Paleostress Analysis from Calcite Twins at the Longshan Dome (Central Hunan, South China): Mesozoic Mega-Fold Superimposition in the Reworked Continent

It is generally accepted that during the Mesozoic NE−NNE-trending folds overprinted E−W-trending folds to form the Longshan dome in the central South China continent, although the interference map does not tell the relative ages of the fold sets. In an effort to deepen our understanding of the proce...

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Autores principales:	Jian Zheng, Yehua Shan, Simin Hu
Formato:	article
Lenguaje:	EN
Publicado:	MDPI AG 2021
Materias:	calcite twins paleostress analysis Longshan dome superimposed fold South China Mesozoic Geology QE1-996.5
Acceso en línea:	https://doaj.org/article/21387b49ae624004afc0a35ba85b9807
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spelling	oai:doaj.org-article:21387b49ae624004afc0a35ba85b98072021-11-25T17:42:56ZPaleostress Analysis from Calcite Twins at the Longshan Dome (Central Hunan, South China): Mesozoic Mega-Fold Superimposition in the Reworked Continent10.3390/geosciences111104562076-3263https://doaj.org/article/21387b49ae624004afc0a35ba85b98072021-11-01T00:00:00Zhttps://www.mdpi.com/2076-3263/11/11/456https://doaj.org/toc/2076-3263It is generally accepted that during the Mesozoic NE−NNE-trending folds overprinted E−W-trending folds to form the Longshan dome in the central South China continent, although the interference map does not tell the relative ages of the fold sets. In an effort to deepen our understanding of the process of reworking the continent, paleostress analysis using calcite twins was carried out in this study to verify or falsify this model. Ten limestone samples were collected from Upper-Paleozoic limestones on the flanks of the dome and were measured using the universal stage for calcite e-twins. E-twins in the samples are divisible into two kinds, thick (≥1 μm) and thin (<1 μm), indicative of relatively higher and lower deformation temperatures, respectively. Stress estimates obtained using the improved version of Shan et al.’s (2019) method were grouped into two layer-parallel shortening (LPS) subsets and three non-LPS subsets. These subsets comprise four tectonic regimes: NWW−SEE compression (LPS1 and non-LPS1), NNE−SSW compression (LPS2 and non-LPS2), NW−SE extension (non-LPS3a) and NNE−SSW extension (non-LPS3b). They were further arranged in a temperature-decreasing order to establish a complex deformation sequence of the study area. In the sequence NE−NNE-trending folds have an older age than E−W-trending folds, something different from the model. The approximately N−S regional compression responsible for the former folds should have a profound effect on the intensely deformed continent, something ignored in earlier work.Jian ZhengYehua ShanSimin HuMDPI AGarticlecalcite twinspaleostress analysisLongshan domesuperimposed foldSouth ChinaMesozoicGeologyQE1-996.5ENGeosciences, Vol 11, Iss 456, p 456 (2021)
institution	DOAJ
collection	DOAJ
language	EN
topic	calcite twins paleostress analysis Longshan dome superimposed fold South China Mesozoic Geology QE1-996.5
spellingShingle	calcite twins paleostress analysis Longshan dome superimposed fold South China Mesozoic Geology QE1-996.5 Jian Zheng Yehua Shan Simin Hu Paleostress Analysis from Calcite Twins at the Longshan Dome (Central Hunan, South China): Mesozoic Mega-Fold Superimposition in the Reworked Continent
description	It is generally accepted that during the Mesozoic NE−NNE-trending folds overprinted E−W-trending folds to form the Longshan dome in the central South China continent, although the interference map does not tell the relative ages of the fold sets. In an effort to deepen our understanding of the process of reworking the continent, paleostress analysis using calcite twins was carried out in this study to verify or falsify this model. Ten limestone samples were collected from Upper-Paleozoic limestones on the flanks of the dome and were measured using the universal stage for calcite e-twins. E-twins in the samples are divisible into two kinds, thick (≥1 μm) and thin (<1 μm), indicative of relatively higher and lower deformation temperatures, respectively. Stress estimates obtained using the improved version of Shan et al.’s (2019) method were grouped into two layer-parallel shortening (LPS) subsets and three non-LPS subsets. These subsets comprise four tectonic regimes: NWW−SEE compression (LPS1 and non-LPS1), NNE−SSW compression (LPS2 and non-LPS2), NW−SE extension (non-LPS3a) and NNE−SSW extension (non-LPS3b). They were further arranged in a temperature-decreasing order to establish a complex deformation sequence of the study area. In the sequence NE−NNE-trending folds have an older age than E−W-trending folds, something different from the model. The approximately N−S regional compression responsible for the former folds should have a profound effect on the intensely deformed continent, something ignored in earlier work.
format	article
author	Jian Zheng Yehua Shan Simin Hu
author_facet	Jian Zheng Yehua Shan Simin Hu
author_sort	Jian Zheng
title	Paleostress Analysis from Calcite Twins at the Longshan Dome (Central Hunan, South China): Mesozoic Mega-Fold Superimposition in the Reworked Continent
title_short	Paleostress Analysis from Calcite Twins at the Longshan Dome (Central Hunan, South China): Mesozoic Mega-Fold Superimposition in the Reworked Continent
title_full	Paleostress Analysis from Calcite Twins at the Longshan Dome (Central Hunan, South China): Mesozoic Mega-Fold Superimposition in the Reworked Continent
title_fullStr	Paleostress Analysis from Calcite Twins at the Longshan Dome (Central Hunan, South China): Mesozoic Mega-Fold Superimposition in the Reworked Continent
title_full_unstemmed	Paleostress Analysis from Calcite Twins at the Longshan Dome (Central Hunan, South China): Mesozoic Mega-Fold Superimposition in the Reworked Continent
title_sort	paleostress analysis from calcite twins at the longshan dome (central hunan, south china): mesozoic mega-fold superimposition in the reworked continent
publisher	MDPI AG
publishDate	2021
url	https://doaj.org/article/21387b49ae624004afc0a35ba85b9807
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Paleostress Analysis from Calcite Twins at the Longshan Dome (Central Hunan, South China): Mesozoic Mega-Fold Superimposition in the Reworked Continent

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