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首页> 外文期刊>Canadian journal of earth sciences >U-Pb ages of granitoid rocks in the northwestern Makkovik Province, Labrador: evidence for 175 million years of episodic synorogenic and postorogenic plutonism
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U-Pb ages of granitoid rocks in the northwestern Makkovik Province, Labrador: evidence for 175 million years of episodic synorogenic and postorogenic plutonism

机译：拉布拉多西北马克科维克省的花岗岩岩石的U-Pb年龄：1.75亿年的偶发性成因和后造山成岩作用证据

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摘要

New U-Pb zircon, titanite, and monazite ages reported here, along with existing age data, demonstrate that granitoid bodies in the northwestern segment of the Paleoproterozoic Makkovik Province, Labrador, are of three distinct ages. The redefined Island Harbour Bay plutonic suite consists of varied dioritic to granitic units that were syntectonically emplaced into Archean crust of the Kaipokok domain between ca. 1895 Ma and 1870 +- 2 Ma. This plutonism occurred during the early stages of the Makkovikian Orogeny in an obliquely convergent, Andean continental margin setting. The Hares Islands and Drunken Harbour granites form smaller, discrete plutons that were emplaced in or adjacent to the Island Harbour Bay plutonic suite at 1805 +- 5 Ma and 1791 +- 2 Ma, respectively, during dextral strike-slip deformation that accompanied accretion of an outboard juvenile terrane. Magmatic activity during this period was preferentially sited along active structural zones, but also occurred outside of these zones. The unreformed Blacklers Bight A-type granite was emplaced in the Kaipokok domain at 1716 +- 1 Ma late in the development of the orogen. A-type granites of this age form a significant component of the southeastern Makkovik Province, and their generation is linked to mafic underplating and heterogeneous regional extension. The new age data support the conclusion of earlier workers that crustal growth via synorogenic and postorogenic plutonism was episodic, and allow, along with field and geochemical data, inferences to be made regarding the tectonic setting of individual plutonic events.
机译：此处报道的新的U-Pb锆石，钛矿和独居石年龄以及现有的年龄数据表明，拉布拉多古元古代马克科维克省西北段的花岗岩体具有三个不同的年龄。重新定义的Island Harbour Bay岩体套件由不同的闪长岩到花岗岩单元组成，这些单元被共晶地置于Caipokok域之间的太古宙地壳中。 1895马和1870 +-2马。这种倾斜现象发生在马克科维奇造山运动的早期，在一个倾斜地汇聚的安第斯大陆边缘地区。 Hares群岛和Drunken Harbor花岗岩形成较小的离散云母，在右旋走滑形变并伴有积聚的过程中，分别在1805 + -5 Ma和1791 +-2 Ma处放置在Island Harbour湾云母组中或附近。舷外的幼体。在此期间，岩浆活动优先位于活动构造带，但也发生在这些带外。未造形的Blacklers Bight A型花岗岩在造山带发展的晚期被置于Kaipokok域中，位于1716±1 Ma。这个年龄的A型花岗岩是东南马克科维克省的重要组成部分，其生成与镁铁质底板和异质区域扩展有关。新的年龄数据支持早期工人得出的结论，即通过协同成因和造山后的成岩作用，地壳的生长是偶发的，并且可以与野外和地球化学数据一起推断出单个岩体事件的构造环境。

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