A stratigraphic unit converted to fault rocks in the Northland Allochthon of New Zealand: Response of a siliceous claystone to obduction

Author(s):  
K. Bernhard Spörli
2020 ◽  
Author(s):  
Michael Ofman ◽  
Steven Smith

<p>The southern Glade Fault Zone is a crustal-scale, subvertical dextral strike-slip fault zone on the eastern margin of Fiordland, New Zealand. For a distance of c. 40 km between Lake Te Anau and the Hollyford Valley, the fault cuts plutonic host rocks and has an estimated total dextral separation of c. 6-8 km. We report previously unidentified mylonites, cataclasites, pseudotachylites and fault gouge subparallel to pervasive sets of planar cooling joints in the Hut Creek-Mistake Creek area plutonic suites. The outcropping assemblage of joints and fault rocks record thermal, seismic and rheological conditions in the southern Glade Fault. Here we integrate methods to characterise the fault rocks and fracture damage zone of the southern Glade Fault from Glade Pass to Mt Aragorn. We use (i) EDS (Energy Dispersive x-ray Spectroscopy), XRD (X-Ray Diffraction) and EBSD (Electron Backscatter Diffraction) analysis to describe the mineralogy, kinematics and microstructures of fault rocks and, (ii) drone orthophotography and traditional structural measurements to detail geometrical relationships between structural features. Field mapping of glacially polished outcrops identifies the zone of brittle fault-related damage (i.e. damage zone + fault rock sequence) is up to one order of magnitude narrower than documented along other strike-slip faults with similar displacements, suggesting that the Glade Fault Zone represents an “end-member” of extreme localization of brittle deformation and fault displacement. This is interpreted to result from linkage of pre-existing cooling joints (and mylonitic shear zones), which allowed the younger brittle fault zone to establish its length and planarity relatively efficiently compared to the case of fault nucleation and growth in more isotropic host rocks.</p>


1981 ◽  
Vol 9 (1) ◽  
pp. 197-210 ◽  
Author(s):  
R. H. Sibson ◽  
S. H. White ◽  
B. K. Atkinson

2012 ◽  
Vol 13 (1) ◽  
pp. n/a-n/a ◽  
Author(s):  
C. Boulton ◽  
B. M. Carpenter ◽  
V. Toy ◽  
C. Marone

2021 ◽  
Author(s):  
AR Niemeijer ◽  
Carolyn Boulton ◽  
VG Toy ◽  
John Townend ◽  
Rupert Sutherland

©2016. The Authors. The Alpine Fault, New Zealand, is a major plate-bounding fault that accommodates 65-75% of the total relative motion between the Australian and Pacific plates. Here we present data on the hydrothermal frictional properties of Alpine Fault rocks that surround the principal slip zones (PSZ) of the Alpine Fault and those comprising the PSZ itself. The samples were retrieved from relatively shallow depths during phase 1 of the Deep Fault Drilling Project (DFDP-1) at Gaunt Creek. Simulated fault gouges were sheared at temperatures of 25, 150, 300, 450, and 600°C in order to determine the friction coefficient as well as the velocity dependence of friction. Friction remains more or less constant with changes in temperature, but a transition from velocity-strengthening behavior to velocity-weakening behavior occurs at a temperature of T = 150°C. The transition depends on the absolute value of sliding velocity as well as temperature, with the velocity-weakening region restricted to higher velocity for higher temperatures. Friction was substantially lower for low-velocity shearing (V < 0.3 μm/s) at 600°C, but no transition to normal stress independence was observed. In the framework of rate-and-state friction, earthquake nucleation is most likely at an intermediate temperature of T = 300°C. The velocity-strengthening nature of the Alpine Fault rocks at higher temperatures may pose a barrier for rupture propagation to deeper levels, limiting the possible depth extent of large earthquakes. Our results highlight the importance of strain rate in controlling frictional behavior under conditions spanning the classical brittle-plastic transition for quartzofeldspathic compositions.


2021 ◽  
Author(s):  
AR Niemeijer ◽  
Carolyn Boulton ◽  
VG Toy ◽  
John Townend ◽  
Rupert Sutherland

©2016. The Authors. The Alpine Fault, New Zealand, is a major plate-bounding fault that accommodates 65-75% of the total relative motion between the Australian and Pacific plates. Here we present data on the hydrothermal frictional properties of Alpine Fault rocks that surround the principal slip zones (PSZ) of the Alpine Fault and those comprising the PSZ itself. The samples were retrieved from relatively shallow depths during phase 1 of the Deep Fault Drilling Project (DFDP-1) at Gaunt Creek. Simulated fault gouges were sheared at temperatures of 25, 150, 300, 450, and 600°C in order to determine the friction coefficient as well as the velocity dependence of friction. Friction remains more or less constant with changes in temperature, but a transition from velocity-strengthening behavior to velocity-weakening behavior occurs at a temperature of T = 150°C. The transition depends on the absolute value of sliding velocity as well as temperature, with the velocity-weakening region restricted to higher velocity for higher temperatures. Friction was substantially lower for low-velocity shearing (V < 0.3 μm/s) at 600°C, but no transition to normal stress independence was observed. In the framework of rate-and-state friction, earthquake nucleation is most likely at an intermediate temperature of T = 300°C. The velocity-strengthening nature of the Alpine Fault rocks at higher temperatures may pose a barrier for rupture propagation to deeper levels, limiting the possible depth extent of large earthquakes. Our results highlight the importance of strain rate in controlling frictional behavior under conditions spanning the classical brittle-plastic transition for quartzofeldspathic compositions.


1999 ◽  
Vol 190 ◽  
pp. 563-566
Author(s):  
J. D. Pritchard ◽  
W. Tobin ◽  
J. V. Clausen ◽  
E. F. Guinan ◽  
E. L. Fitzpatrick ◽  
...  

Our collaboration involves groups in Denmark, the U.S.A. Spain and of course New Zealand. Combining ground-based and satellite (IUEandHST) observations we aim to determine accurate and precise stellar fundamental parameters for the components of Magellanic Cloud Eclipsing Binaries as well as the distances to these systems and hence the parent galaxies themselves. This poster presents our latest progress.


Author(s):  
Ronald S. Weinstein ◽  
N. Scott McNutt

The Type I simple cold block device was described by Bullivant and Ames in 1966 and represented the product of the first successful effort to simplify the equipment required to do sophisticated freeze-cleave techniques. Bullivant, Weinstein and Someda described the Type II device which is a modification of the Type I device and was developed as a collaborative effort at the Massachusetts General Hospital and the University of Auckland, New Zealand. The modifications reduced specimen contamination and provided controlled specimen warming for heat-etching of fracture faces. We have now tested the Mass. General Hospital version of the Type II device (called the “Type II-MGH device”) on a wide variety of biological specimens and have established temperature and pressure curves for routine heat-etching with the device.


Author(s):  
Sidney D. Kobernick ◽  
Edna A. Elfont ◽  
Neddra L. Brooks

This cytochemical study was designed to investigate early metabolic changes in the aortic wall that might lead to or accompany development of atherosclerotic plaques in rabbits. The hypothesis that the primary cellular alteration leading to plaque formation might be due to changes in either carbohydrate or lipid metabolism led to histochemical studies that showed elevation of G-6-Pase in atherosclerotic plaques of rabbit aorta. This observation initiated the present investigation to determine how early in plaque formation and in which cells this change could be observed.Male New Zealand white rabbits of approximately 2000 kg consumed normal diets or diets containing 0.25 or 1.0 gm of cholesterol per day for 10, 50 and 90 days. Aortas were injected jin situ with glutaraldehyde fixative and dissected out. The plaques were identified, isolated, minced and fixed for not more than 10 minutes. Incubation and postfixation proceeded as described by Leskes and co-workers.


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