scholarly journals Effects of Cenozoic subduction along the outboard margin of the Northern Cordillera: Derived from e-book on the Northern Cordillera (Alaska and Western Canada) and adjacent marine areas

Geosphere ◽  
2019 ◽  
Vol 16 (1) ◽  
pp. 33-61
Author(s):  
Warren J. Nokleberg ◽  
David W. Scholl ◽  
Thomas K. Bundtzen ◽  
David B. Stone
Keyword(s):  
Continental Margin ◽  
Subduction Zones ◽  
Hot Springs ◽  
Sedimentary Basins ◽  
Oceanic Lithosphere ◽  
Popular Science ◽  
Strike Slip ◽  
Western Canada ◽  
Regional Effects ◽  
Marine Areas

Abstract This article describes the regional effects of Cenozoic subduction along the outboard margin of the Northern Cordillera (Alaska, USA, and Western Canada), and thereby acquaints the reader with several chapters of the e-book Dynamic Geology of the Northern Cordillera (Alaska, Western Canada, and Adjacent Marine Areas). This article and the e-book are written for earth-science students and teachers. The level of writing for the article and the source e-book is that of popular science magazines, and readers are encouraged to share this article with students and laypersons. The main thrust of the article is to present and describe a suite of ten regional topographic, bathymetric, and geologic maps, and two figures portraying deep-crustal sections that illustrate the regional effects of Cenozoic subduction along the outboard margin of the North American Cordillera. The regional maps and cross sections are described in a way that a teacher might describe a map to students. Cenozoic subduction along the margin of the Northern Cordillera resulted in the formation of the following: (1) underthrusting of terranes and oceanic lithosphere beneath Southern Alaska; (2) landscapes, including narrow continental shelves along Southern and Southeastern Alaska and Western Canada (the Canadian Cordillera) and continental-margin mountain ranges, including the Alaska Peninsula, Chugach Range, Saint Elias Mountains, and Cascade Mountains; (3) sedimentary basins; (4) an array of active continental strike-slip and thrust faults (inboard of subduction zones); (5) earthquake belts related to subduction of terranes and oceanic plates; (6) active volcanoes, including continental-margin arcs (the Aleutian, Wrangell, and Cascade Arcs) linked to subduction zones, and interior volcanic belts related to strike-slip faulting or to hot spots; (7) lode and placer mineral deposits related to continental margin arcs or subduction of oceanic ridges; (8) hot springs related to continental-margin arcs; (9) plate movements as recorded from GPS measurements; and (10) underthrusting of terranes and oceanic lithosphere beneath the Northern Cordillera.

scholarly journals Forearc strike-slip displacement as an alternative to subduction erosion, with examples from Mexico and California (sinistral Nacimiento fault)

2019 ◽  
Vol 56 (12) ◽  
pp. 1285-1296 ◽  
Author(s):  
Raymond V. Ingersoll
Keyword(s):  
Sierra Nevada ◽  
Continental Margin ◽  
Subduction Zones ◽  
Strike Slip ◽  
Southern Mexico ◽  
Flat Slab ◽  
Franciscan Complex ◽  
Flat Slab Subduction ◽  
Subduction Erosion ◽  
Convergent Plate Margin

Slip on the Nacimiento fault of the central Coast Ranges of California has been variably interpreted as dextral, sinistral, or reverse. The currently prevailing interpretation is that the Nacimiento fault represents subduction erosion, by which the central to eastern part of the Cretaceous California batholith was thrust over the western part of the batholith and forearc basin, resulting in juxtaposition of the Salinian batholithic block against the Franciscan Complex, concurrently with Laramide flat-slab subduction (75–55 Ma) and underplating of the Pelona-Orocopia-Rand schist. No modern convergent plate margin includes such overthrusting. The closest modern analog to the likely configuration of the Salinian continental margin near the end of the Laramide deformation is southern Mexico, where arc plutons are exposed near the trench. Although commonly considered an example of subduction erosion, this margin is “missing” parts of the plutonic arc and forearc because they have been displaced to the southeast by sinistral slip. By analogy, the Nacimiento forearc was modified as a trench-trench-transform triple junction migrated southeastward along the continental margin during flat-slab subduction. This model makes testable predictions involving northwest-to-southeast younging of deep-marine deposits on batholithic crust underlain by contemporaneous schist. Correct restoration of later Cenozoic primarily dextral slip and Maastrichtian – Early Eocene primarily sinistral slip must result in realignment of north–south-trending belts of the Sierra Nevada – Salinia – Peninsular Ranges batholith, Great Valley forearc, and Franciscan Complex. These modern and ancient examples suggest that several “erosional” subduction zones are more plausibly explained by strike-slip truncation of forearcs.

Seismic Energy Release from Intra-Basin Sources along the Dead Sea Transform and Its Influence on Regional Ground Motions

2020 ◽  
Author(s):  
Roey Shimony ◽  
Zohar Gvirtzman ◽  
Michael Tsesarsky
Keyword(s):  
Ground Motions ◽  
Seismic Energy ◽  
Sedimentary Basins ◽  
Seismic Wave Propagation ◽  
Dead Sea ◽  
Strike Slip ◽  
Dead Sea Transform ◽  
Bay Area ◽  
The Dead ◽  
Surrounding Areas

ABSTRACT The Dead Sea Transform (DST) dominates the seismicity of Israel and neighboring countries. Whereas the instrumental catalog of Israel (1986–2017) contains mainly M<5 events, the preinstrumental catalog lists 14 M 7 or stronger events on the DST, during the past two millennia. Global Positioning System measurements show that the slip deficit in northern Israel today is equivalent to M>7 earthquake. This situation highlights the possibility that a strong earthquake may strike north Israel in the near future, raising the importance of ground-motion prediction. Deep and narrow strike-slip basins accompany the DST. Here, we study ground motions produced by intrabasin seismic sources, to understand the basin effect on regional ground motions. We model seismic-wave propagation in 3D, focusing on scenarios of Mw 6 earthquakes, rupturing different active branches of the DST. The geological model includes the major structures in northern Israel: the strike-slip basins along the DST, the sedimentary basins accompanying the Carmel fault zone, and the densely populated and industrialized Zevulun Valley (Haifa Bay area). We show that regional ground motions are determined by source–path coupling effects in the strike-slip basins, before waves propagate into the surrounding areas. In particular, ground motions are determined by the location of the rupture nucleation within the basin, the near-rupture lithology, and the basin’s local structure. When the rupture is located in the crystalline basement or along material bridges connecting opposite sides of the fault, ground motions behave predictably, decaying due to geometrical spreading and locally amplified atop sedimentary basins. By contrast, if rupture nucleates or propagates into shallow sedimentary units of the DST strike-slip basins, ground motions are amplified within, before propagating outside. Repeated reflections from the basin walls result in a “resonant chamber” effect, leading to stronger regional ground motions with prolonged durations.

scholarly journals Magmatic flare-up causes crustal thickening at the transition from subduction to continental collision

2021 ◽  
Vol 2 (1) ◽  
Author(s):  
Carlos E. Ganade ◽  
Pierre Lanari ◽  
Daniela Rubatto ◽  
Joerg Hermann ◽  
Roberto F. Weinberg ◽  
...  
Keyword(s):  
Production Rate ◽  
Continental Margin ◽  
Subduction Zones ◽  
Continental Collision ◽  
Crustal Thickening ◽  
Time Intervals ◽  
West Gondwana ◽  
Continental Arc ◽  
Order Of Magnitude

AbstractAbove subduction zones, magma production rate and crustal generation can increase by an order of magnitude during narrow time intervals known as magmatic flare-ups. However, the consequences of these events in the deep arc environment remain poorly understood. Here we use petrological and in-situ zircon dating techniques to investigate the root of a continental arc within the collisional West Gondwana Orogen that is now exposed in the Kabyé Massif, Togo. We show that gabbros intruded 670 million years ago at 20–25 km depth were transformed to eclogites by 620 million years ago at 65–70 km depth. This was coeval with extensive magmatism at 20–40 km depth, indicative of a flare-up event which peaked just prior to the subduction of the continental margin. We propose that increased H2O flux from subduction of serpentinized mantle in the hyper-extended margin of the approaching continent was responsible for the increased magma productivity and crustal thickening.

The petrological and geochemical study of granitoid rocks from Mashhad area, Iran: Evidence for the Late Triassic Collisional Belt Northeast of Iran

2021 ◽  
Author(s):  
Banafsheh Vahdati ◽  
Seyed Ahmad Mazaheri
Keyword(s):  
Subduction Zones ◽  
Tectonic Setting ◽  
Crustal Contamination ◽  
Oceanic Lithosphere ◽  
Late Triassic ◽  
Common Belief ◽  
Thrust Tectonics ◽  
Wide Range ◽  
Lree Enrichment ◽  
Granitoid Rocks

<p>Mashhad granitoid complex is part of the northern slope of the Binalood Structural Zone (BSZ), Northeast of Iran, which is composed of granitoids and metamorphic rocks. This research presents new petrological and geochemical whole-rock major and trace elements analyses in order to determine the origin of granitoid rocks from Mashhad area. Field and petrographic observations indicate that these granitoid rocks have a wide range of lithological compositions and they are categorized into intermediate to felsic intrusive rocks (SiO<sub>2</sub>: 57.62-74.39 Wt.%). Qartzdiorite, tonalite, granodiorite and monzogranite are common granitoids with intrusive pegmatite and aplitic dikes and veins intruding them. Based on geochemical analyses, the granitoid rocks are calc-alkaline in nature and they are mostly peraluminous. On geochemical variation diagrams (major and minor oxides versus silica) Na<sub>2</sub>O and K<sub>2</sub>O show a positive correlation with silica while Al<sub>2</sub>O<sub>3</sub>, TiO<sub>2</sub>, CaO, Fe<sub>2</sub>O<sub>3</sub>, and MgO show a negative trend. Therefore fractional crystallization played a considerable role in the evolution of Mashhad granitoids. Based on the spider diagrams, there are enrichments in LILE and depletion in HFSE. Low degrees of melting or crustal contamination may be responsible for LILE enrichment. Elements such as Pb, Sm, Dy and Rb are enriched, while Ba, Sr, Nd, Zr, P, Ti and Yb (in monzogranites) are all depleted. LREE enrichment and HREE depletion are observed in all samples on the Chondrite-normalized REE diagram. Similar trends may be evidence for the granitoids to have the same origin. Besides, LREE enrichment relative to HREE in some samples can indicate the presence of garnet in their source rock. Negative anomalies of Eu and Yb are observed in monzogranites. Our results show that Mashhad granitoid rocks are orogenic related and tectonic discrimination diagrams mostly indicate its syn-to-post collisional tectonic setting. No negative Nb anomaly compared with MORB seems to be an indication of non-subduction zone related magma formation. According to the theory of thrust tectonics of the Binalood region, the oceanic lithosphere of the Palo-Tethys has subducted under the Turan microplate. Since the Mashhad granitoid outcrops are settled on the Iranian plate, this is far from common belief that these granitoid rocks are related to the subduction zones and the continental arcs. The western Mashhad granitoids show more mafic characteristics and are possibly crystallized from a magma with sedimentary and igneous origin. Thus, Western granitoid outcrops in Mashhad are probably hybrid type and other granitoid rocks, S and SE Mashhad are S-type. Evidences suggest that these continental collision granitoid rocks are associated with the late stages of the collision between the Iranian and the Turan microplates during the Paleo-Tethys Ocean closure which occurred in the Late Triassic.</p>

Paleozoic formations of the Northeast margin of the European platform

2006 ◽  
Author(s):  
A. I. Eliseev ◽  
◽  
A. I. Antoshkina ◽  
V. A. Saldin ◽  
N. Yu. Nikulova ◽  
...  
Keyword(s):  
Continental Margin ◽  
Sedimentary Basins ◽  
Passive Continental Margin ◽  
European Continent ◽  
History Of ◽  
Geodynamic Reconstructions

Paleozoic sedimentary basins of the northeast European Platform is a component of large megabasin of the northeast passive continental margin of the European continent in the Paleozoic. The establishment of a connection between a paleodynamic history of a basin and its sedimentary formations types, which are the most reliable indicators of geodynamic conditions, is one of the primary problems of modern lithology. Reliable indicators at geodynamic reconstructions are genetically predetermined by laterial and vertical lines of the sedimentary formations. Formations and lithological complexes being the brightest indicators of the paleodynamic regimes change of the basin have been considered formations lines of the passive continental margin of the westuralian type during the Paleozoic.

scholarly journals Three-dimensional approach to understanding the relationship between the Plio-Quaternary stress field and tectonic inversion in the Triassic Cuyo Basin, Argentina

2015 ◽  
Vol 7 (1) ◽  
pp. 459-494
Author(s):  
L. Giambiagi ◽  
S. Spagnotto ◽  
S. M. Moreiras ◽  
G. Gómez ◽  
E. Stahlschmidt ◽  
...  
Keyword(s):  
Stress Field ◽  
Three Dimensional ◽  
Sedimentary Basins ◽  
Strike Slip ◽  
Stress Regime ◽  
Basin Inversion ◽  
Structural Style ◽  
Tectonic Inversion ◽  
The Impact ◽  
The Relationship

Abstract. The Cacheuta sub-basin of the Triassic Cuyo Basin is an example of rift basin inversion contemporaneous to the advance of the Andean thrust front, during the Plio-Quaternary. This basin is one of the most important sedimentary basins in a much larger Triassic NNW-trending depositional system along the southwestern margin of the Pangea supercontinent. The amount and structural style of inversion is provided in this paper by three-dimensional insights into the relationship between inversion of rift-related structures and spatial variations in late Cenozoic stress fields. The Plio-Quaternary stress field exhibits important N–S variations in the foreland area of the Southern Central Andes, between 33 and 34° S, with a southward gradually change from pure compression with σ1 and σ2 being horizontal, to a strike-slip type stress field with σ2 being vertical. We present a 3-D approach for studying the tectonic inversion of the sub-basin master fault associated with strike-slip/reverse to strike-slip faulting stress regimes. We suggest that the inversion of Triassic extensional structures, striking NNW to WNW, occurred during the Plio–Pleistocene in those areas with strike-slip/reverse to strike-slip faulting stress regime, while in the reverse faulting stress regime domain, they remain fossilized. Our example demonstrates the impact of the stress regime on the reactivation pattern along the faults.

Sign in / Sign up

Export Citation Format

Share Document