scholarly journals Evidence of Segmentation in the Iberia–Africa Plate Boundary: A Jurassic Heritage?

Geosciences ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 343 ◽  
Author(s):  
Manel Fernàndez ◽  
Montserrat Torne ◽  
Jaume Vergés ◽  
Emilio Casciello ◽  
Chiara Macchiavelli
Keyword(s):  
Cross Sections ◽  
Tectonic Evolution ◽  
Gravity Data ◽  
Plate Boundary ◽  
Early Jurassic ◽  
Bouguer Gravity ◽  
Local Tomography ◽  
Gorringe Bank ◽  
Plate Reconstruction ◽  
Roll Back

The present structure of the Iberia–Africa plate boundary between the Gorringe Bank and the Algerian Basin is characterized by a highly segmented geometry and diffused seismicity. Filtered Bouguer gravity data show conspicuous highs coinciding with the Gorringe Bank, the Guadalquivir–Portimao Bank, and the Ronda/Beni–Bousera massifs, reflecting the current geometry of the plate boundary segments. The Africa–Eurasia Alpine convergence produced crustal-scale thrusting in the Atlantic segments and roll-back subduction in the Ligurian–Tethys segments. Despite the growing consensus that the Gorringe and the Guadalquivir–Portimao Banks resulted from tectonic inversion of hyperextended margin structures inherited from the Early Jurassic, this heritage is more debatable for the Ronda/Beni–Bousera massifs lacking models linking the Atlantic and Mediterranean realms. On the basis of gravity analysis combined with plate reconstruction models, geological cross-sections, and recent local tomography, we infer a strong Jurassic heritage of the present-day segmentation and substantiate a comprehensive tectonic evolution model of the Iberia–Africa plate boundary since the Early Jurassic to Recent that includes the Atlantic and the Mediterranean domains.

Integrated Cretaceous–Cenozoic plate tectonics and structural geology in southern Mexico

2020 ◽  
pp. SP504-2020-70
Author(s):  
Rod Graham ◽  
James Pindell ◽  
Diego Villagómez ◽  
Roberto Molina-Garza ◽  
James Granath ◽  
...  
Keyword(s):  
Cross Sections ◽  
Tectonic Evolution ◽  
Plate Tectonics ◽  
Plate Boundary ◽  
Structural Evolution ◽  
Thrust Belt ◽  
Cocos Plate ◽  
Southern Mexico ◽  
Arc Volcanism ◽  
Fold And Thrust Belt

AbstractThe structural evolution of southern Mexico is described in the context of its plate tectonic evolution and illustrated by two restored crustal scale cross-sections through Cuicateco and the Veracruz Basin and a third across Chiapas. We interpret the Late Jurassic–Early Cretaceous opening of an oblique hyper-stretched intra-arc basin between the Cuicateco Belt and Oaxaca Block of southern Mexico where Lower Cretaceous deep-water sediments accumulated. These rocks, together with the hyper-stretched basement beneath them and the Oaxaca Block originally west of them, were thrust onto the Cretaceous platform of the Cuicateco region during a Late Cretaceous–Eocene orogenic event. The mylonitic complex of the Sierra de Juárez represents this hyper-stretched basement, perhaps itself an extensional allochthon. The Chiapas fold-and-thrust belt is mainly Neogene in age. Shallowing of the subduction angle of the Cocos Plate in the wake of the Chortis Block, suggested by seismicity and migrating arc volcanism, is thought to play an important role in the development of the Chiapas fold-and-thrust belt itself, helping to explain the structural dilemma of a vertical transcurrent plate boundary fault (the Tonalá Fault) at the back of an essentially dip-slip fold-and-thrust belt.

scholarly journals On the enigmatic birth of the Pacific Plate within the Panthalassa Ocean

2016 ◽  
Vol 2 (7) ◽  
pp. e1600022 ◽  
Author(s):  
Lydian M. Boschman ◽  
Douwe J. J. van Hinsbergen
Keyword(s):  
Triple Junction ◽  
Tectonic Evolution ◽  
Plate Boundary ◽  
Pacific Plate ◽  
Plate Tectonic ◽  
Point Location ◽  
Marine Magnetic Anomalies ◽  
The Pacific ◽  
History Of ◽  
Ridge System

The oceanic Pacific Plate started forming in Early Jurassic time within the vast Panthalassa Ocean that surrounded the supercontinent Pangea, and contains the oldest lithosphere that can directly constrain the geodynamic history of the circum-Pangean Earth. We show that the geometry of the oldest marine magnetic anomalies of the Pacific Plate attests to a unique plate kinematic event that sparked the plate’s birth at virtually a point location, surrounded by the Izanagi, Farallon, and Phoenix Plates. We reconstruct the unstable triple junction that caused the plate reorganization, which led to the birth of the Pacific Plate, and present a model of the plate tectonic configuration that preconditioned this event. We show that a stable but migrating triple junction involving the gradual cessation of intraoceanic Panthalassa subduction culminated in the formation of an unstable transform-transform-transform triple junction. The consequent plate boundary reorganization resulted in the formation of a stable triangular three-ridge system from which the nascent Pacific Plate expanded. We link the birth of the Pacific Plate to the regional termination of intra-Panthalassa subduction. Remnants thereof have been identified in the deep lower mantle of which the locations may provide paleolongitudinal control on the absolute location of the early Pacific Plate. Our results constitute an essential step in unraveling the plate tectonic evolution of “Thalassa Incognita” that comprises the comprehensive Panthalassa Ocean surrounding Pangea.

Tectonic evolution of a low-angle extensional fault system from restored cross-sections in the Northern Apennines (Italy)

Tectonics ◽  
2011 ◽  
Vol 30 (6) ◽  
pp. n/a-n/a ◽  
Author(s):  
F. Mirabella ◽  
F. Brozzetti ◽  
A. Lupattelli ◽  
M. R. Barchi
Keyword(s):  
Cross Sections ◽  
Tectonic Evolution ◽  
Northern Apennines ◽  
Fault System

Mesozoic Tectonic Setting of SE Sundaland After Magmatism and Suture Evidences in JS-1 Ridge Area

2021 ◽  
Keyword(s):  
Early Cretaceous ◽  
Late Cretaceous ◽  
Tectonic Setting ◽  
Plate Boundary ◽  
Early Jurassic ◽  
The South ◽  
Magmatic Arc ◽  
Plate Convergence ◽  
Ridge Area ◽  
Cretaceous Subduction

Mesozoic plate convergence in SE Sundaland has been a source of debate for decades. A determination of plate convergence boundaries and timing have been explained in many publications, but not all boundaries were associated with magmatism. Through integration of both plate configurations and magmatic deposits, the basement can be accurately characterized over time and areal extents. This paper will discuss Cretaceous subductions and magmatic arc trends in SE Sundaland area with additional evidence found in JS-1 Ridge. At least three subduction trends are captured during the Mesozoic in the study area: 1) Early Jurassic – Early Cretaceous trend of Meratus, 2) Early Cretaceous trend of Bantimala and 3) Late Cretaceous trend in the southernmost study area. The Early Jurassic – Early Cretaceous subduction occurred along the South and East boundary of Sundaland (SW Borneo terrane) and passes through the Meratus area. The Early Cretaceous subduction occurred along South and East boundary of Sundaland (SW Borneo and Paternoster terranes) and pass through the Bantimala area. The Late Cretaceous subduction occurred along South and East boundary of Sundaland (SW Borneo, Paternoster and SE Java – South Sulawesi terranes), but is slightly shifted to the South approaching the Oligocene – Recent subduction zone. Magmatic arc trends can also be generally grouped into three periods, with each period corresponds to the subduction processes at the time. The first magmatic arc (Early Jurassic – Early Cretaceous) is present in core of SW Borneo terrane and partly produces the Schwaner Magmatism. The second Cretaceous magmatic arc (Early Cretaceous) trend is present in the SW Borneo terrane but is slightly shifted southeastward It is responsible for magmatism in North Java offshore, northern JS-1 Ridge and Meratus areas. The third magmatic arc trend is formed by Late Cretaceous volcanic rocks in Luk Ulo, the southern JS-1 Ridge and the eastern Makassar Strait areas. These all occur during the same time within the Cretaceous magmatic arc. Though a mélange rock sample has not been found in JS-1 Ridge area, there is evidence of an accretionary prism in the area as evidenced by the geometry observed on a new 3D seismic dataset. Based on the structural trend of Meratus (NNE-SSW) coupled with the regional plate boundary understanding, this suggests that both Meratus & JS-1 Ridge are part of the same suture zone between SW Borneo and Paternoster terranes. The gradual age transition observed in the JS-1 Ridge area suggests a southward shift of the magmatic arc during Early Cretaceous to Late Cretaceous times.

scholarly journals Supplemental Material: Plate boundary trench retreat and dextral shear drive intracontinental fault-slip histories: Neogene dextral faulting across the Gabbs Valley and Gillis Ranges, Central Walker Lane, Nevada

2020 ◽  
Author(s):  
J. Lee ◽  
et al.
Keyword(s):  
Cross Section ◽  
Cross Sections ◽  
Plate Boundary ◽  
Fault Slip ◽  
Cross Sectional ◽  
Walker Lane ◽  
Dextral Shear ◽  
The Cross

<div>Figure 6. Interpretative cross sections illustrating the cross-sectional geometry of several paleovalleys. See Figure 3 for location of all cross sections and Figure 8 for location of cross section CCʹ. Cross sections AAʹ and BBʹ are plotted at the same scale, and cross section CCʹ is plotted at a smaller scale. Figure 6 is intended to be viewed at a width of 45.1 cm.</div>

How does the Alpine belt end between Spain and Morocco ?

2002 ◽  
Vol 173 (1) ◽  
pp. 3-15 ◽  
Author(s):  
André Michard ◽  
Ahmed Chalouan ◽  
Hugues Feinberg ◽  
Bruno Goffé ◽  
Raymond Montigny
Keyword(s):  
Subduction Zone ◽  
Plate Boundary ◽  
Western Alps ◽  
Late Eocene ◽  
African Plate ◽  
Northern Margin ◽  
Thrust Tectonics ◽  
Rif Belt ◽  
Transitional Crust ◽  
Roll Back

Abstract The Betic-Rif arcuate mountain belt (southern Spain, northern Morocco) has been interpreted as a symmetrical collisional orogen, partly collapsed through convective removal of its lithospheric mantle root, or else as resulting of the African plate subduction beneath Iberia, with further extension due either to slab break-off or to slab retreat. In both cases, the Betic-Rif orogen would show little continuity with the western Alps. However, it can be recognized in this belt a composite orocline which includes a deformed, exotic terrane, i.e. the Alboran Terrane, thrust through oceanic/transitional crust-floored units onto two distinct plates, i.e. the Iberian and African plates. During the Jurassic-Early Cretaceous, the yet undeformed Alboran Terrane was part of a larger, Alkapeca microcontinent bounded by two arms of the Tethyan-African oceanic domain, alike the Sesia-Margna Austroalpine block further to the northeast. Blueschist- and eclogite-facies metamorphism affected the Alkapeka northern margin and adjacent oceanic crust during the Late Cretaceous-Eocene interval. This testifies the occurrence of a SE-dipping subduction zone which is regarded as the SW projection of the western Alps subduction zone. During the late Eocene-Oligocene, the Alkapeca-Iberia collision triggered back-thrust tectonics, then NW-dipping subduction of the African margin beneath the Alboran Terrane. This Maghrebian-Apenninic subduction resulted in the Mediterranean basin opening, and drifting of the deformed Alkapeca fragments through slab roll back process and back-arc extension, as reported in several publications. In the Gibraltar area, the western tip of the Apenninic-Maghrebian subduction merges with that of the Alpine-Betic subduction zone, and their Neogene roll back resulted in the Alboran Terrane collage astride the Azores-Gibraltar transpressive plate boundary. Therefore, the Betic-Rif belt appears as an asymmetrical, subduction/collision orogen formed through a protracted evolution straightfully related to the Alpine-Apenninic mountain building.

scholarly journals Evaluation of Gravity Data Derived from Global Gravity Field Models Using Terrestrial Gravity Data in Enugu State, Nigeria

2018 ◽  
Vol 8 (1) ◽  
pp. 145-153 ◽  
Author(s):  
O.I. Apeh ◽  
E.C. Moka ◽  
V.N. Uzodinma
Keyword(s):  
Gravity Field ◽  
Gravity Data ◽  
Gravity Anomalies ◽  
Mean Square ◽  
Bouguer Gravity ◽  
Bouguer Anomalies ◽  
The Earth ◽  
Global Gravity ◽  
Enugu State ◽  
Gravity Field Models

Abstract Spherical harmonic expansion is a commonly applied mathematical representation of the earth’s gravity field. This representation is implied by the potential coeffcients determined by using elements/parameters of the field observed on the surface of the earth and/or in space outside the earth in the spherical harmonic expansion of the field. International Centre for Gravity Earth Models (ICGEM) publishes, from time to time, Global Gravity Field Models (GGMs) that have been developed. These GGMs need evaluation with terrestrial data of different locations to ascertain their accuracy for application in those locations. In this study, Bouguer gravity anomalies derived from a total of eleven (11) recent GGMs, using sixty sample points, were evaluated by means of Root-Mean-Square difference and correlation coeficient. The Root-Mean-Square differences of the computed Bouguer anomalies from ICGEMwebsite compared to their positionally corresponding terrestrial Bouguer anomalies range from 9.530mgal to 37.113mgal. Additionally, the correlation coe_cients of the structure of the signal of the terrestrial and GGM-derived Bouguer anomalies range from 0.480 to 0.879. It was observed that GECO derived Bouguer gravity anomalies have the best signal structure relationship with the terrestrial data than the other ten GGMs. We also discovered that EIGEN-6C4 and GECO derived Bouguer anomalies have enormous potential to be used as supplements to the terrestrial Bouguer anomalies for Enugu State, Nigeria.

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