Vegetation and climate of the Lop Nur area, China, during the past 7 million years

Abstract

Lop Nur in Xinjiang, Northwest China, is located in the lowest part of the Tarim Basin at an altitude of 780 m and experiences an extremely dry climate with an annual precipitation of only 17 mm and a high evaporation rate of 2,728 mm. The pollen and spores from the Late Miocene strata of a borehole in Lop Nur were analyzed with a view to interpreting the paleoenvironmental evolution of Lop Nur. Main types of pollen such as Chenopodiaceae, Nitraria, Ephedra and Artemisia reflect an arid climate. By collating the palynological data in this area as recorded in other literature and by applying the method of Coexistence Analysis, we have obtained the paleoclimatic parameters from Late Miocene to Holocene in Lop Nur. These suggest that temperatures increased from the Late Miocene (10.2°C) to the Pliocene (13.4°C), decreased from Pliocene to Pleistocene (4.7°C), and were more stable from Holocene (12.1°C) until now (11.5°C). The precipitation was stable (about 900 mm) from Late Miocene to Early Pleistocene, then decreased markedly (to about 300 mm) in Middle and Late Pleistocene, and reached its lowest value (17.4 mm) in the Holocene. The changes in paleoclimate at Lop Nur provide new evidence for understanding the uplift of the Qinghai-Tibetan Plateau.

Quantifying East Asian Summer Monsoon Dynamics in the ECP4.5 Scenario With Reference to the Mid‐Piacenzian Warm Period

“…The simulated precipitation in the mid‐Piacenzian shows an increase over East Asia (Figure a, colored areas), which is consistent with the wetter conditions indicated by seven geologic records collated by R. Zhang et al (), including six pollen records (Hao et al, ; Jiang & Ding, ; Li et al, ; Ma et al, ; Wu, ; Wu et al, ) and one fruit‐seed record (Zhao et al, ). Moreover, increased precipitation during the mid‐Piacenzian is a common feature of the majority of PlioMIP1 models (Figure S3).…”

Less Dryland Aridity During Pliocene Warmth

“…However, our simulated drier western region compared to the preindustrial period disagrees with increasing precipitation estimated from rodent paleofaunas, large herbivorous mammals and pollen records during the early Villafranchian in southwestern Europe, which was followed by progressive aridification since the early Pleistocene (Eronen et al., 2010, 2012; Fernández et al., 2007; Jimenez‐Moreno et al., 2013). For Central Asia (Figure 4), pollen records indicate that wet conditions with high precipitation levels (approximately 900 mm) existed in Lop Nur, Xinjiang, Northwest China, during the mid‐Pliocene (Hao et al., 2012), which is consistent with our simulated lower aridity conditions. For West and South Asia (Figure 4), the simulated low aridity likely agrees with the wet conditions shown by the low C 4 respiration of soil carbonate at approximately 3.2–2.2 Ma in Northwest India (Gaur & Chopra, 1984; Sanyal et al., 2004).…”

Late Pliocene vegetation turnover on the NE Tibetan Plateau (Central Asia) triggered by early Northern Hemisphere glaciation

“…According to Zhao et al (2012), the A/C ratio provides reliable semi-quantitative estimates for the moisture variability in steppe/desert environments during the Holocene if (i) annual precipitation is <500 mm and (ii) the sum of Artemisia and Chenopodiaceae (A+C) pollen grains exceeds ~45 % of the total pollen sum. In a number of studies, the A/C ratio has also been applied to pre-Holocene pollen assemblages, such as the Pleistocene (Herb et al, 2015;Koutsodendris et al, 2018), Pliocene (Wang et al, 2006;Cai et al, 2012), and Miocene (Hao et al, 2012a).…”