Landscape evolution and geodynamic controls in the Gulf of Cadiz (Huelva coast, SW Spain) during the Late Quaternary

OSL and radiocarbon dating of core TBF-1 on the outer shelf of the East China Sea and implications for late Quaternary stratigraphic correlation

The distribution and age of Pleistocene marine terraces fringing the northern Raukumara Peninsula, North Island, New Zealand, is revised. Two terraces, the higher Otamaroa Terrace and the lower Te Papa Terrace, are present from the eastern Bay of Plenty to near east cape. Six optically stimulated luminescence (OSL) ages obtained from the terrace deposits and coverbeds represent the first radiometric ages from these terraces. Loess from the Te Papa Terrace has an age of 62.6 ± 6 ka and the underlying sand has an age of 58.3 ± 4.1 ka. Four OSL ages obtained from sand resting on the bedrock strath of the higher Otamaroa Terrace range from 64.5 ± 4.7 to 79.2 ± 5.5 ka. These OSL ages suggest that the Te Papa Terrace was formed during early Oxygen Isotope Stage (OIS) 3 and the Otamaroa Terrace was formed during OIS 5a. however, global geomorphological and regional loess unit correlations would imply the extensive Otamaroa Terrace correlates with OIS 5e and the loess on the Te Papa Terrace correlates to the Porewan loess of OIS 4, indicating the Te Papa Terrace formed during OIS 5a or earlier. Regardless of terrace age, the morphology of the terraces shows the coastal uplift mechanism is not related to upper plate faults, but is probably driven by deep‐seated subduction zone processes.

OSL chronology of the Huksan Mud Belt, south-eastern Yellow Sea, and its paleoenvironmental implications

Late Pleistocene landscape response to climate change: eolian and alluvial fan deposition, Cape Liptrap, southeastern Australia

Alluvial fans formed from sediments derived from erosion of the Juarez Mountains in northernmost Mexico have a significant flood impact on the Ciudad Juarez, which is built on the fan system. The northern part of Ciudad Juarez is the most active; further south, older parts of the fan, upon which the rest of the city is built, were largely eroded by natural processes prior to human habitation and subsequently modified only recently by human construction. Three aeolian sand samples, collected from the uppermost (youngest) parts of the fan system in the city area, in places where human intervention has not disturbed the sediment, and constrain the latest dates of fan building. Depositional ages of the Quaternary alluvial fans were measured using Optically Stimulated Luminescence (OSL) on aeolian sands that have inter-fingered with alluvial fan material. These dates are: a) sample P1, 31 ka; b) sample P2, 41 ka; c) sample P3, 74 ka, between Oxygen Isotope Stages (OIS) 3 to 5. They demonstrate that fan development, in the area now occupied by the city, terminated in the Late Pleistocene, immediately after what we interpret to have been an extended period of erosion without further deposition, lasting from the Late Pleistocene to Holocene. The three dates broadly correspond to global glacial periods, implying that the cool, dry periods may reflect periods of aeolian transport in northern Mexico in between phases that were wetter to form the alluvial fans. Alluvial fan margins inter-finger with fluvial terrace sediments derived from the Rio Bravo, indicating an additional component of fan dissection by Rio Bravo lateral erosion, presumed to be active during earlier times than our OSL ages, but these are not yet dated. Further dating is required to ascertain the controls on the fan and fluvial system.

When applying luminescence dating to sediment deposited in aquatic environments, a key issue for accurate age determination is resetting of acquired luminescence in sediment by surface exposure (bleaching) before burial. The time needed for bleaching is known to vary among the signals used in three methods: optically stimulated luminescence (OSL), infrared stimulated luminescence (IRSL), and post-infrared IRSL (pIRIR). A comparison of luminescence ages from these different signals is therefore useful to assess whether a sample was fully bleached before burial. In a comparison of OSL, IRSL50/225 and pIRIR225 ages of eight samples of fine-grained sediment from a 294-cm-long sediment core from Lake Yogo, a small-catchment lake in central Japan, the IRSL50/225 and pIRIR225 ages were much older than the OSL ages. The IRSL50/225 residual signals were close to zero, and the difference between pIRIR225 and OSL signals was much larger than the pIRIR225 residual signals. Thus, IRSL50/225 and pIRIR225 signals were not completely bleached, which we attribute to the short sediment transport distance in this small catchment. Five corrected bulk radiocarbon (14C) ages agreed with the OSL ages, except for two intervals in which OSL ages were about 500 and 1,900 years older than the corrected 14C ages. These discrepancies are attributable to incomplete bleaching related to sediment transport, whereas the rest of the OSL ages show no evidence of incomplete bleaching. This study shows that even in samples in which the pIRIR225 and IRSL50/225 signals are not well-bleached, OSL dating yields accurate age estimates because of the faster bleaching rate.

An improved single grain OSL chronology for the sedimentary deposits from Diepkloof Rockshelter, Western Cape, South Africa

Revisiting the slip rate of Quaternary faults in the Iberian Chain, NE Spain. Geomorphic and seismic-hazard implications

Terrestrial cosmogenic nuclide (TCN) dating has emerged as one of the most useful techniques in the last two decades for quantifying geomorphological processes and building the chronology of late Quaternary glacial advances/retreats. The chronology based on TCN and optically stimulated luminescence (OSL) dating of glacial landforms from the northwestern (NW) Himalaya suggests that glaciers responded to a complex interaction between temperature and moisture essentially derived from either of the climate systems, the Indian Summer Monsoon (ISM) and the Mid‐latitude Westerlies (MLW). The discrepancies between the TCN ages obtained on moraine boulders/bedrock surfaces, and the OSL ages on the stratigraphically equivalent deposits, highlighted the need for a detailed investigation. The present study attempts to build the chronology of Quaternary glaciation events in the Karakoram and Ladakh Ranges using TCN dating of stratigraphically constrained moraine boulders and striated bedrock surfaces. The TCN ages from glacially eroded surfaces (GES) having prominent striations are narrowly clustered around the Marine Isotopic Stage‐2 (MIS‐2). Agreement between GES TCN ages and OSL ages on the stratigraphically equivalent moraines suggests negligible geological inheritance. The glacial advance during MIS‐2 can be attributed to the combined effect of reduction in north hemispheric insolation and enhanced westerly precipitation. However, relict non‐glacial surfaces and moraine boulders with minimal ice flow modifications yield wide age distributions, most likely suggesting denudational events (interglacials) and/or contribution from tributary valley flanks.

Accurate chronology plays a crucial role in reconstructing delta evolution. Radiocarbon (14C) and optically stimulated luminescence (OSL) dating are widely used to establish a stratigraphic chronology of the late Quaternary sediments. The Chaoshan plain is located on the southern coast of China and borders the South China Sea. The thickness of Quaternary sediments in this area extends to a depth of 140 m and is considered a valuable archive for studying the evolution of the delta in response to climate and sea-level changes. However, reliable chronological data are still very limited. In this paper, eighteen accelerator mass spectrometry (AMS) 14C and thirteen quartz OSL ages were obtained from two cores from the Rongjiang plain, the middle part of the Chaoshan plain: ZK001 (90.85 m in depth) and ZK002 (100 m in depth). The present study aims to provide a reliable chronology of the Chaoshan plain based on OSL and 14C dating methods and examine the upper limit of the 14C dating on plant remains. Our results show that (1) OSL ages of cores ZK001 and ZK002 range from 56 to 1.7 ka and from 177 to 15 ka, respectively; (2) 14C ages of core ZK002 range from 8.8 to 41 cal ka BP, showing that all 14C ages below ca. 30 m depth are younger than OSL ages and that the upper limit of plant remains is around 35 cal ka BP. OSL ages are consistent with stratigraphic order within uncertainties. The oldest OSL age obtained from core ZK002 is 177 ± 20 ka at a depth of 93 m, and is considered a minimum age. This indicates that the Quaternary deposition in the Rongjiang plain can trace back to at least the marine isotope stage (MIS) 6 during sea-level lowstand, during which the plain is mainly influenced by the fluvial process. The comparison between 14C and OSL ages in the Chaoshan plain suggests that 14C ages older than 35 cal ka BP need to be re-evaluated. However, the OSL dating method proves reliable for establishing a comprehensive chronological framework for the late Quaternary sediments in this area.

The glacial chronostratigraphy for South Westland established by Almond in 1996 was based on the soil stratigraphy of loess coverbeds on glacial landforms in and around Saltwater Forest. Loess sheets and morphologically identified soil features were correlated with global climatic events established by the marine oxygen isotope record. Pollen analysis and few radiocarbon ages supported the chronostratigraphy. In this study, we have used total element, mineral and phytolith analysis, and luminescence dating of loess to test the current correlation of loess/soil stratigraphic units with climatic events. Data from new sections in Okarito Forest have been incorporated. Luminescence dating was found to be of limited value. Thermoluminescence dating yielded unacceptable and low‐precision ages that were anomalously old, and in strati‐graphically reversed sequence. Optical (IRSL) dating removed some of these anomalies but uncertainty about accuracy remained a problem. Some optical ages were significantly younger than associated radiocarbon ages. We suspect the highly weathered nature of the sediments being dated in combination with sediment provenance may be the cause of these effects. Routine optical dating which targets potassium feldspars or quartz cannot be applied in Westland. Loess sheets Lla, Lib, L2, L3, and L4 are now thought to be of Last (Otira) Glacial age. L 1a accumulated in marine oxygen isotope stage (OIS) 2 before 16 ka, but after 24 ka, and Lib also accumulated in OIS 2 but between 24 and c. 36 ka. L2 accumulated during OIS 3 from 45 to c. 50 ka. Loess sheets L3 and L4 are now correlated with OIS 4. Soil alteration in loess sheet L5 indicates significant weathering consistent with deposition before the last interglacial, probably during OIS 6. On the basis of the revised loess stratigraphy, glacial advances M5 and M6, and associated landforms, which have no loess cover, both occurred during OIS 2. Two glacial advances, M4a and M4b, are both assigned to OIS 3, and are thought to have occurred between 45 and 50 ka and c. 24 and 36 ka, respectively. Moraines associated with advances M2 and M3 are conformably overlain by L4 and are correlated to OIS 4. Moraine Ml, which is draped by loess sheets L1‐L5, is thought to be of Waimea Glaciation age (OIS 6). Our present work is consistent with recent studies in Fiordland, which suggest a more complex glacial stratigraphy for the Otiran than is recognised in North Westland.

Luminescence dating of quartz from ironstones of the Xingu River, Eastern Amazonia

At Stoke Goldington in the valley of the Great Ouse in Buckinghamshire a river terrace at a height of about 7 m above the floodplain is underlain by fluvial sediments representing climatic fluctuations in the late Middle Pleistocene. Near the base of the succession, at a level only 1 m above the modern floodplain, a fossil assemblage, including pollen, plant macrofossils, molluscs, insects and ostracods, provides evidence for the local development of herb-rich grassland under temperate climatic conditions. The fossil record, amino-acid racemisation ratios and uranium disequilibrium dating all suggest deposition of this material during Oxygen Isotope Stage 7. The deposits containing the temperate assemblage are immediately overlain by typical cold-climate gravels of the Great Ouse. These have been subjected to a later cut-and-fill episode, with the fill accumulating in cool climatic conditions. The cut-and-fill episode was succeeded by aggradation, forming the overlying terrace surface. Amino-acid racemisation ratios indicate that the fill was emplaced, and the terrace surface created, during or after Oxygen Isotope Stage 5. © 1996 John Wiley & Sons, Ltd.

Comparison between luminescence and radiocarbon dating of late Quaternary loess from the Ili Basin in Central Asia

Quartz OSL and TL dating of pottery, burnt clay, and sediment from Beicun archaeological site, China