Chronology and climatic implications of Late Quaternary glaciations in the Goriganga valley, central Himalaya, India

• Geomorpholocgical mapping reveals four Stages of Glaciation with decreasing magnitude.
• Stratigraphically constrained OSL dates suggest glacier expansion during LGM.
• LGM glaciation was associated with temperature decline and enhanced westerlies.
• Phase of deglaciation started with the onset of Indian summer monsoon.

Goriganga valley, which is located in the transition zone between the dry steppe of the Tibetan plateau in the north and the sub-humid Himalayan climate in the south, has preserved four events of glaciation with decreasing magnitude. The oldest Stage-I glaciation is represented by a ∼12.5 km long discontinuous diamictite ridge which terminates north of Rilkot (∼3100 m asl). The Stage-II glaciation is represented by sub-rounded and partially eroded lateral moraines and terminates around Martoli village (∼3240 m asl). The Stage-III and IV glacial moraines are sharp crested, unstable and terminate proximal to the present day glacier at ∼3640 m asl and ∼3740 m asl respectively. The Stage-II moraines have been optically dated between 25 ± 2 ka and 22 ± 1 ka implying that glacier expanded during the global Last Glacial Maximum (LGM). This is contrary to the suggestion that during Last Glacial maximum (LGM) glaciation was limited in extent due to weak Indian Summer Monsoon (ISM) in the monsoon dominated regions of the Himalaya. We ascribe the LGM glaciations to a combination of the lowered temperature and enhanced mid-latitude westerlies. Following the LGM glaciation, Goriganga valley experienced two major pulses of deglaciation. The older event is dated between 16 and 12 ka and is coeval with the initiation of the ISM whereas the younger events (10−8 ka) represent the early to mid-Holocene strengthened ISM. The Stage-III and IV glaciations which terminated proximal to the modern glacier are speculated to occur during the mid-Holocene and Little Ice Age (LIA) respectively.