What Caused the Inconsistency between Rb-Sr and Ar-40-Ar-39 Ages of Authigenic Illites?

Liu E., UYSAL I. T., Zhao J., Zhang Z., Lin X.

JOURNAL OF EARTH SCIENCE, cilt.33, sa.5, ss.1145-1151, 2022 (SCI-Expanded) identifier identifier

  • Yayın Türü: Makale / Tam Makale
  • Cilt numarası: 33 Sayı: 5
  • Basım Tarihi: 2022
  • Doi Numarası: 10.1007/s12583-022-1643-z
  • Dergi Adı: JOURNAL OF EARTH SCIENCE
  • Derginin Tarandığı İndeksler: Science Citation Index Expanded (SCI-EXPANDED), Scopus, Academic Search Premier, Aerospace Database, Aquatic Science & Fisheries Abstracts (ASFA), CAB Abstracts, Communication Abstracts, Geobase, INSPEC, Metadex, Civil Engineering Abstracts
  • Sayfa Sayıları: ss.1145-1151
  • Anahtar Kelimeler: authigenic illite, isotope dating, Rb-Sr isochron, Ar-40-Ar-39 dating, inconsistency, geochemistry, FLUID-FLOW EVENTS, K-AR SYSTEMATICS, SOUTH CHINA SEA, CLAY-MINERALS, TRIASSIC SANDSTONES, ORDOS BASIN, PARIS BASIN, ROCKS, GEOCHEMISTRY, PETROGENESIS
  • İstanbul Üniversitesi Adresli: Hayır

Özet

Radiogenic isotope dating of illitic clays has been widely used to reconstruct thermal and fluid flow events in siliciclastic sedimentary basins, the information of which is critical to investigate mechanisms of hydrocarbon maturation. This study carried out Rb-Sr and Ar-40-Ar-39 dating of authigenic illitic clay samples separated from the Palaeogene sandstone in the northern South China Sea. Our Rb-Sr data further confirm the previously reported three periods of fluid flow events (at 34.5 +/- 0.9, 31.2 +/- 0.6, and 23.6 +/- 0.8 Ma, respectively) in the northern South China Sea, which are related to regional episodic tectonism. However, Ar-40-Ar-39 ages of illite obtained in this study are significantly younger than the corresponding Rb-Sr ages. The significantly younger Ar-40-Ar-39 ages were probably due to Ar-40 loss caused by later dry heating events on the Hainan Island that have not affected the Rb-Sr isotopic systematics. The inconsistency between Rb-Sr and Ar-40-Ar-39 data should be attributed to different isotopic behaviors of K-Ar and Rb-Sr isotopic systematics in illite. Our results indicate that Rb-Sr isotopic dating method may be a preferential approach for clay dating in geological settings where exist younger dry heating events.