4 results on '"Fujioka, Toshiyuki"'
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2. Impact of Quaternary Glaciations on Denudation Rates in North Pamir—Tian Shan Inferred From Cosmogenic 10Be and Low‐Temperature Thermochronology
- Author
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Kudriavtseva, Anna, Codilean, Alexandru T., Sobel, Edward R., Landgraf, Angela, Fülöp, Réka‐H., Dzhumabaeva, Atyrgul, Abdrakhmatov, Kanatbek, Wilcken, Klaus M., Schildgen, Taylor, Fink, David, Fujioka, Toshiyuki, Gong, Lingxiao, Rosenwinkel, Swenja, Merchel, Silke, and Rugel, Georg
- Abstract
We explore the spatial and temporal variations in denudation rates in the northern Pamir—Tian Shan region using 10Be‐derived denudation rates from modern (n= 110) and buried sediment (2.0–2.7 Ma; n= 3), and long‐term exhumation rates from published apatite fission track (AFT; n= 705) and apatite (U‐Th‐Sm)/He (AHe; n= 211) thermochronology. We found moderate correlations between denudation rates and topographic metrics and weak correlations between denudation rates and annual rainfall, highlighting complex linkages among tectonics, climate, and surface processes that vary locally. The 10Be data show a spatial trend of decreasing modern denudation rates from west to east, suggesting that deformation and precipitation control denudation in the northern Pamir and western Tian Shan. Farther east, the denudational response of the landscape to Quaternary glaciations is more pronounced and reflected in our data. Modern 10Be denudation rates are generally higher than the long‐term AFT and AHe exhumation rates across the studied area. In the Kyrgyz Tian Shan, on average, the highest 10Be denudation rates are recorded in the Terskey range, south of Lake Issyk‐Kul. Here, modern denudation rates are higher than 10Be‐derived paleo‐denudation rates, which are comparable in magnitude with the long‐term exhumation rates inferred from AFT and AHe. We propose that denudation in the region, particularly in the Terskey range, remained relatively steady during the Neogene and early Pleistocene. Denudation increased due to glacial‐interglacial cycles in the Quaternary, but this occurred after the onset and intensification of the Northern Hemisphere glaciations at 2.7 Ma. Tectonic forces create mountains, while climatically modulated erosion breaks them down into sediment that rivers carry to the final depositional basin. This cycle affects global climate over long periods, but it's unclear whether mountain uplift causes climate change or if climate cooling leads to faster erosion and mountain uplift. To tackle these questions, we explore temporal and spatial changes in rates of denudation in the northern Pamir—Tian Shan region and find that rates remained steady during the Neogene and early Pleistocene but increased due to glacial‐interglacial cycles in the Quaternary. We also find that modern denudation rates decrease from west to east. This suggests that tectonic deformation controls denudation in the northern Pamir and western Tian Shan, while further east the denudational response of the landscape to Quaternary glaciations is more pronounced and reflected in our data. Dominant controls on modern denudation rates vary across the mountain range and reflect local factors. Our results highlight how the evolution of mountain belts strongly depends on denudation, which reflects complex interactions between tectonics, climatic changes, and surface processes, and show how in the northern Pamir—Tian Shan region, climate cooling during the Quaternary period resulted in faster erosion rates. Modern denudation rates are higher than paleo‐denudation rates from 2.0 to 2.7 Ma and exhumation rates inferred from thermochronologyDenudation in the Terskey range remained steady during the Neogene and early Pleistocene and then increased in the Quaternary after 2.0 MaThe denudational response to Quaternary glaciations is detectable in the Kyrgyz and Chinese portions of the Tian Shan Modern denudation rates are higher than paleo‐denudation rates from 2.0 to 2.7 Ma and exhumation rates inferred from thermochronology Denudation in the Terskey range remained steady during the Neogene and early Pleistocene and then increased in the Quaternary after 2.0 Ma The denudational response to Quaternary glaciations is detectable in the Kyrgyz and Chinese portions of the Tian Shan
- Published
- 2023
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3. History of Australian aridity: chronology in the evolution of arid landscapes
- Author
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Fujioka, Toshiyuki and Chappell, John
- Abstract
Australian climate and vegetation, known from marine and lacustrine sediments and fossils, varied dramatically throughout the Cenozoic Era, with several warm reversals superimposed on overall drying and cooling. A suite of landforms, including stony deserts, dunefields and playa lakes, formed in response to the advancing aridity but their age generally remained uncertain until fairly recently, owing to a lack of suitable dating methods. Within the last 5 years, the chronology of Late Quaternary fluctuations of lakes, dunes and dust-mantles has been established by luminescence dating methods, and mid-Pleistocene onset of playa conditions in a few closed basins has been estimated using palaeomagnetic reversal chronology. Only recently has it been shown, by cosmogenic isotope dating, that major tracts of arid landforms including the Simpson Desert dunefield, and stony deserts of the Lake Eyre Basin, were formed in early Pleistocene and late Pliocene times, respectively. These landscapes represent a stepwise response to progressive climatic drying and, speculatively, were accompanied by biological adaptations. Recent molecular DNA studies indicate that Australia's arid-adapted species evolved from mesic-adapted ancestors during the Pliocene or earlier, but whether speciation rapidly accompanied the development of stony deserts and other arid geomorphological provinces awaits further studies of arid landscape chronology.
- Published
- 2010
4. Purification of opioid-binding materials from rat brain
- Author
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Fujioka, Toshiyuki, Inoue, Fumiko, and Kuriyama, Masayuki
- Abstract
Opiate receptors were solubilized from rat brain with digitonin and treated with an affinity resin, AH-Sepharose coupled with [D-Ala2, Leu5]enkephalin. The eluted materials from the resin with the opioid peptide had opioid-binding activity. Based on the protein content of the purified materials, 450-fold purification over the solubilized receptors was achieved. Analyses by gel electrophoresis revealed that the purified materials were rich in one polypeptide with a molecular weight of 62,000.
- Published
- 1985
- Full Text
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