Representative of bimodal magmatic activity

Representative of bimodal magmatic activity

Bimodal igneous assemblage of Jiuhuashan is represented by late mafic dykes and felsic A-type syenogranite. Zircon U-Pb geochronology indicates that mafic magmatic rocks and syenogranite were products of the same age (about 125Ma). It is generally accepted that bimodal magmatic activity formed in continental rift environment or back-are extensional environment is closely related to extensional structures. The mafic rock endmember is considered to be the product of partial melting of the upper mantle. However, up to now,there is still some dispute in the relationship between mafic and associated felsic rocks.

Syenogranite (known as Jiuhuahong)

Syenogranite belongs to A-type granite, and its formation age is about 127+2 Ma