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Tropical seabirds play a key role in coral island ecosystems, but there are still many uncertainties regarding their paleoecology. Seabird paleoecology was investigated on Nandao Island, Xisha Islands, South China Sea, from sub-fossil remains spanning the past 800 years. Ornithogenic sediments were collected beneath seabird-inhabited shrubs where a large number of seabird/fish sub-fossils were recovered. We used reflectance spectroscopy to show that seabird population size was overall higher during the Little Ice Age (LIA) compared to periods before and after this event. Nonetheless, the number of seabirds also fluctuated during the LIA. Seabird populations on Nandao reached their highest points at 1480–1550 and 1650–1800 CE, respectively, but the population remained low from 1550 to 1650 CE. A large migration of seabirds from Nandao Island to the adjacent Beidao Island, where the population size surged at that time, is hypothesized to explain the corresponding decrease in the seabirds at Nandao. Stable isotope (δ 15 N and δ 13 C) analyses also suggest a change in foraging behavior by seabirds at Nandao during the period 1550–1650 CE. Seabirds at low population size foraged near the island and preyed upon smaller flying fish as inferred from low δ 15 N and high δ 13 C values in fish scales, but fed upon larger flying fish farther from the island during times of high population. This shift in foraging behavior is in accordance with predictions for Ashmole's Halo in that islands with high densities of birds will cause a depletion of resources near the colonies and force more distant foraging away from the colony. [ABSTRACT FROM AUTHOR]

The Tongling district is one of the most important non-ferrous metal producers in China. The origin of Cu-Au deposits in the region is closely related to Late Mesozoic intermediate intrusions, which are mainly high-K calc-alkaline and shoshonitic series. Geochemical characteristics indicate that these granitic rocks are mixtures of more than two compositional end-members, i.e. mantle-derived melts and crust components incorporated through assimilation. Three important magmatic intrusions related to the Cu-Au deposits in the Tongling region - the Jiguanshi quartz monzodiorite, the Xishizishan quartz diorite and the Miaojia diorite porphyry - were selected for this study. Zircon U-Pb dating by LA ICP-MS yielded two groups of ages (∼130-132 and 138-140 Ma) for these intrusions. Pyrite Re-Os age for the Xinqiao Cu-Fe-S deposit in the Tongling region is 126±11 Ma. Trace elements of zircon grains show that the earlier Cu-Au mineralization event was associated with adakitic rocks characterized by high positive Ce anomalies, produced at an elevated oxygen fugacity range. In contrast, later iron-sulphur mineralization was closely related to low positive Ce anomalies, reflecting low oxygen fugacities. Considering that Pacific lithospheric subduction was the dominant factor that controlled major tectonic evolution in eastern China during the Early Cretaceous, the geochemical characteristics of these coeval ore-forming intermediate intrusive rocks in the Tongling district were likely the result of Pacific plate underflow. [ABSTRACT FROM AUTHOR]