Synkinematic emplacement of Lassiter Coast Intrusive Suite plutons during the Palmer Land Event: evidence for mid-Cretaceous sinistral transpression at the Beaumont Glacier in eastern Palmer Land
Synkinematic emplacement of Lassiter Coast Intrusive Suite plutons during the Palmer Land Event: evidence for mid-Cretaceous sinistral transpression at the Beaumont Glacier in eastern Palmer Land
复制标题
帕尔默地事件期间拉西特海岸侵入岩组岩体的同运动侵位：帕尔默地东部博蒙特冰川白垩纪中期左旋扭压的证据
DOI：
10.1144/jgs2011-160
复制
发表时间：
2012
影响因子：
2.7
通讯作者：
M. Curtis
中科院分区：
文献类型：
--
作者：
A. Vaughan;C. Storey;S. Kelley;T. Barry;M. Curtis
来自博蒙特冰川附近的东部帕尔默陆地剪切带的新的构造和地质年代学资料首次证明，在白垩纪中期的帕尔默陆地事件造山过程中，第119-95 Ma，&Gt；13000 km2白垩纪拉西特海岸侵入岩套的侵位受到了过时的构造控制。沿NW-SE轴侵位于116.5 ± 1.5 Ma(Ar-Ar黑云母冷却年龄)，与NW-SE挤压变形同时代，可能受沿博蒙特冰川剪切带的左旋扭压作用控制。石英英云闪长岩保留了两种变形样式，可能是在岩浆冷却过程中，随着岩脉内部镁铁质包体的初始变形和岩墙边缘原始糜棱岩向糜棱岩的最终形成，逐渐发生了正左行剪切变形。石英英云闪长岩切割了与棕榈陆事件第一阶段有关的褶皱，表明该褶皱的年龄超过116 Ma，将第一阶段的开始时间延长到了以前。石英英云闪长岩片状边缘的糜棱岩随后在拉西特海岸侵入岩系岩浆活动高峰期被热重置至约107 Ma(Ar-Ar黑云母法)。补充材料：围岩岩性数据、英云闪长岩的岩相学描述和Ar-Ar地质年代学数据可在www.geoloc.org.uk/SUP18552上查阅。
New structural and geochronological data from the Eastern Palmer Land Shear Zone, in the vicinity of Beaumont Glacier, provide the first evidence of dated structural control on emplacement of the 119–95 Ma, >13000 km2 Cretaceous Lassiter Coast Intrusive Suite, during the accretionary mid-Cretaceous Palmer Land Event orogeny. A previously undated >100 m thick dyke-like quartz tonalite intrusion was emplaced at 116.5 ± 1.5 Ma (Ar–Ar biotite cooling age) along a NW–SE axis, coeval with NW–SE compressional deformation, and possibly controlled by sinistral transpression along the Beaumont Glacier shear zone. The quartz tonalite preserves two styles of deformation and was probably progressively deformed by normal-sinistral shearing during magmatic cooling with initial deformation of mafic enclaves in the dyke interior and final formation of proto-mylonite to mylonite on the dyke margin. The quartz tonalite cuts folding associated with Phase 1 of the Palmer Land Event, indicating that this folding is older than 116 Ma, extending the onset of Phase 1 back in time. Mylonite on the quartz tonalite sheet margin was subsequently thermally reset at c. 107 Ma (Ar–Ar biotite method), during a peak in Lassiter Coast Intrusive Suite magmatism. Supplementary material: Country rock lithological data, petrographic description of tonalite and Ar–Ar geochronology data are available at www.geolsoc.org.uk/SUP18552.