Abstract Four oroclinal structures have been identified from structural, magnetic and gravity trends across a Carboniferous continental arc, forearc basin [Tamworth Belt (TB)] and conjugate accretionary complex in the southern New England Orogen (SNEO) of eastern Australia. None of the structures has yet been confirmed conclusively by paleomagnetism as oroclinal. Ignimbrites are common within the forearc basin and have been demonstrated to retain primary magnetisations despite prevalent overprinting. They are well exposed across six major tectono-stratigraphic blocks with partly interlinked stratigraphies, making the forearc basin highly prospective to oroclinal testing by comparing pole path segments for individual blocks across curved structures. Paleomagnetic studies have shown no noticeable rotation across the western/southwestern TB (Rocky Creek, Werrie and Rouchel blocks), but documented herein is a minor counter-clockwise rotation of the Gresford Block of the southern TB. This study details paleomagnetic, rock magnetic and magnetic fabric results for 87 sites (969 samples) across the southern Gresford Block. Predominantly thermal, also alternating field and liquid nitrogen, demagnetisations show a widely present low-temperature overprint, attributed to regional late Oligocene weathering, and high-temperature primary and overprint components residing in both mainly magnetite and mainly hematite carriers. Subtle, but systematic, directional differences between magnetite and hematite subcomponents show the latter as the better cleaned, better-defined, preferred results, detailing nine primary poles of middle and late Carboniferous ages and Permian and Permo-Triassic overprints as observed elsewhere in the western/southwestern TB. The primary poles update a poorly defined mid-Carboniferous section of the SNEO pole path and demonstrate counter-clockwise rotation, quantified at about 15° ± 13° from comparison of mid-Carboniferous Martins Creek Ignimbrite Member poles for the Rouchel and Gresford blocks, that may not necessarily have been completed prior to the Hunter–Bowen phase of the Gondwanide Orogeny. This minor counter-clockwise rotation of the Gresford Block accentuates a primary curvature of the southwestern/southern TB and heralds further, more complex, rotations of the Myall Block of the southeastern TB.

中文翻译：

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新英格兰造山带南部塔姆沃思带石炭纪 Gresford 地块的古地磁：初级弧段逆时针小旋转

摘要 根据横跨石炭纪大陆弧、弧前盆地 [Tamworth Belt (TB)] 和澳大利亚东部新英格兰造山带 (SNEO) 南部共轭增生杂岩的构造、磁力和重力趋势，已经确定了四种斜斜构造。古地磁学还没有最终确认这些结构是口斜的。Ignimbrites 在弧前盆地中很常见，并且已被证明尽管普遍存在叠印，但仍能保持初级磁化。它们在具有部分相互连接的地层的六个主要构造地层块体中充分暴露，通过比较弯曲结构中单个块体的极路径段，使弧前盆地高度有望进行斜向测试。古地磁研究表明，TB 西部/西南部（Rocky Creek、Werrie 和 Rouchel 地块）没有明显的旋转，但这里记录的是南部 TB 的 Gresford 地块的轻微逆时针旋转。这项研究详细介绍了 Gresford Block 南部 87 个地点（969 个样本）的古地磁、岩石磁性和磁性结构结果。主要是热，还有交变场和液氮，退磁显示出广泛存在的低温叠印，归因于区域晚渐新世风化，以及主要存在于主要磁铁矿和主要赤铁矿载体中的高温初级和叠印成分。磁铁矿和赤铁矿子成分之间微妙但系统的方向差异表明，后者是更清洁、更明确、更优选的结果，详细描述了石炭纪中期和晚期的九个主要极地以及二叠纪和二叠纪-三叠纪叠印，如在西部/西南部 TB 的其他地方观察到的。初级极更新了 SNEO 极路径的一个定义不清的石炭纪中部部分，并展示了逆时针旋转，从 Rouchel 和 Gresford 区块的石炭纪中部 Martins Creek Ignimbrite 成员极点的比较中量化为大约 15°±13°，即可能不一定在冈瓦尼德造山运动的亨特-鲍恩阶段之前完成。Gresford 地块的这种逆时针小幅旋转突出了西南/南部 TB 的主要曲率，并预示着 TB 东南部 Myall 地块的进一步、更复杂的旋转。