Laiyang Gr
Type Locality and Naming
Jiaolai Basin. Tan Xichou erected the Laiyang bed in 1923. The type locality for the designation is in Laiyang of Shandong. The reference section is from Wawukuang to Xidoushan about 12 km southeast of the Laiyang County of Shandong.
Lithology and Thickness
The Laiyang Group is represented by yellow green and yellow brown conglomerate, siltstone and shale, which are divided in ascending order into four members. First member is built up by gray black calcareous siltstone and gray black and yellow green shale and sandy shale. Second member is gray green conglomerate, sandy conglomerate and grit occasionally with sandy limestone in the lower part, and gray brown silty clayey and crystalline limestone, shelly clayey siltstone and shale occasionally with fine sandstone in the upper part. Third member is yellow green siltstone, fine sandstone and gray green shale with gravel-bearing arkose at the base. Fourth member is gray green calcareous siltstone, fine sandstone and light yellow and purple red shale. The Laiyang Group is 1277.3 m thick.
Relationships and Distribution
Lower contact
The base of the group marked by granitic conglomerate lies unconformably on the Archean Jiaodong Gr.
Upper contact
The top marked by purple medium- and coarse-grained sandstone is distinguished from gray brown gravel-bearing sandstone of the overlying Qingshan Gr, showing a conformable contact with the latter.
Regional extent
The present group is distributed in the Jiaolai depression including the Laiyang City, Haiyang County, Gaomi County, Wulian County, Jiaozhou County and Zhucheng City. The first member is stratigraphically distributed in a limited area and is seen only in Wawukuang and Zhifengzhuang of the Laiyang City, and the basal conglomerate is relatively developed north of Wawukuang. In the Maershan area of the northeast Laiyang County, the second member is almost totally built up by coarse-grained arkose with small amounts of conglomerate; in Huangyadi of north Laiyang city, conglomerate is developed in the lower part and overlies the metamorphosed rocks of the Jiaodong Gr. In the Songjia Village east of Nanwu there is a layer of gray white rhyolitic tuff of about 10 cm thick in the middle and upper parts of the second member. The third member does not vary considerably in lithology and is coarse- grained only in the Tuanwang area of south Laiyang as compared to other areas. The fourth member is rather coarse in grain size and varies considerably in thickness in the southern part of the Laiyang City, and becomes fine in grain size and decreases slightly in thickness in the eastern and northeastern parts.
GeoJSON
Fossils
This group yields estherias Yanjiestheria sinensis, Y. kyongsangensis, Eosestheria sp.; floras Pagiophyllum sp.; in Huangyadi, Houzigou, Tuanwang and Beipazi; Fish Lycopteria sinensis, L. laiyangensis, Sinamia sp.; Gastropods Cicinna zhuchengensis; insects Mesolygaeus laiyangensis, Proteroscarabaeus yeni, Schizopteryx shandongensis; floras Cupressinocladus elegans, Brachyphyllum obesum; in Jiangluozhuang-Wawukuang Onychiopsis elongata; in Huadian of Zhuchenghuang Ruffordia gopperti; bivalves Sphaerium cf. wilfuicum; in Huangyadi and Huangxian sporopollen grains represented by Cicatricosisporites- Classopollis-Pinuspollenites assemblage.
Age
Depositional setting
It is of lacustrine deposition.
Additional Information