干旱区生态环境知识资源中心

In the arid environment, due to the scarcity of a continuous terrestrial archive, lacustrine sequences are often employed as a paleoenvironmental repository. However, numerous spatial and temporal heterogeneities exist concerning previously studied sites in arid central Asia. Furthermore, surveys using a XRF core scanning technique on lacustrine sequences retrieved in hyperarid desert settings are largely rare. Hence, two parallel sediment cores (ONW I; ONW II) were retrieved from Orog Nuur, in the Gobi Desert of Mongolia. Continuous, high-resolution elemental abundances at a 1-cm scanning step size were examined in core ONW II using XRF core scanning. To constrain the data quality, elements with high error margins relative to measured peak areas and those elements/proxies below the significance level during the multivariate statistics are excluded for environmental/provenance implications. Based on multivariate statistical evaluation, the bulk-geochemistry of the core sediments are governed by (1) grain-size composition, (2) authigenic productivity (Ca, Cl, CaCO3) in an alkaline environment, (3) allochthonous organic material (TOC and C/N-atomic), and (4) terrigenous input via fluvial inflows, as well as quasi-constant aeolian input through the late Quaternary (Al, Si, K, Ti, and Fe). Disparate source lithotypes, as well as authigenic productivity of the lake system existed before and after Termination I. The Holocene was dominated by a distinct high productivity alkaline environment with more felsic and alkaline input relative to the late Pleistocene. This might be attributed to an increased hydrodynamic strength of riverine inflow and/or intensified erosion and weathering of felsic source rocks in the upper catchment of the Orog Nuur. Therefore, in order to gain a better understanding of the bulk-geochemistry of lake sediments, the coupled provenance and environmental signatures, as well as land surface processes in the catchment need to be systematically discerned. Thus, the XRF core scanning data obtained in this study would have practical and complimentary merit for other lacustrine studies focused on the desert realm across the globe.