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During their flow through an area, the streams are used to erode, transport and re-deposit sediments in the number of cycles following the climatic variation in an area. This cycle in turn affect the chemistry of these sediments and hence the geochemical study of these sediments helps to understand the palaeo-climate, source-area weathering and provenance of the study area. In order to understand the geochemical classification of sediments, palaeo-climate, source-area weathering and provenance for stream sediments of the Eastern Ghats Mobile Belt (EGMB), 364 stream sediment samples were collected from the area around Daringbadi, Kandhamal district, Odisha, India and analyzed for major oxides, trace elements and rare earth elements. These sediments are geochemically classified as shaly and wacke type, moderately mature and derived through the high intensity of weathering of source rock under warm and humid climatic condition. The positive correlation between Al2O3 and Fe2O3, MnO, and MgO, indicates multiple sources for sediment and these oxides are associated with clay minerals. The discrimination function diagram suggests a felsic igneous as well as quartzo-sedimentary provenance for these sediments whereas the ratio of Al2O3/TiO2 and concentration of V-Ni-Th suggest a felsic igneous source rock. The high concentration of LREE, slight enrichment of HREE and negative Eu anomaly indicate terrestrial or continental crust source rock. Hence the source rock for these sediments are granite gneiss, charnokite and khondalite present in and around Daringbadi area. [ABSTRACT FROM AUTHOR]

Abstract: We present new major and trace element data, together with U–Pb ages for zircon sand grains from the major tributaries of the Indus River, as well as the adjacent Ghaggar and Yamuna Rivers and from bedrocks within the Sutlej Valley, in order to constrain the origin of the sediment reaching the Arabian Sea. Zircon grains from the upper Indus are generally younger than 200Ma and contrast with those from the eastern tributaries eroded from Himalayan sources. Grains younger than 15Ma, which typify the Nanga Parbat Massif, comprise no more than 1–2% of the total, even in the upper Indus, showing that this terrain is not a major sediment producer, in contrast with the Namche Barwe Massif in the eastern Himalayan syntaxis. The Sutlej and Yamuna Rivers in particular are very rich in Lesser Himalayan-derived 1500–2300Ma zircons, while the Chenab is dominated by 750–1250Ma zircons, mostly eroded from the Greater Himalaya. The upper Indus, Chenab and Ravi yield zircon populations broadly consistent with the outcrop areas, but the Jhelum and the Sutlej contain many more 1500–2300Ma zircons than would be predicted from the area of Lesser Himalayan rock within their drainages. A significant population of grains younger than 200Ma in the sands of the Thar Desert indicates preferential eolian, monsoon-related transport from the Indus lower reaches, rather than reworking from the local rivers. Modelling of observed zircon ages close to the delta contrasts with modern water discharge. The delta is rich in zircons dating 1500–2300Ma, while discharge from modern rivers carrying such grains is low. The modest size of the Sutlej, the richest source of these materials in the modern system, raises the possibility that the compositionally similar Yamuna used to flow westwards in the recent past. Our data indicate a non-steady state river with zircon transport times of 5–10k.y. inferred from earlier zircon dating of delta sands. The modern delta zircons image an earlier, likely Early-Mid Holocene, erosional state, in which the Lesser Himalaya were more important as sediment suppliers. Early-Mid Holocene sands show much less erosion from the Karakoram–Transhimalaya compared to those deposited at the Last Glacial Maximum, or calculated from the modern discharge. We favour variations in summer monsoon intensity as the primary cause of these temporal changes. [Copyright &y& Elsevier]

Abstract: We report rates of Australian dust deposition in New Zealand over the last ~8000 years using records extracted from an ombrotrophic peat bog. The trace element chemistry of deposited dust is used to identify the Australian source areas, and to calculate Australian dust deposition rates in New Zealand. This is used to infer patterns of aridity and climate variability in eastern Australia during the Holocene. Prior to 4800 cal. BP, dust deposition patterns imply that the Australian climate was relatively wet due to an active/persistent monsoon. Southern Australian source regions supplied the majority of dust transported to New Zealand at this time. After 4800 cal. BP the Australian climate became significantly more arid and variable, attributed to the onset of ENSO-type conditions. The Lake Eyre Basin switched on as a dust source, while overall Australian dust deposition in New Zealand increased >4 times. Rates of Australian dust deposition were found to match patterns of increased ENSO variability, which is attributed to the combined effect of enhanced sediment supply to Australian dust source areas (during wet La Niña events) and preferable conditions for dust transport (during El Niño induced drought). Results also show that Australian dust deposition is a significant sedimentary process in New Zealand and is likely to influence both geochemical cycles and soil development suggesting that it may contribute up to 90% of material in the bog. [Copyright &y& Elsevier]