page_title: Pre-collisional Himalaya
section_title: Problems
hierarchical_section_title: Pre-collisional Himalaya / Concepts / Passive continental margin model / Problems
caption_attribution_description: English: Tectonic Evolution of the Passive Continental Margin Model
context_page_description: Pre-collisional Himalaya is a term describing the arrangement of the Himalayan rock units before the mountain-building process resulted from the collision between the continents of Asia and India. The collision began in the Cenozoic and it is a type locality of a continental-continental collision. The reconstruction of the initial configuration of the rock units and the relationship between them is highly controversial, and major concerns relate to the arrangements of the different rock units in three dimensions. Several models have been advanced to explain the possible arrangements and petrogenesis of the rock units.
context_section_description: Brookfield opposes the model by explaining that in the Lesser Himalaya, thick and well developed strata, younger than Precambrian of age, are absent, while it is very well preserved in Tethyan Himalaya. DeCelles et al. also demonstrated that this model fails to explain the relationship of Greater Himalaya and Lesser Himalaya, along the main central thrust in Nepal. In addition, Spencer et al. achieved contrasting results in the εNd values, revealing a more negative value in Lesser Himalaya compared to both the Greater Himalaya and Tethyan Himalaya, suggesting different sources amongst the sequences. The latter two have values that resemble the Arabian Shield and Eastern Antarctica, which conflict with the Indian Shield source that composes Lesser Himalaya.
caption: Tectonic evolution of the passive continental margin model
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