Events----INSTITUTE OF GEOLOGY AND GEOPHYSICS, CHINESE ACADEMY OF SCIENCES

A four day spring geology field excursion was organized from May 8 to 11, 2014 by the Institute of Geology and Geophysics Chinese Academy of Sciences to examine the geology of East Hebei-Jixian area. This area is situated in the east of North China Craton where Archean metamorphosed basement and Late Paleo- to Mesopropterozoic sedimentary sequences are exposed.

A group of 42 doctoral and graduate students from IGGCAS participated in the excursion, which was supervised by Profs Chen Daizhao, Chu Xuelei, Peng Peng and Zhang Lianchang. Students were also thrilled to find Deputy Director Prof. Wu Fuyuan in the troop. As always, the trip was open to all students of the IGGCAS.

This trip focused on different Archean rock types and Proterozoic sediments and aimed to help the students understand the geological conditions and paleo-environments of Archean and Proterozoic eras. The field expedition started at the Sijiaying banded iron formation (BIF) open pit mine, which is the largest iron mine in Asia. This Late Archean BIF is sedimentary in origin, but metamorphosed to amphibolite facies. It has TFe of 25-35 wt.% (avg. 30 wt.%). The second location for the excursion was Caozhuang, where one of the oldest Early Archean crustal relics in China can be found (~3850 million years old detrital zircons within fuchsite quartzite). Then charnockites, grey gneisses (TTG) and granulites were observed at Taipingzhai, Sahe and Xuanmenzi, respectively. These rocks are all typical for Archean aged materials, which makes research on these rocks an essential part of understanding early crustal evolution.

During the last two days, the group went to the Jixian National Geological Park to see Late Paleo- to Mesoproterozoic sedimentary sequences. During the hike through the area, varied types of sedimentary rocks such as sandstone with large trough cross-bedding, hummocky stratified dolomite and black shales, which were deposited in fluvial to shallow marine depositional systems, were observed. Though it was raining for the entire last day, the trip was continued. One of the most impressive outcrops was the well developed stromatolites in Tieling Formation, which was deposited in subtidal environment.

The participants found the field trip exciting and enjoyable. It helped to increase IGGCAS students’ geological knowledge and appreciation for Precambrian geology.

(Photo by REN Hui)