Maroa Caldera

The Maroa Caldera (Maroa Volcanic Centre) is approximately 16 x 25 km 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.

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 897 m.

Eruptive history
The Maroa Caldera's last major eruption produced 140 km3 of tephra about 230,000 years ago (230 ka). Its earliest eruption was about 300 ka with decreasing frequency and volume to as recently as 11.3 ± 1.7 ka, when an eruption of about 0.25 km3 occurred from the Puketarata volcanic complex (-38.55057°N, 176.05452°W to distinguish from another older volcano of this name near Te Kawa). The caldera is now mainly dome lava in filled. In summary going back in time:
 * 11,300 ± 1,700 years ago most recent eruption Puketarata tuff ring, which formed with total volume of 0.25 km3 in a complex series of eruptions including maar formation
 * 229,000 to 196,000 years ago Pukeahua deposits and dome building
 * 220,000 years ago unclear where Mokai ignimbrite that outcrop in some of 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