ABSTRACT

This paper presents a reappraisal of datasets from Titihaoa-1, an offshore petroleum exploration drillhole that intersects a ∼2740 m-thick Holocene to early-middle Miocene sedimentary succession in the Titihaoa Sub-basin, part of the Hikurangi accretionary wedge. The well provides an important datapoint in the offshore southern Hikurangi subduction margin. We present new and revised foraminiferal biostratigraphic and paleoenvironmental interpretations that help to constrain age, depositional paleo-water depths, sedimentation rates, and oceanicity. Analysis of open-hole wireline and image-log datasets, combined with analogues from nearby outcrops, provide an improved understanding of the sedimentary architecture, depositional systems, and present-day in-situ stress at the drillhole site. The succession within Titihaoa-1 comprises a shallowing-upward succession of thin-bedded lower- to middle-bathyal turbidites, overlain by mudstone-dominated lithofacies deposited in the middle- to upper-bathyal and mid-shelf environments. The geological history and stratigraphic trends within the Titihaoa Sub-basin are analogous to other Neogene accretionary wedge basins within the Hikurangi Margin.

摘要

本文介绍了对 Titihaoa-1 数据集的重新评估，这是一个海上石油勘探钻孔，与 Hikurangi 增生楔的一部分 Titihaoa 次盆地中约 2740 米厚的全新世至早中期中新世沉积序列相交。该井为 Hikurangi 南部近海俯冲边缘提供了一个重要的数据点。我们提出了新的和修订的有孔虫生物地层和古环境解释，有助于限制年龄、沉积古水深度、沉积速率和海洋性。对裸眼电缆和图像测井数据集的分析，结合附近露头的类似物，可以更好地了解沉积结构、沉积系统和当今的原位钻孔部位的应力。Titihaoa-1 内部的层序包括一个浅层向上层序的薄层下至中深海浊积岩，其上覆以沉积在中至上深海和中陆架环境中的以泥岩为主的岩相。Titihaoa 次盆地内的地质历史和地层趋势类似于 Hikurangi 边缘内的其他新近系增生楔形盆地。