The High Glacial (pre-LGM and LGM) glaciation of SE-Iranian mountains exemplified by Kuh- i -Jupar massif in The Zagros (Part two
Subject Areas : Geopolitic
1 - ندارد
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Abstract :
The three end moraine ramps are followed by outwash aprons (incline ation:7 to15 (Kْuhle 1984; 1989; 1990). In the farther piedmont area their material become moreand more sorted and layered (cf. Fig. 5). In the following text the whole form of afrontal moraine with its Outwash apron is described as “Bortensander”, i. e. icemarginal ramp (IMR). It is marked by the change from polymict coarse bouldermaterial “floating” chaotically and isolated in a fine material matrix to a well-sortedglaciofluvial, steeply bedded gravel body (cf. Fig.5).Due to the fact that, in relation to the glacier feeding area in the interior of theKuh-i-Jupar massif, the piedmont glaciation of the northern mountain foreland (cf.Fig.7) is very extended (see 5.), the glacier margin did not react to minor fluctuationsof the snow line. So, an uplift of the ELA after the glacier advance only resulted in adecreasing thickness of the ice margin, but not in a glacier retreat. This is verifiable bythe truncation of frontal moraines (Fig.5B), which initially had been upthrusted by theadvancing ice margin (Fig. 5A). The advancing ice margin was inevitably- for this hascaused the advance- the thickest. With the then decreasing, thawing-out ice margin,the supraglacial meltwater, which first seeped through the frontal moraine (Fig.5A),finally removed it and displaced it glaciofluvial edimentis. Owing to this, a horizontalchange of material developed in the IMR. This process also led to the truncation of theprimarily steeper glaciofluvial layers in the distal area of the IMR and to the coveringof this unconformity by less inclined layers of gravel (Fig. 5B right half).In the area of the old moraines, up to three levels of the ice surface of thethawing-out piedmont glacier margin are verifiable by exposures in distal IMRsectionsof this kind (Fig. 6 and Photo 5).In the SW-slope of the Kuh-i-Jupar two glacier lobes reached down into theforeland (Fig. 7). A glacier flowed down from the Dare Balutschi and Dare Bidestan inthe E (Fig. 2), but no end moraine has been preserved to mark its lowest ice marginposition (Fig. 7). W of this valley exit a 30 to 40 m-high old end moraine ridge runs down to the southwestern foothill chain at 2’550 m (Fig. 4: southeastern most bolddrawnred moraine with IMR). There the piedmont lobe, which flowed down from thehigh summits of the Kuh-i-Jupar main ridge (Fig. 2 between No. 1 and 8) and met thefoothill chain, was diverted up to the end of this chain in a westward direction. Itstongue basib as well as its fringe were strongly reworked by glaciofluvial and fluvialmorphodynamics which, because of the diversion, were especially concentrated. Herein the W, the southwestern piedmont glacier of the Kuh-i-Jupar reached its lowest icemargin at c. 2’450 m a.s.l. during the Older Glaciation (Fig. 7).