Early Oligocene—Late Miocene Wildfire History in the Northern Tibetan Plateau and Links to Temperature-Driven Precipitation Changes

Yunfa Miao,Hong Chang,Lin Li,Feng Cheng,Carmala Garzione,Yongheng Yang

doi:10.3389/feart.2022.850809

Abstract

Late Cenozoic wildfire evolution in Inner Asia has been attributed to both ice-volume modulating precipitation changes and surface uplift of the Tibetan Plateau. Whether this is the case or not requires additional research and wildfire records from older periods. In this study, 251 microcharcoal samples from the Huatugou section in the western Qaidam Basin are used to reconstruct the early Oligocene-middle Miocene wildfire history of the northern Tibetan Plateau. The results show that wildfires remained relatively frequent before ∼26 Ma, then reduced gradually until ∼14 Ma, and finally increased slightly but still at low level between 14 and 12 Ma. The wildfire variations can be correlated to the steppe-based dryness changes, and both of which are coincident with global temperature changes. We infer that mean annual temperature might have played a dominant role in controlling wildfire frequencies in the northern Tibetan Plateau through modulating atmospheric moisture content. This conclusion is in line with previous studies including microcharcoal-based wildfire records of 18–5 Ma successions from the Qaidam Basin as well as soot-based wildfire records from Quaternary glacial–interglacial cycles of the Chinese Loess Plateau.

Highlights

The Earth’s surface has experienced wildfires since the appearance of terrestrial plants around 420 million years ago (Ma) (Scott and Glasspool, 2006)
We focus on sedimentary records of the microcharcoals from the Qaidam Basin to reconstruct the early Oligocene-middle Miocene wildfire history of the northern Tibetan Plateau, and integrate this new record with our previous reconstruction from the same basin for the middle Miocene-early Pliocene (Miao et al, 2019), to assess the drivers of wildfire in this region over a long period
We present a new microcharcoal dataset of 251 samples from the early Oligocene-late Miocene section in the western Qaidam Basin, northern Tibetan Plateau

Summary

Introduction

The Earth’s surface has experienced wildfires since the appearance of terrestrial plants around 420 million years ago (Ma) (Scott and Glasspool, 2006). Wildfire is driven by factors such as carbon-rich vegetation, seasonally dry climates, atmospheric oxygen, widespread lightning, and volcanic ignition sources (Bowman et al, 2009). Charred grass cuticles from tropical Africa have been used as a proxy for late Cenozoic wildfires, which indicates essentially dry periods since 8 Ma (Morley and Richards, 1993). In East Asia, the high-resolution soot record shows unique and distinct glacial–interglacial cycles that are synchronous with marine δ18O records, suggesting that aridity, which was driven by global ice volume, controlled wildfire intensity during the past 2.6 Ma (Han et al, 2020). Similar correlations between global temperature and regional wildfire intensity have been found in the northern Tibetan Plateau for the middle Miocene-early Pliocene (18–5 Ma) period, while tectonic activities of the northern Tibetan Plateau may have only played a secondary role (Miao et al, 2019)

Results

Discussion

Conclusion