scholarly journals Active faulting, 3-D basin architecture and Plio-Quaternary structural evolution of extensional basins: a 4-D perspective on the central Apennine chain evolution, Italy

2016 ◽  
Author(s):  
Stefano Gori ◽  
Emanuela Falcucci ◽  
Chiara Ladina ◽  
Simone Marzorati ◽  
Fabrizio Galadini
Keyword(s):  
Tectonic Setting ◽  
Structural Evolution ◽  
Normal Fault ◽  
Basin And Range ◽  
Early Pleistocene ◽  
Fault System ◽  
Late Pliocene ◽  
North East ◽  
The North ◽  
Apennine Chain

Abstract. The general “basin and range” aspect of the Apennine relief is generally attributed to the presently active normal fault systems, whose activity throughout the Quaternary is supposed to have created alternating morphological/structural highs and lows. By coupling field geological survey and geophysical investigations, we reconstructed the 3-D geometry of one of the innermost tectonic basins of the central Apennines, the Subequana Valley, bounded to the north-east by an active and seismogenic normal fault. Our analyses revealed that, since the Late Pliocene, the depression experienced a double polarity, half graben-mode nucleation. An early phase, Late Pliocene-Early Pleistocene in age, was led by the ENE-WSW trending and SSE dipping Avezzano-Bussi fault, that determined the formation of an early depocentre towards the N-NW; subsequently, the main fault became the NW-SE trending, SW dipping and presently active normal fault system, that led the formation during the Quaternary of a new fault-related depocentre towards the NE. By considering the available geological information, a similar structural evolution has likely involved three close tectonic basins aligned along the Avezzano-Bussi fault, namely the Fucino basin, the Subequana Valley and the Sulmona basin, and it has been probably experienced by other tectonic basins of the chain. The present work therefore points out that the morpho-tectonic setting of the Apennine chain results from the superposition of deformation events whose “legacy” must be considered in a wider evolutionary perspective. Within this light, our results testify that a simple “basin and range” model – often adopted for morpho-tectonic and kinematic evaluations in active extensional contexts, as in the Apennines – may be actually simplistic, as it could not be applied everywhere, owing to peculiar complexities of the local tectonic histories.

scholarly journals Active faulting, 3-D geological architecture and Plio-Quaternary structural evolution of extensional basins in the central Apennine chain, Italy

Solid Earth ◽  
2017 ◽  
Vol 8 (2) ◽  
pp. 319-337 ◽  
Author(s):  
Stefano Gori ◽  
Emanuela Falcucci ◽  
Chiara Ladina ◽  
Simone Marzorati ◽  
Fabrizio Galadini
Keyword(s):  
Large Scale ◽  
Tectonic Setting ◽  
Structural Evolution ◽  
Basin And Range ◽  
Early Pleistocene ◽  
Fault System ◽  
Normal Faults ◽  
Tectonic Deformation ◽  
Late Pliocene ◽  
Apennine Chain

Abstract. The general basin and range Apennine topographic characteristic is generally attributed to the presently active normal fault systems, whose long-term activity (throughout the Quaternary) is supposed to have been responsible for the creation of morphological/structural highs and lows. By coupling field geological survey and geophysical investigations, we reconstructed the 3-D geological model of an inner tectonic basin of the central Apennines, the Subequana Valley, bounded to the northeast by the southern segment of one of the major active and seismogenic normal faults of the Apennines, known as the Middle Aterno Valley–Subequana Valley fault system. Our analyses revealed that, since the late Pliocene, the basin evolved in a double half-graben configuration through a polyphase tectonic development. An early phase, Late Pliocene–Early Pleistocene in age, was controlled by the ENE–WSW-striking and SSE-dipping Avezzano–Bussi fault, that determined the formation of an early depocentre towards the N–NW. Subsequently, the main fault became the NW–SE-striking faults, which drove the formation during the Quaternary of a new fault-related depocentre towards the NE. By considering the available geological information, a similar structural evolution has likely involved three close tectonic basins aligned along the Avezzano–Bussi fault, namely the Fucino Basin, the Subequana Valley, and the Sulmona Basin, and it has been probably experienced by other tectonic basins of the chain. The present work therefore points out the role of pre-existing transverse tectonic structures, inherited by previous tectonic phases, in accommodating the ongoing tectonic deformation and, consequently, in influencing the structural characteristics of the major active normal faults. This has implications in terms of earthquake fault rupture propagation and segmentation. Lastly, the morpho-tectonic setting of the Apennine chain results from the superposition of deformation events whose geological legacy must be considered in a wider evolutionary perspective. Our results testify that a large-scale basin and range geomorphological feature – often adopted for morpho-tectonic and kinematic evaluations in active extensional contexts, as in the Apennines – just led by range-bounding active normal faults may be actually simplistic, as it could not be applied everywhere, owing to peculiar complexities of the local tectonic histories.

West Timor: a key for the eastern Indonesian geodynamic evolution

2013 ◽  
Vol 184 (6) ◽  
pp. 569-582
Author(s):  
Michel Villeneuve ◽  
Hervé Bellon ◽  
Rossana Martini ◽  
Agus Harsolumakso ◽  
Jean-Jacques Cornée
Keyword(s):  
Accretionary Prism ◽  
Early Pleistocene ◽  
Late Oligocene ◽  
The South ◽  
Geodynamic Evolution ◽  
Late Pliocene ◽  
Early Pliocene ◽  
North East ◽  
The North ◽  
West Timor

Abstract Timor Island was at time considered as an example of “accretionary prism” linked to the collision between the Australian block and the Banda arc. However, its geological evolution is more complex. Five main superimposed structural units are distinguished in West Timor. The today structure is the result of three main tectonic events that occurred during the Late Oligocene, Late Early Pliocene and Late Pliocene-Early Pleistocene times, respectively. Our field investigations in the 1990 to 2000 decade completed with geochemical analyses and K-Ar datings (Jurassic and Miocene ages) of magmatism allow to precise the geodynamic evolution of Timor that can be summarized as follows: a first block was detached from Gondwana (unit 2) and drifted to the Asiatic margin until the Late Oligocene when it collided with the Asiatic active margin (unit 3). Then, the new block formed by both 2 and 3 units drifted to the south during the Miocene and the Early Pliocene until it collided with the Australian margin (ASM), by the Late Early Pliocene. Then, the Australian and Timor blocks moved together towards the North-North East during the Late Pliocene until they collided with the Banda fore-arc (unit 4). Later on (Pleistocene), Timor island was capped by the “autochthon” (unit 5) and then on (Quaternary?) by the Banda volcanic arc northward thrusted over the South Banda basin. Taking in consideration its close relationships with both the Australian plate and the Eurasian one. Timor may be considered as a key area for building this geodynamical scenario of Indonesia.

scholarly journals The 31 March 2020 Mw 6.5 Stanley, Idaho, Earthquake: Seismotectonics and Preliminary Aftershock Analysis

2020 ◽  
Author(s):  
Lee M. Liberty ◽  
Zachery M. Lifton ◽  
T. Dylan Mikesell
Keyword(s):  
Surface Displacement ◽  
Volcanic Belt ◽  
Normal Fault ◽  
Fault System ◽  
Basin And Range Province ◽  
Ground Shaking ◽  
The North ◽  
Show Evidence ◽  
Tectonic Framework ◽  
Tectonic Belt

Abstract We report on the tectonic framework, seismicity, and aftershock monitoring efforts related to the 31 March 2020 Mw 6.5 Stanley, Idaho, earthquake. The earthquake sequence has produced both strike-slip and dip-slip motion, with minimal surface displacement or damage. The earthquake occurred at the northern limits of the Sawtooth normal fault. This fault separates the Centennial tectonic belt, a zone of active seismicity within the Basin and Range Province, from the Idaho batholith to the west and Challis volcanic belt to the north and east. We show evidence for a potential kinematic link between the northeast-dipping Sawtooth fault and the southwest-dipping Lost River fault. These opposing faults have recorded four of the five M≥6 Idaho earthquakes from the past 76 yr, including 1983 Mw 6.9 Borah Peak and the 1944 M 6.1 and 1945 M 6.0 Seafoam earthquakes. Geological and geophysical data point to possible fault boundary segments driven by pre-existing geologic structures. We suggest that the limits of both the Sawtooth and Lost River faults extend north beyond their mapped extent, are influenced by the relic trans-Challis fault system, and that seismicity within this region will likely continue for the coming years. Ongoing seismic monitoring efforts will lead to an improved understanding of ground shaking potential and active fault characteristics.

Synrift evaporite deposition and structural characterization of the onshore Alagoas subbasin

2019 ◽  
Vol 7 (4) ◽  
pp. SH19-SH31
Author(s):  
Gabriela Salomão Martins ◽  
Webster Ueipass Mohriak ◽  
Nivaldo Destro
Keyword(s):  
Structural Characterization ◽  
Oil And Gas ◽  
Hanging Wall ◽  
Structural Evolution ◽  
Gas Production ◽  
North East ◽  
The North ◽  
Half Graben ◽  
Well Data

The Sergipe-Alagoas Basin, situated in the north-east Brazilian margin, has a long tradition of oil and gas production and the presence and distribution of evaporites play an important role in petroleum systems in the basin. However, little research has focused on the structural evolution of the older, synrift evaporitic sections of the basin. We have focused explicitly in the detailed subsurface structural characterization of the rift in the Alagoas subbasin and the distribution of the Early Aptian evaporites. To accomplish this objective, we interpreted selected 2D and 3D seismic and well data located in two areas known as the Varela Low (VL) and Fazenda Guindaste Low (FGL). We identified diverse deformation styles in those two basin depocenters. Our interpretation indicates that VL consists of a half-graben with a significant rollover structure, controlled by two listric northeast–southwest border faults. The deformation in the hanging wall is also accommodated by release faults and minor antithetic faults. In this depocenter, we mapped in the seismic and the well data an older evaporitic sequence within the Coqueiro Seco Fm., known as Horizonte Salt. This evaporitic section occurs in the internal part of the VL half graben, where it is limited by release and antithetic faults. Significant salt strata growing toward the antithetic fault is observed. Whereas, the FGL represents a graben elongated along the north-east direction and is controlled by several types of structures. We recognized normal synthetic and antithetic faults, transfer zones, release faults, and rollover anticlines in the seismic throughout this depocenter. We mapped an evaporitic section within the Maceió Fm., known as Paripueira Salt, which consists of disconnected salt bodies, restricted to the hanging walls of synrift faults.

Normal fault growth and segment linkage in a gravitationally detached delta system: evidence from 3D seismic reflection data from the Ceduna Sub-basin, Great Australian Bight

2015 ◽  
Vol 55 (2) ◽  
pp. 467
Author(s):  
Alexander Robson ◽  
Rosalind King ◽  
Simon Holford
Keyword(s):  
Seismic Reflection ◽  
Fault Plane ◽  
Structural Evolution ◽  
Normal Fault ◽  
Fault System ◽  
Seismic Reflection Data ◽  
Reflection Data ◽  
Listric Fault ◽  
Dip Angle ◽  
Fault Growth

The authors used three-dimensional (3D) seismic reflection data from the central Ceduna Sub-Basin, Australia, to establish the structural evolution of a linked normal fault assemblage at the extensional top of a gravitationally driven delta system. The fault assemblage presented is decoupled at the base of a marine mud from the late Albian age. Strike-linkage has created a northwest–southeast oriented assemblage of normal fault segments and dip-linkage through Santonian strata, which connects a post-Santonian normal fault system to a Cenomanian-Santonian listric fault system. Cenomanian-Santonian fault growth is on the kilometre scale and builds an underlying structural grain, defining the geometry of the post-Santonian fault system. A fault plane dip-angle model has been created and established through simplistic depth conversion. This converts throw into fault plane dip-slip displacement, incorporating increasing heave of a listric fault and decreasing in dip-angle with depth. The analysis constrains fault growth into six evolutionary stages: early Cenomanian nucleation and radial growth of isolated fault segments; linkage of fault segments by the latest Cenomanian; latest Santonian Cessation of fault growth; erosion and heavy incision during the continental break-up of Australia and Antarctica (c. 83 Ma); vertically independent nucleation of the post-Santonian fault segments with rapid length establishment before significant displacement accumulation; and, continued displacement into the Cenozoic. The structural evolution of this fault system is compatible with the isolated fault model and segmented coherent fault model, indicating that these fault growth models do not need to be mutually exclusive to the growth of normal fault assemblages.

Geomorphic evidence for active, co-seismic slip along a low-angle normal fault: Panamint Valley, California

2020 ◽  
Author(s):  
Eric Kirby ◽  
Israporn (Grace) Sethanant ◽  
John Gosse ◽  
Eric McDonald ◽  
J Doug Walker
Keyword(s):  
Seismic Hazard ◽  
Normal Fault ◽  
Basin And Range ◽  
Detachment Fault ◽  
Airborne Lidar ◽  
Fault System ◽  
Seismic Slip ◽  
The Past ◽  
Detachment Faults ◽  
Fault Scarps

<p>The mechanical feasibility of co-seismic displacement along low-angle normal fault systems remains an outstanding problem in tectonics.  In the southwestern Basin and Range of North America, large magnitude extension during Miocene – Pliocene time was accommodated along a regionally extensive system of low-angle detachment faults.  Whether these faults remain active today and, if so, whether they rupture during large earthquakes are questions central to understanding the geodynamics of distributed lithospheric deformation and associated seismic hazard.  Here we evaluate the geometric and kinematic relationships of fault scarps developed in Pleistocene – Holocene alluvial and lacustrine deposits with low-angle detachment faults observed along the western flank of the Panamint Range, in eastern California.  We combine analysis of high-resolution topography generated from airborne LiDAR and photogrammetry with a detailed chronology of alluvial fan surfaces and a calibrated soil chronosequence to characterize the recent activity of the fault system.  The range-front fault system is coincident with a low-angle (15-20°), curviplanar detachment fault that is linked to strike-slip faults at its southern and northern ends.  Fanglomerate deposits in the hanging wall of the detachment are juxtaposed with brecciated bedrock in the footwall across a narrow fault surface marked by clay-rich gouge.  Isochron burial dating of the fanglomerate using the <sup>26</sup>Al and <sup>10</sup>Be requires displacement in the past ~800 ka.  The degree of soil development in younger alluvial deposits in direct fault contact with the footwall block suggest displacement along the main detachment in the past as ~80-100 ka.  The geometry of recent fault scarps in Holocene alluvium mimic range-scale variations in strike of the curviplanar detachment fault, suggesting that scarps merge with the detachment at depth.  Moreover, fault kinematics inferred from displaced debris-flow levees and from fault striae on the bedrock range front are consistent with slip on a low-angle detachment system beneath the valley.  Finally, paleoseismic results from a trench at the southern end of the fault system suggest 3-4 surface ruptures during past ~4-5 ka, the most recent of which (MRE) occurred ~330-485 cal yr BP.  Scarps related to the MRE can be traced for at least ~50 km northward along the range front and imply surface displacements of 2-4 meters during this event.  Thus, we conclude that ongoing dextral shear along the margin of the Basin and Range is, in part, accommodated by co-seismic slip along low-angle detachment faults in Panamint Valley.  Our results have important implications for the interaction of fault networks and seismic hazard in the region.</p>

scholarly journals A review of the Pan-African evolution of the Arabian Shield

GeoArabia ◽  
2002 ◽  
Vol 7 (1) ◽  
pp. 103-124 ◽  
Author(s):  
Pierre Nehlig ◽  
Antonin Genna ◽  
Fawzia Asfirane ◽  
C. Guerrot ◽  
J.M. Eberlé ◽  
...  
Keyword(s):  
Structural Evolution ◽  
Sedimentary Basins ◽  
Fault Zones ◽  
Fault System ◽  
Arabian Shield ◽  
Geologic History ◽  
Lower Paleozoic ◽  
The North ◽  
Pan African ◽  
History Of

ABSTRACT Recent fieldwork and the synthesis and reappraisal of aeromagnetic, geologic, structural, geochemical, and geochronologic data have provided a new perspective on the structural evolution and geologic history of the Arabian Shield. Although Paleoproterozoic rocks are present in the eastern part of the Shield, its geologic evolution was mainly concentrated in the period from 900 to 550 Ma during which the formation, amalgamation, and final Pan-African cratonization of several tectonostratigraphic terranes took place. The terranes are separated by major NW-trending faults and by N-, NW- and NE-oriented suture zones lined by serpentinized ultramafic rocks (ophiolites). Terrane analysis using the lithostratigraphy and geochronology of suture zones, fault zones, overlapping basins, and stitching plutons, has helped to constrain the geologic history of the Arabian Shield. Ophiolites and volcanic-arcs have been dated at between 900 and 680 Ma, with the southern terrane of Asir being older than the Midyan terrane in the north and the Ar Rayn terrane in the east. Final cratonization of the terranes between 680 and 610 Ma induced a network of anastomosing, strike-slip faults consisting of the N-trending Nabitah belt, the major NW-striking left-lateral transpressive faults (early Najd faults), lined by gneiss domes and associated with sedimentary basins, and N- to NE-trending right-lateral transpressive faults. Following the Pan-African cratonization, widespread alkaline granitization was contemporaneous with the deposition of the Jibalah volcanic and sedimentary rocks in transtensional pull-apart basins. Crustal thinning was governed by the Najd fault system of left-lateral transform faults that controlled the formation of the Jibalah basins and was synchronous with the emplacement of major E- to NW-trending dike swarms throughout the Arabian Shield. The extensional episode ended with a marine transgression in which carbonates were deposited in the Jibalah basins. Continuation of the thinning process may explain the subsequent deposition of the marine formations of the lower Paleozoic cover. Our interpretation of the distribution and chronology of orogenic zones does not correspond entirely to those proposed in earlier studies. In particular, the N-trending Nabitah and NW-trending Najd fault zones are shown to be part of the same history of oblique transpressional accretion rather than being two distinct events related to accretion and dispersion of the terranes.

Slip-sense inversion in Iran: Implications for Eurasian tectonics

2020 ◽  
Author(s):  
Bernard Guest
Keyword(s):  
Structural Evolution ◽  
Sediment Supply ◽  
Process Models ◽  
Fault System ◽  
Free Boundaries ◽  
Iranian Plateau ◽  
Existing Structures ◽  
The North ◽  
Collision Zone ◽  
Late Neogene

<p>The left-lateral Doruneh Fault System (DFS) bounds the north margin of the Central Iranian microplate, and has played an important role in the structural evolution of the Turkish-Iranian Plateau and of Afghanistan. The western termination of the DFS is a sinistral synthetic branch fault array that shows clear kinematic evidence of having undergone recent slip sense inversion from a dextral array to a sinistral array in the latest Neogene or earliest Quaternary. Similarly, kinematic evidence from the Anarak Metamorphic complex at the southwestern most branch of the DFS terminal fault array suggests that this core complex formed at a transpressive left stepping termination and that it was inverted in the latest Neogene to a transtensional fault termination. The recognition that the DFS and possibly other faults in NE Iran were inverted from dextral to sinistral strike slip in the latest Neogene, and the likely connection between the DFS and the Herat Fault of Afghanistan suggests that the evolutions of Afghanistan and the Indo-Asian collisional system are linked to the tectonic evolution of the Turkish-Iranian Plateau. This speculative model explains the Late Neogene tectonic realignment of the Arabia-Eurasia collision zone in terms of the interaction between the Afghan blocks that were extruding west from the Indo-Asian collision and the Turkish Iranian collision zone that was evolving to the east as Arabia sutured diachronously with Eurasia. The collision of the Afghan blocks with East Iran effectively locked the respective eastern and western free boundaries for the Arabia-Eurasia, and Indo-Asian collisional belts and forced them to diverge away from one another.<span> If confirmed,</span> this explains the Late Miocene to Pliocene tectonic reorganization that is recognized across the Middle East and has implications for geologic process models across the region. Regional tectonic reorganization and/or inversion may (1) invert and possibly breach older Cenozoic structures while forming a younger generation of post-Miocene structures, (2) reorganize drainage and sediment supply networks, and sealing and obscuring older structural and stratigraphic bodies under younger sediments, (3) rejuvenate existing structures and trigger secondary fluid migration, and (4) increase exhumation, sediment supply, and subsidence in late Neogene basins across the region.</p>

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