View in EDS PDF Full Text

Late Jurassic-Early Cretaceous tectonic switching in Liaodong Peninsula of the North China Craton and the implications for gold mineralisation.

Saved in:
Bibliographic Details
Title: Late Jurassic-Early Cretaceous tectonic switching in Liaodong Peninsula of the North China Craton and the implications for gold mineralisation.
Authors: Yan, Dan-Ping1 (AUTHOR) yandp@cugb.edu.cn, Kong, Ruoyan1 (AUTHOR), Dong, Xiaoyu1 (AUTHOR), Qiu, Liang1 (AUTHOR), Liu, Huilong1,2 (AUTHOR)
Source: SCIENCE CHINA Earth Sciences. Sep2021, Vol. 64 Issue 9, p1537-1556. 20p.
Subjects: Fault zones, Peninsulas, Gold, Erosion, Thrust, Gold ores
Abstract: Constraining the processes of deformation during tectonic switching from compression to extension is difficult because of the scarcity or absence of associated sedimentary and magmatic rocks and weak metamorphism. The east margin of the eastern North China Craton experienced Early to Middle Jurassic compression and Early Cretaceous extension. However, the period of tectonic quiescence lasting ∼13 million years (between 153 and 140 Ma) during which this transition occurred is poorly understood. This paper reports the identification of small-scale N-S-trending thrust and sinistral strike-slip faults (TSS) and NW-trending thrust and dextral strike-slip faults (TDS) in the Tongyuanpu-Aiyang region, which is part of the northern Liaodong Peninsula. Calculation of the tectonic stress field using striations, fault planes and kinematics reveals a NW-SE-oriented maximum principal axis (σ1) and sub-horizontal σ2 and σ3. Assemblages of N-S-trending TSS and NW-trending TDS were arranged with right stepping and resulted in local uplift and erosion at the junctions between fault terminations, which partitioned the Early and Middle Jurassic basins into residual smaller volcanic-sedimentary basins. These basins were unconformably overlain by small Early Cretaceous volcanic-sedimentary basins, such as those at Tongyuanpu and Fangjiaweizi. Magmatic ages and the timing of basin formation constrain the initiation of tectonic switching to 156–153 Ma, and its termination to 140–139 Ma. We suggest that R-R′ Riedel shears controlled the formation of the N-S-trending TSS and NW-trending TDS. The R-R′ shears were produced by continued sinistral strike-slip and northward growth along the Bohai Bay segment of the Tan-Lu fault zone during the Late Jurassic to early Early Cretaceous, simultaneous with a gradual weakening in the tectonic stress field during a switch in the direction of subduction of the Palaeo-Pacific plate from NW-ward to NNW-ward. This tectonic switching might have promoted the dissolution of gold and migration of gold-bearing fluids. [ABSTRACT FROM AUTHOR]
Copyright of SCIENCE CHINA Earth Sciences is the property of Springer Nature and its content may not be copied or emailed to multiple sites without the copyright holder's express written permission. Additionally, content may not be used with any artificial intelligence tools or machine learning technologies. However, users may print, download, or email articles for individual use. This abstract may be abridged. No warranty is given about the accuracy of the copy. Users should refer to the original published version of the material for the full abstract. (Copyright applies to all Abstracts.)
Database: Engineering Source
Description
Abstract:Constraining the processes of deformation during tectonic switching from compression to extension is difficult because of the scarcity or absence of associated sedimentary and magmatic rocks and weak metamorphism. The east margin of the eastern North China Craton experienced Early to Middle Jurassic compression and Early Cretaceous extension. However, the period of tectonic quiescence lasting ∼13 million years (between 153 and 140 Ma) during which this transition occurred is poorly understood. This paper reports the identification of small-scale N-S-trending thrust and sinistral strike-slip faults (TSS) and NW-trending thrust and dextral strike-slip faults (TDS) in the Tongyuanpu-Aiyang region, which is part of the northern Liaodong Peninsula. Calculation of the tectonic stress field using striations, fault planes and kinematics reveals a NW-SE-oriented maximum principal axis (σ1) and sub-horizontal σ2 and σ3. Assemblages of N-S-trending TSS and NW-trending TDS were arranged with right stepping and resulted in local uplift and erosion at the junctions between fault terminations, which partitioned the Early and Middle Jurassic basins into residual smaller volcanic-sedimentary basins. These basins were unconformably overlain by small Early Cretaceous volcanic-sedimentary basins, such as those at Tongyuanpu and Fangjiaweizi. Magmatic ages and the timing of basin formation constrain the initiation of tectonic switching to 156–153 Ma, and its termination to 140–139 Ma. We suggest that R-R′ Riedel shears controlled the formation of the N-S-trending TSS and NW-trending TDS. The R-R′ shears were produced by continued sinistral strike-slip and northward growth along the Bohai Bay segment of the Tan-Lu fault zone during the Late Jurassic to early Early Cretaceous, simultaneous with a gradual weakening in the tectonic stress field during a switch in the direction of subduction of the Palaeo-Pacific plate from NW-ward to NNW-ward. This tectonic switching might have promoted the dissolution of gold and migration of gold-bearing fluids. [ABSTRACT FROM AUTHOR]
ISSN:16747313
DOI:10.1007/s11430-020-9770-6