1. Department of Earth Sciences, Sun Yat-Sen University, Guangzhou 510275, China 2. Guangdong Key Laboratory of Geological Process and Mineral Resources Exploration, Guangzhou 510275, China
Abstract：Red pigment of continental red-bed is known originating from the fine-particle hematite in the rocks. Advance of researches on the origin of continental red-bed demonstrates that the red pigment of red-bed originated from its diagenetic but not depositional process. The high diagenetic temperature causes the dehydration of iron hydrate to form hematite, generating the red pigment. For examining the above hypothesis, the authors of this paper designed an experiment to approach the reddening process, i.e. formation of the red pigment of continental red-bed. Black ooze sampled from the Holocene sediments of the Pearl River Delta was heated in different ways. The diffuse reflectance spectroscopy (DRS) of those heated ooze samples were detected with Perkin-Elmer Lamdba 950 ultraviolet/visible/near-infrared spectrophotometer, and moreover, red-values of the samples were calculated for determining their coloring levels. Iron in black ooze sediment is predominantly in the form of goethite. Experimental results verified that initial dehydration-temperature of goethite is about 150 ℃, either enhancing temperature or prolonging heating time is accompanied with decreasing goethite and increasing hematite, and a positive relationship exists between red-value of samples and peak-height of hematite. The experimental results strongly support the idea of thermal origin of continental red-bed.
[1] Turner P. Continental Red Beds. Developments in Sedimentology. Amsterdam: Elsevier, 1980. 1. [2] Van Houten F B. Annual Review of Earth Planetary Sciences, 1973, 1: 39. [3] CHEN Hai-xia(陈海霞). Research of Paleoenviro nment and Paleoclimate of Cretaceous in Ya′an Area of Western Sichuan Basin (川西雅安地区白垩纪古环境古气候研究). Chengdu University of Technology(成都理工大学), 2009. 1. [4] CAO Ying-chang, WANG Jian, GAO Yong-jin, et al(操应长, 王 健, 高永进, 等). Journal of Palaeogeography(古地理学报), 2011, 13: 375. [5] Weibel R, Grobety B. Clay Minerals, 1999, 34: 657. [6] DeBoer C B, Dekkers M J. Geophysical Journal International, 2001, 144: 481. [7] Chen G N, Grapes R. Granite Genesis: In-situ Melting and Crustal Evolution. The Netherlands: Springer, 2007. [8] Deaton B C, Balsam W L. Journal of Sedimentary Research, 1991, 61: 628. [9] Ji Junfeng, Balsam W, Chen Jun, et al. Clays and Clay Minerals, 2002, 50: 208. [10] Torrent J, Barrón V, Liu Qing-song. Geophysical Research Letters, 2006, 33: L02401. [11] Baslsam W L, Damuth J E. Further Investigations of Shipboard vs Shore-Based Spectral Data: Implications for Interpreting Leg 164 Sediment Composition. In Paull C K, Matsumoto R, Wallace P J, et al (ed), Proceedings ODP Scientific Results 164. Texa: Ocean Driling Program, Texas A ＆ M University, 2000. 313. [12] JI Jun-feng, CHEN Jun, Balsam W, et al(季峻峰, 陈 骏, Balsam W，等). Quaternary Sciences(第四纪研究), 2007, 27: 221. [13] LI Chao, YANG Shou-ye(李 超, 杨守业). Earth Science-Journal of China University of Geosciences(地球科学-中国地质大学学报), 2012, 37(Suppl.): 11. [14] Ji Junfeng, Zhao Liang, Balsam W, et al. Clays and Clay Minerals, 2006, 54: 266.
