Geochemical evidence of pollutants from coalfired generating stations in late Pleistocene palaeosols in the Dalijia Shan, northwestern China
Surface palaeosols in two tills and a diamicton from an area in northwestern China were analysed for geochemical pollutants. Elevated levels of Br, As and Sb indicate that pollution from coal-burning and/or coal-fired electricity generating stations is delivered by aeolian transport into palaeosols dating from the last glaciation. Because the climate in the field area is sub-humid (precipitation <760 mm) the relative movement of soluble elements in palaeosols dating from early and late stades of the last glaciation is not expected to be high. The glacial and aeolian parent materials of the palaeosols indicate differences that are probably related to their source areas and to the incorporation of geochemical pollutants.
Extractable FeAl and geochemistry of late pleistocene paleosols in the Dalijia Shan, western China
Surface paleosols in two tills and a diamicton were analyzed for extractable Fe and Al and to determine if elemental distributions would assist in the interpretation of past and present soil-forming environments. Extractable Fe and Al distributions indicate that leaching (based on movement of Fep) is pronounced in paleosols dating from the last glaciation. Moreover, analysis of oxalate extractable Fe and dithionite extractable Fe (FeoFed) shows that amorphous Fe increases with depth in all three paleosola with similar rates of conversion to crystalline Fe. Data for extractable forms of Al-oxides show somewhat higher values of pyrophosphate extractable Al with time. Because the climate in the field area is dry (precipitation < 760 mm) the amounts of crystalline Fe (Fed) in paleosols dating from early and late stades of the last glaciation are not high. Using values in the paleosol sola the difference amounts to 0.4%. Pyrophosphate extractable Fe shows a pronounced increase in the two older paleosols that may result from interstadial paleoclimates of the last glaciation. The geochemistry of the glacial and aeolian sediments (paleosols) indicates differences that they are probably related to the source areas of the different parent materials.
Taphonomy of Isisfordia duncani specimens from the Lower Cretaceous (upper Albian) portion of the Winton Formation, Isisford, central-west Queensland
Taphonomic analysis of fossil material can benefit from including the results of actualistic decay experiments. This is crucial in determining the autochthony or allochthony of fossils of juvenile and adult Isisfordia duncani, a basal eusuchian from the Lower Cretaceous (upper Albian) distal-fluvial-deltaic lower Winton Formation near Isisford. The taphonomic characteristics of the I. duncani fossils were documented using a combination of traditional taphonomic analysis alongside already published actualistic decay data from juvenile Crocodylus porosus carcasses. We found that the I. duncani holotype, paratypes and referred specimens show little signs of weathering and no signs of abrasion. Disarticulated skeletal elements are often found in close proximity to the rest of the otherwise articulated skeleton. The isolated and disarticulated skeletal elements identified, commonly cranial, maxillary and mandibular elements, are typical of lag deposits. The holotype QM F36211 and paratype QM F34642 were classified as autochthonous, and the remaining I. duncani paratypes and referred specimens are parautochthonous. We propose that I. duncani inhabited upper and lower delta plains near the Eromanga Sea in life. Their carcasses were buried in sediment-laden floodwaters in delta plain overbank and distributary channel deposits. Future studies should refer to I. duncani as a brackish water tolerant species.