Stratigraphy of Reinga and Aotea basins, NW New Zealand: constraints from dredge samples on regional correlations and reservoir character

Sandstone, mudstone and limestone samples dredged in the Reinga and Aotea basins, NW New Zealand during voyage TAN1312 provide age and lithological constraints on the Cretaceous–Neogene succession. A total of 46 micropaleontology and 7 macropaleontology samples were examined along with 84 thin-sectioned petrographical samples. Some were examined by X-ray diffraction and porosity-permeability analyses. Late Cretaceous sandstones are dominated by feldspathic and lithofeldspathic compositions, with mixed granitic plutoniclastic and volcaniclastic provenance; a comparison with Pakawau Group of Taranaki Basin is appropriate. Late Cretaceous–Paleogene mudstones are widespread and display close petrographical and age similarities to the Whangai Formation facies of other parts of New Zealand and fine-grained carbonate facies of the Weber and Amuri formations of eastern North and South Islands, respectively. Cretaceous limestone and Paleogene sandstone were not recovered. Carbonates and mudstones dominate the Neogene succession of Reinga and Aotea basins; rare Neogene sandstones have feldspatholithic compositions and resemble Waitemata Group sandstones of the northern North Island. In terms of petroleum prospectivity, Cretaceous sandstones represent a potential reservoir facies but are lithic with low permeability.

于新西兰西北部雷恩加盆地（Reinga）与奥特亚盆地（Aotea）通过TAN1312航次疏浚采集的砂岩、泥岩及石灰岩样品，为区域白垩纪-新近纪层序提供了年代学与岩性约束依据。本次研究共分析了46件微体古生物学（micropaleontology）样品、7件大古生物学（macropaleontology）样品，以及84件薄片岩相学样品；其中部分样品还开展了X射线衍射（X-ray diffraction）及孔隙度-渗透率测试分析。晚白垩世砂岩以长石质与岩屑长石质组分为主，物源兼具花岗质深成碎屑与火山碎屑双重来源，可与塔拉纳基盆地的帕卡沃组（Pakawau Group）进行类比研究。晚白垩世-古近纪泥岩分布广泛，其岩相学与年代学特征分别与新西兰其他区域的旺盖组（Whangai Formation）沉积相，以及北岛东部韦伯组（Weber Formation）、南岛东部阿穆里组（Amuri Formation）的细粒碳酸盐岩相高度相似。本次研究未采获白垩纪石灰岩与古近纪砂岩。雷恩加与奥特亚盆地的新近纪层序以碳酸盐岩与泥岩为主；少量新近纪砂岩具有长石岩屑质组分，其特征与北岛北部的怀塔马塔组（Waitemata Group）砂岩相近。从油气勘探潜力来看，晚白垩世砂岩具备潜在储集岩相的勘探价值，但属于岩屑砂岩且渗透率较低。