No abstract

No abstract

In situ detrital zircons U-Pb and Hf isotope analyses from the Min and Jiulong River of Southeast China were carried out to identify sediment provenance and crustal evolution of the northeast Cathaysia Block. Detrital zircons from both rivers displayed similar spectrum peaks at 236, 155, and 110 Ma, but samples from the Min River displayed a distinct Caledonian peak (ca. 460 Ma) and contained more Precambrian particles (ca. 1.8 Ga), which likely stemmed from the upstream area of the Wuyishan terrain. Interestingly, because Taiwan Island cannot supply Caledonian and Paleoproterozoic detrital materials and because the Ou and Jiulong River also lack components from these two populations, it is highly likely that the sediment in the western Taiwan coast partially originates from the Min River. The sediments from the Min River in Fujian are also considered the most likely source of the beach sands of western Taiwan (Chen et al. 2006). However, we stress that the ~1.8 Ga age source in the western Taiwan sediments was found and recognized. Combining U-Pb dating and Hf-isotope suggests that the northeast Cathaysia Block contains some Neoarchean detrital zircons, which derived from the incorporation of juvenile mantle materials and re-melting of ancient crustal substances. The wide ranges of ε Hf (t) value in the Paleoproterozoic and Neoproterozoic demonstrate the re-melting of ancient crustal materials with minor juvenile mantle materials. Phanerozoic zircons stemmed from re-melting and recycling of Proterozoic crustal materials with or without the invasion of juvenile mantle-derived magmas.

It was recognized 50 years ago that coseismic gravity changes take place during a large earthquake.

Heavy metal contamination of aquatic environment has attracted global attention owing to its abundance, persistence, and environmental toxicity, especially in developing countries like Bangladesh. Five heavy metals, namely chromium (Cr), copper (Cu), nickel (Ni), lead (Pb) and zinc (Zn) were investigated in surface and core sediments of the Karnaphuli River (KR) estuary in Chittagong, Bangladesh, in order to reveal the heavy metal contamination history in estuarine sediments and its response to catastrophic events and human activities. The surface sediment was predominantly composed of silt and sand, and the surface sediment was contaminated with Cr and Pb. Based on the 210Pb chronology, the sedimentation rate in the inter-tidal zone of KR estuary was 1.02 cm/a before 2007, and 1.14 cm/a after 2008. The core sediment collected from 8 to 20 cm below the surface mainly originated from terrestrial materials induced by catastrophic events such as cyclone, heavy rainfall and landslides in 2007 and 2008. The values of contamination factor (CF) showed that the sediment became moderately contaminated with Cr and Pb in the last 30 years. The variation and accumulation of heavy metals in core sediment before 2000 was mainly related to natural variations in sediment sources; however, in subsequent years, the anthropogenic inputs of heavy metals have increased due to rapid physical growth of urban and industrial areas in the Chittagong city. In general, the accumulation pattern of heavy metals after normalization to Aluminum in sediments of KR estuary indicated an accelerated rate of urbanization and industrialization in the last 30 years, and also suggested the influence of natural catastrophic event on estuarine environment.