Geoscience

Contribution of Tibetan Plateau Eco-system to Global Change

The Tibetan Plateau occupies one-fourth of the Chinese land. It has fundamentally ecological and environmental significance to China, Asia and even to the world. The plateau is the water source for main river systems in China, and south Asia; it also acts as an ecological barrier for China in terms of monsoon and air circulation. A minor climatic flux would lead to magnified effects on China and south Asia. Climatic change has been embodied as more severe phenomena across the Tibetan Plateau than the global average, as shown by more dramatic warming. Phenology is a sensitive and critical feature of vegetation, and it could reflect the effects of climate variability and change on vegetation growth. Numerous studies have reported the effects of global warming on phenology of Tibtan plateau vegetation ecosystem. However, they documented inconsistent findings when they were based on different version of data. A research group led by prof. Zhang Yangjian of the Institute of Geographic Sciences and Natural Sciences, CAS has been exploring the impacts of global change on Tibetan plateau vegetation by combining field monitoring and remote sensing for the past several years. Through a synthesis of multiple remote sensing and field monitoring data, Dr. Zhang found that the start of growing season on Tibetan plateau has advanced in the past three decades, with some areas advancing for almost one month. This finding reveals that vegetation on Tibetan plateau has responded positively to global warming. The advancement in vegetation start of growing season may extend the length of the plant growing season and provide richer grass food source for local livestock. This study can be used as a solid theoretic basis for government policy making and formulating sustainable development plan for the Tibetan plateau. Due to its novelty and fundamental impacts caused, the research finding has been published on the American magazine of Proceeding of the National Academy of Sciences (PNAS).

Achievements of Research on Formation Mechanism of the Shilu Iron Ore Deposit

The Shilu iron ore deposit, once known as “Asia’s largest hematite-rich iron ore”, is located in Hainan Province of South China. This super large deposit is mainly hematite, symbiotic or associated with Co, Cu polymetallic mineralization. However, the genesis of the deposit has been ambiguous, owing to the complex geological processes such as polymetamorphism, obvious shearing and mylonitization, and hydrothermal alteration partially or fully obliterate the primary mineral components, textures and structures of host rocks and ore source beds. In recent years, a research group led by Prof. Xu Deru in the Guangzhou Institute of Geochemistry, CAS, revisited the genesis of the deposit. Through a comprehensive study on petrography, mineralogy, structural deformation and the relationship between the deformation and mineralization of the deposit, as well as isotopic dating using Sm-Nd and 40Ar-39Ar methods, it is convinced that the formation of the deposit was related to a series of processes including sedimentation, structural deformation, metamorphism, hydrothermal alteration, etc. The group concluded that the deposit resulted from multi-stage evolutionary processes, i.e. an initial formation followed by several subsequent and overprinting events which, in turn, significantly modified the ores. An updated four-stage metallogenic model is proposed. Hereby, the Shilu deposit is interpreted as a reworked and re-enriched BIF-type (Lake Superior-type) ore deposit. The work was published in Ore Geology Reviews (doi:10.1016/j.oregeorev.2013.01.015). The mining company of Shilu appreciated the new conceptual model, and has applied it to recent exploration actions, which has led to significant new findings of new mineral resources in Shilu mining district.