Provenance of the Highland Border Complex: constraints on Laurentian margin accretion in the Scottish Caledonides
Provenance of the Highland Border Complex: constraints on Laurentian margin accretion in the Scottish Caledonides
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DOI：
10.1144/0016-76492011-076
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发表时间：
2012-09
影响因子：
2.7
通讯作者：
Peter A. Cawood;R. Merle;R. Strachan;P. Tanner
中科院分区：
文献类型：
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作者：
Peter A. Cawood;R. Merle;R. Strachan;P. Tanner
苏格兰加里东的高地边界复合体的构造模型相对照，认为它要么是Iapetus海洋的劳伦森裂谷边缘的一部分，要么是一个海洋的边缘。杂岩砂岩中碎屑锆石的年龄峰值在2.8-2.6，1.3和1.1- 1.0Ga，次峰值在c. 1.7-1.9 Ga。这些特征与邻近的格兰扁群岛的上达尔拉德超群和东劳伦西亚的记录密切相关。这些数据也与复杂的古生物学证据所表明的劳伦起源一致，并与Dalradian超群连续性的实地证据。加里东前陆的寒武纪Salterella砂砾岩的碎屑年龄与高地边界杂岩的大致年龄相当的砂岩进行比较。两者都是同时期的回归霍克湾事件，占相似的起源，并进一步连接高地边境复杂的劳伦。在奥陶纪和志留纪期间，格兰扁古陆一直在抬升，并不断脱落碎屑。在米德兰河谷或南部高地地区的碎屑锆石记录中没有出现这一事件，这表明在志留纪结束之前，这些地块不可能处于相对于格兰扁海的当前位置。补充材料：完整的分析数据集和阴极发光图像可在http://www.geolsoc.org.uk/SUP18531上获得。
Contrasting tectonic models for the Highland Border Complex in the Scottish Caledonides view it either as part of the rifted Laurentian margin of the Iapetus Ocean or as an oceanic terrane. Detrital zircon data from sandstones of the complex yield age peaks at 2.8–2.6, 1.3 and 1.1–1.0 Ga and minor peaks at c. 1.7–1.9 Ga. These characteristics compare closely with those of the upper Dalradian Supergroup of the adjacent Grampian terrane, and with the record of eastern Laurentia. The data are also consistent with the Laurentian provenance indicated by palaeontological evidence from the complex, and field evidence for continuity with the Dalradian Supergroup. Detrital ages for the Cambrian Salterella Grit of the Caledonian foreland compare with those for approximately age-equivalent sandstones from the Highland Border Complex. Both were contemporaneous with the regressive Hawke Bay event, accounting for similarities in provenance, and further linking the Highland Border Complex to Laurentia. The Grampian terrane was being uplifted and shedding detritus throughout the Ordovician and Silurian. The absence of this event from the detrital zircon records of either the Midland Valley or Southern Upland terranes suggests that these blocks cannot have been in their current location relative to the Grampian terrane before the end of the Silurian. Supplementary material: The complete analytical dataset and cathodoluminescence images are available at http://www.geolsoc.org.uk/SUP18531.