Figure 6 - uploaded by Ikra Wahyu Pratama
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Ilustration of Ijo Caldera Formation. (1) Ijo Paleovolcano started active since Late Oligocene, (2) explosive eruption occurred and accompanied by formation of ignimbrite, (3) magma became more alkaline, produced andesite pyroclastic breccia, (4) magma chamber collapsed due to decompression, (5) in the Early Miocene, an new intrusion of andesitic magma was formed.

Ilustration of Ijo Caldera Formation. (1) Ijo Paleovolcano started active since Late Oligocene, (2) explosive eruption occurred and accompanied by formation of ignimbrite, (3) magma became more alkaline, produced andesite pyroclastic breccia, (4) magma chamber collapsed due to decompression, (5) in the Early Miocene, an new intrusion of andesitic magma was formed.

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Conference Paper
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Volcanism in Java has been starting since Upper Eocene. Some of them are associated with caldera formation. Some researches using remote sensing mention the existence of caldera morphology in Kulonprogo Mountains, but there is no field evidence supporting that result. In this paper we describe the discovery of ignimbrite deposits in the southern pa...

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... study supporting several previous studies that mentioned the presence of caldera in the southern part of Kulonprogo Mountains by presenting direct field evidences of ignimbrite deposit that associated with caldera-forming eruption of Ijo Paleovolcano. The presence of andesite pyroclastic breccia, andesitic lava, and andesite intrusion younger than ignimbrite deposits indicates that Ijo Paleovolcano experienced a changes in magma composition after the formation of caldera which transforms magma composition more intermediate ( Figure 6). In order to know the exact age of this event further study should be conducted, including radioactive dating and geochemistry analysis. ...

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