16. Application of Low-Temperature Thermochronometry to Extensional Tectonic Settings

2005 ◽  
pp. 411-448 ◽  
Author(s):  
Daniel F. Stockli
Author(s):  
Donald H. W. Hutton

ABSTRACTThis paper is a structural and tectonic approach to the emplacement and deformation of granitoids. The main methods available in structural geology are briefly reviewed and this emphasises that (a) a wealth of data, particularly strain and shear sense, which pertain to these problems, can be determined in and around plutons; (b) given the nature, unlike many other crustal rock types, of granites to crystallise from isotropic through weakly anisotropic crystal suspension fluids, that deformation which has occurred in these states may not be well preserved; and (c) it is entirely possible, using this methodology, to separate deformation resulting from externally originating tectonic stresses from that which is associated with internal magma-related stresses. It is also recommended that the genetically-based Cloosian classification of granite fabrics and structures into “primary” (magmatic flow/magmatic flow current) and “secondary”, be abandoned and that a more observationally-based approach which classifies granite deformation fabrics and structures according to their time of occurrence relative to the crystallisation state of the congealing magma, be adopted (i.e. pre-full crystallisation deformation and crystal plastic strain deformation).Examples of recent, structurally based, studies of emplacement mechanisms of plutons within tectonic settings are described and these show that, in general, space for magma can be created by the combination of tectonically-created cavities and internal magma-related buoyancy. This occurs in both transcurrent and extensional tectonic settings and there is no reason to doubt that it can happen in compressive-contractional regimes. It is concluded that transient and permanent space creation, such as may be exploited by available magmas, is a typical feature of the tectonically stressed and deforming lithosphere and this, in combination with the natural buoyancy and ascending tendency of magmas, can generate the varied emplacement mechanisms of granites.


1999 ◽  
Vol 104 (B10) ◽  
pp. 23069-23079 ◽  
Author(s):  
D. Robinson ◽  
V. V. Reverdatto ◽  
R. E. Bevins ◽  
O. P. Polyansky ◽  
V. S. Sheplev

2016 ◽  
Vol 82 ◽  
pp. 1-15 ◽  
Author(s):  
Jörg Meixner ◽  
Eva Schill ◽  
Jens C. Grimmer ◽  
Emmanuel Gaucher ◽  
Thomas Kohl ◽  
...  

2002 ◽  
Vol 59 (1-4) ◽  
pp. 163-210 ◽  
Author(s):  
Lyal B. Harris ◽  
Hemin A. Koyi ◽  
Haakon Fossen

Minerals ◽  
2021 ◽  
Vol 11 (2) ◽  
pp. 100
Author(s):  
Zepeng Wang ◽  
Qinping Tan ◽  
Yong Xia ◽  
Jianzhong Liu ◽  
Chengfu Yang ◽  
...  

Southwestern Guizhou, China, is famous for hosting clusters of Carlin-type Au, Sb, and Hg-Tl deposits. These deposits are thought to be the products of a low-temperature hydrothermal metallogenic event. Calcite and fluorite are common and widespread gangue minerals in Au and Sb deposits, respectively. Ore-related calcite commonly coexists with stibnite, realgar, and orpiment at the periphery of high-grade orebodies in Au deposits, while ore-related fluorite is generally intergrown with stibnite in Sb deposits. In this study, ore-related calcite and fluorite samples from representative Au (Zimudang) and Sb (Dachang) deposits, respectively, were separated, and the rare earth element (REE) concentrations, Sm/Nd isotope ratios, and Sm–Nd isochron ages were analyzed. This study aims to determine the formation ages of the calcite and fluorite and to constrain the age of low-temperature metallogenic event in Southwestern Guizhou. The calcite and fluorite samples contain relatively high total concentrations of REEs (8.21–22.5 μg/g for calcite, 21.7–36.6 μg/g for fluorite), exhibit variable Sm/Nd ratios (0.51–1.01 for calcite, 0.35–0.49 for fluorite), and yield Sm–Nd isochron ages of 148.4 ± 4.8 and 141 ± 20 Ma, respectively. These ages are consistent with the age range constrained by the low-temperature thermochronology of zircon (132–160 Ma), crosscutting relationships of stratigraphy or intrusions (96–160 Ma), and previous dating results (135–150 Ma) in Southwestern Guizhou. Collectively, the ages obtained in this study add new evidence to previous geochronology studies, such that the low-temperature hydrothermal mineralization in Southwestern Guizhou can be constrained to 135–150 Ma, corresponding to the Yanshanian orogeny, which was associated with a weak extensional tectonic environment.


Geomorphology ◽  
2021 ◽  
pp. 108082
Author(s):  
Phillip H. Larson ◽  
Ronald I. Dorn ◽  
Brian F. Gootee ◽  
Yeong Bae Seong

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