Seismic evidence for crustal architecture and stratigraphy of the Limpopo Corridor: New insights into the evolution of the sheared margin offshore southern Mozambique
|Author(s)||Li He1, 2, Tang Yong2, 4, 5, 6, 7, Moulin Maryline3, Aslanian Daniel3, Evain Mikael3, Schnurle Philippe3, Lepretre Angélique3, Li Jiabiao2, 4, 5, 6, 7|
|Affiliation(s)||1 : School of Earth Sciences, Zhejiang University, Hangzhou 310007, China
2 : Key Laboratory of Submarine Geosciences, Second Institute of Oceanography, Ministry of Natural Resources, Hangzhou 310012, China
3 : IFREMER, REM/GM/LGS, Centre de Brest, 29280 Plouzané, France
4 : School of Oceanography, Shanghai Jiao Tong University, Shanghai 200240, China
5 : Southern Marine Science and Engineering Guangdong Laboratory, Zhuhai 519080, China
6 : College of Marine Science and Technology, China University of Geosciences, Wuhan 430074, China
7 : College of Marine Geosciences, Ocean University of China, Qingdao 266100, China
|Source||Marine Geology (0025-3227) (Elsevier BV), 2021-05 , Vol. 435 , P. 106468 (15p.)|
|WOS© Times Cited||5|
|Keyword(s)||Limpopo Corridor (LC), Sheared/transform margin, Seismic stratigraphy, Basement architecture, Southern Mozambique margin|
The Gondwana breakup along the Mozambique continental margin caused the formation of extensional and/or sheared margins. One of these sheared margins offshore southern Mozambique, the Limpopo Corridor (LC), is a key area for understanding the evolution of the southward movement of Eastern Gondwana with respect to Western Gondwana. However, crustal architecture and stratigraphy in this area have been inadequately studied, mainly due to the lack of deep seismic data.
In this study, we present interpretations of new multichannel seismic reflection profiles oriented west to east across the LC and Mozambique Fracture Zone (MFZ). Our results show that the basement of the LC is characterized by dipping and alternating strong and weak reflectors, revealing a thick Volcano-Sedimentary Sequence (VSS). To the west of the LC, a marginal basement high zone extends from north to south, consisting of an eroded and fractured VSS. Besides, the acoustic basement is characterized by an eastward dipping or flat VSS in the LC. Sediments overlying the top of the VSS reveal an onlap geometry against the basement high. Five major stratigraphic units (U1-U5) with well-layered sedimentary sequences are mainly constrained from the western boundary of the basement high to the eastern MFZ, and dated to Neocomian, Middle Cretaceous, Late Cretaceous, Paleogene, and Neogene times respectively.
We propose that the VSS in the acoustic basement likely formed in pre-Neocomian time. An uplift event occurred continuously from the Oxfordian-Kimmeridgian to Middle Cretaceous, resulting in a basement high that represents the western limit of the LC. Between this limit and the MFZ, the LC experienced the intracontinental rifting, wrench faulting, and discrepant subsidence associated with the southward strike-slip movement of East Gondwana along the MFZ. The earliest sediments overlying the fractured and deformed VSS consist of a wedge-shaped unit (U1) that deposited along the entire LC during the active transform stage. When the spreading centre passed the adjacent segment of the LC in the Mozambique Basin, the depocentre rapidly shifted to the basin, and the LC entered a passive transform margin stage. We propose that the LC results from three successive stages: (1) intracontinental rifting stage with substantial uplift and erosion, (2) active transform margin stage with strike-slip movement along the MFZ, and (3) passive transform margin with a different sedimentary setting.