Introduction and Background: Quaternary is the newest life span of the planet. Contrary to the shortness of time, evidences show the diversity and significance of the events that took place. Aims: In this paper, based on the of climate and Structural geomorphology, the history of natural changes in the Cheshmeh-Langan Basin located northwest of Isfahan province during the late quaternary period has been studied. Methodology: This basin is located in central part of Zagros mountain range and Sanandaj–Sirjan zone and Zagros' fault passes from its west. In order to achieve such a goal, using available climatic data and combining it with Write method, the temperature was measured in the last glacial period and the morphology of the area was rebuilt at that time. Also, Morphological indices of active tectonic have been measured using Digital Elevation Model from topography in accuracy of 30 m in ARCMAP, ARC INFO, and GOLOBAL MAPER software.
Conclusion: According to the evidence given, at the last Quaternary glacial phase, 72 Percent of the zone has been covered constantly with snow and ice. In such these conditions, the snow cumulated over mountainous cirques may have formed the glaciers inclined toward the foot of a mountain and U-shape valleys. These secondary glaciers have been extended after connecting each other in direction of general earth slope and directed to out of the basin. There are many valleys in this area in V form and not only their orientation has no correspondence with glacial directions, but also they intersect glacial directions. Studying different indices indicating dynamic tectonic and the faults of the zone reveals that after the last glacial period, the faults have been active in this zone, caused new tectonic movements. That has led to a renewal of the erosion cycle and has transformed the area into a decaying plateau. These matters are matched with Theodore Oberlander theory about Zagros stream. Accordingly, it is expected that in the future, the erosion rate in the area will still be high and tidal activities will also occur.
Aims: Murghab River is one of the main tributaries of the Zayandeh River. There have been no significant Neotectonic studies conducted in the river's basin. However, Shazand, Khansar and Dalan faults cross the basin. This study aimed to investigate the possibility of Neotectonic activities in a part of the Murghab basin near the Shazand fault. Methodology: A digital height model with an accuracy of 30 meters was prepared for this area and the geological layers were added afterward. The basin was divided into 18 sub-basins and Hi, Bs, Af, SL, S, Facet%, and V indices were calculated using Arc Map, Arc View and Global Amper software. The relative index of Active tectonics (IAT) was calculated, as well. Field visits were used for the complementary studies. All data were combined in the final analysis. Findings: The relative index of active tectonic (IAT) shows that the majority of the sub-basins are active and semi-active. Along fault, some displacements were observed in the Slikenside of the fault. The network of streams in the Murghab Basin shows evidence that some of the streams have rotated 90-degree, which approves Neotectonic activities and lowering of the lake base level and its rupture in the studied area. Conclusion: other nearby studies provide some evidence of the Shazand fault activity in this area. Highly likely tectonic activities in the future might be dangerous for people and facilities in the area and policymakers need to take it into consideration in future planning.
