Paleoproterozoic P-T-t evolution in the Hengshan-Wutai-Fuping area, North China Craton: Evidence from petrological and geochronological data
Paleoproterozoic P-T-t evolution in the Hengshan-Wutai-Fuping area, North China Craton: Evidence from petrological and geochronological data
复制标题
华北克拉通横山-五台-富平地区古元古代P-T-t演化：来自岩石学和年代学资料的证据
DOI：
10.1016/j.precamres.2017.02.016
复制
发表时间：
2017
影响因子：
3.8
通讯作者：
Yin Changqing
中科院分区：
文献类型：
--
作者：
Qian Jiahui;Wei Chunjing;Yin Changqing
This contribution carries out zircon dating and a review of the previous metamorphic and geochronological work on the Hengshan–Wutai–Fuping area in the central trans-North China Orogen, for elucidating its Paleoproterozoic orogenic evolution. The Hengshan Complex can be subdivided into North Hengshan and South Hengshan Complexes, separated by the strike-slip Zhujiafang shear zone. High-pressure (HP) mafic granulite and garnet-absent amphibolite collected from the North Hengshan Complex yield metamorphic ages of 1963–1769 Ma and 1882–1793 Ma, respectively, both with weighted mean ages of ∼1.85 Ga. In the HP mafic granulite, zircons of >1.90 Ga and those of < 1.90 Ga have consistent REE patterns and low crystallization temperatures of 650 ± 50 °C calculated by Ti-in-zircon thermometer, where the temperatures are compatible with the cooling temperatures of the rock. Thus the zircon ages are interpreted to mainly represent the cooling stage. Garnet amphibolite collected from the Zhujiafang shear zone yields a metamorphic age of 1864 ± 31 Ma (crystallizationT= 650 ± 50 °C), consistent with the deformation age (amphibole/mica40Ar/39Ar method) of the shear zone. Metamorphic zircons in this rock show steep REE patterns and high concentration of HREE, possibly indicating that they grew later than the relict garnet. Therefore, these zircons could have grown or re-crystallized during mylonitization of the shear zone. A summary of metamorphic ages and metamorphicP–Tpaths in the Hengshan–Wutai–Fuping area indicates that age peaks increase regularly from granulite facies North Hengshan and Fuping Complexes (∼1.85 Ga), to upper-amphibolite facies South Hengshan Complex (∼1.92 Ga) and to lower-amphibolite facies Wutai Complex (∼1.95 Ga). The Hengshan–Wutai–Fuping area may have undergone a protractedP–T–tevolution, including a crustal thickening at ∼1.95 Ga, followed by exhumation and (isobaric) cooling of high-grade terranes from 1.92 to 1.85 Ga. The final uplift of the Hengshan Complex could be attributed to the strike-slip movement of the Zhujiafang shear zone.
