JpGU-AGU Joint Meeting 2017

Presentation information

[EJ] Oral

B (Biogeosciences) » B-PT Paleontology

[B-PT05] [EJ] Decoding the history of Earth: From Hadean to Modern

Tue. May 23, 2017 3:30 PM - 5:00 PM 201B (International Conference Hall 2F)

convener:Tsuyoshi Komiya(Department of Earth Science & Astronomy Graduate School of Arts and Sciences The University of Tokyo), Yasuhiro Kato(Department of Systems Innovation, Graduate School of Engineering, University of Tokyo), Katsuhiko Suzuki(Research and Development Center for Submarine Resources, Japan Agency for Marine-Earth Science and Technology), Chairperson:Hisashi Asanuma(Tokyo institute of Technology)

4:45 PM - 5:00 PM

[BPT05-12] Reconstruction of stratigraphy and tectonic setting in El Dabbah, Eastern Egypt: Neoproterozoic banded iron formations

*TAISHI SUZUKI1, Shoichi Kiyokawa1, Minoru Ikehara2, Takashi Sano3, Maher Dawood4, Mohamed Abouelhassan4 (1.kyushu Univ., 2.Kochi Univ., 3.National Museum of Nature and Science, 4.Menoufia Univ.)

Keywords:banded iron formation, Neoproterozoic

In the Eastern Desert of Egypt, Neoproterozoic Banded Iron Formations (BIFs) are reported within Nubia greenstone belt whose geological structure and stratigraphy are not well understood. In this study, the geological structure was established to reconstruct the stratigraphy including Iron formations (IFs) in El Dabbah in the middle of the Eastern Desert.
Greenstone sequence in El Dabbah area, strike-slip basin on Nubia shield during pan African orogeny, is covered by Hammamat Group. The greenstone sequence preserved the thick volcano-sedimentary rocks with gabbro, coarse-grained volcaniclastics rocks, pillow lavas, black shales, and BIFs. Reconstruction of stratigraphy in this greenstone sequence, which is 4000m in total thickness, composes Basal, Lower, Middle, and Upper members. There are 13 iron sections within this greenstone sequence.
Especially, BIFs sequence preserved within Lower and Upper members. BIFs sequences are well preserved within massive - pillow lavas sections and it contain laminated greenish - black shales. BIFs are composed of magnetite and/or hematite. Magnetite are oxidized from rims and become hematite.
We have determined major and trace element compositions of whole rock of volcanics and BIFs by using XRF and ICP-MS analysis. Trace elements compositions indicate that the volcanics are arc origin in term of a Nb-Zr-Y discrimination diagram and a MORB normalized spider diagram. Major elements in BIFs in this area are characterized by their higher content of Al2O3 than the other Archean BIFs. In addition, REE in BIFs show pattern of light REE enrichment and negative Eu anomalies.
This Volcaniclastic sedimentary sequence would be related at island arc sedimentary sequence with volcanic activity.