Can Terrestrial Grass Tissue Particles from Deep Indian Ocean Sediment Answer the Indian Winter Monsoon Mystery?
Abstract
Phytolith containing tissue particles (PCTP) were extracted from the deep oceanic sediment of the Indian Ocean sediment core YDY09 (water depth of 3520m at 85.960985 N, 9.99351 E). According to the microscopic observations, these tissue particles are composed of 2 to 10 phytolith cells and possibly a matrix of organic matter. Absolute abundance of these PCTP were counted according to the three size classes throughout the past 50 ka B.P. The higher abundances of the PCTP were recorded as 10000 particle/ gram to 20000 particles/ gram, during 17 to 18 ka, 24 to 27 ka, 43 to 45 ka and the absolute abundance was less from 15 ka to present. Considering the taphonomy of the phytoliths, PCTP occur on or in the terrestrial soil profiles. But when transported into the deep oceanic sediment, due to the abrasion and microbial activities along the pathway, the cells should be separated. Thus, preservation of PCTP in Deep Ocean would be unlikely. These PCTP could have resulted from the byproduct of burnt vegetation. But charcoal data from the same core disagree with the fact that the PCTP can be the remains of burnt vegetation. Lack of land masses in the vicinity of the core location render the possible explanation of grass vegetation to be wind-blown in higher amounts into the ocean with strong wind currents [Indian Winter Monsoon (IWM) or Indian Summer Monsoon (ISM)]. If these are blown by IWM wind currents, according to the core location in the Bay of Bengal and present wind patterns over the core location suggests that mid latitude area of a Indian subcontinent [longitude 80° - 110° (East) and the Latitude above 15° (North)] could be the source of these PCTP. Possibility of PCTP to blown by ISM is lower when considering the ISM wind current patterns and lack of land masses over the core location along the ISM direction. IWM has been a mystery of all time due to the lack of direct proxies to trace the IWM strength. Increased IWM strength during Heinrich events and aridity during IWM periods are some available discussions on IWM. Absolute abundance of PCTP may have a correlation with Heinrich events and separate phytolith derived aridity index from the same core shows the higher aridity during PCTP abundant periods. The possibility of using high resolution PCTP records as a direct proxy to reconstruct IWM strength needs to be further investigated. Keywords: Indian Winter monsoon, Phytolith in marine sediment, Aeolian flux, Tissue particles
- Publication:
-
AGU Fall Meeting Abstracts
- Pub Date:
- December 2021
- Bibcode:
- 2021AGUFMPP55B0654T