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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MDPI AG
2021-11-01
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| Online Access: | https://www.mdpi.com/2076-3263/11/11/456 |
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| author | Jian Zheng Yehua Shan Simin Hu |
| author_facet | Jian Zheng Yehua Shan Simin Hu |
| author_sort | Jian Zheng |
| collection | DOAJ |
| 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. |
| first_indexed | 2024-03-10T05:27:17Z |
| format | Article |
| id | doaj.art-21387b49ae624004afc0a35ba85b9807 |
| institution | Directory Open Access Journal |
| issn | 2076-3263 |
| language | English |
| last_indexed | 2024-03-10T05:27:17Z |
| publishDate | 2021-11-01 |
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| record_format | Article |
| series | Geosciences |
| spelling | doaj.art-21387b49ae624004afc0a35ba85b98072023-11-22T23:29:57ZengMDPI AGGeosciences2076-32632021-11-01111145610.3390/geosciences11110456Paleostress Analysis from Calcite Twins at the Longshan Dome (Central Hunan, South China): Mesozoic Mega-Fold Superimposition in the Reworked ContinentJian Zheng0Yehua Shan1Simin Hu2State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, ChinaState Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, ChinaState Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, ChinaIt 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.https://www.mdpi.com/2076-3263/11/11/456calcite twinspaleostress analysisLongshan domesuperimposed foldSouth ChinaMesozoic |
| spellingShingle | 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 Geosciences calcite twins paleostress analysis Longshan dome superimposed fold South China Mesozoic |
| title | 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_short | 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 |
| topic | calcite twins paleostress analysis Longshan dome superimposed fold South China Mesozoic |
| url | https://www.mdpi.com/2076-3263/11/11/456 |
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