Search

Uplift and exhumation are important factors affecting the preservation of deposits. The anatomy of uplift‐cooling evolution and exhumation in the East Longshou Mountain is of significant research value in understanding changes in the Jinchuan Ni‐Cu‐PGE deposit since its formation. This study uses apatite fission track (AFT) thermochronology to reconstruct the thermal history of the East Longshou Mountain, including the Jinchuan mine, revealing the uplift and exhumation history of the East Longshou Mountain and elucidating the preservation status of the Jinchuan deposit. The AFT ages in the East Longshou Mountain are distributed from 62.3 ± 3.0 Ma to 214.7 ± 14 Ma, with significant differences in ages in distinct areas, the central and pooled ages being consistent within the margin of error. Inverse thermal history models reveal two rapid cooling events associated with exhumation from the Early Jurassic to the Early Cretaceous (200–100 Ma) and since the Miocene (15–0 Ma), the former attributable to the far‐afield response to the closure of the Paleo‐Tethys Ocean and plate assembly at the southern margin of Eurasia, the latter associated with the initial India‐Eurasia plate collision. A slow cooling event from the Early Cretaceous to the Miocene (100–15 Ma) is thought to be related to the arid environment in northwest China since the Cretaceous. These cooling events have diverse responses and cooling rates in different blocks of the East Longshou Mountain: the southwest and centre of which are mainly cooled over 200–120 Ma and 120–0 Ma, with cooling rates of ~0.25 and ~0.33 °C/Ma (~1.25 and ~0.33 °C/Ma in the centre); the Jinchuan mine primarily cooled over 160–100 Ma, 100–15 Ma and 15–0 Ma, with cooling rates of ~1.33, ~0.25 and ~2.00 °C/Ma. These differentiated coolings imply that the uplift of the East Longshou Mountain before the Miocene (~15 Ma) was integral. Strong uplift then occurred in the vicinity of the mining area, which is a critical period for the uplift of the Jinchuan deposit to the surface, meaning that the Jinchuan deposit was exposed no earlier than the Miocene (~15 Ma). Based on mineralization depth information obtained by previous researchers, in conjunction with the calculation and simulation results of this study, it can be seen that the bulk of the Jinchuan intrusion may still be preserved at depth. [ABSTRACT FROM AUTHOR]

Biodiversity can stabilise productivity through different mechanisms, such as asynchronous species responses to environmental variability and species stability. Global changes, like intensified drought, could negatively affect species richness, species asynchrony and species stability, but it is unclear how changes in these mechanisms will affect the stability of above‐ground primary productivity (ANPP) across ecosystems.We studied the effects of a 4‐year extreme drought on ANPP stability and the underlying mechanisms (species richness, species asynchrony and species stability) across six grasslands in Northern China. We also assessed the relative importance of these mechanisms in determining ANPP stability under extreme drought.We found that extreme drought decreased ANPP stability, species richness, species asynchrony and species stability across the six grasslands. However, structural equation modelling revealed that species asynchrony, not species richness or species stability, was the most important mechanism promoting stability of ANPP, regardless of drought across the six grasslands.Synthesis. Our results suggest that species asynchrony, not species richness and species stability, consistently buffers ecosystem stability against extreme drought across and within grasslands spanning a broad precipitation gradient. Thus, species asynchrony may be a more general mechanism for promoting stability of ANPP in grasslands in the face of intensified drought. [ABSTRACT FROM AUTHOR]