Strengthening the argument for a large Greater India
Jun Meng1, Stuart A Gilder2, Xiaodong Tan3
1State Key Laboratory of Biogeology and Environmental Geology, School of Earth Sciences and Resources, China University of Geosciences Beijing, Beijing 100083, China.
Summary
The Sangdanlin section reveals interlaced Early Cretaceous and Paleocene strata, not a continuous sequence. This finding revises paleogeographic models for the India-Asia collision, suggesting it began 55 million years ago.
Area of Science:
- Geology
- Paleontology
- Geophysics
Background:
- The Sangdanlin section in Tibet is crucial for understanding the India-Asia collision.
- Divergent interpretations exist regarding the age of its strata and paleomagnetic record.
Purpose of the Study:
- To re-evaluate the geologic age and paleomagnetic record of the Sangdanlin section.
- To refine models of the India-Asia collision initiation.
Main Methods:
- Paleontologic analysis
- Petrographic examination
- Paleomagnetic data acquisition and interpretation
Main Results:
- The Sangdanlin section is identified as a thrust complex with interlayered Early Cretaceous (Barremian-Albian) and Paleocene strata.
- Stratigraphic superposition is disrupted by thrust faults, indicating distinct formations of different ages.
- Paleomagnetic data were reassigned to the Early Cretaceous units.
Conclusions:
- The revised dating supports a large extent (2,000–3,000 km) for Greater India.
- The India-Asia collision is constrained to initiation at 55 ± 5 Ma in the western Himalayas.
- Asia's southern margin formation is not attributed to successive accreted terrains but a contiguous Neotethys plate.
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