Tectonic significance of ductile deformation in low-grade sandstones in the mesozoic Otago subduction wedge, New Zealand

2011 ◽  
Vol 311 (1) ◽  
pp. 27-62 ◽  
Author(s):  
J. M. Rahl ◽  
M. T. Brandon ◽  
H. Deckert ◽  
U. Ring ◽  
N. Mortimer
Keyword(s):  
New Zealand ◽  
Ductile Deformation ◽  
Low Grade ◽  
Tectonic Significance ◽  
Subduction Wedge

Deformational geometry and tectonic significance of a portion of the Chilliwack Group, northwestern Cascades, Washington

1988 ◽  
Vol 25 (3) ◽  
pp. 433-441 ◽  
Author(s):  
Moira Smith
Keyword(s):  
High Pressure ◽  
Volcanic Rocks ◽  
Ductile Deformation ◽  
Metamorphic Rocks ◽  
Low Grade ◽  
North Cascades ◽  
Clastic Rocks ◽  
Tectonic Significance ◽  
Group A ◽  
Event Based

The northwestern Cascades structural province can be interpreted as an accretionary complex comprising fault-bounded blocks of pre-Tertiary metamorphic rocks of diverse age and lithologic type. This paper documents the deformation in a portion of the Chilliwack Group, a unit in this complex. The Chilliwack Group is a thick sequence of volcaniclastic sedimentary rocks, calc-alkaline volcanic rocks, and limestone that is metamorphosed to low-grade blueschist facies. The rocks underwent ductile deformation during a Late Cretaceous orogenic event, producing a subhorizontal foliation and, in appropriate lithologies, subhorizontal stretching lineations that trend N20°W. Finite strain sustained by coarse clastic rocks produced RXZ values averaging 3.5. The deformation at least partially postdates the high pressure metamorphic event, based on the presence of bent and broken high-pressure mineral grains. Although early studies postulated west-vergent thrust imbrication of units in the northwest Cascades, the N20°W direction of apparent elongation in the Chilliwack Group, consistent with the direction of motion along segments of the Shuksan fault elucidated in other more recent studies, may reflect significant, highly oblique components of convergence during formation of the western North Cascades collisional orogen.

Progressive Regional Metamorphism in Southern New Zealand

1938 ◽  
Vol 75 (4) ◽  
pp. 160-174 ◽  
Author(s):  
F. J. Turner
Keyword(s):  
New Zealand ◽  
Regional Metamorphism ◽  
Parent Rock ◽  
Chemical Compositions ◽  
Low Grade ◽  
Scottish Highlands ◽  
The Past ◽  
Structural Peculiarities ◽  
Chemical Conditions ◽  
Pelitic Rocks

During the past ten years a number of papers dealing with progressive regional metamorphism in the southern portion of New Zealand have been published. In the following pages a brief summary of the assemblages of minerals typical of the various metamorphic zones is given, but the writer's main object is to draw attention to certain mineralogical and structural peculiarities that appear to differ in some degree from what are usually regarded as the normal features of regional metamorphism in such classic areas as the Scottish Highlands and the Caledonian chain of Norway. The possibility that such departures from the normal may in some instances be connected with chemical peculiarities in the parent rock is suggested by such phenomena as the well-known general limitation of chloritoid, staurolite, and low-grade garnets to pelitic rocks of special chemical compositions. Other unusual features, especially when found to recur in widely separated regions, may well be governed by some particular combination of physical rather than chemical conditions.

40Ar/ 39Ar laser dating of Zongwulong ductile shear zone in northeastern Tibetan Plateau ：Constrains on the closure time of the northmost Paleo-Tethys ocean

2021 ◽  
Author(s):  
Wanli Gao ◽  
Zongxiu Wang
Keyword(s):  
Shear Deformation ◽  
Shear Zone ◽  
Ductile Deformation ◽  
Low Grade ◽  
Ductile Shear Zone ◽  
The South ◽  
Oblique Collision ◽  
Ductile Shear ◽  
Tethys Ocean ◽  
Tectonic Belt

<p><strong><img src="https://contentmanager.copernicus.org/fileStorageProxy.php?f=gepj.67d6c7216eff55356050161/sdaolpUECMynit/12UGE&app=m&a=0&c=5572aca4b392eef83f52919e1be673e9&ct=x&pn=gepj.elif&d=1" alt="">Abstract</strong>：The Zongwulong tectonic belt (ZTB) is located between the northern Qaidam tectonic belt and the south Qilian orogenic belt and contains Late Paleozoic and Early- Middle Triassic strata. Structural features and geochronology of Zongwulong ductile shear zone have key implications for the tectonic property of the ZTB. This study integrated field structure, microscopic structure and <sup>40</sup>Ar/<sup>39</sup>Ar laser probe analysis. The shear zone strikes ~NEE-SWW and dips at a high angle, with a NWW-SEE trending and WE stretching lineation, indicating the shear zone as a thrust- slip shear ductile shear. The asymmetric folds, rotating porphyroclast,structural lens and crenulation cleavage can be seen in the field. Mica fish, S − C fabrics, σ type quartz porphyroclastic and quartz wire drawing structure can also be observed under microscope, indicating that the strike- slip- related ductile deformation and mylonitization occurred under low- grade greenschist facies conditions at temperatures of <em>300° C − 400° C</em>.  The highly deformed<br>mylonite schist yielded <sup>40</sup>Ar/<sup>39</sup>Ar ages <em>(245.8±1.7)Ma </em>and <em>(238.5±2.6)</em>Ma for muscovite and biotite, respectively, indicating that the shear deformation occurred during the Early- Mid Triassic. Combined with comprehensive analysis of regional geology and petrology, the authors hold that the age of ductile shear deformation represents the time of Triassic orogeny in the ZTB. The oroginic activity was probably related to the oblique collision between the South Qilian block and the Oulongbuluke block after the closure of the northermost Paleo-Tethys ocean.</p>

The Blind Creek Limestone, Keremeos, British Columbia: Structure and Regional Tectonic Significance

1975 ◽  
Vol 12 (11) ◽  
pp. 1929-1933
Author(s):  
W. C. Barnes ◽  
J. V. Ross
Keyword(s):  
British Columbia ◽  
Compressive Stress ◽  
Ductile Deformation ◽  
Large Block ◽  
Stress Direction ◽  
Upper Paleozoic ◽  
Tectonic Significance ◽  
Regional Tectonic ◽  
Similar Body ◽  
Paleozoic Rocks

A large block of Upper Paleozoic limestone at Blind Creek near Keremeos, B.C. was emplaced by dry gravity sliding, probably associated with uplift related to nearby Eocene volcanism. The block is a nearly flat tabular unit, exposed over an area of 650 m by 1300 m, and is separated from underlying chaotic breccias derived from adjacent Paleozoic rocks and from Eocene volcanic flow rocks by a sole fault. The block comprises two lithologically and tectonically distinct units, a lower imbricated unit consisting of several slices repeating the same sequence of strata, separated from an upper unit of massive limestone by a low-angle fault. Within the imbricated unit, early faults emanate from lenticular masses of breccia along the sole, become increasingly steeper upward, and are truncated above by the upper low angle fault. Associated minor folds and fractures have a clockwise sense of rotation. Later fractures and associated minor folds have the opposite dip and sense of rotation. These two subsets comprise a conjugate set whose inferred compressive stress direction coincides with the present overall dip direction of the entire mass.The northwesterly adjacent autochthonous Olalla limestone, or a similar body now buried by younger units, is a likely source for the Blind Creek allochthon.Absence of any structures within the limestone indicative of ductile deformation contrasts markedly with those of the highly deformed rocks of the Old Tom and Shoemaker Formations, the Kobau Group, and the nearby gneisses of the western Shuswap Complex.

The stilpnomelane group of minerals

1938 ◽  
Vol 25 (163) ◽  
pp. 172-206 ◽  
Author(s):  
C. Osborne Hutton
Keyword(s):  
New Zealand ◽  
Analytical Data ◽  
Low Grade ◽  
Preliminary Work ◽  
Mineral Assemblages

Work which has been in progress during the last few years on the low-grade regionally metamorphosed rocks of western Otago, New Zealand, has shown that members of the stilpnomelane group, hydrous iron- (or manganese-) rich silicates, are exceedingly widespread in rocks with the most varied mineral assemblages. In many cases the mineral in question is in sufficient quantity to rank as an essential constituent and may even be the most abundant one present. Hence in view of the importance of this mineral in the rocks of this region, it was considered that exact analytical data were necessary, and preliminary work in this connexion was carried out by Dr. F. J. Turner and the writer in 1934, but at that time, owing to the difficulties of separation, the pure minerals could not be obtained for analysis.

Accretion tectonics in northern Eritrea revealed by remotely sensed imagery

1993 ◽  
Vol 130 (2) ◽  
pp. 177-190 ◽  
Author(s):  
S. A. Drury ◽  
S. M. Berhe
Keyword(s):  
Remotely Sensed ◽  
Ductile Deformation ◽  
Low Grade ◽  
Arc Volcanism ◽  
Remotely Sensed Imagery ◽  
Pan African ◽  
Major Fault ◽  
High Level ◽  
Back Arc ◽  
Layered Sequence

AbstractNew details from remotely sensed images of the structure and disposition of broad lithological variations in the Pan-African of northern Eritrea are discussed in the context of accretionary tectonics. The recognition of major north-south structural discontinuities allows the area to be divided into three discrete terranes with apparently different histories of deformation and metamorphism, magmagenesis and sedimentation. The central Hagar Terrane is dominated by large ultramafic masses with a volcano-sedimentary layered sequence, and shows the effects of major sinistral transpression and lateral expulsion. It is bounded to the west by a major fault, the Barka suture, and abuts the older Barka Terrane that comprises metasediments with evidence for polyphase ductile deformation and pre-kinematic dyke emplacement. The Hagar Terrane is thrust against the eastern Nacfa Terrane, which is dominated by low-grade calc-alkaline metavolcanics and immature volcanoclastic sediments intruded by syn-kinematic plutons. These units are pre-dated by an earlier high-grade basement and post-dated by high-level unmetamorphosed silicic volcanics and redbed sediments. The complex is suggested to have been assembled by oblique accretion from the southeast after arc volcanism in the Nacfa Terrane and back-arc extension in the Hagar Terrane ended with the cease of subduction.

PARAGON: Phase II study of aromatase inhibitors in women with potentially hormone responsive recurrent/metastatic gynecologic neoplasms: ANZGOG 0903.

2013 ◽  
Vol 31 (15_suppl) ◽  
pp. TPS5614-TPS5614 ◽  
Author(s):  
Michael Friedlander ◽  
Katrin Marie Sjoquist ◽  
Dirkje Willemien Sommeijer ◽  
Lisa Bailey ◽  
Julie Martyn ◽  
...  
Keyword(s):  
New Zealand ◽  
Phase Ii ◽  
Aromatase Inhibitors ◽  
Clinical Benefit ◽  
Stopping Rules ◽  
Low Grade ◽  
Oncology Group ◽  
Gynaecological Oncology ◽  
Resistant Refractory ◽  
Rare Tumours

TPS5614 Background: Many gynaecological cancers of different pathological type express estrogen and/or progesterone hormone receptors (ER/PR). Reports of tumour response and clinical benefit with hormonal therapies show variable rates of activity. There is a need to prospectively study the role of aromatase inhibitors in women with potentially hormone responsive recurrent gynaecological cancers to establish response rates, clinical benefit, quality of life (QoL) and identify predictors of response. Methods: PARAGON is phase II Gynecologic Cancer InterGroup trial lead by the Australia New Zealand Gynaecological Oncology Group, Cancer Research UK and the Belgian Gynaecological Oncology Group. The study is designed to facilitate research in rare tumours. The protocol allows postmenopausal women with recurrent gynaecological cancers to enrol into one of 7 subgroups; epithelial ovarian cancer (EOC) with only rising CA125 after first line chemotherapy, platinum resistant/refractory EOC, low grade EOC, endometrial carcinomas, endometrial stromal sarcomas, miscellaneous sarcomas and granulosa cell tumours and other sex cord stromal tumours. ER/PR positivity must be confirmed by immunohistochemistry. Each subgroup will enrol 25-50 patients with defined stopping rules based on response and reviewed by independent data monitoring committee (IDMC). Eligible patients receive 1 mg anastrozole daily until disease progression or unacceptable toxicity. Primary objective: clinical benefit (partial or complete response or stable disease). Secondary objectives: progression free survival, response duration, QoL, toxicity. Blood and tumour samples are being collected for translational studies and confirmation of ER/PR positivity. Recruitment commenced in 2011 in Australia, New Zealand and the United Kingdom. One hundred and fourteen of 350 planned patients have been enrolled to January 2013. In November 2012 IDMC recommended continuing recruitment to the EOC with rising Ca125 only and resistant/refractory subgroups based on review of activity outcomes for the first 25 patients. The trial will open in Belgium in April 2013. ACTRN12610000796088 Clinical trial information: 12610000796088.

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