Origin of iron-rich minerals,ooids and pisoids in the Jurassic ooidal ironstones of the Labino-Malkin region(Caucasus)  

作　　者：Natalia A.Kalinina Maxim A.Rudmin Mikhail Sherstyukov Prokopiy Maximov Abdul-Gapur Kerimov 

机构地区：[1]Division for Geology,School of Earth Sciences&Engineering,Tomsk Polytechnic University,634050,Tomsk,Russia [2]Laboratory of Sedimentology and Paleobiosphere Evolution,University of Tyumen,625003 Tyumen,Russia [3]Institute of Earth Science,North-Caucasus Federal University,355009,Stavropol,Russia

出　　处：《Journal of Palaeogeography》2024年第3期475-494,共20页古地理学报（英文版）

基　　金：supported by project FSWW-2023-0010.

摘　　要：This study investigates the Middle Jurassic rocks of the Labino-Malkin zone(Caucasus),represented by ooidal ironstones,biogenic limestones,and nodular phosphorites.All rocks contain ooids/pisoids.Based on the mineral composition,nine types of ooids and three possible scenarios for their formation have been identified.The mineral composition of ooids indicates the variable conditions of their deposition and repeated changes in physical and chemical conditions of the environment,including fluctuations in theredox regime.The access of oxygen in the bottom environment as a factor of increasing oxic conditions was associated with the regression of the sea and/or the inflow of meteoric waters.The main sources of ooids are the drift of material from the continent and convecting metal-bearing meteoric and/or deep solutions.

关 键 词：Ooidal ironstones Mineral formation OOIDS Pisoids Mineral chemistry 

分 类 号：P534.52[天文地球—古生物学与地层学] P588.248[天文地球—地质学]