith ◽  
...  
Keyword(s):  
Late Quaternary ◽  
Tectonic Setting ◽  
Central Italy ◽  
Stress Transfer ◽  
Normal Fault ◽  
Normal Faults ◽  
Coulomb Stress ◽  
Seismic Sequence ◽  
Seismogenic Fault ◽  
Seismogenic Source

The Apenninic chain, in central Italy, has been recently struck by the Norcia 2016 seismic sequence. Three mainshocks, in 2016, occurred on August 24 (MW6.0), October 26 (MW 5.9) and October 30 (MW6.5) along well-known late Quaternary active WSW-dipping normal faults. Coseismic fractures and hypocentral seismicity distribution are mostly associated with failure along the Mt Vettore-Mt Bove (VBF) fault. Nevertheless, following the October 26 shock, the aftershock spatial distribution suggests the activation of a source not previously mapped beyond the northern tip of the VBF system. In this area, a remarkable seismicity rate was observed also during 2017 and 2018, the most energetic event being the April 10, 2018 (MW4.6) normal fault earthquake. In this paper, we advance the hypothesis that the Norcia seismic sequence activated a previously unknown seismogenic source. We constrain its geometry and seismogenic behavior by exploiting: 1) morphometric analysis of high-resolution topographic data; 2) field geologic- and morphotectonic evidence within the context of long-term deformation constraints; 3) 3D seismological validation of fault activity, and 4) Coulomb stress transfer modeling. Our results support the existence of distributed and subtle deformation along normal fault segments related to an immature structure, the Pievebovigliana fault (PBF). The fault strikes in NNW-SSE direction, dips to SW and is in right-lateral en echelon setting with the VBF system. Its activation has been highlighted by most of the seismicity observed in the sector. The geometry and location are compatible with volumes of enhanced stress identified by Coulomb stress-transfer computations. Its reconstructed length (at least 13 km) is compatible with the occurrence of MW≥6.0 earthquakes in a sector heretofore characterized by low seismic activity. The evidence for PBF is a new observation associated with the Norcia 2016 seismic sequence and is consistent with the overall tectonic setting of the area. Its existence implies a northward extent of the intra-Apennine extensional domain and should be considered to address seismic hazard assessments in central Italy.

Late Devonian – Early Carboniferous volcanism in western Cape Breton Island, Nova Scotia

1984 ◽  
Vol 21 (7) ◽  
pp. 762-774 ◽  
Author(s):  
Marie-Claude Blanchard ◽  
Rebecca A. Jamieson ◽  
Elizabeth B. More
Keyword(s):  
Tectonic Setting ◽  
Early Carboniferous ◽  
Alluvial Fan ◽  
Late Devonian ◽  
Fluvial Sediments ◽  
Western Cape ◽  
Cape Breton Island ◽  
The North ◽  
Cape Breton ◽  
Geochemical Studies

The Fisset Brook Formation of western Cape Breton Island and its equivalents at MacMillan Mountain and the north Baddeck River are examples of Late Devonian and Early Carboniferous volcanic sequences associated with the formation of post-Acadian successor basins in the northeastern Appalachians. They consist of bimodal basalt–rhyolite suites interbedded with alluvial fan, lacustrine, and rare fluvial sediments. The earliest volcanic products are rhyolites and somewhat evolved basalts associated with coarse sediments, followed by tholeiitic to transitional basalt flows interlayered with lacustrine-type deposits. Geochemical studies on the Fisset Brook Formation indicate extensive remobilization of alkalies, Ca, Rb, and Sr, making these elements inappropriate for determining tectonic setting or magmatic affinity. Use of less mobile elements (Ti, Nb, Y, and Zr) suggests that the basalts are tholeiitic and that the apparent alkalinity of the type section lavas is a result of alteration. We conclude that volcanism in western Cape Breton Island started at MacMillan Mountain and migrated westwards, probably towards the centre of the deepening Magdalen Basin.

The tectonic origin of Planum Boreum spiral troughs, Mars

2020 ◽  
Author(s):  
Costanza Rossi ◽  
Paola Cianfarra ◽  
Francesco Salvini
Keyword(s):  
Tectonic Setting ◽  
Ice Sheet ◽  
Normal Faults ◽  
Origin And Evolution ◽  
Tectonic Model ◽  
Ice Cap ◽  
The North ◽  
Ice Sheet Dynamics ◽  
The Antarctic ◽  
Tectonic Origin

<p>The spiral troughs of the North Polar Layered deposits on Mars are deep depressions that dissect the Planum Boreum ice cap. These are enigmatic structures whose puzzling origin is still under debate. Advanced hypotheses on their genesis and evolution range between erosional to structural scenario. In this work, a double approach was followed to explore the structural/tectonic origin of the spiral troughs by means of Hybrid Cellular Automata (HCA) numerical modelling and lineament domain analysis. The SHARAD profile data were used to replicate the ice internal layering architecture associated to buried troughs in Gemina Lingula. Analysis of the lineament domains automatically detected at the ice surface from satellite images of the Mars Orbiter Camera strengthened the structural/tectonic interpretation of their origin and evolution. Similar, twofold approach was used for the investigation of a terrestrial analog identified in the Antarctic ice sheet. It presents at depth blind structures recognized as fractures/faults produced by ice sheet dynamics. Radargrams of Operation IceBridge mission and images from Sentinel-2 were used to produce a tectonic model that was in turn compared with the Planum Boreum one. Obtained results, and their comparison, show that the troughs of Gemina Lingula result from the activity of low-angle normal faults with listric geometry. The activity of listric faults is modelled and compared with the antarctic analog. At the surface the detected lineament domains confirm the tectonic setting by tracing the buried trough/fault orientations. The proposed tectonic model refers to extensional regime characterized by the presence of a deep detachment connecting the troughs at depth. This represents an internal ductile layer placed at depth greater than 1000 m whose kinematics induces the troughs/faults deformation. The extensional tectonics developed in Planum Boreum is possibly related to the ice cap collapse that induces internal dynamics. In this way, katabatic winds play a secondary role by maintaining at the surface the troughs nearly orthogonal to their directions.</p>

scholarly journals Defining a mid-Holocene earthquake through speleoseismological and independent data: implications for the outer Central Apennines (Italy) seismotectonic framework

Solid Earth ◽  
2017 ◽  
Vol 8 (1) ◽  
pp. 161-176 ◽  
Author(s):  
Alessandra Di Domenica ◽  
Alberto Pizzi
Keyword(s):  
Normal Fault ◽  
Transitional Zone ◽  
Quantitative Modeling ◽  
Normal Faults ◽  
Independent Data ◽  
The West ◽  
Central Apennines ◽  
Strong Earthquakes ◽  
Surrounding Areas ◽  
Karst Conduit

Abstract. A speleoseismological study has been conducted in the Cavallone Cave, located in the easternmost carbonate sector of the Central Apennines (Maiella Massif), in a seismically active region interposed between the post-orogenic extensional domain, to the west, and the contractional one, to the east. The occurrence of active silent normal faults, to the west, close to blind thrusts, to the east, raises critical questions about the seismic hazard for this transitional zone. Large collapses of cave ceilings, fractures, broken speleothems with new re-growing stalagmites on their top, preferential orientation of fallen stalagmites and the absence of thin and long concretions have been observed in many portions of the karst conduit. This may indicate that the cave suffered sudden deformation events likely linked to the occurrence of past strong earthquakes. Radiocarbon dating and, above all, the robust correspondence with other coeval on-fault and off-fault geological data collected in surrounding areas outside the cave, provide important constraints for the individuation of a mid-Holocene paleoearthquake around 4.6–4.8 kyr BP. On the basis of the available paleoseismological data, possible seismogenic sources can be identified with the Sulmona normal fault and other active normal fault segments along its southern prosecution, which recorded synchronous strong paleoevents. Although the correlation between speleotectonic observations and quantitative modeling is disputed, studies on possible effects of earthquake on karstic landforms and features, when corroborated by independent data collected outside caves, can provide a useful contribution in discovering past earthquakes.

The Alwyn North Field, Blocks 3/9a, 3/4a, UK North Sea

1991 ◽  
Vol 14 (1) ◽  
pp. 21-32 ◽  
Author(s):  
I. Inglis ◽  
J. Gerard
Keyword(s):  
North Sea ◽  
Oil And Gas ◽  
Normal Fault ◽  
Alluvial Fan ◽  
The West ◽  
Southeastern Part ◽  
Structural Style ◽  
Fan Delta ◽  
Marine Influence

AbstractAbstract: Situated in the southeastern part of the East Shetland Basin, the Alwyn North Field produces oil and gas from Brent Group reservoirs and gas and condensate from the Statfjord Formation. The structural style is of tilted and eroded fault blocks dipping to the west and aligned north-south conforming to the principal normal fault trend. NE-SW cross elements further separate the hydrocarbon accumulations. The hydrocarbon columns are restricted to the Tarbert and upper part of the Ness Formation of the Brent Group, in sediments associated with the retreat of the Brent delta. The Statfjord Formation was deposited in an alluvial, fan-delta setting with increasing marine influence towards the top of the formation.

scholarly journals Heavy-mineral provenance signatures during the infill and uplift of a foreland basin: An example from the Jaca basin (southern Pyrenees, Spain)

2020 ◽  
Vol 90 (12) ◽  
pp. 1747-1769
Author(s):  
Xavier Coll ◽  
David Gómez-Gras ◽  
Marta Roigé ◽  
Antonio Teixell ◽  
Salva Boya ◽  
...  
Keyword(s):  
Foreland Basin ◽  
Source Area ◽  
Late Eocene ◽  
Alluvial Fan ◽  
Heavy Mineral ◽  
Heavy Minerals ◽  
Source Areas ◽  
The North ◽  
Sediment Routing ◽  
Central Pyrenees

ABSTRACT In the Jaca foreland basin (southern Pyrenees), two main sediment routing systems merge from the late Eocene to the early Miocene, providing an excellent example of interaction of different source areas with distinct petrographic signatures. An axially drained fluvial system, with its source area located in the eastern Central Pyrenees, is progressively replaced by a transverse-drained system that leads to the recycling of the older turbiditic foredeep. Aiming to provide new insights into the source-area evolution of the Jaca foreland basin, we provide new data on heavy-mineral suites, from the turbiditic underfilled stage to the youngest alluvial-fan systems of the Jaca basin, and integrate the heavy-mineral signatures with available sandstone petrography. Our results show a dominance of the ultrastable Ap-Zrn-Tur-Rt assemblage through the entire basin evolution. However, a late alluvial sedimentation stage brings an increase in other more unstable heavy minerals, pointing to specific source areas belonging to the Axial and the North Pyrenean Zone and providing new insights into the response of the heavy-mineral suites to sediment recycling. Furthermore, we assess the degree of diagenetic overprint vs. provenance signals and infer that the loss of unstable heavy minerals due intrastratal dissolution is negligible at least in the Peña Oroel and San Juan de la Peña sections. Finally, we provide new evidence to the idea that during the late Eocene the water divide of the transverse drainage system was located in the North Pyrenean Zone, and areas constituted by the Paleozoic basement were exposed in the west-Central Pyrenees at that time. Our findings provide new insights into the heavy-mineral response in recycled foreland basins adjacent to fold-and-thrust belts.

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