U-Pb and 40Ar/39Ar age constrains on protolith and high-P/T type metamorphism of the Heilongjiang Complex in the Jiamusi Massif, NE China

Abstract

The Heilongjiang Complex is mainly composed of high -P/T type metamorphic rocks of blueschists and pelitic schists, and is distributed along the western margin of the Jiamusi Massif in NE China. LA -ICP -MS U -Pb ages of detrital zircons in pelitic schist (LG1 -3) from the Mudanjiang district give a weighted mean age of 250.6 ± 2. Ar phengite age of 189.8 ± 0.8 Ma as total gas age (apparent age distribution from 183 Ma to 196 Ma) was also obtained for Yilan garnet -barroisite schist (423YJ -1). Reliable geochronological data suggest that a paleo -ocean located between the Jiamusi Massif and the Songnen Massif to the west was still present at least up to 199 -231 Ma, and subduction -related high -P/T type metamorphism occurred during the Jurassic at 145 -184 Ma.

Structures, strain analyses, and 40Ar/39Ar ages of blueschist‐bearing Heilongjiang Complex (NE China): Implications for the Mesozoic tectonic evolution of NE China

“…Biotites in dioritic gneiss were dated by Rb‐Sr and 40 Ar‐ 39 Ar methods at 184 ± 4 Ma and 190.0 ± 4.8 Ma and were considered as representing the blueschist facies metamorphism (Wu et al, ). A younger age of 164.7 ± 0.7 Ma, also interpreted as dating the high‐pressure metamorphism, was obtained on phengite in micaschists by the 40 Ar‐ 39 Ar method (Li et al, ).…”

“…In the Yilan area, different U‐Pb ages on zircon were also carried out to constrain the timing of protolith formation of mafic rocks and range from 281 Ma (Ge et al, ) to 200 Ma (Zhou et al, ). Recently, a metagabbro located near the Yilan city was dated at 256 ± 2 Ma (Dong et al, ), while the U‐Pb ages of detrital zircons from micaschists range from 2512 Ma to 180 Ma (Dong et al, ; Li et al, ; Zhou et al, ). However, recent U‐Pb dating performed on metabasites located in the east of the Yilan area indicates younger 162–141 Ma protolith ages than the previously reported ones (Zhu et al, ; Zhu, Zhao, Sun, Eizenhöfer, Liu, et al, ; Zhu, Zhao, Ji, et al, ).…”

“…Recent radiometric dating (Rb‐Sr and 40 Ar‐ 39 Ar dating on micas, 40 Ar‐ 39 Ar dating on amphiboles) was performed in the Yilan area and indicates that the metamorphism occurred during Jurassic time between 189 and 170 Ma and 161–145 Ma (Li et al, ; Li et al, ; Wu et al, ; Zhou et al, ; Zhu, Zhao, Ji, et al, ). In detail, the amphibolites were dated at 189.8 ± 0.8 Ma by 40 Ar‐ 39 Ar method on phengite (Li et al, ).…”

“…Recent radiometric dating (Rb‐Sr and 40 Ar‐ 39 Ar dating on micas, 40 Ar‐ 39 Ar dating on amphiboles) was performed in the Yilan area and indicates that the metamorphism occurred during Jurassic time between 189 and 170 Ma and 161–145 Ma (Li et al, ; Li et al, ; Wu et al, ; Zhou et al, ; Zhu, Zhao, Ji, et al, ). In detail, the amphibolites were dated at 189.8 ± 0.8 Ma by 40 Ar‐ 39 Ar method on phengite (Li et al, ). The blueschist units were dated at 172.9 ± 0.7 Ma, 161.1 ± 6 Ma, and 158.8 ± 1 Ma by 40 Ar‐ 39 Ar method on glaucophane (Zhu, Zhao, Ji, et al, ) and at 144.6 ± 0.8 Ma and 146.1 ± 1.3 Ma by 40 Ar‐ 39 Ar dating on phengite (Li et al, ).…”

“…An older age of 185.2 ± 4.4 Ma was also recorded in blueschist units located near the Dongqing village by 40 Ar‐ 39 Ar method on amphibole (Zhou et al, ). Metapelites were dated by 40 Ar‐ 39 Ar method on phengite at 179.9 ± 0.5 Ma (Li et al, ), 173.6 ± 0.5 Ma, 175.3 ± 0.4 Ma (Wu et al, ), and 170.9 ± 0.8 Ma (Li et al, ). In addition, phengites from blueschist facies rocks located near the Hunan city close to the Yilan area were dated at 176.5± 1.9 Ma and 184.5± 2.1 Ma by the 40 Ar‐ 39 Ar method, providing similar timing for the blueschist metamorphism (Zhao & Zhang, ).…”