Analysis of paleiclimateshit emphasis on the ferequency Ostracoda (case study :Arjan l plains lakecatchment


tehra-shahid beheshti-


Extended Abstract
1- Introduction
Understanding the current climate change conditions and planning for the future requires the knowledge of paleoclimatic conditions which has been studied less in Iran. Although there are diverse methods to detect these changes, to select the proper one, the range of time period, environmental conditions and data access should be taken into account. Due to the time frame and conditions of these studies and the facilities available to choose the best way to inevitable. According to the available facilities and conditions in the study area, this study is based on the frequency macrofossils (Ostracoda) to determine the appropriate indicator of past climates is taken.

9 core purpose of the depth of 1 to 3 meters from the lake plain Gulf Arjan was removed. The sediments in the sections to separate and count 5CM Ostracoda it was divided. To determine the exact age of sediments, dating was conducted using C14. Calculating the sediment load and sediment song in a different lake depths, the counting and the prevalence of different depths of Lake Ostracoda spent. Finally, 15 climate zones during the course of 11 thousand years Arjan Gulf Plains region were identified and introduced. Became clear during this volatility in the number Ostracoda there at different times that show the natural fluctuations in climate, this region.
11 thousand years ago, climate region later than times more saline and warmer was. But in later periods longer period of up to about 2000 years ago, despite the climate of this region to cold damping is gone. Then to the present Covenant to climate warmth and dryness is gone.
Some of these zones, which included a long period, would have been to suggest climate change is too slow and some climate in the far shorter period of a few hundred years has experienced drastic changes. But the overall climate in the area of 11 thousand years ago since the Holocene period to warmth and dryness is gone.