LATE QUATERNARY (POST 28,000 YEAR BP) TEPHROSTRATIGRAPHY OF NORTHEASTAND CENTRAL TARANAKI, NEW-ZEALAND

Mt. Egmont/Taranaki in western North Island, New Zealand, has been ina ctive during historic time and thus its pattern of eruptive history mu st be reconstructed by inference from the stratigraphy and chronology of associated volcanic and pyroclastic deposits. The most complete rec ord of eruptive activity from Egmont Volcano is found on the surroundi ng ring plain rather than on the volcanic cone, where surficial deposi ts are readily removed by erosion or deeply buried by the products of more recent eruptions. In this study, a comprehensive post-28 ka recor d of the volcano's eruptive history is presented, and the relationship of andesitic tephra beds to andic soil material, Egmont-sourced volca niclastic detritus, and two silicic tephra beds from Taupo Volcano are discussed, along with implications for inter-regional correlation. Th e post-28 ka tephra succession is recorded in sixteen andesitic tephra formations. These formations and their approximate ages are as follow s: Manganui tephra (4 beds; c. 3.1 ka), Inglewood Tephra (2 beds; c. 3 .6 ka), Korito Tephra (2 beds; c. 4.1 ka), Mangatoki Tephra (2 beds; c . 4.4 ka), Tariki Tephra (6 beds; c. 4.6-4.7 ka), Waipuku Tephra (1 be d; c. 5.2 ka), Kaponga Tephra (10 beds; c. 8.0-10.0 ka), Konini Tephra (2 beds; c. 10.1 ka), Mahoe Tephra (4 beds; c. 11.0-11.4 ka), Kaihour i tephra (8 beds; c. 12.9-18.8 ka), Paetahi Tephra (6 beds; c. 19.4-20 .2 ka), Poto Tephra (15 beds; c. 20.9-22.7 ka), Tuikonga Tephra (4 bed s; c. 23.4-24.0 ka), Koru Tephra (2 beds; c. 24.8-25.2 ka), Pukeiti Te phra (1 bed; c. 26.2 ka) and Waitepuke Tephra (3 beds; c. 27.5-28.0 ka ). Many of these tephra beds are sufficiently distinct and widespread enough to permit the dating and correlation of ring-plain forming volc aniclastic deposits with which they are interbedded. The post-28 ka te phra succession can also be subdivided into three broad sequences on t he basis of major variations in the morphological and mineralogical ch aracteristics of inter-bedded andic soil material. At least 76 tephra events from Egmont Volcano with volumes exceeding 10(7) m(3) have been recorded since c. 28 ka with an average eruptive periodicity of one i n every c. 330 years. This frequency is considered minimal since more tephras of lesser magnitude may have been erupted but are only represe nted on the ring plain as intermittent accretion of fine-grained ash t hat has rapidly weathered to andic soil material.