INTERNATIONAL JOURNAL OF SCIENTIFIC & TECHNOLOGY RESEARCH VOLUME 10, ISSUE 07, JULY 2021 ISSN 2277-8616 81 IJSTR©2021 www.ijstr.org Infrared Analyzes And New U/Th Dating Of Travertine (Erfoud’s Radier, Morocco): Consequences On Global Climatic Variations Samer Farkh, Soumaya Hamieh, Louis Rousseau, Bassel Ismail Abstract: The aim of this work is to study the climate variations on a global scale by providing new radiometric data from the travertine of Erfoud’s Radier. This travertine is formed of two units, lower and upper, separated by a discontinuity surface. Our U/Th dating allowed to position the lower unit between 262 ka and 177 ka, which is contemporary with isotopic stages 8 and 6. As for the upper unit, it is between 30 ka and 11 ka, contemporary with isotopic stage 2. The even isotopic stages indicate that the climate was cold in Europe at that time while it was hot and humid in Morocco, favoring the formation of this travertine. From the obtained data, this study can rely on the climatic correspondence hypothesis described by Petit-Maire for the last two climatic extremes (18000 ± 2000 and 8000 ± 1000 ka) in the world, could be extended for a long time. Index Terms: Travertine, Morocco, Erfoud, U/Th dating, Radier, Isotopic stages, Infrared, Paleoclimate. ——————————  —————————— 1 INTRODUCTION Ravertines and speleothems are calcite concretions that retain the isotopic and chemical characteristics of the water from which they are deposited. They thus provide a record of climate variations in the continental domain. Speleothems are concretions that are deposited in caves. They can be stalactites, stalagmites or stalagmitic floors. The latter have the advantage that they are formed in archaeological layers, their dating is of great importance in Prehistory. Travertines are concretions that deposits in open air from hot springs. When rainwater mixes with atmospheric CO 2 , it forms the carbonic acid H 2 CO 3 that dissolves the carbonates CaCO3. The reactions are summarized as follows: H 2 O + CO 2 → H 2 CO 3 H 2 CO 3 → H + + HCO 3 - CaCO 3 → Ca 2+ + CO 3 2- As the compressed gases under pressure burst and formed cracks, the water becomes saturated with Ca 2+ and HCO 3 - ions as well, reaches the surface and spills on the vegetation, mixing CO 2 with captured during respiration of plants, mosses, algae, and cyanobacteria. The carbonate precipitation occurs by releasing CO 2 and evaporating water according to the reaction: Ca 2+ + HCO 3 - ⇄ CaCO 3 + CO 2 + H 2 O The most known travertines are those of the Central Massif in France, the volcanic zone in central Italy, the eastern Greece, the western Turkey and the northern Africa including the Moroccan travertine studied here. Travertines have the advantage over speleothems that they are rich in uranium. The dating of travertine began a long time ago [22] [24], it allowed to date the skull cap of archaic Homo erectus from Kocabas in Turkey between 1 and 1.6 Ma (Lebatardet al. [1] [2]). The method used in this work is based on uranium-series disequilibrium. Indeed, uranium (U) is incorporated alone in the calcic concretion at the time of its formation while thorium (Th) is adsorbed on clay. Therefore, there is a disequilibrium between uranium and thorium. Uranium then decays to thorium, thus re-establishing the equilibrium. Determining the U/Th ratio in a given sample makes it possible to calculate its age. 2 TYPES OF TRAVERTINES Travertines are formed in geodynamically very active regions allowing the emergence of hot springs on the surface. They can have the shape of a dome by successive addition of lamines forming lenticular units limited by convex surfaces. They can also have the shape of ride by accumulation of fine carbonate precipitation lamines. This form develops along the line of a fault with symmetry in the morphology of the deposit on either side of this fault, giving a rided appearance to the deposit in transverse view. Travertines can also be in terraces with a carbonate wall separating each terrace. When this wall is high, the travertine is called a cascade which consists of encrustments due to a waterfall caused by a vertical surface. By comparison, limestone tuffs come from cold springs, they may be of fluviatile or lacustrine origin. The fluviatile model is formed by limestone deposits in oncoids forms where the river dries up. The lake model is formed by carbonate reefs on the shores of the lake colonized by cyanobacteria and algae that promote their deposition. 3 POSITION OF THE TRAVERTINE STUDIED The travertine outcrop studied is that of the Erfoud’s radier or Yerdi. It is located in the Errachidia region of Morocco in the Anti-Atlas [11] (Figure 1). It appears on the geological map of Tafilalt-Taouz [14]. It is bounded to the north by the southern flank of the eastern High Atlas and to the west by the northern and eastern flanks of the Anti-Atlas. T ———————————————— Corresponding author: samer.farkh@ul.edu.lb  Samer Farkh, Soumaya Hamieh, Bassel Ismail, Lebanese University, Faculty of Sciences I, Department of Life and Earth Sciences, Beirut, Lebanon.  Louis Rousseau, University of Picardy Jules Verne, EA 7511, 80000, Amiens, France.