Exploring for the Future geomechanical testing program data release, NDI Carrara 1, Carrara Sub-basin, Australia

NDI Carrara 1 is a deep stratigraphic borehole that was drilled in 2020 under the MinEx CRC’s National Drilling Initiative (NDI) program in collaboration with Geoscience Australia and the Northern Territory Geological Survey. NDI Carrara 1 is the first stratigraphic test of the recently described Carrara Sub-basin, a Proterozoic aged depocentre located in the South Nicholson region of northwest Queensland and the Northern Territory. The borehole was drilled to a total depth of 1751 m and penetrated a succession of Cambrian aged Georgina Basin carbonate and siliciclastic rocks that unconformably overly a thick succession of Proterozoic age siliciclastic and carbonate-rich sediments. Although drilled on the western flank of the Carrara Sub-basin, NDI Carrara 1 did not penetrate to basement. Interpretation of the L210 deep-crustal seismic survey suggests that further Proterozoic sedimentary packages known from the northern Lawn Hill Platform in northwest Queensland are likely to be found underlying the succession intersected in NDI Carrara 1. The borehole was continuously cored from 283 m to total depth, and an extensive suite of wireline logs was acquired. Geoscience Australia and partners have undertaken an extensive analytical program to understand the depositional, structural, and diagenetic history of the sediments intersected in NDI Carrara 1. This program includes a targeted geomechanical study that aims to characterise the physical properties of these Proterozoic rocks through laboratory analysis of core samples, the results of which are summarised in this data release.This data release provides data from new unconfined compressive strength (UCS), single-stage triaxial testing, and laboratory ultrasonic testing for 36 sample plugs from NDI Carrara 1. These tests were performed at the CSIRO Geomechanics and Geophysics Laboratory in Perth, during January to June 2022. The full results as provided by CSIRO to Geoscience Australia are provided as an attachment to this document.

NDI Carrara 1是一口深部地层钻井，于2020年由MinEx CRC国家钻探计划（National Drilling Initiative，NDI）项目资助，联合澳大利亚地质调查局（Geoscience Australia）与北领地地质调查局共同实施钻探。该钻井是针对新近被描述的卡拉拉次盆（Carrara Sub-basin）开展的首次地层钻探试验，卡拉拉次盆为元古代（Proterozoic）沉积中心，坐落于昆士兰州西北部与北领地交界的南尼科尔森区域。该钻井总进尺达1751米，揭露了一套寒武纪（Cambrian）时期的乔治亚盆地碳酸盐岩与硅质碎屑岩（siliciclastic rocks）地层，该地层不整合覆于一套厚层元古代硅质碎屑岩及富碳酸盐沉积物之上。尽管该井布置于卡拉拉次盆西侧翼部，但并未钻遇结晶基底（basement）。通过对L210深地壳地震勘探（deep-crustal seismic survey）数据的解释可知，在昆士兰州西北部劳恩希尔台地（Lawn Hill Platform）北部已识别的元古代沉积地层组（sedimentary packages），大概率赋存于NDI Carrara 1所揭露地层的下方。该钻井自283米至总进尺段实施了连续取心，并采集了一套完整的测井曲线（wireline logs）数据。澳大利亚地质调查局及其合作方已开展系统性分析项目，以解析NDI Carrara 1所揭露沉积物的沉积、构造及成岩演化历史。该分析项目包含一项针对性岩土力学研究（geomechanical study），旨在通过岩心样品实验室测试表征这套元古代岩石的物理特性，相关研究成果总结于本数据发布内容中。本数据发布提供了采自NDI Carrara 1的36个岩芯柱样品的全新测试数据，包括无侧限抗压强度（unconfined compressive strength，UCS）、单级三轴试验及实验室超声测试结果。上述测试于2022年1月至6月期间在珀斯的澳大利亚联邦科学与工业研究组织（CSIRO）岩土与地球物理实验室完成。CSIRO提交给澳大利亚地质调查局的完整测试结果已作为本文档的附件一并提供。