scholarly journals Fault evolution in the Potiguar rift termination, Equatorial margin of Brazil

2014 ◽  
Vol 6 (2) ◽  
pp. 2885-2913
Author(s):  
D. L. de Castro ◽  
F. H. R. Bezerra
Keyword(s):  
Sedimentary Basins ◽  
Strike Slip ◽  
Normal Faults ◽  
South American ◽  
Sedimentary Sequences ◽  
Lateral Shearing ◽  
Isolated Structures ◽  
The Right ◽  
Fault Architecture ◽  
Fault Evolution

Abstract. The transform shearing between South American and African plates in the Cretaceous generated a series of sedimentary basins on both plate margins. In this study, we use gravity, aeromagnetic, and resistivity surveys to identify fault architecture and to analyse the evolution of the eastern Equatorial margin of Brazil. Our study area is the southern onshore termination of the Potiguar rift, which is an aborted NE-trending rift arm developed during the breakup of Pangea. The Potiguar rift is a Neocomian structure located in the intersection of the Equatorial and western South Atlantic and is composed of a series of NE-trending horsts and grabens. This study reveals new grabens in the Potiguar rift and indicates that stretching in the southern rift termination created a WNW-trending, 10 km wide and ~40 km long right-lateral strike-slip fault zone. This zone encompasses at least eight depocenters, which are bounded by a left-stepping, en-echelon system of NW- to EW-striking normal faults. These depocenters form grabens up to 1200 m deep with a rhomb-shaped geometry, which are filled with rift sedimentary units and capped by post-rift sedimentary sequences. The evolution of the rift termination is consistent with the right-lateral shearing of the Equatorial margin in the Cretaceous and occurs not only at the rift termination, but also as isolated structures away from the main rift.

scholarly journals Fault evolution in the Potiguar rift termination, equatorial margin of Brazil

Solid Earth ◽  
2015 ◽  
Vol 6 (1) ◽  
pp. 185-196 ◽  
Author(s):  
D. L. de Castro ◽  
F. H. R. Bezerra
Keyword(s):  
Sedimentary Basins ◽  
Strike Slip ◽  
South Atlantic ◽  
Normal Faults ◽  
South American ◽  
Sedimentary Sequences ◽  
The North ◽  
Lateral Shearing ◽  
The Right ◽  
Fault Evolution

Abstract. The transform shearing between South American and African plates in the Cretaceous generated a series of sedimentary basins on both plate margins. In this study, we use gravity, aeromagnetic, and resistivity surveys to identify architecture of fault systems and to analyze the evolution of the eastern equatorial margin of Brazil. Our study area is the southern onshore termination of the Potiguar rift, which is an aborted NE-trending rift arm developed during the breakup of Pangea. The basin is located along the NNE margin of South America that faces the main transform zone that separates the North and the South Atlantic. The Potiguar rift is a Neocomian structure located at the intersection of the equatorial and western South Atlantic and is composed of a series of NE-trending horsts and grabens. This study reveals new grabens in the Potiguar rift and indicates that stretching in the southern rift termination created a WNW-trending, 10 km wide, and ~ 40 km long right-lateral strike-slip fault zone. This zone encompasses at least eight depocenters, which are bounded by a left-stepping, en echelon system of NW–SE- to NS-striking normal faults. These depocenters form grabens up to 1200 m deep with a rhomb-shaped geometry, which are filled with rift sedimentary units and capped by postrift sedimentary sequences. The evolution of the rift termination is consistent with the right-lateral shearing of the equatorial margin in the Cretaceous and occurs not only at the rift termination but also as isolated structures away from the main rift. This study indicates that the strike-slip shearing between two plates propagated to the interior of one of these plates, where faults with similar orientation, kinematics, geometry, and timing of the major transform are observed. These faults also influence rift geometry.

scholarly journals Basin inversion and structural architecture as constraints on fluid flow and Pb-Zn mineralisation in the Paleo-Mesoproterozoic sedimentary sequences of northern Australia

2020 ◽  
Author(s):  
George M. Gibson ◽  
Sally Edwards
Keyword(s):  
Oil And Gas ◽  
Sedimentary Basins ◽  
Normal Faults ◽  
Northern Australia ◽  
Tectonic Event ◽  
Basin Inversion ◽  
Petroleum Systems ◽  
Sedimentary Sequences ◽  
Structural Architecture ◽  
Migration Pathways

Abstract. As host to several world-class sediment-hosted Pb-Zn deposits and unknown quantities of conventional and unconventional gas, the variably inverted 1730–1640 Ma Calvert and 1640–1580 Ma Isa superbasins of northern Australia have been the subject of numerous seismic reflection studies with a view to better understanding basin architecture and fluid migration pathways. Strikingly similar structural architecture has been reported from much younger inverted sedimentary basins considered prospective for oil and gas elsewhere in the world. Such similarities suggest that the mineral and petroleum systems in Paleo-Mesoproterozoic northern Australia may have spatially and temporally overlapped consistent with the observation that basinal sequences hosting Pb-Zn mineralisation in northern Australia are bituminous or abnormally enriched in hydrocarbons. This points to the possibility of a common tectonic driver and shared fluid pathways. Sediment-hosted Pb-Zn mineralisation coeval with basin inversion first occurred during the 1650–1640 Ma Riversleigh Tectonic Event towards the close of the Calvert Superbasin with further pulses accompanying the 1620–1580 Ma Isa Orogeny which brought about closure of the Isa Superbasin. Mineralisation in all cases is hosted by the syn-inversion fraction of basin fill, contrary to most existing interpretations of Pb-Zn ore genesis where the ore-forming fluids are introduced during the rifting or syn-extensional phase of basin development. Syn-extensional normal faults of Calvert and Isa age are mutually orthogonal, giving rise to a complex compartmentalisation of sub-basins with predominantly NNW and ENE strikes. Basin inversion subsequent to 1640 Ma occurred overall in a transpressive tectonic regime linked to continent-continent collision accompanied by orogen-parallel extensional collapse and right-stepping strike-slip faulting.

scholarly journals NEOTECTÔNICA DA REGIÃO AMAZÔNICA: ASPECTOS TECTÔNICOS, GEOMORFOLÓGICOS E DEPOSICIONAIS

1996 ◽  
Author(s):  
João Batista Sena Costa ◽  
Ruth Léa Bemerguy ◽  
Yociteru Hasui ◽  
Maurício da Silva Borges ◽  
Carlos Roberto Paranhos Ferreira Júnior ◽  
...  
Keyword(s):  
Hot Springs ◽  
Strike Slip ◽  
Sediment Deposition ◽  
Normal Faults ◽  
South American ◽  
Thrust Faults ◽  
South American Plate ◽  
Upper Pleistocene ◽  
Drainage Systems ◽  
Right Hand

Several types of structures are observed in the Precambrian, Mesozoic and Cenozoic rocks of theAmazon region, which represent the major features of the neotectonic framework developed since theMiocene. They controlled the sediment deposition of the Upper Tertiary and Quaternary, as well as haveinfluenced the development of the present landform patterns and drainage systems. Transpressive andtranstensive areas are recognized based on their nature and geometry, and related to two main episodes oftranscurrent displacement of Miocene/Pliocene and Upper Pleistocene /Recent ages. Sets of E-W, ENEWSWand NE-SW right-hand strike-slip faults are present in most of these areas. These sets are linked bynormal faults trending NW-SE and NNW-SSE, or by thrust faults trendig NE-SW and ENE-WSW,depending upon their geometry. Large areas with N-S trending younger normal faults are also observed.Earthquakes, the phenomenon of “fallen lands”, fluvial channels migration, hot springs, etc., are related toareas where some of these faults remain active. All these structures are related to an intraplate E-W righthandshear system induced by the rotation of South American Plate towards west.

The role of tectonic inheritance during multiphase rifting: insights from analogue model experiments

2021 ◽  
Author(s):  
Guido Schreurs ◽  
Mario Bühler
Keyword(s):  
Strike Slip ◽  
Normal Faults ◽  
Second Phase ◽  
Linear Segment ◽  
Relative Order ◽  
Tectonic Inheritance ◽  
Oblique Rifting ◽  
Two Phases ◽  
Fault Evolution

<p>Rift systems worldwide are influenced by pre-existing crustal or lithospheric structures. Here, we use brittle-viscous analogue models to examine the role of tectonic inheritance on fault evolution during two non-coaxial rift phases. In our experiments the tectonic inheritance is a linear crustal weakness zone consisting of two offset and parallel linear segments connected by a central oblique linear segment. The first phase of rifting is either orthogonal and followed by a second phase of oblique rifting or vice versa.</p><p> </p><p>The experiments reveal that the tectonic inheritance localizes initial faulting during early rifting, with faults in the domains away from it forming later. The nature and orientation of early faults depends on first-phase rift obliquity, with a progressive switch from dip-slip dominated faulting to strike-slip dominated faulting with increasing obliquity, even resulting in local transpressional structures at very high rift obliquities. First-phase rift structures, in particular those above the tectonic inheritance, exert an important control on the overall fault geometry during the second phase of rifting. Our experiments show that two-phase rifting results in fault patterns evolving by the formation of second-phase new faults and the reactivation of first-phase faults.  Irrespective of the order of the applied two phases of non-coaxial rifting and the difference in rift obliquity angle between the two phases, a major rift (master rift) forms above the tectonic inheritance, underlining its strong control on fault evolution despite markedly different multiphase rift histories.</p><p> </p><p>Nevertheless, close inspection of the master rift reveals differences related to the relative order of the two rift phases: (i) Oblique rifting superseding orthogonal rifting results in a major master rift, whose rift-boundary faults are not reactivated during second-phase rifting. Instead, first-phase intra-rift normal faults are being reactivated with an important strike-slip component of displacement.</p><p>Above the oblique segment of the tectonic inheritance, first-phase en echelon intra-rift normal faults are mostly reactivated and propagate along strike reorienting their tips into high angles to the local principal stretching direction (ii) Orthogonal rifting overprinting oblique rifting, on the other hand, produces first-phase strike-slip faults that link up and trend (sub)-parallel to later formed rift-boundary faults and intra-rift normal faults.</p><p> </p><p>Away from the tectonic inheritance faults have more freedom to evolve in response to the regional rift obliquity, and although they may reactivate, propagate sideways and slightly reorient their fault tips during the second phase of rifting, their trend at the end of the second-phase of rifting with respect to the orientation of the master rift reflects whether first-phase rifting was orthogonal or oblique. Our model results can be used to assess the influence of tectonic inheritance on faulting, the relative order of rifting and the relative difference in obliquity in natural settings that have undergone two phases of rifting.</p>

scholarly journals Pleistocene Mammals from Pampean Region (Argentina). Biostratigraphic, Biogeographic, and Environmental Implications

Quaternary ◽  
2021 ◽  
Vol 4 (2) ◽  
pp. 15
Author(s):  
José Luis Prado ◽  
María Teresa Alberdi ◽  
Jonathan Bellinzoni
Keyword(s):  
South America ◽  
The State ◽  
Historical Study ◽  
South American ◽  
Environmental Implications ◽  
Sedimentary Sequences ◽  
Pampean Region ◽  
Mammalian Faunas ◽  
Pleistocene Mammals ◽  
Fossil Records

The Pampean Region contains sedimentary sequences with abundant mammal fossil records, which constitute the chronological outline of the Plio–Pleistocene of South America. These classic localities have been used for more than a century to correlate with other South American regions. Throughout this time, a series of misinterpretations have appeared. To understand the stratigraphic significance of these localities and the geochronological situation of each unit referring to the Pleistocene, a critical historical study of the antecedents was carried out, evaluating the state of each unit. The biostratigraphic studies of the Pampean Region’s mammalian faunas improved the understanding of biogeographic changes taking into account the environmental fluctuations of the Pleistocene.

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.

A Hazard and Risk Management System for Large Rock Slope Hazards Affecting Pipelines in Mountainous Terrain

2002 ◽  
Author(s):  
Michael Porter ◽  
Alex Baumgard ◽  
K. Wayne Savigny
Keyword(s):  
Risk Management ◽  
Rock Slope ◽  
Management Program ◽  
South American ◽  
Mountainous Terrain ◽  
Hazard Exposure ◽  
Access Road ◽  
Hazard And Risk ◽  
The Right ◽  
Hazard Rating

Pipelines and other linear facilities that traverse mountainous terrain may be subject to rock fall and rock slide hazards. A system is required to determine which sites pose the greatest hazard to the facility. Once sites are ranked according to hazard exposure, a risk management program involving inspection, monitoring, contingency planning and/or mitigation can be implemented in a systematic and defensible manner. A hazard rating methodology was developed to identify and characterize rock slope hazards above a South American Concentrate Pipeline, and to provide a relative ranking of hazard exposure for the pipeline, an access road and operational personnel. The rating methodology incorporates the geometry of the right-of-way, estimated pipe depth, staff and vehicle occupancy time, failure mechanism and magnitude, and the annual probability of hazard occurrence. This information is used in a risk-based framework to assign relative hazard ratings within rock slope sections of relatively uniform hazard exposure. This paper outlines a general framework for natural hazard and risk management along linear facilities, describes the rock slope hazard rating methodology, and illustrates how the system was applied along a South American Concentrate Pipeline.

Rampart seismic zone of central Alaska

1983 ◽  
Vol 73 (3) ◽  
pp. 813-829
Author(s):  
P. Yi-Fa Huang ◽  
N. N. Biswas
Keyword(s):  
Main Shock ◽  
Fault Plane ◽  
B Value ◽  
Aftershock Sequence ◽  
Strike Slip ◽  
Lithospheric Plate ◽  
Normal Faults ◽  
Seismic Zone ◽  
The West ◽  
Fault Plane Solutions

abstract This paper describes the characteristics of the Rampart seismic zone by means of the aftershock sequence of the Rampart earthquake (ML = 6.8) which occurred in central Alaska on 29 October 1968. The magnitudes of the aftershocks ranged from about 1.6 to 4.4 which yielded a b value of 0.96 ± 0.09. The locations of the aftershocks outline a NNE-SSW trending aftershock zone about 50 km long which coincides with the offset of the Kaltag fault from the Victoria Creek fault. The rupture zone dips steeply (≈80°) to the west and extends from the surface to a depth of about 10 km. Fault plane solutions for a group of selected aftershocks, which occurred over a period of 22 days after the main shock, show simultaneous occurrences of strike-slip and normal faults. A comparison of the trends in seismicity between the neighboring areas shows that the Rampart seismic zone lies outside the area of underthrusting of the lithospheric plate in southcentral and central Alaska. The seismic zone outlined by the aftershock sequence appears to represent the formation of an intraplate fracture caused by regional northwest compression.

Late Pleistocene extension and strike-slip in the Dead Sea Basin

2004 ◽  
Vol 141 (5) ◽  
pp. 565-572 ◽  
Author(s):  
YUVAL BARTOV ◽  
AMIR SAGY
Keyword(s):  
Internal Structure ◽  
Slip Rate ◽  
Dead Sea ◽  
Strike Slip ◽  
Normal Faults ◽  
Small Scale ◽  
Dead Sea Basin ◽  
Pull Apart Basin ◽  
Western Border ◽  
The Dead

A newly discovered active small-scale pull-apart (Mor structure), located in the western part of the Dead Sea Basin, shows recent basin-parallel extension and strike-slip faulting, and offers a rare view of pull-apart internal structure. The Mor structure is bounded by N–S-trending strike-slip faults, and cross-cut by low-angle, E–W-trending normal faults. The geometry of this pull-apart suggests that displacement between the two stepped N–S strike-slip faults of the Mor structure is transferred by the extension associated with the normal faults. The continuing deformation in this structure is evident by the observation of at least three deformation episodes between 50 ka and present. The calculated sinistral slip-rate is 3.5 mm/yr over the last 30 000 years. This slip rate indicates that the Mor structure overlies the currently most active strike-slip fault within the western border of the Dead Sea pull-apart. The Mor structure is an example of a small pull-apart basin developed within a larger pull-apart. This type of hierarchy in pull-apart structures is an indication for their ongoing evolution.

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.

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