Great Artesian Basin - Hydrogeology and Extent Boundary

The GAB hydrogeological boundary follows the geological margins of its four component sub-basins - the Eromanga, Carpentaria, Surat and Clarence-Moreton sub-basins - except where the water table indicates groundwater divides within these regions that delineate externally-draining regions. In some regions, this drainage divide changes geographically through the GAB sequence. In such areas as the GAB boundary within the Clarence-Moreton Basin, the broadest hydrogeological extent has been adopted as the GAB boundary. This dataset documents a basin-wide hydrostratigraphy of the GAB comprising five major aquifers, four intervening aquitards, and the cover of these units by Cenozoic rocks and sediments. The extensive Quaternary sediment cover is considered permeable and not an impediment to the recharge of underlying aquifers. However, the underlying Paleogene-Neogene rocks and sediments have highly variable hydrogeological character that can influence deeper connectivity. In this map individual aquifers and aquitards within the Paleogene-Neogene sequence have not been differentiated.There are two data layers in the Great Artesian Basin - Hydrogeology map dataA: Hydrogeological unit boundariesB: GAB BoundaryThis is a regional interpretation for mapping at approximately 1:1 000 000 to produce a broad scale overview, and examination of small areas by collecting extra data is most likely to produce results that differ from this regional interpretation.This dataset and associated metadata can be obtained from www.ga.gov.au, using catalogue number 81672.REFERENCES:Ransley, T., Radke, B., Feitz, A., Kellett, J., Owens, R., Bell, J. and Stewart, G., 2015. Hydrogeological Atlas the Great Artesian Basin. Geoscience Australia. Canberra. [available from www.ga.gov.au using catalogue number 79790]Habermehl, M. A. and J. E. Lau (1997). Hydrogeology of the Great Artesian Basin Australia (Map at scale 1:2,500,000). Canberra, Australian Geological Survey Organisation

大自流盆地（Great Artesian Basin，以下简称GAB）的水文地质边界遵循其四个组成子盆地——埃罗曼加（Eromanga）、卡奔塔利亚（Carpentaria）、苏拉特（Surat）及克拉伦斯-莫顿（Clarence-Moreton）子盆地——的地质边界，仅当潜水位指示出这些区域内划分外流区的地下水分水岭时，边界会作出相应调整。
在部分区域内，这类地下水分水岭会随GAB的地层序列发生空间迁移。以克拉伦斯-莫顿盆地内的GAB边界为例，本次研究采用最宽泛的水文地质范围作为GAB的正式边界。

本数据集记录了GAB全盆地尺度的水文地层学（hydrostratigraphy）特征，包含5个主要含水层（aquifer）、4套夹层式隔水层（aquitard），以及覆盖上述地层的新生代岩石与沉积物。大范围分布的第四纪沉积物盖层具备渗透性，不会阻碍下伏含水层的补给过程。但下伏的古近纪-新近纪岩石与沉积物的水文地质特征存在显著空间异质性，会对深部含水层的水力连通性产生影响。在本次绘制的地图中，古近纪-新近纪序列内的单个含水层与隔水层未做区分。

本大自流盆地数据集包含两类水文地质地图图层：
A. 水文地质单元边界
B. GAB边界

本数据集为1:100万比例尺的区域解译成果，仅用于呈现宏观概览；若需对小范围区域开展精细化研究，需补充采集实测数据，所得结果大概率与本区域解译成果存在差异。

本数据集及相关元数据可通过澳大利亚地球科学局官网www.ga.gov.au获取，目录编号为81672。

参考文献：
1. Ransley T, Radke B, Feitz A, Kellett J, Owens R, Bell J, Stewart G. 2015. 大自流盆地水文地质图集[M]. 堪培拉：澳大利亚地球科学局。可通过www.ga.gov.au获取，目录编号79790。
2. Habermehl M A, Lau J E. 1997. 澳大利亚大自流盆地水文地质（1:250万比例尺地图）[M]. 堪培拉：澳大利亚地质调查组织。