Holocene vegetation and volcanic activity, Auckland Isthmus, New Zealand

Abstract

A 12 000 to 4000 yr BP pollen and tephra-bearing profile from Auckland, New Zealand, provides insights into the vegetation history and evidence for early Holocene volcanic activity in this area centred on the Mount Wellington basaltic volcano. Possibly 500 yr separated initial scoriaceous ash deposition (ca. 9500 yr ago) and subsequent major lava flows (ca. 9000 yr ago) from Mount Wellington. The local vegetation, topography, and drainage patterns were substantially modified during this time, and damming by the lava flows resulted in the formation of Lake Waiatarua in a shallow valley head ca. 9000 yr ago. Diatom evidence indicates that this N r d o f Q w t e r M r y k i e n c e lake was initially deep (> 5 m) but was shallowing around 4000 yr ago. In contrast to the Mount Wellington eruptions, tephra deposition resulting from distant rhyolitic volcanic activity of the central North Island and Mayor island has had little effect on the Auckland vegetation during this time interval (12 000 -4000 yr ago).Between ca. 12 000 and 10 000 yr ago, conifer-angiosperm forest was the predominant vegetation cover on Auckland Isthmus, but during the early Holocene, forest dominated by Metrosideros expanded, probably on to fresh volcanic surfaces resulting from the Mount Wellington eruptions. At this time, swamp forest communities developed in Waiatarua valley basin, and included species indicative of moist, mild, relatively frost-free climates. Some taxa show histories consistent with other records from the northern New Zealand region, including the rise of Ascarina lucida ca. 11 000 to 9000 yr ago, and its subsequent decline, and the expansion of Agathis australis (kauri) forest communities from ca. 6000 yr ago. Taken together the history of local and regional vegetation points to a mild, moist and weakly seasonal early Holocene climate, which subsequently became drier with greater seasonal temperature extremes.

Stratigraphy and chronology of a 15 ka sequence of multi‐sourced silicic tephras in a montane peat bog, eastern North Island, New Zealand

“…It has a unique ferromagnesian mineralogical assemblage dominated by sodic phases, especially aegirine (Table 1), and a distinctive peralkaline (molar [Na 2 O + K2O]/ Al O3 >1) major element composition (anal. 17, Table 2), consistent with previous mineralogical and glass compositional analyses of this tephra (Lowe 1988a, b;Stokes & Lowe 1988;Froggatt & Lowe 1990;Newnham & Lowe 1991;Pillans & Wright 1992;Newnham et al 1995b). The glass, although silicic, has relatively low amounts of AI2O3 (9.5%) and CaO (0.3%) but characteristically high amounts of FeO totai (5.5%) and Na 2 O (5.3%).…”

“…Tuhua Tephra (6130 ± 30 14 C yr BP), previously identified in the Auckland and Waikato regions northwest and southwest, respectively, of the source volcano at Mayor Island ( Fig. 1; Lowe 1988b;Newnham & Lowe 1991), was clearly distributed in a southeasterly direction as well (see also Kennedy & Froggatt 1984). With its distinctive composition, Tuhua Tephra forms an important regional marker of mid-Holocene age (Newnham et al 1995b).…”

New Zealand forest dynamics: a review of past and present vegetation responses to disturbance, and development of conceptual forest models

“…3c) (e.g. Nicholls 1959;McGlone et al 1988;Newnham & Lowe 1991;Lees & Neall 1993;Wilmshurst & McGlone 1996). The 1850 years BP Taupō eruption, for example, overwhelmed 20 000 km 2 of forest with ignimbrite, and damaged forests up to 170 km east of the vent with windblown ash-fall (Pullar et al 1977;Wilmshurst & McGlone 1996).…”

“…From the Bay of Plenty northwards L. scoparium and Kunzea may be replaced by, or co-occur with, Metrosideros excelsa on cliffs (Nicholls 1959), raw volcanic substrates (e.g. lava, scoria) (Clarkson 1990;Newnham & Lowe 1991;Clarkson et al 2015), or in coastal areas (Smale 1993;Atkinson 2004). A similar role is played by M. umbellata on the subantarctic Auckland Islands, where neither L. scoparium nor Kunzea occur (Wardle 1971(Wardle , 1991.…”

An occurrence of Tuhua Tephra in deep‐sea sediments from offshore eastern North Island, New Zealand

“…2001) 30-50 mm thick, coarse-med, (Newnham et al 1999) 10-15 mm (Newnham & Lowe 1991) Waikato study area (Hogg &McCraw 1983;Lowe (1988a) Turnagain, off eastern North Island, New Zealand (40°2 2.935' S, 177° 59.68' E, Fig. 1).…”