Geochemical characteristics and paleoclimate implication of Middle Jurassic coal in the Ordos Basin, China

Coals are highly enriched in critical elements (rare earth elements, etc.), containing much information of paleoenvironmental and paleoclimatic during deposition. The Jurassic period is a significant coal-forming the world. Yan’an Formation Ordos Basin north China among largest Middle coal fields purpose this study to investigate geochemical characteristics Aalenian coals their paleoclimate significance. Sixty-two samples were collected from two mines Dongsheng area northeast Basin. major trace analyzed using X-ray fluorescence (XRF) inductively coupled plasma-mass spectrometry (ICP-MS). main oxides SiO2 CaO. In comparison with average values for China, have slight enrichment CaO MgO. Strontium Mo also slightly enriched. Yttrium rare depleted coals, range 8–269 ?g/g (average = 48.5 ?g/g; on an ash basis). negative Eu anomaly, suggesting that peat bog had stable terrigenous material supply period. continental saline water system oxygen-suboxygenic environment inferred Sr/Ba, U/Th, Ni/Co, Sr/Cu. Sr/Cu Sr/Ba data seams indicate climate change relatively arid condition more humid climate, which consistent marine Aalenian. Global cooling may triggered strengthened moisture transport by westerlies mid-latitude inland Asia, therefore