Indian monsoon climate records from the Palaeogene-Early Miocene soil repositories in the Kangra sub-basin of the NW Himalaya

The Indian monsoon system, a component of the Asian monsoon, was established and evolved during the Cenozoic because of the Himalayan orogeny. Numerous studies have found that its inception is commonly associated with a Late Miocene tectonic event. This is possibly due to voluminous studies conducted on the Neogene Himalayan Foreland Basin (HFB) deposits. However, it is equally essential to explore Palaeogene HFB deposits to improve understanding of the origin of the Indian monsoon and its temporal and spatial evolution during episodes of Himalayan orogeny. Thus, this study focused on identifying seasonal/monsoon climate signatures from the underexplored Palaeogene HFB palaeosols in the Kangra sub-basin using systematic morphological, micromorphological, and representative stable C & O isotope analyses. The studied Palaeogene and Early Miocene-age HFB palaeosols reveal abundant matrix and intrusive pedofeatures indicative of seasonal conditions during their formation, similar to those characteristic of Indo-Gangetic soils formed under the present-day monsoon climate. Most conspicuous evidence includes intermixing and the occurrence of Fe–Mn oxide/sesquioxide pedofeatures and carbonate pedofeatures together. Also, the thick carbonate horizon consists of widely dispersed Fe–Mn oxide nodules/concretions along-with calcareous nodules/concretions. The study is the first of its kind from this part of the HFB deposits and provides additional data documenting seasonal-to-monsoon-like conditions during the Palaeogene, i.e., well before the Late Miocene tectonic episode of the Himalayan orogeny. Further, it paves the way for more such studies on the abundant and well-preserved yet overlooked Palaeogene-dated HFB palaeosols in the NW Himalaya (India).