ON THE MAPPING UNITS OF THE FANGSHAN INTRUSION OF BEIJING

The bulk of the Fangshan intrusion of Beijing——granogranite——has long been divided into three circular facies tracts. The authors, however, consider that they are not"tracts" but different units formed by multiple upwellings of magmas. In this paper concrete evidence is presented and various units are named. In addition to quartz diorite that is in pulsatory intrusive contact with graniodiorite, the Fangshan intrusion may be divided into four mapping units. The four mapping units of the Fangshan intrusion and the smaller intrusions in its surrounding areas are Combined into a mapping unit of the next higher rank——sequence, which is named the Fangshan sequence.