Neotethys closure history of Anatolia: insights from 40 Ar-39 Ar geochronology and P-T estimation in high-pressure metasedimentary rocks

2013 ◽  
Vol 31 (6) ◽  
pp. 585-606 ◽  
Author(s):  
A. Pourteau ◽  
M. Sudo ◽  
O. Candan ◽  
P. Lanari ◽  
O. Vidal ◽  
...  
Keyword(s):  
High Pressure ◽  
Metasedimentary Rocks ◽  
History Of ◽  
Ar Geochronology

Geochemical and Nd isotopic constraints for the origin of eclogite protoliths, northern Cordillera: implications for the Paleozoic tectonic evolution of the Yukon-Tanana terrane

1999 ◽  
Vol 36 (10) ◽  
pp. 1697-1709 ◽  
Author(s):  
Robert A Creaser ◽  
Jo-Anne S Goodwin-Bell ◽  
Philippe Erdmer
Keyword(s):  
High Pressure ◽  
Subduction Zone ◽  
Convergent Margins ◽  
Metasedimentary Rocks ◽  
High Pressure Metamorphism ◽  
Distal Edge ◽  
History Of ◽  
Convergent Plate Margin ◽  
Ocean Ridge ◽  
Subduction Zone Magmatism

On the basis of trace-element data, basaltic protoliths for Paleozoic eclogites from the Yukon-Tanana terrane (YTT) have diverse origins. Eclogites from Stewart Lake and the Simpson Range have characteristics of basaltic protoliths generated by subduction-zone magmatism, are hosted by serpentinitic-gabbroic rocks, and record Mississippian high-pressure metamorphism and cooling. In contrast, eclogites from Faro, Ross River, and Last Peak show either within-plate geochemistry or mid-ocean ridge protolith geochemistry with a small subduction component, are hosted by continental metasedimentary rocks of the Nisutlin assemblage, and record Permian high-pressure metamorphism and cooling. We interpret these results to derive from the following tectonic events in the Paleozoic history of the YTT: (1) activity at a Devonian-Mississippian convergent plate margin at the distal edge of North America, with near-contemporaneous subduction-zone magmatism and high-pressure metamorphism; (2) Mississippian rifting of that margin to form the outboard YTT, the Slide Mountain marginal basin, and the Faro, Ross River, and Last Peak eclogite protoliths; and (3) west-dipping subduction of the Slide Mountain Ocean under the outboard YTT in Permian time, to produce the Faro, Ross River, and Last Peak eclogites and Permian arc magmatism throughout the YTT. The basaltic protoliths of the Paleozoic YTT eclogites bear close similarity to those produced in rifted convergent margins, such as the Miocene Japanese arc - back-arc system.

Deformation timing and strain in Neoproterozoic strata, Jebel Akhdar, northern Oman

2020 ◽  
Author(s):  
Christopher Bailey ◽  
Claire Rae
Keyword(s):  
Strain Analysis ◽  
Low Grade ◽  
Depositional History ◽  
Fine Grained ◽  
Metasedimentary Rocks ◽  
Aspect Ratios ◽  
Deformation Kinematics ◽  
History Of ◽  
Penetrative Foliation ◽  
Ar Geochronology

<p>Neoproterozoic rocks exposed in the Jebel Akhdar massif of northern Oman preserve glaciogenic deposits associated with multiple Cryogenian glaciations. Although the depositional history of these rocks is well understood, the significance of post-depositional deformation is poorly constrained. In this study, we examine low-grade metasedimentary rocks exposed in the Ghubrah Bowl, an erosional window in the Jebel Akhdar massif, in order to quantify the 3D finite strain, understand deformation kinematics, and determine the timing of deformation/metamorphism.</p><p>In the Jebel Akhdar massif, the older Ghubrah (Sturtian glaciation) and younger Fiq (Marinoan glaciation) formations comprise a >1 km thick sequence of diamictite interbedded with sandstone, siltstone, conglomerate, volcanic rock, and minor carbonate. Diamictites contain abundant clasts of siltstone and sandstone, with lesser amounts of granite and metavolcanic rock in a fine-grained quartz + sericite ± chlorite matrix. Clasts range from granules to boulders. Harder clasts tend to be subangular and poorly aligned with low aspect ratios, whereas fine-grained rock clasts are well-aligned with large aspect ratios. Bedding generally dips to the NW, but is gently folded in accord with the overall structure of the Jebel Akhdar massif. A penetrative foliation strikes E-W and dips to the S. At some locations, a prominent elongation lineation/pencil structure occurs and plunges gently to moderately to the S.</p><p>R<sub>f</sub>/phi strain analysis in the diamictites reveals a range of 3D strain geometries (apparent flattening to apparent constriction) with strain ratios up to 2.8 in XZ sections. Strain is strongly partitioned, as clasts of igneous rock have low aspect ratios and are only weakly aligned. Penetrative strain in clast-supported sandstones is negligible (XZ ratios of <1.2). Outsized clasts of granite and sandstone are mantled by distinctive symmetric pressure shadows (double-duckbill structures) that include more recrystallized minerals than elsewhere in the diamictite. <sup>40</sup>Ar/<sup>39</sup>Ar geochronology of sericite in pressure shadows yields ages as young as 90 Ma, which are interpreted as mixed ages containing an older detrital component and a younger fraction formed during growth. Deformation is associated with southward emplacement and loading by the Oman ophiolite & Hawasina Group sediments over the autochthonous sequence in the late Cretaceous.</p>

scholarly journals The dynamothermal aureole of the Donqiao ophiolite (northern Tibet)

1997 ◽  
Vol 34 (1) ◽  
pp. 59-65 ◽  
Author(s):  
Mei-Fu Zhou ◽  
John Malpas ◽  
Paul T. Robinson ◽  
Peter H. Reynolds
Keyword(s):  
High Pressure ◽  
Subduction Zone ◽  
Greenschist Facies ◽  
Metamorphic Rocks ◽  
High Grade ◽  
Mineral Paragenesis ◽  
Metasedimentary Rocks ◽  
Northern Tibet ◽  
Suprasubduction Zone ◽  
Ar Geochronology

Metamorphic rocks found at the base of the Jurassic Donqiao ophiolite of northern Tibet are interpreted as a basal dynamothermal aureole produced during obduction of the massif. The rocks form a sequence some 8 m thick, varying from high-grade amphibolites at the contact with overlying harzburgites to greenschist facies metasedimentary rocks lower down. The mineral paragenesis is similar to other such aureoles, and indicates that temperatures in excess of 750 °C may have been reached during metamorphism. The lack of high-pressure minerals suggests that the rocks were produced by subcretion in a relatively shallow dipping subduction zone. Ar–Ar geochronology on amphibole separates provides dates of 175–180 Ma for the displacement of the ophiolite, significantly older than the age of emplacement estimated from stratigraphie relationships. The ophiolite was clearly obducted very soon after its formation in a suprasubduction zone environment.

Metasedimentary rocks, intrusions and deformation history in the south-east part of the c. 1800 Ma Ketilidian orogen, South Greenland: Project SUPRASYD 1996

1997 ◽  
pp. 60-65
Author(s):  
Adam A. Garde ◽  
Brian Chadwick ◽  
John Grocott ◽  
Cees Swager
Keyword(s):  
Field Work ◽  
Deformation History ◽  
The South ◽  
Present Contribution ◽  
East Part ◽  
Metasedimentary Rocks ◽  
Deformational History ◽  
Base Camp ◽  
History Of ◽  
Geological Map

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Garde, A. A., Chadwick, B., Grocott, J., & Swager, C. (1997). Metasedimentary rocks, intrusions and deformation history in the south-east part of the c. 1800 Ma Ketilidian orogen, South Greenland: Project SUPRASYD 1996. Geology of Greenland Survey Bulletin, 176, 60-65. https://doi.org/10.34194/ggub.v176.5063 _______________ The south-east part of the c. 1800 Ma Ketilidian orogen in South Greenland (Allaart, 1976) is dominated by strongly deformed and variably migmatised metasedimentary rocks known as the ‘Psammite and Pelite Zones’ (Chadwick & Garde, 1996); the sediments were mainly derived from the evolving Julianehåb batholith which dominates the central part of the orogen. The main purpose of the present contribution is to outline the deformational history of the Psammite Zone in the region between Lindenow Fjord and Kangerluluk (Fig. 2), investigated in 1994 and 1996 as part of the SUPRASYD project (Garde & Schønwandt, 1995 and references therein; Chadwick et al., in press). The Lindenow Fjord region has high alpine relief and extensive ice and glacier cover, and the fjords are regularly blocked by sea ice. Early studies of this part of the orogen were by boat reconnaissance (Andrews et al., 1971, 1973); extensive helicopter support in the summers of 1992 and 1994 made access to the inner fjord regions and nunataks possible for the first time.A preliminary geological map covering part of the area between Lindenow Fjord and Kangerluluk was published by Swager et al. (1995). Hamilton et al. (1996) have addressed the timing of sedimentation and deformation in the Psammite Zone by means of precise zircon U-Pb geochronology. However, major problems regarding the correlation of individual deformational events and their relationship with the evolution of the Julianehåb batholith were not resolved until the field work in 1996. The SUPRASYD field party in 1996 (Fig. 1) was based at the telestation of Prins Christian Sund some 50 km south of the working area (Fig. 2). In addition to base camp personnel, helicopter crew and the four authors, the party consisted of five geologists and M.Sc. students studying mafic igneous rocks and their mineralisation in selected areas (Stendal et al., 1997), and a geologist investigating rust zones and areas with known gold anomalies.

Review of Deep-Ocean High-Pressure Simulation Systems

2020 ◽  
Vol 54 (3) ◽  
pp. 68-84
Author(s):  
Wentao Song ◽  
Weicheng Cui
Keyword(s):  
High Pressure ◽  
Coming Out ◽  
Deep Sea ◽  
Mathematical Theory ◽  
Deep Ocean ◽  
Cold Isostatic Pressing ◽  
Future Design ◽  
Stress Coefficient ◽  
History Of ◽  
Simulation Systems

AbstractDeep-sea technology and equipment are required to explore the oceans and utilize ocean resources in the 21st century. Deep-ocean simulation systems (DOSs) play an essential role in the development of deep-sea equipment. This paper gives a detailed overview of deep-ocean high-pressure simulation systems (DOHPSs) worldwide. First, the history of DOS is introduced, and then the primary available equipment, particularly coming out of China, is described. Next, the new concept of the cold isostatic pressing (CIP) chamber and its technology and equipment are reviewed. Then, the basic mathematical theory for the design of pressure chambers is introduced to illustrate the limitations of the traditional monobloc chamber. To easily understand the pre-stressed wire-wound (PSWW) design, the pre-stress coefficient is introduced in theoretical analysis. Some valuable researches of PSWW are presented. Finally, the sealing design of DOS, especially tooth-locked quick-actuating closures (TLQAC), is discussed. The paper aims to inspire readers to develop innovative ideas about the future design of DOS.

40Ar-39Ar and Rb-Sr geochronology of high-pressure metamorphism and exhumation history of the Tavsanli Zone, NW Turkey

1999 ◽  
Vol 137 (1-2) ◽  
pp. 46-58 ◽  
Author(s):  
Sarah Sherlock ◽  
Simon Kelley ◽  
Simon Inger ◽  
Nigel Harris ◽  
Aral Okay
Keyword(s):  
High Pressure ◽  
High Pressure Metamorphism ◽  
Nw Turkey ◽  
History Of ◽  
Exhumation History

Origin and mechanical significance of honeycomb garnet in high-pressure metasedimentary rocks from the Tauern Window, Eastern Alps

2007 ◽  
Vol 25 (5) ◽  
pp. 565-583 ◽  
Author(s):  
A. T. HAWKINS ◽  
J. SELVERSTONE ◽  
A. J. BREARLEY ◽  
R. J. BEANE ◽  
R. A. KETCHAM ◽  
...  
Keyword(s):  
High Pressure ◽  
Eastern Alps ◽  
Tauern Window ◽  
Metasedimentary Rocks
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