Chronology of relict lake deposits in the Spiti River, NW Trans Himalaya: Implications to Late Pleistocene–Holocene climate-tectonic perturbations

Tectonic versus climate influence on landscape evolution: A case study from the upper Spiti valley, NW Himalaya

“…In particular, large-scale mass movements (landslides) in the Spiti valley (Mane and Hansa, Fig. 1) have been attributed to intensified monsoon (Bookhagen et al, 2005;Phartiyal et al, 2009). However, the role of regional tectonic instability in triggering landslides has not been sufficiently explored in the Himalayan region.…”

“…landslide debris, Bhargava and Bassi, 1998;Bookhagen et al, 2005) and few lacustrine outcrops in the Lingti valley and Hansa palaeo-lake sediments (e.g. Phartiyal et al, 2009). The Spiti valley shows extensive lake outcrops that were deposited due to the landslide damming of the Spiti River during the geologic past; however, not all the deposits are chronologically constrained.…”

“…In the present work, we have investigated only the early Holocene palaeo-lake sediments formed by the landslide damming near Mane village (hereafter referred to as Mane palaeo-lake) in the upper Spiti valley. Previous dating on the Mane palaeo-lake sediments indicates an early Holocene age: 14 C dates show lake existence between 8.7 and 6.1 cal ka (Bookhagen et al, 2005), while Optically Stimulated Luminescence (OSL) dating indicates age boundaries between 13 ± 2 ka to 8±1 ka (Phartiyal et al, 2009). Based on the inferred age of the Mane landslide in the Spiti valley, and its comparison with the monsoon proxy records, Bookhagen et al (2005) and Phartiyal et al (2009) have suggested that this landslide occurred during the early Holocene intensified monsoon period.…”

“…Previous dating on the Mane palaeo-lake sediments indicates an early Holocene age: 14 C dates show lake existence between 8.7 and 6.1 cal ka (Bookhagen et al, 2005), while Optically Stimulated Luminescence (OSL) dating indicates age boundaries between 13 ± 2 ka to 8±1 ka (Phartiyal et al, 2009). Based on the inferred age of the Mane landslide in the Spiti valley, and its comparison with the monsoon proxy records, Bookhagen et al (2005) and Phartiyal et al (2009) have suggested that this landslide occurred during the early Holocene intensified monsoon period. However, the continuously deposited Mane palaeo-lake sediments have a high potential of recording tectonic perturbations and providing data on the long-term stability of the region.…”

“…For this we have (i) undertaken field mapping of geomorphic features and palaeo-lake sediments in the upper Spiti valley; (ii) analysed digital elevation models to evaluate geomorphic parameters for active deformation in the region; (iii) for the first time, compiled a detailed tectonic map of the upper Spiti valley based on previously published and new data from our study; (iv) examined the Mane palaeolake sediments for evidence of neotectonic activity; and (v) compared the timing of the Holocene (Mane) landslide with the newly available (Fleitmann et al, 2003), (b) Arabian sea core (Gupta et al, 2003), (c) paleoclimate records from central Asia (the area shown in red dotted line), (Herzschuh, 2006), (d) Western Tibetan lakes (Van Campo and Gasse, 1993), (e) Tsokar lake (Demske et al, 2009). (B) The geologic succession and tectonic map of the Spiti valley (compiled after Mohindra and Bagati, 1996;Bhargava and Bassi, 1998;Steck, 2003;Phartiyal et al, 2009;Hintersberger et al, 2010). The seismites and landslides reported from the region are also shown.…”