Late Paleozoic collision, delamination, short-lived magmatism, and rapid denudation in the Meguma Terrane (Nova Scotia, Canada): constraints from 40Ar/39Ar isotopic data
Late Paleozoic collision, delamination, short-lived magmatism, and rapid denudation in the Meguma Terrane (Nova Scotia, Canada): constraints from 40Ar/39Ar isotopic data
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DOI：
10.1139/e95-054
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发表时间：
1995-05
影响因子：
1.4
通讯作者：
J. Keppie;R. D. Dallmeyer
中科院分区：
文献类型：
--
作者：
J. Keppie;R. D. Dallmeyer
Meguma地体由8-15 km的早古生代层状岩石组成，沉积在大陆基底上，在晚古生代期间由于岩石圈板块碰撞而变形和变质。最古老的卵裂（先前发表的，全岩，40 Ar/39 Ar坪年龄为415-395 Ma）的日期开始地壳增厚，其次是大量的，但短暂的，晚泥盆世花岗质和少量镁铁质岩浆活动（380-370 Ma）。这种岩浆作用可能是岩石圈下部拆沉和软流圈上涌的产物，它影响了新莫霍面之上的熔融，并导致了5-12 km深处的侵入。角闪石、白云母和黑云母的40 Ar/39 Ar坪年龄表明，在目前的侵蚀水平下，大部分的Meguma地体在368-360 Ma时冷却到300 °C，略早于Meguma地体西南部（约100 ° C）。345 Ma）。目前的侵蚀水平是由最新的泥盆纪-早石炭世（Visean）发掘的：
The Meguma Terrane consists of 8–15 km of early Paleozoic stratified rocks, deposited on a continental basement, that were deformed and metamorphosed during the late Paleozoic as a result of lithospheric plate collision. The oldest cleavage (previously published, whole-rock, 40Ar/39Ar plateau ages of 415–395 Ma) dates the onset of crustal thickening, which was followed by voluminous, but short-lived, Late Devonian granitic and minor mafic magmatism (380–370 Ma). This magmatism may have been the product of delamination of the lower lithosphere and upwelling of asthenosphere, which effected melting above the new Moho and resulted in intrusion at depths of 5–12 km. 40Ar/39Ar plateau ages of hornblende, muscovite, and biotite indicate that, at the present erosion level, most of the Meguma Terrane cooled through ~300 °C by 368–360 Ma, slightly earlier than for the southwestern Meguma Terrane (ca. 345 Ma). The present erosion level was exhumed by the latest Devonian–Early Carboniferous (Visean): the age of the ...