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>

Holocene subsidence at the transition between strike-slip and subduction on the Pacific-Australian plate boundary, Marlborough Sounds, New Zealand

2010 ◽  
Vol 29 (5-6) ◽  
pp. 648-661 ◽  
Author(s):  
Bruce W. Hayward ◽  
Hugh R. Grenfell ◽  
Ashwaq T. Sabaa ◽  
Jon Kay ◽  
Rhiannon Daymond-King ◽  
...  
Keyword(s):  
New Zealand ◽  
Plate Boundary ◽  
Strike Slip ◽  
Australian Plate ◽  
The Pacific

Albian syndepositional block rotation and its geological consequences, Basque–Cantabrian Basin (western Pyrenees)

2013 ◽  
Vol 150 (6) ◽  
pp. 986-1001 ◽  
Author(s):  
LUIS MIGUEL AGIRREZABALA ◽  
JAUME DINARÈS-TURELL
Keyword(s):  
Slip Rate ◽  
Vertical Axis ◽  
Strike Slip ◽  
Block Rotation ◽  
Minimum Block ◽  
Magmatic Intrusions ◽  
Axis Rotation ◽  
High Level ◽  
Basque Cantabrian Basin ◽  
Dextral Strike Slip

AbstractStratigraphic, structural, palaeocurrent and palaeomagnetic analyses of Upper Albian deep-water deposits in and around the Deba block (Northern Iberia) are presented. Results indicate an anticlockwise vertical-axis rotation of this block by 35° during a maximum time span of c. 1 Ma (Late Albian intra-C. auritus ammonite Subzone). This Albian syndepositional block rotation is interpreted to be the consequence of the coeval activity of conjugate major sinistral strike-slip faults and minor (antithetic) dextral strike-slip faults, which border the Deba block. On the base of conservative estimations, a minimum block-rotation rate of 35° Ma−1 and a sinistral strike-slip rate of 1.2 km Ma−1 are calculated. As a consequence of the interaction of the rotated Deba block with adjacent non-rotated blocks, its corners experienced coeval transpressive (NW and SE corners) and transtensional deformations (SW and, possibly, NE corners). At the transtensional SW corner, two domal high-reflective seismic structures have been recorded and interpreted as high-level magmatic laccoliths. These magmatic intrusions triggered the development of a mineralizing hydrothermal system, which vented to the Late Albian seafloor warm to hot hydrocarbon-rich fluids. Vented hydrocarbon was generated from Albian organic-rich sediments by contact alteration with hydrothermal fluids.

Zircon geochronology and paleomagnetism of an Archean harzburgite intrusion, eastern Bighorn Mountains, Wyoming

2020 ◽  
Vol 57 (1) ◽  
pp. 21-40
Author(s):  
Alexandra Wallenberg ◽  
Michelle Dafov ◽  
David Malone ◽  
John Craddock
Keyword(s):  
Hanging Wall ◽  
Vertical Axis ◽  
Shear Zones ◽  
Strike Slip ◽  
Zircon Geochronology ◽  
Weighted Mean ◽  
Mafic Complex ◽  
Laramide Orogeny ◽  
Axis Rotation ◽  
Bighorn Mountains

A harzburgite intrusion, which is part of the trailside mafic complex) intrudes ~2900-2950 Ma gneisses in the hanging wall of the Laramide Bighorn uplift west of Buffalo, Wyoming. The harzburgite is composed of pristine orthopyroxene (bronzite), clinopyroxene, serpentine after olivine and accessory magnetite-serpentinite seams, and strike-slip striated shear zones. The harzburgite is crosscut by a hydrothermally altered wehrlite dike (N20°E, 90°, 1 meter wide) with no zircons recovered. Zircons from the harzburgite reveal two ages: 1) a younger set that has a concordia upper intercept age of 2908±6 Ma and a weighted mean age of 2909.5±6.1 Ma; and 2) an older set that has a concordia upper intercept age of 2934.1±8.9 Ma and a weighted mean age 2940.5±5.8 Ma. Anisotropy of magnetic susceptibility (AMS) was used as a proxy for magmatic intrusion and the harzburgite preserves a sub-horizontal Kmax fabric (n=18) suggesting lateral intrusion. Alternating Field (AF) demagnetization for the harzburgite yielded a paleopole of 177.7 longitude, -14.4 latitude. The AF paleopole for the wehrlite dike has a vertical (90°) inclination suggesting intrusion at high latitude. The wehrlite dike preserves a Kmax fabric (n=19) that plots along the great circle of the dike and is difficult to interpret. The harzburgite has a two-component magnetization preserved that indicates a younger Cretaceous chemical overprint that may indicate a 90° clockwise vertical axis rotation of the Clear Creek thrust hanging wall, a range-bounding east-directed thrust fault that accommodated uplift of Bighorn Mountains during the Eocene Laramide Orogeny.

Geodetic strain and the deformational history of the North Island of New Zealand during the late Cainozoic

1987 ◽  
Vol 321 (1557) ◽  
pp. 163-181 ◽  
Keyword(s):  
New Zealand ◽  
Subduction Zone ◽  
East Coast ◽  
Late Quaternary ◽  
Plate Boundary ◽  
Boundary Zone ◽  
Metamorphic Belt ◽  
Volcanic Region ◽  
The North ◽  
Plate Boundary Zone

The subduction zone under the east coast of the North Island of New Zealand comprises, from east to west, a frontal wedge, a fore-arc basin, uplifted basement forming the arc and the Central Volcanic Region. Reconstructions of the plate boundary zone for the Cainozoic from seafloor spreading data require the fore-arc basin to have rotated through 60° in the last 20 Ma which is confirmed by palaeomagnetic declination studies. Estimates of shear strain from geodetic data show that the fore-arc basin is rotating today and that it is under extension in the direction normal to the trend of the plate boundary zone. The extension is apparently achieved by normal faulting. Estimates of the amount of sediments accreted to the subduction zone exceed the volume of the frontal wedge: underplating by the excess sediments is suggested to be the cause of late Quaternary uplift of the fore-arc basin. Low-temperature—high-pressure metamorphism may therefore be occurring at depth on the east coast and high-temperature—low-pressure metamorphism is probable in the Central Volcanic Region. The North Island of New Zealand is therefore a likely setting for a paired metamorphic belt in the making.

scholarly journals Constraints on the rheology of the lower crust in a strike-slip plate boundary: evidence from the San Quintín xenoliths, Baja California, Mexico

Solid Earth ◽  
2017 ◽  
Vol 8 (6) ◽  
pp. 1211-1239 ◽  
Author(s):  
Thomas van der Werf ◽  
Vasileios Chatzaras ◽  
Leo Marcel Kriegsman ◽  
Andreas Kronenberg ◽  
Basil Tikoff ◽  
...  
Keyword(s):  
Grain Size ◽  
Upper Mantle ◽  
Lower Crust ◽  
Baja California ◽  
Plate Boundary ◽  
Volcanic Field ◽  
Strike Slip ◽  
Low Viscosity ◽  
The Pacific ◽  
Flow Laws

Abstract. The rheology of lower crust and its transient behavior in active strike-slip plate boundaries remain poorly understood. To address this issue, we analyzed a suite of granulite and lherzolite xenoliths from the upper Pleistocene–Holocene San Quintín volcanic field of northern Baja California, Mexico. The San Quintín volcanic field is located 20 km east of the Baja California shear zone, which accommodates the relative movement between the Pacific plate and Baja California microplate. The development of a strong foliation in both the mafic granulites and lherzolites, suggests that a lithospheric-scale shear zone exists beneath the San Quintín volcanic field. Combining microstructural observations, geothermometry, and phase equilibria modeling, we estimated that crystal-plastic deformation took place at temperatures of 750–890 °C and pressures of 400–560 MPa, corresponding to 15–22 km depth. A hot crustal geotherm of 40 ° C km−1 is required to explain the estimated deformation conditions. Infrared spectroscopy shows that plagioclase in the mafic granulites is relatively dry. Microstructures are interpreted to show that deformation in both the uppermost lower crust and upper mantle was accommodated by a combination of dislocation creep and grain-size-sensitive creep. Recrystallized grain size paleopiezometry yields low differential stresses of 12–33 and 17 MPa for plagioclase and olivine, respectively. The lower range of stresses (12–17 MPa) in the mafic granulite and lherzolite xenoliths is interpreted to be associated with transient deformation under decreasing stress conditions, following an event of stress increase. Using flow laws for dry plagioclase, we estimated a low viscosity of 1.1–1.3×1020 Pa ⋅ s for the high temperature conditions (890 °C) in the lower crust. Significantly lower viscosities in the range of 1016–1019 Pa ⋅ s, were estimated using flow laws for wet plagioclase. The shallow upper mantle has a low viscosity of 5.7×1019 Pa ⋅ s, which indicates the lack of an upper-mantle lid beneath northern Baja California. Our data show that during post-seismic transients, the upper mantle and the lower crust in the Pacific–Baja California plate boundary are characterized by similar and low differential stress. Transient viscosity of the lower crust is similar to the viscosity of the upper mantle.

New c. 270 kyr strike-slip and uplift rates for the southern Alpine Fault and implications for the New Zealand plate boundary

2014 ◽  
Vol 64 ◽  
pp. 39-52 ◽  
Author(s):  
N.C. Barth ◽  
D.K. Kulhanek ◽  
A.G. Beu ◽  
C.V. Murray-Wallace ◽  
B.W. Hayward ◽  
...  
Keyword(s):  
New Zealand ◽  
Plate Boundary ◽  
Strike Slip ◽  
Alpine Fault ◽  
Uplift Rates

Late Eocene – Early Miocene facies and stratigraphic development, Taranaki Basin, New Zealand: the transition to plate boundary tectonics during regional transgression

2019 ◽  
Vol 156 (10) ◽  
pp. 1751-1770 ◽  
Author(s):  
Dominic P. Strogen ◽  
Karen E. Higgs ◽  
Angela G. Griffin ◽  
Hugh E. G. Morgans
Keyword(s):  
New Zealand ◽  
Tectonic Setting ◽  
Plate Boundary ◽  
Late Eocene ◽  
Early Miocene ◽  
Fault System ◽  
Initial Development ◽  
Early Oligocene ◽  
Well Data ◽  
Latest Eocene

AbstractEight latest Eocene to earliest Miocene stratigraphic surfaces have been identified in petroleum well data from the Taranaki Basin, New Zealand. These surfaces define seven regional sedimentary packages, of variable thickness and lithofacies, forming a mixed siliciclastic–carbonate system. The evolving tectonic setting, particularly the initial development of the Australian–Pacific convergent margin, controlled geographic, stratigraphic and facies variability. This tectonic signal overprinted a regional transgressive trend that culminated in latest Oligocene times. The earliest influence of active compressional tectonics is reflected in the preservation of latest Eocene – Early Oligocene deepwater sediments in the northern Taranaki Basin. Thickness patterns for all mid Oligocene units onwards show a shift in sedimentation to the eastern Taranaki Basin, controlled by reverse movement on the Taranaki Fault System. This resulted in the deposition of a thick sedimentary wedge, initially of coarse clastic sediments, later carbonate dominated, in the foredeep close to the fault. In contrast, Oligocene active normal faulting in a small sub-basin in the south may represent the most northerly evidence for rifting in southern Zealandia, related to Emerald Basin formation. The Early Miocene period saw a return to clastic-dominated deposition, the onset of regional regression and the southward propagation of compressional tectonics.

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.

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