Exploration of marl and shale in Ilam for brick production was carried out by Geosciences Development Company. At the beginning of the project, shale and marl units of the formations in the study area were located using geological maps. Geological and stratigraphic data of shale and marl facies were collected. In addition to Garu, Surgah, Gurpey, Pabdeh and Aghajari formations, other formations like Amiran and Lahbari Member of Aghajari Fm. were studied. Based on the field studies, Garu and Surgah outcrops are not significant because they are limited and inaccessible. Also, rocks of Surgah Fm. are shaly limestone and inappropriate for field study and work. During exploration, 103 samples were taken from outcrops and 10 trenches were dug. Amounts of main oxides were measured and XRD analysis was performed. Geological – topographic map of shale and marl outcrops at 1:100000-scale was prepared using available geological, topographic maps. Sampling and trenching points were specified on the map. Based on the results of the study of sampling and trenching points, samples taken from trenches No. T2 & T4 of Gurpey Fm., T5 of Amiran Fm., T3 of Lahbari Member of Aghajari Fm., T6, T7 & HIS-1 of Aghajari Fm. were selected and sent to a lab for baking test. The results of baking test for all 7 samples were positive. The maximum compressive strength belonged to sample HIS-1 of Aghajari Fm. (363.6 kg/cm2) and the minimum belonged to T2 of Gurpey Fm. (198 kg/cm2). The test was performed at 1100 degrees centigrade. 4 samples out of 7 samples were selected for volume annealing test at a factory. The 4 samples include T5 of Amiran Fm., T4 of Gurpey Fm., HIS-1 of Aghajari and T3 of Lahbari Member of Aghajari Fm. Bricks produced from samples T5 and T4 were appropriate built-in bricks while samples HIS-1 and T3 did not have suitable strength. Firing (baking) temperature was 1050 degrees centigrade. Due to the inappropriate results of samples HIS-1 and T3 at 1050 degrees centigrade, the samples were tested again at 850 degrees centigrade in a lab. Compressive strength of sample HIS-1 deceased to one third of its strength at the first test (7/122 kg/cm2). The compressive strength of T3 was inappropriate again (2.25 kg/cm2). In general, the results of the tests performed at 1100 centigrade degrees were better and more proper.
Sampling points, test results and prior exploration zones were shown in the map of shale and marl outcrops (1:100000 and 1:250000 scales) and finally, some suggestions were presented for semi-detailed exploration.