Strain Analysis of Deformed Metaconglomerates in the Northwest of Konya Region, Central Anatolia

Abstract

The purpose of this study is to estimate strain ratio and determine deformation characteristics of Palaeozoic Mesozoic aged rocks using the metaconglomerate. Marbles, metaclastics and metamagmatics of Silurian-Lower Triassic Sızma Complex are the oldest rocks of the region and they are deformed by pre-Alpine orogeny. This assemblage is overlain unconformably by Triassic-Cretaceous Ardıçlı Group consisting mainly of metaclastic, marble and metachert. Miocene-Quaternary aged continental and volcanic rocks form the unmetamorphosed cover rocks of the region. Both the Sızma Compleks and Ardıçlı Group were deformed folded, cleaved and metamorphosed during the Alpine orogenic events. In the both rock units, metaconglomerates are commonly encountered. The pebbles of metaconglomerates were flattened paralel to the cleavage surface and their long axes were oriented. Metaconglomerates vary greatly in origin according to the composition of the gravel and size, binding materials and textural characteristics. For this reason, strain variations were observed in the rocks. In order to reveal these variations method was used for clast strain and Fry analysis for whole rock strain. The clasts plot within the fields of apparent flattening and apparent constriction and are characterized by kvalues between 2.39-0.31 on the Flinn diagram. Plot on the Nadai (Hsü) diagram shows that Strain magnitude –Es and Lode’s parameter-v values of metaconglomerate ranges between 0,5 -1,5, +0,5 -0,5 respectively. In other words the shape of the pebbles range from oblate or pancake to the cigar-like shape. According to the composition, pebbles of quartz and quartzite are least deformed while the pebbles of originally pelitic rocks are deformed the most. The long axes of the pebbles developed both parallel and perpendicular to the earlieast fold hinges. Similarly, some of the long axes of the pebbles are parallel to the north-south trending tectonic transport directions, where as others are perpendicular.