Maroa Caldera
The Maroa Caldera is approximately in size and is located in the north-east corner of the earlier Whakamaru caldera in the Taupō Volcanic Zone in the North Island of New Zealand. Volcanic activity in the complex commenced over 300,000 years ago and the most recent volcanic eruption within it was 9,400 years BCE.
Geography
Its northern rim is to the south of the Waikato River at Ātiamuri. At Ātiamuri the Ohakuri Caldera which had a paired eruption with the Rotorua Caldera is to its immediate north. The eastern boundary is also defined by the present Waikato River and it extends as far south as probably opposite Orakei Korako on the river. The southern boundary is somewhat ill defined given the subsequent deep deposits from the Taupō Volcano but includes a number of domes of which the highest is Maroanui at.Eruptive history
The Maroa Caldera's last major eruption produced of tephra about 230,000 years ago. Its earliest eruption was about 300 ka with decreasing frequency and volume to as recently as 11.3 ± 1.7 ka before present, when an eruption of about occurred from the Puketarata volcanic complex. The caldera is now mainly dome lava in filled.In summary going back in time:
- 11,300 ± 1,700 years ago most recent eruption of Puketarata tuff ring, which formed with total volume of in a complex multiphase series of eruptions including maar formation
- 229,000 to 196,000 years ago Pukeahua deposits and dome building
- 220,000 years ago but unclear where this Mokai ignimbrite that outcrops in some of the Maroa area comes from
- 229,000 ± 12,000 years ago Ātiamuri deposits from northern Maroa
- 251,000 ± 17,000 years ago onward two large parallel dome complexes developed
- 256,000 ± 12,000 years ago Orakonui pyroclastics from a central Maroa source
- 272,000 ± 10,000 years ago Putauaki pyroclastics from a central Maroa source
- 275,000 to 240,000 years ago small-scale pyroclastic eruptions
- 283,000 ± 11,000 years ago Korotai deposits from northern Maroa
- 305,000 ± 17,000 years ago oldest Maroa dome