GLACIAL AND PERIGLACIAL MORPHOGENETIC ENVIRONMENTS AROUND THE HIDAKA RANGE IN THE WÜRM GLACIAL AGE
GLACIAL AND PERIGLACIAL MORPHOGENETIC ENVIRONMENTS AROUND THE HIDAKA RANGE IN THE WÜRM GLACIAL AGE
复制标题
乌尔姆冰川时代日高山脉周围的冰川和冰缘形态环境
DOI：
10.4157/grj.48.1
复制
发表时间：
1975
期刊：
影响因子：
--
通讯作者：
K. Hirakawa
中科院分区：
文献类型：
--
作者：
Y. Ono;K. Hirakawa
在前一篇论文（Hirakawa & Ono，1974）中，作者描述了十胜平原的地貌演变。揭示了十胜平原地貌演化受十胜川下游海平面变化和上游冲积扇区气候变化的控制。当冰川范围在日高山脉（波罗尻体育场）达到最大值时，十胜平原发生了明显的山谷填充和冲积扇扩张。而在冲积扇区和上游地区，当日高山脉（Tottabetsu Stadial）的冰川作用范围小得多时，沉积和下切都不明显。为了阐明冰川作用与平原地貌演化的相互关系，有必要重建整个地区的地貌环境。本文通过对日高山脉冰川或冰缘地貌、冰缘现象化石、阶地砾石和斜坡沉积物的研究，以及花粉分析，恢复了乌尔姆冰川期的地貌环境。没有这些综合，就不可能把许多零碎的资料联系起来，并加以解释。通过对冰川地形的研究，建立了两个冰川作用基准站，与一般认为较老的冰川地形与里斯冰川年龄相关的观点相反。这两个冰帽的冰川作用所反映的气候条件与同时分析的阶地砾石和斜坡沉积所反映的气候条件是一致的。在每个冰阶期间，该地区的冰川范围、斜坡发育、河流过程和冰缘现象都有很大的不同，如下所述：1）波罗尻冰阶该冰阶的特点是冰川的最大延伸，日高的泥质斜坡沉积物的丰富供应。在平原上的范围和填土梯田/冲积扇的建设。根据冰川地形估计的雪线深度为1200- 1500米，整个山脉的面积应在林木线之外。木材线的降低导致了碎片供应的增加，特别是来自山谷墙壁的碎片。与现今河床的砾石相比，填土顶部阶地砾石的直径较小，圆度较差（图12）。虽然该冰场早期的冰缘现象化石很少，但在后期观察到冰楔铸造和许多内卷（图16）。2)在日高山脉的Tottabetsu Stadial冰川在延伸上比Poroshiri Stadial冰川要有限得多。在波罗尻体育场发掘的大型冰斗中，冰川只占据了一部分（图2）。斜坡沉积物的供应减少。冲积扇区没有明显的沉积和下切迹象。十胜平原上分布着大量的沙丘，冰楔铸造、内卷等冰缘现象十分发育。这些事实使作者能够推断出每个Stadial的形态发生环境如下。波罗尻体育场的气候有利于冰川的延伸;冬季多雪，夏季凉爽。另一方面，户别体育场的气候干燥寒冷，尤其是在冬季（图16）。
In the former paper (Hirakawa & Ono, 1974), the authors described the landform evolution of the Tokachi Plain. I t was revealed that the landform evolution of the Tokachi Plain had been controlled by the sea level changes in the lowest reaches of the Tokachi River and by the climatic changes in the alluvial fan areas or the upper reaches. The conspicuous valley filling and expansion of alluvial fans occurred in the Tokachi Plain, when the glacial extent reached its maximum in the Hidaka Range (Poroshiri Stadial). Whereas neither deposition nor downcutting was remarkable inthe alluvial fan areas and the upper reaches, when the glaciation was much less extensive in the Hidaka Range (Tottabetsu Stadial). In order to clarify the interrelationship between the glaciation and the landform evolution in the plain, it is necessary to reconstruct the morphogenetic environments of the whole region. In the present paper, the authors intend the reconstruction of the morphogenetic envi-ronments around the Hidaka Range during the Wurm Glacial age, through the study of glacial or periglacial landforms, fossil periglacial phenomena, and the analysis of terrace gravels and slope deposits, and also by pollen analysis. Without these syntheses, it is impossible to relate many fragmental data, and to ex-plain them in accordance. Through the study of glacial topography, two stadials of gla-ciation are established, contrary to the generally held view that the older glacial topogra-phy is correlated to the Riss Glacial in age. The climatic conditions suggested by the glaciation of these two stadials are in good agreement with those which are suggested by the analysis of terrace gravels and slope deposits at the same time. During each Stadial, glacial extent, slope development, fluvial process and periglacial phenomena of this region were quite different, as described below: 1) Poroshiri Stadial This Stadial is characterized by the largest extension of the glacier, the abundant supply of muddy slope deposits in the Hidaka. Range and the construction of filltop terraces/allu-vial fans in the plain. As the snow line depression estimated from the glacial topography is 1200- 1500 m, the whole area of the range should have been beyond the timber line. The lowering of the timber line caused an increase in debris supply, especially from the valley walls. The filltop terrace gravels are smaller in diameter and poorer in roundness compared with the gravels of the present river bed (Fig. 12). Though there are few fossil periglacial phenomena in the earlier part of this stadial, ice-wedge cast and many involu-tions are observed in the later part (Fig. 16). 2) Tottabetsu Stadial Glaciation in the Hidaka Range was much more limited in extension than that of the Poroshiri Stadial. Glaciers occupied only a part of the large cirques excavated in the Poro-shiri Stadial (Fig. 2). The supply of slope deposits decreased. And there are no evidences of remarkable deposition nor downcutting in the area of alluvial fans. A number of dunes were distributed all over the Tokachi Plain, and the structures such as ice-wedge cast, involutions and other periglacial phenomena were developed. These facts allow the authors to deduce the morphogenetic environments of each stadial as follows. The climate of the Poroshiri Stadial was favorable to the extension of the glacier ; much snow in winter and cool in summer. On the other hand, the climate of the Tottabetsu Stadial was dry and cold especially in winter (Fig. 16).