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STEFANO ANDREUCCI MARK D. BATEMAN CLAUDIO ZUCCA SELIM KAPUR İHSAN AKŞIT ADAM DUNAJKO VINCENZO PASCUCCI 《Sedimentology》2012,59(3):917-938
A multi‐disciplinary approach was followed to investigate two thick palaeosol strata that alternate with wind‐blown dominated deposits developed along the Alghero coast (North‐west Sardinia, Italy). Optically stimulated luminescence ages reveal that both palaeosols were developed during cooler drier periods: the first one at around 70 ka Marine Isotope Stage 4 and the latter around 50 ka (Marine Isotope Stage 3). In contrast, the pedological features indicate that the palaeosols underwent heavy weathering processes under warm humid to sub‐humid conditions, characteristic of the Sardinian climate during the last interglacial stage (Marine Isotope Stage 5e). To reconcile this apparent data discrepancy, a range of sedimentological and pedological analyses were conducted. These analyses reveal that the palaeosols possess a complex history, with accumulation and weathering occurring during Marine Isotope Stage 5e, and erosion, colluviation and final deposition taking place during the following cold stages. Thus, even if these reddish palaeosols were last formed during the glacial period, the sediments building up these strata probably record the climate of the last interglacial stage (Marine Isotope Stage 5e). Trace element and X‐ray diffraction analyses, together with scanning electron microscope images, reveal the presence of Saharan dust in the parent material of the palaeosols. However, no evidence of any far‐travelled African dust has been observed in the Marine Isotope Stage 4–3 aeolian deposits. It is possible to conclude that in the West Mediterranean islands, Saharan dust input, even if of modest magnitude, is preserved preferentially in soils accumulated and weathered during interglacial stages. 相似文献
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Vivesh V. KAPUR Kamlesh KUMAR Pranav J. PANDYA Amit K. GHOSH Arindam CHAKRABORTY Anupam SHARMA Gaurav CHAUHAN M. G. THAKKAR 《《地质学报》英文版》2022,96(6):1867-1883
The oldest Asian record of alpheid shrimps, assigned to genus Alpheus, based on snapping claw fingertips from the Miocene Khari Nadi Formation in the Kutch Basin, western India reported herein, extends the fossil record of the family Alpheidae from Asia by ~22 million years. An early Miocene (Aquitanian) age is estimated based on the associated assemblage of calcareous nannofossils, Sphenolithus disbelemnos, Cyclicargolithus floridanus, and Reticulofenestra haqii. The co-occurring microbiota includes bony fish otolith remains, identified as “genus Gobiidarum”, isolated teeth of Dasyatis rays, Sphyrna sharks, and teleosts, ctenoid and placoid scales, ostracods, belonging to the genera Paractinocythereis, Alocopocythere, Ruggieria? Aglaiocypris, Bairdoppilata, and echinoid spines. Taken together, the microfossil assemblage and data from chemical analyses using Energy Dispersive Spectroscopy, X-Ray Diffraction and Wavelength Dispersive X-Ray Fluorescence of host and associated lithologies suggests prevalence of a shallow (neritic) to coastal marine (intertidal) depositional paleoenvironment. 相似文献
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This paper reviews research on coprolites from India, providing the first evidence of microcoprolites from the early Miocene (Aquitanian) Khari Nadi Formation sedimentary succession, exposed about 1.5 km northeast of the village of Kotada, Kachchh (Kutch) District, Gujarat State, western India. Morphometric and size comparisons (in a statistical framework) with known coprolites from the Mesozoic-Cenozoic successions of India (including those recorded herein) and globally suggest that fishes were the likely producers of the Kotada coprolites. Scanning electron microscopy confirms the presence of fish dental remains within the coprolites, while both Scanning Electron Microscopy (SEM) and Energy Dispersive X-ray Spectroscopy (EDS) reveal the phosphatic nature of the microscopic coprolite specimens (recorded herein) hinting that the producer(s) were predominantly carnivorous (ichthyophagous) in their diet. Furthermore, X-Ray Fluorescence (XRF) analysis of the host and associated lithologies allows us to deduce that the Kotada coprolites were deposited in a shallow marine environment, with possible aerial exposure of the host lithology occurring at some point after deposition. To the best of our knowledge, the present report is the first record of microscopic fish coprolites from India, as well as being the first from the Aquitanian of India and the oldest Neogene record from India. 相似文献
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