ESR studies on bleached sedimentary quartz

Walther, R.; Zilles, D.

doi:10.1016/0277-3791(94)90086-8

Cited by 39 publications

(22 citation statements)

References 4 publications

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“…After deposition, the paramagnetic centers are formed again by radiation emitted from natural radioactive elements and cosmic rays, and then they become changed over time. Previous studies have shown that Ge centers in quartz grains are sensitive to sunlight or grinding, and that these mechanisms effectively could bleach the sediment (Tanaka et al, 1985;Buhay et al, 1988;Ye et al, 1993Ye et al, , 1998Walther and Zilles, 1994). Tanaka et al (1985) suggested that a 3 mm thin layer of the deltaic sands, the ESR signal at g-value of 1.997 (thought to be associated with the Ge center) disappeared completely after only seven hours of bleaching by sunlight.…”

Section: Mechanism Of Ge Centers Bleaching In Glacial Quartz Grainsmentioning

confidence: 95%

Quaternary glacial chronology of the Ateaoyinake River Valley, Tianshan Mountains, China

Jing-bo

Liu

et al. 2009

Geomorphology

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Section: Mechanism Of Ge Centers Bleaching In Glacial Quartz Grainsmentioning

confidence: 95%

Quaternary glacial chronology of the Ateaoyinake River Valley, Tianshan Mountains, China

Jing-bo

Liu

et al. 2009

Geomorphology

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“…The samples were pretreated in the OSL chronology laboratory at the Cold and Arid Regions Environmental and Engineering Research Institute, Chinese Academy of Sciences (CAREERI, CAS), Lanzhou. Previous studies showed that the signal intensity of Ge centers in quartz grains exposed under room nature light did not decrease [5,22], therefore, all samples were treated under natural light condition and no special measurements have been used during this procedure. The procedures of the samples' preparation and measurements could be referred to refs.…”

Section: Methods and Resultsmentioning

confidence: 99%

“…Jin et al [26] found that the Ge centers in the quartz grains from loess could be reset by sunlight within 4 h. An elaborated optical bleaching experiment (in order to observe a very obvious changes of the signal intensity of the Ge centers, the samples were irradiated by Co60 with 920 Gy dose) on the beach quartz sand by Ye et al [27] indicated that the Ge centers in quartz grains were completely disappeared within 1 h. However, a remarkable result in this study is that the intensity of the signal decreased to half within 15 min ( Figure 5(B)). Walther and Zilles [22] also observed that sunlight bleached the Ge centers to zero in about 2 days. Ye et al [28] conducted grinding experiments on the quartz grains that were derived from the debris-flow deposits, and found that the intensity of the Ge centers decreased 38% after the samples were ground for 1minute.…”

Section: Mechanism Of Ge Centers Reset In Quartz Grains and The Reliamentioning

confidence: 91%

“…Ge centers in quartz grains were chosen as dating signals in this study. Previous studies showed that Ge centers were sensitive to sunlight, UV-light, and grinding, and that these mechanisms could bleach them effectively [22,[24][25][26][27][28]. In a pioneering work, Tanaka et al [24] suggested that a 3 mm thin layer of the deltaic sands with an ESR signal at g-value of 1.997 (thought to be associated with the Ge center) disappeared completely after only 7 h of sunlight irradiation.…”

Section: Mechanism Of Ge Centers Reset In Quartz Grains and The Reliamentioning

confidence: 99%

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Glacial advances and ESR chronology of the Pochengzi Glaciation, Tianshan Mountains, China

Jing-bo

Liu

Wang

et al. 2009

Sci. China Earth Sci.

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The Pochengzi Glaciation is a typical glaciation in Quaternary in the Tianshan Mountains. The glacial landforms comprise several integrated end moraines, like a fan spreading from the north to the south at the mouth of the Muzhaerte River valley and on the piedmont on the southeastern slope of the Tumur Peak, the largest center of modern glaciation in the Tianshan Mountains. The landforms recorded a complex history of the ancient glacier change and contained considerable information of the glacial landscape evolution, and dating these landforms helps us understand the temporal and spatial shifts of the past cryosphere in this valley and reconstruct the paleoenvironment in this region. Electron spin resonance (ESR) dating of the glacial tills in the upper stratum from a well-exposed section, end moraines, and associated outwashes was carried out using Ge centers in quartz grains, which are sensitive to the sunlight and grinding. The results could be divided into three clusters, 13. 6-25.3, 39.5-40.4 and 64.2-71.7 ka. Based on the principle of geomorphology and stratigraphy and the available paleoenvironmental data from northwestern China, the end moraines were determined to deposit in the Last Glaciation. The landforms and the three clusters of ages demonstrate that at least three large glacial advances occurred during the Pochengzi Glaciation, which are corresponding to marine oxygen isotope stage 4 (MIS4), MIS3b and MIS2. The landforms also indicate that the glaciers were compound valley glacier in MIS2 and MIS3b and piedmont glacier in MIS4, and the ancient Muzhaerte glacier were 94, 95 and 99 km at their maximum extensions in these three glacial advances.

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“…The samples were prepared in the chronology laboratory at the MOE Key Laboratory of Western China's Environmental System, Lanzhou University, Lanzhou. Previous studies have shown that the signal intensity of the Ge centers in quartz grains exposed under natural room light does not decrease [24,25]; therefore, all of the samples were treated under natural light conditions, and no special measurements were used. The sample preparations and measurements follow the literature [26,27].…”

Section: Methodsmentioning

confidence: 99%

Quaternary glacial geomorphology and glaciations of Kongur Mountain, eastern Pamir, China

Wang

Zhou

Jing-bo

et al. 2011

Sci. China Earth Sci.

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Kongur Mountain is the largest center of modern glaciation on the Pamir Plateau. During the glacial-interglacial cycles of the Quaternary, Kongur Mountain was extensively and repeatedly glaciated, and the glacial landforms from multiple glaciations are well-preserved in valleys, in basins, and on the piedmonts. Dating samples have been collected according to the distribution and weathering of the glacial tills, the relationship among the glacial deposits, and the loess or soil developed on the moraines. Electron spin resonance (ESR) dating of the samples was done using the germanium (Ge) centers in the glacial quartz grains, which are sensitive to both sunlight and grinding. The ages of the glacial deposits can be divided into four clusters, i.e., 13.1±0.8-27.0±2.2, 36.4±3.3-48.7±5.7, 65.6±6.8-86.6±8.9, and 105.6±9.4-178.3±17.8 ka. Six glacial advances in this region have been confirmed, which are equivalent in age to the Little Ice Age (LIA), Neoglaciation, marine oxygen isotope stages (MIS) 2, mid-MIS3, MIS4, and MIS6. The largest local last glacial maximum (LGM L ) occurred during MIS4 rather than the global Last Glacial Maximum (LGM G ) of MIS2, and a glacial advance that occurred during mid-MIS3 was also larger than the LGM G . Furthermore, deeply weathered tills below 3500 m a.s.l. on the western slope of Kongur Mountain, when compared with the ages of the oldest glaciation of the Muztag Ata region, likely occurred prior to the penultimate glacial cycle. The glacial landforms prior to the penultimate glacial cycle on the northern slope are not well-preserved due to erosion after deposition. Several glacial deposits are only speculated to be distributed at higher elevations on the southwest side of the Gaizi Checkpoint. The extensive hummocky moraines on the western slope were formed by multiple glacial advances, and the latest glacial advance corresponded to mid-MIS3.

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ESR studies on bleached sedimentary quartz

Cited by 39 publications

References 4 publications

Quaternary glacial chronology of the Ateaoyinake River Valley, Tianshan Mountains, China

Quaternary glacial chronology of the Ateaoyinake River Valley, Tianshan Mountains, China

Glacial advances and ESR chronology of the Pochengzi Glaciation, Tianshan Mountains, China

Quaternary glacial geomorphology and glaciations of Kongur Mountain, eastern Pamir, China

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