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 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 Superposition of two kinematically distinct extensional phases in southern Death Valley: Implications for extensional tectonics

Geosphere ◽  
2021 ◽  
Author(s):  
Z.D. Fleming ◽  
T.L. Pavlis ◽  
S. Canalda
Keyword(s):  
Early Period ◽  
Rock Avalanche ◽  
Strike Slip ◽  
Death Valley ◽  
Normal Faults ◽  
Geologic Mapping ◽  
The North ◽  
Transcurrent Deformation ◽  
Two Phases

Geologic mapping in southern Death Valley, California, demonstrates Mesozoic contractional structures overprinted by two phases of Neogene extension and contemporaneous strike-slip deformation. The Mesozoic folding is most evident in the middle unit of the Noonday Formation, and these folds are cut by a complex array of Neogene faults. The oldest identified Neogene faults primarily displace Neoproterozoic units as young as the Johnnie Formation. However, in the northernmost portion of the map area, they displace rocks as young as the Stirling Quartzite. Such faults are seen in the northern Ibex Hills and con­sist of currently low- to moderate-angle, E-NE– dipping normal faults, which are folded about a SW-NE–trending axis. We interpret these low-angle faults as the product of an early, NE-SW extension related to kinematically similar deformation recognized to the south of the study area. The folding of the faults postdates at least some of the extension, indicating a component of syn-exten­sional shortening that is probably strike-slip related. Approximately EW-striking sinistral faults are mapped in the northern Saddlepeak Hills. However, these faults are kinematically incompatible with the folding of the low-angle faults, suggesting that folding is related to the younger, NW-SE extension seen in the Death Valley region. Other faults in the map area include NW- and NE-striking, high-angle normal faults that crosscut the currently low-angle faults. Also, a major N-S–striking, oblique-slip fault bounds the eastern flank of the Ibex Hills with slickenlines showing rakes of <30°, which together with the map pattern, suggests dextral-oblique movement along the east front of the range. The exact timing of the normal faulting in the map area is hampered by the lack of geochronology in the region. However, based on the map relationships, we find that the older extensional phase predates an angular unconformity between a volcanic and/or sedimentary succession assumed to be 12–14 Ma based on correlations to dated rocks in the Owlshead Mountains and overlying rock-avalanche deposits with associated sedimentary rocks that we correlate to deposits in the Amargosa Chaos to the north, dated at 11–10 Ma. The mechanism behind the folding of the northern Ibex Hills, including the low- angle faults, is not entirely clear. However, transcurrent systems have been proposed to explain extension-parallel folding in many extensional terranes, and the geometry of the Ibex Hills is consistent with these models. Collectively, the field data support an old hypothesis by Troxel et al. (1992) that an early period of SW-NE extension is prominent in the southern Death Valley region. The younger NW-SE extension has been well documented just to the north in the Black Mountains, but the potential role of this earlier extension is unknown given the complexity of the younger deformation. In any case, the recognition of earlier SW-NE extension in the up-dip position of the Black Mountains detachment system indicates important questions remain on how that system should be reconstructed. Collectively, our observations provide insight into the stratigraphy of the Ibex Pass basin and its relationship to the extensional history of the region. It also highlights the role of transcurrent deformation in an area that has transitioned from extension to transtension.

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.

Strain partitioning around an indenter during oroclinal bending: kinematics of the Circum-Moesian fault system of the Carpatho-Balkanides

2021 ◽  
Author(s):  
Nemanja Krstekanic ◽  
Liviu Matenco ◽  
Uros Stojadinovic ◽  
Ernst Willingshofer ◽  
Marinko Toljić ◽  
...  
Keyword(s):  
Large Scale ◽  
Strike Slip ◽  
Fault System ◽  
Normal Faults ◽  
Strain Partitioning ◽  
The South ◽  
The Carpathians ◽  
The North ◽  
Moesian Platform ◽  
Parallel Extension

<p>The Carpatho-Balkanides of south-eastern Europe is a double 180° curved orogenic system. It is comprised of a foreland-convex orocline, situated in the north and east and a backarc-convex orocline situated in the south and west. The southern orocline of the Carpatho-Balkanides orogen formed during the Cretaceous closure of the Alpine Tethys Ocean and collision of the Dacia mega-unit with the Moesian Platform. Following the main orogen-building processes, the Carpathians subduction and Miocene slab retreat in the West and East Carpathians have driven the formation of the backarc-convex oroclinal bending in the south and west. The orocline formed during clockwise rotation of the Dacia mega-unit and coeval docking against the Moesian indenter. This oroclinal bending was associated with a Paleocene-Eocene orogen-parallel extension that exhumed the Danubian nappes of the South Carpathians and with a large late Oligocene – middle Miocene Circum-Moesian fault system that affected the orogenic system surrounding the Moesian Platform along its southern, western and northern margins. This fault system is composed of various segments that have different and contrasting types of kinematics, which often formed coevally, indicating a large degree of strain partitioning during oroclinal bending. It includes the curved Cerna and Timok faults that cumulate up to 100 km of dextral offset, the lower offset Sokobanja-Zvonce and Rtanj-Pirot dextral strike-slip faults, associated with orogen parallel extension that controls numerous intra-montane basins and thrusting of the western Balkans units over the Moesian Platform. We have performed a field structural study in order to understand the mechanisms of deformation transfer and strain partitioning around the Moesian indenter during oroclinal bending by focusing on kinematics and geometry of large-scale faults within the Circum-Moesian fault system.</p><p>Our structural analysis shows that the major strike-slip faults are composed of multi-strand geometries associated with significant strain partitioning within tens to hundreds of metres wide deformation zones. Kinematics of the Circum-Moesian fault system changes from transtensional in the north, where the formation of numerous basins is controlled by the Cerna or Timok faults, to strike-slip and transpression in the south, where transcurrent offsets are gradually transferred to thrusting in the Balkanides. The characteristic feature of the whole system is splaying of major faults to facilitate movements around the Moesian indenter. Splaying towards the east connects the Circum-Moesian fault system with deformation observed in the Getic Depression in front of the South Carpathians, while in the south-west the Sokobanja-Zvonce and Rtanj-Pirot faults splay off the Timok Fault. These two faults are connected by coeval E-W oriented normal faults that control several intra-montane basins and accommodate orogen-parallel extension. We infer that all these deformations are driven by the roll-back of the Carpathians slab that exerts a northward pull on the upper Dacia plate in the Serbian Carpathians. However, the variability in deformation styles is controlled by geometry of the Moesian indenter and the distance to Moesia, as the rotation and northward displacements increase gradually to the north and west.</p>

Uplift history of the Western Ecuadorian Andes: new constraints from low-temperature thermochronology

2020 ◽  
Author(s):  
Audrey Margirier ◽  
Peter Reiners ◽  
Ismael Casado ◽  
Stuart Thomson ◽  
Alexandra Alvarado ◽  
...  
Keyword(s):  
Strike Slip ◽  
South American ◽  
South American Plate ◽  
Ridge Subduction ◽  
The North ◽  
Western Cordillera ◽  
Deformational History ◽  
History Of ◽  
Long Term Impact

<p>The Cenozoic growth of the Ecuadorian Andes has been strongly influenced by the compressional reactivation of inherited crustal anisotropies, strike-slip faulting and uplift, and the erosional effects of a wet tropical climate superposed on the deforming orogen. Some authors have linked uplift in the Western Cordillera to the interaction between the South American Plate and the subduction of the oceanic Carnegie Ridge. However, recent studies have alternatively suggested that the tectonic evolution of a northward-escaping crustal sliver in western Ecuador along the Pallatanga strike-slip zone may equally well explain mountain building and topographic growth in this region. While the importance of the Pallatanga Fault has been recognized in the context of seismic hazards, its long-term impact on the development of topography and relief has not been explored in detail. To evaluate the possible roles of oceanic ridge subduction and/or strike-slip motion in prompting the growth of the Western Cordillera, we present new thermochronological data to constrain the deformational history of the Western Cordillera at different latitudes. We focus on two sites in the vicinity of the Pallatanga strike-slip fault (3°S and 1°30’S) and a location farther to the north (0°30’N). Our apatite and zircon (U-Th-Sm)/He dates range from 26.0 ± 0.4 Ma to 3.9 ± 0.1 Ma and from 23.7 ± 0.3 to 5.9 ± 0.1 Ma, respectively. The three sampled sites record a clear age-elevation relationship. The inverse modeling of apatite and zircon (U-Th-Sm)/He dates and upcoming apatite fission-track data is expected to provide new constraints on the recent uplift and exhumation history of the Western Ecuadorian Andes and thus furnish information on the paleo-geographical evolution of the northern Andes.</p>

Seismic stratigraphy of the East-Siberian and Chukchi seas as a key to the Amerasia Basin stratigraphy end evolution

2020 ◽  
Author(s):  
Kseniia Startseva ◽  
Anatoly Nikishin
Keyword(s):  
Foreland Basin ◽  
Sedimentary Basins ◽  
Geological Structure ◽  
Seismic Survey ◽  
Normal Faults ◽  
Seismic Profiles ◽  
The North ◽  
Sea Bottom ◽  
Reported Study ◽  
Bottom Sampling

<p>Based on new seismic survey, offshore drilling and geological structure of the adjacent onshore a new model of geological evolution of sedimentary basins of the East-Siberian and Chukchi seas since the Mesozoic has been constructed. The main stages of their tectonic history are highlighted: 1) forming of the foreland basin in Jurassic – Early Creatceous time; 2) synrift extension in Aptian-Albian time; 3) start of postrift subsidence in Later Cretaceous; 4) uplift and deformations at the turn of Cretaceous and Paleogene, start of forming of the thick (up to 4-6 km) clinoform complex; 5) episode of synrift extension in Middle-Later Eocene, forming of the system of multiple low-amplitude normal faults; 6) inversion deformations in Oligocene-Miocene; 7) relatively calm tectonic conditions in Neogene-Quaternary time. Boundaries of the interpreted seismic complexes corresponding to these stages has been extended to the entire Amerasia basin with regards to the ages of magnetic anomalies in the Gakkel Ridge and sea-bottom sampling on the Mendeleev Rise. Volcanic areas of the De Long Islands and the North Wrangel High has been traced on the seismic profiles toward Mendeleev Rise and Podvodnikov Basin and dated as ±125 Ma. According to the seismic interpretation, the age of the Podvodnikov and Toll basins is not older than Aptian. The reported study was funded by RFBR and NSFB, project number 18-05-70011, 18-05-00495 and 18-35-00133.</p>

scholarly journals Geology reviewed for the Falkland Islands and their offshore sedimentary basins, South Atlantic Ocean

2015 ◽  
Vol 106 (2) ◽  
pp. 115-143 ◽  
Author(s):  
Philip Stone
Keyword(s):  
South Africa ◽  
Atlantic Ocean ◽  
Foreland Basin ◽  
Sedimentary Basins ◽  
South Atlantic ◽  
South Atlantic Ocean ◽  
Original Position ◽  
Falkland Islands ◽  
South American ◽  
The South

ABSTRACTThe position of the Falkland Islands adjacent to the South American continental margin belies the close association of their geology with that of South Africa. A Mesoproterozoic basement is unconformably overlain by a Silurian to Devonian succession of fluvial to neritic and shallow marine, siliciclastic strata. This is disconformably succeeded by a largely Permian succession that, near its base, includes a glacigenic diamictite and, thence, passes upwards into a succession of deltaic and lacustrine strata. The lithological succession and the character of its deformation bear striking similarities to the Cape Fold Belt and Karoo retroarc foreland basin. Swarms of Early Jurassic dykes were coeval with the Karoo magmatism and the initial break-up of Gondwana; Early Cretaceous dykes were intruded during the opening of the South Atlantic Ocean. Offshore sedimentary basins surrounding the archipelago contain Late Jurassic to Palaeogene successions and are currently the focus of hydrocarbon exploration. Best known is the North Falkland Basin, a classic failed rift. To the SE, the passive margin, Falkland Plateau Basin may also be rift-controlled, whilst the South Falkland Basin is a foreland basin created at the boundary of the South American and Scotia plates. The role of the Falkland Islands during the breakup of Gondwana remains controversial. Compelling evidence from the onshore geology favours rotation of an independent microplate from an original position adjacent to the Eastern Cape, South Africa. Alternative interpretations, justified largely from offshore geology, favour extension of the Falkland Plateau as a fixed promontory from the South American margin.

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.

VULCAN SUB-BASIN FAULT STYLES — IMPLICATIONS FOR HYDROCARBON MIGRATION AND ENTRAPMENT

1992 ◽  
Vol 32 (1) ◽  
pp. 138 ◽  
Author(s):  
E.P. Woods
Keyword(s):  
Late Stage ◽  
Structural Complexity ◽  
Strike Slip ◽  
Normal Faults ◽  
Third Order ◽  
Hydrocarbon Migration ◽  
Structural Domains ◽  
The North ◽  
Hydrocarbon Traps ◽  
Timor Sea

Several structural domains are recognised within the Vulcan Sub-basin, Timor Sea. These domains developed during the Jurassic rifting phase and are separated by major transfer zones which trend in a northwest-southeast direction. Within each domain are frequent third order transfers which sub-divide the main northeast trending fault blocks into numerous compartments. These enable structural hydrocarbon traps to be formed, despite a predominant regional dip. They also affect migration pathways.Jurassic fault styles include detached rotational blocks, salt-associated features, tilted fault blocks and 'hourglass' horsts and grabens. These generally have a northeast-southwest orientation. The transfer faulting complicates these features and forms zones of structural complexity with associated poor seismic data quality. A separate fault episode in the north of the sub-basin during the Tithonian resulted in an east-west fault set overprinting the earlier structuring.Intra-Cretaceous fault movement is also recognised and has an important role in early hydrocarbon entrapment.Structural reactivation during the Late Miocene/Early Pliocene of the earlier fault sets modified the geometry of many existing traps. Numerous new traps may also have formed as a result of this tectonism. In many places the resulting geometry is complex, particularly where the younger fault orientation is at an angle to the main Oxfordian fault set. The late-stage movement is primarily extensional, manifested by predominantly normal faults; overall, however, a varying component of strike slip is likely. A divergent strike-slip zone is recognised at the southwest end of the Cartier Trough.The effects of the late stage tectonism tend to mask the seismic expression of Mesozoic hydrocarbon traps resulting in many wells being drilled off-structure at the target horizon. An understanding of the deeper structuring should result in further discoveries in this prospective basin.

Brittle faulting in the Thor–Odin culmination, Monashee complex, southern Canadian Cordillera: constraints on geometry and kinematics

2005 ◽  
Vol 42 (12) ◽  
pp. 2141-2160 ◽  
Author(s):  
Stefan Kruse ◽  
Paul F Williams
Keyword(s):  
Strike Slip ◽  
Normal Faults ◽  
Canadian Cordillera ◽  
The West ◽  
West Side ◽  
The North ◽  
Monashee Complex ◽  
Dextral Strike Slip Fault ◽  
Brittle Faulting ◽  
Dextral Strike Slip

Regionally recognized dextral strike-slip faulting is present in the Monashee complex of the southern Canadian Cordillera but is overprinted and partially obscured by subsequent extension. Eocene brittle faults and fractures within the Thor–Odin culmination of the Monashee complex are divisible into three distinct sets. Initial 340°–010° trending strike-slip faults (set 1) were locally overprinted and reactivated by normal faults with a 325°–020° trend (set 2). A third set of 255°–275° trending fractures (set 3) are interpreted as conjugates to set 1, reactivated as transfer faults to the set 2 normal faults. Large regional faults weather recessively, forming topographic lineaments that transect the Monashee complex. The Victor Creek Fault defines one such lineament. Detailed mapping within the northern Thor–Odin culmination reveals piercement points (fold hinges) on the east side of the fault that are not readily matched on the west side. The minimum displacement required on the Victor Creek Fault to down-drop the fold hinge below the level of exposure on the west side is 1370 m, assuming normal down-to-the-west displacement. The geometry of the fault is consistent with a set 1 dextral strike-slip fault, however. Matching the piercement points in the study area with possible equivalents to the north indicates 55–60 km of dextral strike-slip displacement.

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