Xingzi Gr
Type Locality and Naming
Northernmost Jiangxi. The term Xingzi Gr was proposed by Ma Changxin in 1988. The naming section of this group lies near Louxiansi, about 9 km northwest of Xingzi County, Jiangxi Province; the reference section of this group, near Xiufeng about 10 km west-northwest of Xingzi County, Jiangxi Province.
Synonym: (星子群)
Lithology and Thickness
It is distributed in Xingzi County and southeast piedmont of Lushan Mountain, Jiangxi.
First Formation of the Xingzi Gr principally consists of staurolite biotite schist, sillimanite staurolite garnet biotite schist, secondly, of sericite schist, garnet bi-mica schist, actinolite garnet biotite schist, with a small amount of biotite amphibole schist. The thickness of this formation is some 750 m.
Second Formation principally consists of amphibolite, (staurolite, garnet) biotite plagioclase leptite and (garnet) bi-mica schist, intercalated with garnet biotite schist, sericite schist and a small amount of quartzite. The thickness of this formation is some 850 m.
Third Formation consists of biotite plagioclase leptite, garnet bi-mica quartz schist, staurolite garnet biotite schist, containing a small amount of sericite schist, hornblende schist. The thickness of this formation is some 400 m.
Fourth Formation principally consists of quartzite, staurolite garnet biotite quartz schist, (staurolite) garnet biotite schist, intercalated with sericite quartz schist, bi-mica schist, garnet bi-mica schist, leptite and a small amount of lenticular marble. The thickness of this formation is over 1200 m.
This group had suffered from the Lüliangian middle-pressure, regional dynamo-thermal metamorphism mainly of the low-amphibolite facies with complex deformation. It didn't suffer from the regional migmatization basically. The thickness of this formation is some 750 m. The thickness of this formation is some 850 m. The thickness of this formation is some 400 m. The thickness of this formation is over 1200 m.
Relationships and Distribution
Lower contact
No given
Upper contact
The contact between the Xingzi Group and the Neoproterozoic Pengshan Gr [Not in current Lexicon] is a fault (Xiang Xinkui et al., 1993). [Regionally in NW Jiangxi, the next younger unit may be the Yifeng Fm?]
Regional extent
It is only developed in Xingzi County, Jiangxi Province.
GeoJSON
Fossils
Age
Depositional setting
The protoliths of this group principally consisted of argillaceous and arenaceous clastic sedimentary rocks, secondly, of low-potassium tholeiite.
Additional Information
Single zircon grains from the amphibolite gave U-Pb ages of 1850 Ma to 2100 Ma (Zhao Fengqing et al., 1994). SHRIMP zircon U-Pb age of 840±6 Ma, 833±4 Ma, 831±3 Ma and 825±5 Ma found in the Shaojiwa Formation. (Gao Linzhi et al., 2012).