OSL ages and pedogenic mode of Kobresia mattic epipedon on the northeastern Qinghai-Tibetan Plateau

Kobresia mattic epipedon (ME) is widely distributed on the Qinghai-Tibetan Plateau (QTP) and alpine areas worldwide, which plays a pivotal role in maintaining regional ecological stability. However, the time of ME formation and development is still unclear, which limits the understanding of pedogenic mode of alpine soils on the QTP. In this study, the optically stimulated luminescence (OSL) dating method was used to determine 54 dating samples from 45 MEs on the northeastern QTP (NE-QTP), the deposition rate (DR) and mass deposition rate (MDR) of MEs were calculated based on the OSL sampling depth, OSL age and bulk density (BD). The provenance of ME parent materials was identified by the soil grain-size composition, elemental geochemistry characteristics and bleachability of luminescence signals analysis. The results show: (1) aeolian dust deposition played an important role of ME parent materials; (2) modern ME formed mainly in the Late Holocene (similar to 3 ka) and concentrated during similar to 1.4-0.2 ka. It took average 0.9 ka for a majority thickness of similar to 20 cm ME formation; (3) the average DR of MEs was 0.3 +/- 0.04 mm center dot a(-1), and MDR was 346.3 +/- 45.9 g center dot m(-2)center dot a(-1), which was close to the flux of modern atmospheric fallen dust; (4) the formation of most MEs followed an aeolian dust aggradation mode.

Automated summary

This study used the optically stimulated luminescence (OSL) dating method to determine the formation time of Kobresia mattic epipedon (ME) on the northeastern Qinghai-Tibetan Plateau (NE-QTP). The results showed that aeolian dust deposition was an important source of ME parent materials, and modern ME formation mainly occurred in the Late Holocene, taking an average of 0.9 ka to form a majority thickness of about 20 cm ME. The average deposition rate (DR) of MEs was 0.3 +/- 0.04 mm·a-1, and the mass deposition rate (MDR) was 346.3 +/- 45.9 g·m-2·a-1, which was similar to the flux of modern atmospheric fallen dust. Most MEs were formed by aeolian dust aggradation.