Cenozoic Strike-Slip Tectonics and Structural Controls of Porphyry Cu-Mo and Epithermal Deposits During Geodynamic Evolution of the Southernmost Lesser Caucasus, Tethyan Metallogenic Belt

2019 ◽  
Vol 114 (7) ◽  
pp. 1301-1337 ◽  
Author(s):  
Samvel Hovakimyan ◽  
Robert Moritz ◽  
Rodrik Tayan ◽  
Rafael Melkonyan ◽  
Marianna Harutyunyan
Keyword(s):  
Base Metal ◽  
Strike Slip ◽  
Early Miocene ◽  
Tectonic Plate ◽  
Porphyry Cu ◽  
Metallogenic Belt ◽  
Late Neogene ◽  
Lesser Caucasus ◽  
Dextral Strike Slip ◽  
Epithermal Au

Abstract The Zangezur-Ordubad mining district of the southernmost Lesser Caucasus is located in the central segment of the Tethyan metallogenic belt and consists of porphyry Cu-Mo and epithermal Au and base metal systems hosted by the composite Cenozoic Meghri-Ordubad pluton. Ore-hosting structures and magmatic intrusions are predominantly confined to a central N-S–oriented corridor 40 km long and 10 to 12 km wide, located between two regional NNW-oriented right-lateral faults, the Khustup-Giratagh and Salvard-Ordubad faults. The anatomy and kinematics of the main fault network are consistent with dextral strike-slip tectonics controlled by the NNW-oriented Khustup-Giratagh and Salvard-Ordubad faults. Dextral strike-slip tectonics was initiated during the Eocene, concomitantly with final subduction of the Neotethys, and controlled the emplacement of the Agarak, Hanqasar, Aygedzor, and Dastakert porphyry Cu-Mo and Tey-Lichkvaz and Terterasar epithermal Au and base metal deposits. The Eocene structures were repeatedly reactivated during subsequent Neogene evolution in transition to a postsubduction geodynamic setting. Ore-bearing structures at the Oligocene world-class Kadjaran porphyry Cu-Mo deposit were also controlled by dextral strike-slip tectonics, as well as porphyry mineralization and its epithermal overprint hosted by an early Miocene intrusion at Lichk. Eocene to early Miocene dextral strike-slip tectonics took place during NE- to NNE-oriented compression related to Paleogene Eurasia-Arabia convergence and subsequent Neogene postcollision evolution. Paleostress reconstruction indicates major reorganization of tectonic plate kinematics since the early Miocene, resulting in N-S– to NW-oriented compression. Early Miocene epithermal overprint at the Kadjaran porphyry deposit and left-lateral reactivation of faults and mineralized structures are linked to this late Neogene tectonic plate reorganization.

scholarly journals Neogene Evolution of the Pacific - Australia Plate Boundary Zone in NE Marlborough, South Island, New Zealand

2021 ◽  
Author(s):  
◽  
Dougal B Townsend
Keyword(s):  
New Zealand ◽  
Late Quaternary ◽  
Plate Boundary ◽  
Vertical Axis ◽  
Strike Slip ◽  
Early Miocene ◽  
Crustal Thickening ◽  
The Pacific ◽  
Axis Rotation ◽  
Dextral Strike Slip

<p>Six new palaeomagnetic localities in NE Marlborough, sampled from Late Cretaceous - Early Tertiary Amuri Formation and Middle Miocene Waima Formation, all yield clockwise declination anomalies of 100 - 150 degrees. Similarity in the magnitude of all new declination anomalies and integration of these results with previous data implies that clockwise vertical-axis rotation of this magnitude affected the entire palaeomagnetically sampled part of NE Marlborough (an area of ~700sq. km) after ~18 Ma. Previous palaeomagnetic sampling constrains this rotation to have occurred before ~7 Ma. The regional nature of this rotation implies that crustal-scale vertical-axis rotations were a fundamental process in the Miocene evolution of the Pacific - Australia plate boundary in NE South Island. The Flags Creek Fault System (FCFS) is a fold-and-thrust belt that formed in marine conditions above a subduction complex that developed as the Pacific - Australia plate boundary propagated through Marlborough in the Early Miocene. Thin-skinned fault offset accommodated at least 20 km of horizontal shortening across a leading-edge imbricate fan. Mesoscopic structures in the deformed belt indicate thrust vergence to the southeast. The palaeomagnetically-determined regional clockwise vertical axis rotation of ~100 degrees must be undone in order to evaluate this direction in the contemporary geographic framework of the thrust belt. Therefore the original transport direction of the thrust sheets in the FCFS was to the NE, in accordance with NE-SW plate motion vector between the Pacific and Australian plates during the Early Miocene. The two new palaeomagnetic localities that are within ~3 km of the active dextral strike-slip Kekerengu Fault have the highest clockwise declination anomalies (up to 150 degrees). Detailed structural mapping suggests that the eastern ends of the FCFS are similarly clockwise-rotated, by an extra 45 degrees relative to the regional average, to become south-vergent in proximity to the Kekerengu Fault. This structural evidence implies the presence of a zone of Plio-Pleistocene dextral shear and vertical-axis rotation within 2-3 km of the Kekerengu Fault. Local clockwise vertical-axis rotations of up to 50 degrees are inferred to have accrued in this zone, and to have been superimposed on the older, regional. ~100 degrees Miocene clockwise vertical-axis rotation. The Late Quaternary stratigraphy of fluvial terraces in NE Marlborough has been revised by the measurement of five new optically stimulated luminescence (OSL) dates on loess. This new stratigraphy suggests that the latest aggradation surface in the Awatere Valley (the Starborough-1 terrace) is, at least locally, ~9 ka old, several thousand years younger than the previous 16 ka thermoluminescence age for the same site. This new surface abandonment age implies that terrace-building events in NE Marlborough lasted well after the last glacial maximum (~17 ka). The timing of terrace aggradation in this peri-glacial region is compared with oxygen isotope data. Downstream transport of glacially derived sediment at the time of maximum deglaciation/warming is concluded to be the primary influence on the aggradation of major fill terraces in coastal NE Marlborough. This interpretation is generally applicable to peri-glacial central New Zealand. Patterns of contemporary uplift and directions of landscape tilting have been analysed by assessing the rates of stream incision and by the evolution of drainage networks over a wide tract of NE Marlborough that includes the termination of the dextral strike-slip Clarence Fault. Relative elevations of differentially aged terraces suggests an increase in rates of incision over the last ~10 ka. Uplift is highest in the area immediately surrounding the fault tip and is generally high where Torlesse basement rocks are exposed. Independently derived directions of Late Quaternary tilting of the landscape display a similar pattern of relative uplift in a broad dome to the north and west of the fault tip. This pattern of uplift suggests dissipation of strike-slip motion at the Clarence Fault tip into a dome-shaped fold accommodating: 1) crustal thickening (uplift) and 2) up to 44 degrees of vertical-axis rotation of a ~40 km2 crustal block, relative to more inland domains, into which the fault terminates. The distribution of incision rates is compared with the pattern of crustal thickening predicted by elastic models of strike-slip fault tips. The observed pattern and spatial extent of uplift generally conforms with the distribution of thickening predicted by the models, although the rate of incision/uplift over the last ~120 ka has been variable. These differences may be due to variability in the strike-slip rate of the Clarence Fault, superimposition of the regional uplift rate or to interaction with nearby fault structures not accounted for in the models.</p>

scholarly journals Neogene Evolution of the Pacific - Australia Plate Boundary Zone in NE Marlborough, South Island, New Zealand

2021 ◽  
Author(s):  
◽  
Dougal B Townsend
Keyword(s):  
New Zealand ◽  
Late Quaternary ◽  
Plate Boundary ◽  
Vertical Axis ◽  
Strike Slip ◽  
Early Miocene ◽  
Crustal Thickening ◽  
The Pacific ◽  
Axis Rotation ◽  
Dextral Strike Slip

<p>Six new palaeomagnetic localities in NE Marlborough, sampled from Late Cretaceous - Early Tertiary Amuri Formation and Middle Miocene Waima Formation, all yield clockwise declination anomalies of 100 - 150 degrees. Similarity in the magnitude of all new declination anomalies and integration of these results with previous data implies that clockwise vertical-axis rotation of this magnitude affected the entire palaeomagnetically sampled part of NE Marlborough (an area of ~700sq. km) after ~18 Ma. Previous palaeomagnetic sampling constrains this rotation to have occurred before ~7 Ma. The regional nature of this rotation implies that crustal-scale vertical-axis rotations were a fundamental process in the Miocene evolution of the Pacific - Australia plate boundary in NE South Island. The Flags Creek Fault System (FCFS) is a fold-and-thrust belt that formed in marine conditions above a subduction complex that developed as the Pacific - Australia plate boundary propagated through Marlborough in the Early Miocene. Thin-skinned fault offset accommodated at least 20 km of horizontal shortening across a leading-edge imbricate fan. Mesoscopic structures in the deformed belt indicate thrust vergence to the southeast. The palaeomagnetically-determined regional clockwise vertical axis rotation of ~100 degrees must be undone in order to evaluate this direction in the contemporary geographic framework of the thrust belt. Therefore the original transport direction of the thrust sheets in the FCFS was to the NE, in accordance with NE-SW plate motion vector between the Pacific and Australian plates during the Early Miocene. The two new palaeomagnetic localities that are within ~3 km of the active dextral strike-slip Kekerengu Fault have the highest clockwise declination anomalies (up to 150 degrees). Detailed structural mapping suggests that the eastern ends of the FCFS are similarly clockwise-rotated, by an extra 45 degrees relative to the regional average, to become south-vergent in proximity to the Kekerengu Fault. This structural evidence implies the presence of a zone of Plio-Pleistocene dextral shear and vertical-axis rotation within 2-3 km of the Kekerengu Fault. Local clockwise vertical-axis rotations of up to 50 degrees are inferred to have accrued in this zone, and to have been superimposed on the older, regional. ~100 degrees Miocene clockwise vertical-axis rotation. The Late Quaternary stratigraphy of fluvial terraces in NE Marlborough has been revised by the measurement of five new optically stimulated luminescence (OSL) dates on loess. This new stratigraphy suggests that the latest aggradation surface in the Awatere Valley (the Starborough-1 terrace) is, at least locally, ~9 ka old, several thousand years younger than the previous 16 ka thermoluminescence age for the same site. This new surface abandonment age implies that terrace-building events in NE Marlborough lasted well after the last glacial maximum (~17 ka). The timing of terrace aggradation in this peri-glacial region is compared with oxygen isotope data. Downstream transport of glacially derived sediment at the time of maximum deglaciation/warming is concluded to be the primary influence on the aggradation of major fill terraces in coastal NE Marlborough. This interpretation is generally applicable to peri-glacial central New Zealand. Patterns of contemporary uplift and directions of landscape tilting have been analysed by assessing the rates of stream incision and by the evolution of drainage networks over a wide tract of NE Marlborough that includes the termination of the dextral strike-slip Clarence Fault. Relative elevations of differentially aged terraces suggests an increase in rates of incision over the last ~10 ka. Uplift is highest in the area immediately surrounding the fault tip and is generally high where Torlesse basement rocks are exposed. Independently derived directions of Late Quaternary tilting of the landscape display a similar pattern of relative uplift in a broad dome to the north and west of the fault tip. This pattern of uplift suggests dissipation of strike-slip motion at the Clarence Fault tip into a dome-shaped fold accommodating: 1) crustal thickening (uplift) and 2) up to 44 degrees of vertical-axis rotation of a ~40 km2 crustal block, relative to more inland domains, into which the fault terminates. The distribution of incision rates is compared with the pattern of crustal thickening predicted by elastic models of strike-slip fault tips. The observed pattern and spatial extent of uplift generally conforms with the distribution of thickening predicted by the models, although the rate of incision/uplift over the last ~120 ka has been variable. These differences may be due to variability in the strike-slip rate of the Clarence Fault, superimposition of the regional uplift rate or to interaction with nearby fault structures not accounted for in the models.</p>

scholarly journals Zircon U-Pb, Molybdenite Re-Os and Quartz Vein Rb-Sr Geochronology of the Luobuzhen Au-Ag and Hongshan Cu Deposits, Tibet, China: Implications for the Oligocene-Miocene Porphyry–Epithermal Metallogenic System

Minerals ◽  
2019 ◽  
Vol 9 (8) ◽  
pp. 476
Author(s):  
Hanxiao Huang ◽  
Hong Liu ◽  
Guangming Li ◽  
Linkui Zhang ◽  
Huawen Cao ◽  
...  
Keyword(s):  
Quartz Vein ◽  
Porphyry Copper ◽  
Western China ◽  
Geochronological Data ◽  
Porphyry Cu ◽  
Metallogenic Belt ◽  
Granodiorite Porphyry ◽  
Epithermal Au ◽  
New Discovery ◽  
Metallogenic System

The Gangdese metallogenic belt in Tibet is an important copper and iron polymetallic, metallogenic belt in western China. The Luobuzhen epithermal Au-Ag and Hongshan porphyry Cu deposits, as two new discovery deposits in the last few years, are located in the western Gangdese metallogenic belt. In this paper, we present quartz vein Rb-Sr isochron, zircon U-Pb and molybdenite Re-Os ages for a better understanding of the minerallogenetic epoch of the deposits. Geochronological data show that the Rb-Sr isochron age of a quartz vein in a Luobuzhen Au-Ag deposit is 21.1 ± 1.8 Ma (MSWD (mean standard weighted deviation) = 0.19), zircon U-Pb ages from diorite and granodiorite porphyry in Hongshan Cu deposit are 50.0 ± 0.4 Ma (MSWD = 0.94) and 23.7 ± 0.1 Ma (MSWD = 0.73), respectively, and a Re-Os isochron age of molybdenite in Hongshan Cu deposit is 23.0 ± 2.0 Ma (MSWD = 0.014). These data suggest that the Luobuzhen epithermal Au-Ag and Hongshan porphyry Cu deposits formed at ca. 23–21 Ma, which were controlled by the same magmatic hydrothermal events. Formation of both the Luobuzhen and Hongshan deposits were obviously earlier than the Miocene porphyry metallogenetic events in the Gangdese porphyry copper belt.

STRIKE-SLIP FAULTING DOMINATES THE RESPONSE OF THE LESSER CAUCASUS TO THE ARABIA-EURASIA CONTINENT COLLISION

2018 ◽  
Author(s):  
Nikolas C. Midttun ◽  
◽  
Nathan A. Niemi ◽  
Hektor Babayan ◽  
Hayk Igityan ◽  
...  
Keyword(s):  
Strike Slip ◽  
Lesser Caucasus

scholarly journals Kinematic partitioning in the Southern Andes (39° S–46° S) inferred from lineament analysis and reassessment of exhumation rates

2021 ◽  
Author(s):  
Paul Leon Göllner ◽  
Jan Oliver Eisermann ◽  
Catalina Balbis ◽  
Ivan A. Petrinovic ◽  
Ulrich Riller
Keyword(s):  
Fault Zone ◽  
Vertical Displacement ◽  
Strike Slip ◽  
Structural Studies ◽  
Southern Andes ◽  
Plate Convergence ◽  
Exhumation Rates ◽  
Lineament Analysis ◽  
Dextral Strike Slip ◽  
Data Call

AbstractThe Southern Andes are often viewed as a classic example for kinematic partitioning of oblique plate convergence into components of continental margin-parallel strike-slip and transverse shortening. In this regard, the Liquiñe-Ofqui Fault Zone, one of Earth’s most prominent intra-arc deformation zones, is believed to be the most important crustal discontinuity in the Southern Andes taking up margin-parallel dextral strike-slip. Recent structural studies, however, are at odds with this simple concept of kinematic partitioning, due to the presence of margin-oblique and a number of other margin-parallel intra-arc deformation zones. However, knowledge on the extent of such zones in the Southern Andes is still limited. Here, we document traces of prominent structural discontinuities (lineaments) from the Southern Andes between 39° S and 46° S. In combination with compiled low-temperature thermochronology data and interpolation of respective exhumation rates, we revisit the issue of kinematic partitioning in the Southern Andes. Exhumation rates are maximal in the central parts of the orogen and discontinuity traces, trending predominantly N–S, WNW–ESE and NE–SW, are distributed across the entire width of the orogen. Notably, discontinuities coincide spatially with large gradients in Neogene exhumation rates and separate crustal domains characterized by uniform exhumation. Collectively, these relationships point to significant components of vertical displacement on these discontinuities, in addition to horizontal displacements known from published structural studies. Our results agree with previously documented Neogene shortening in the Southern Andes and indicate orogen-scale transpression with maximal vertical extrusion of rocks in the center of the transpression zone. The lineament and thermochronology data call into question the traditional view of kinematic partitioning in the Southern Andes, in which deformation is focused on the Liquiñe-Ofqui Fault Zone.

scholarly journals Coseismic fault-slip distribution of the 2019 Ridgecrest Mw6.4 and Mw7.1 earthquakes

2021 ◽  
Vol 11 (1) ◽  
Author(s):  
Yang Gao ◽  
HuRong Duan ◽  
YongZhi Zhang ◽  
JiaYing Chen ◽  
HeTing Jian ◽  
...  
Keyword(s):  
Strike Slip ◽  
Fault Slip ◽  
Slip Distribution ◽  
Synthetic Aperture ◽  
Seismic Events ◽  
Interferometric Synthetic Aperture Radar ◽  
The Past ◽  
Dextral Strike Slip Fault ◽  
Fault Slip Distribution ◽  
Dextral Strike Slip

AbstractThe 2019 Ridgecrest, California seismic sequence, including an Mw6.4 foreshock and Mw7.1 mainshock, represent the largest regional seismic events within the past 20 years. To obtain accurate coseismic fault-slip distribution, we used precise positioning data of small earthquakes from January 2019 to October 2020 to determine the dip parameters of the eight fault geometry, and used the Interferometric Synthetic Aperture Radar (InSAR) data processed by Xu et al. (Seismol Res Lett 91(4):1979–1985, 2020) at UCSD to constrain inversion of the fault-slip distribution of both earthquakes. The results showed that all faults were sinistral strike-slips with minor dip-slip components, exception for dextral strike-slip fault F2. Fault-slip mainly occurred at depths of 0–12 km, with a maximum slip of 3.0 m. The F1 fault contained two slip peaks located at 2 km of fault S4 and 6 km of fault S5 depth, the latter being located directly above the Mw7.1hypocenter. Two slip peaks with maximum slip of 1.5 m located 8 and 20 km from the SW endpoint of the F2 fault were also identified, and the latter corresponds to the Mw6.4 earthquake. We also analyzed the influence of different inversion parameters on the fault slip distribution, and found that the slip momentum smoothing condition was more suitable for the inversion of the earthquakes slip distribution than the stress-drop smoothing condition.

The Caledonoid faults of northern Lleyn (North Wales)

1970 ◽  
Vol 107 (3) ◽  
pp. 235-247 ◽  
Author(s):  
W. E. Tremlett
Keyword(s):  
Volcanic Rocks ◽  
Strike Slip ◽  
Metamorphic Rocks ◽  
Red Sandstone ◽  
North Wales ◽  
Dextral Strike Slip

SummaryEvidence of substantial dextral strike-slip displacements along the Caledonoid fault-set of northern Lleyn is revealed by the distribution of Pre-Cambrian igneous and metamorphic rocks, Ordovician volcanic rocks and Caledonian ‘early granodioritic’ intrusions. These apparently occurred prior to some smaller sinistral strike-slip movements which left total net dextral displacements of 91/2 km. Both types of movement were completed before the Caledonoid faults were disrupted by NNW sinistral faulting and more intrusions of Lower Old Red Sandstone age were emplaced.

Acadian strike-slip tectonics in the Gaspé region, Quebec Appalachians

1989 ◽  
Vol 26 (9) ◽  
pp. 1764-1777 ◽  
Author(s):  
Michel Malo ◽  
Jacques Béland
Keyword(s):  
Middle Devonian ◽  
High Strain ◽  
Structural Features ◽  
Fault Zones ◽  
Strike Slip ◽  
Structural Units ◽  
Middle Ordovician ◽  
Southern Margin ◽  
Intense Deformation ◽  
Dextral Strike Slip

At the southern margin of the Cambro-Ordovician Humber Zone in the Quebec Appalachians, on Gaspé Peninsula, three structural units of Middle Ordovician to Middle Devonian cover rocks of the Gaspé Belt are in large part bounded by long, straight longitudinal faults. In one of these units, the Aroostook–Percé anticlinorium, several structural features, which can be ascribed to Acadian deformation, are controlled by three subparallel, dextral, strike-slip longitudinal faults: Grande Rivière, Grand Pabos, and Rivière Garin. These faults follow bands of intense deformation, contrasting with the mildly to moderately deformed intervals that separate them.Most of the structural features observed – rotated oblique folds and cleavage, subsidiary Riedel and tension faults, and offsets of markers – can be integrated in a model of strike-slip tectonics that operated in ductile–brittle conditions. A late increment of deformation in the form of conjugate cleavages and minor faults is restricted to the bands of high strain. An anticlockwise transection of the synfolding cleavage in relation to the oblique hinges may be a feature of the rotational deformation.The combined dextral strike slip that can be measured within the three major longitudinal fault zones amounts to 138 km, to which can be added 17 km of ductile movement in the intervals, for a total of 155 km.

The northern Appalachian terrane wreck model

2021 ◽  
pp. 1-12
Author(s):  
J. Duncan Keppie ◽  
D. Fraser Keppie ◽  
Jaroslav Dostal
Keyword(s):  
Lower Devonian ◽  
Strike Slip ◽  
Late Devonian ◽  
Backarc Basin ◽  
Clockwise Rotation ◽  
Rheic Ocean ◽  
Magmatic Rocks ◽  
Younger Age ◽  
The Common ◽  
Dextral Strike Slip

Ordovician and Siluro-Lower Devonian magmatic rocks in the northern Appalachians south of the Iapetus suture are currently interpreted as distinct belts composed of multiple, small, peri-Gondwanan terranes that amalgamated during the sequential closures of Iapetus (latest Ordovician), the Tetagouche backarc basin (early Silurian), the Acadian seaway (Siluro-Devonian), and the Rheic Ocean (Devono-Carbonferous) (multiple terrane model). Here, the Siluro-Lower Devonian magmatic belts are shown to have slab failure affinities and together with the Ordovician arcs form paired belts parallel to the Iapetus suture, which suggests that they were emplaced along the common, peri-Avalonian margin during pre- and post-collisional processes. The Iapetan suture and the paired belts are inferred to repeat in Atlantic Canada due to dextral, strike-slip processes of mid-Late Devonian or younger age (terrane wreck model). In Newfoundland, the repetition is inferred to be the result of oblique, dextral offset of ca. 250 km. In the Quebec Embayment, the Iapetan paired magmatic belts are repeated twice in the limbs of a Z-shaped orocline related to oblique, dextral offsets of ca. 1200 km of the southern limb. Limited Siluro-Devonian paleomagnetic data indicate no paleolatitudinal differences across the Iapetus suture, however ca. 100° post-mid Silurian clockwise rotation is indicated for the middle fold limb; these data favour the terrane wreck model. The terrane wreck model results in a simple tectonic scenario of southerly subduction of Iapetus beneath a single ribbon continent (Avalonia sensu lato) that was subsequently deformed.

New Evidence of the Dextral Strike-Slip Movement in the Liaohe Basin, China: Results from Sem Experiments

2001 ◽  
Vol 44 (6) ◽  
pp. 779-784
Author(s):  
Jia-Zeng SHAN ◽  
Hong-Jun SUN ◽  
Qian-Hua XIAO ◽  
Dao-Jing WANG ◽  
Kun XU ◽  
...  
Keyword(s):  
Strike Slip ◽  
Liaohe Basin ◽  
New Evidence ◽  
Dextral Strike Slip ◽  
Strike Slip Movement
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