Journals
  Publication Years
  Keywords
Search within results Open Search
Please wait a minute...
For Selected: Toggle Thumbnails
The 850 Ma Continental Flood Basalts in North Altun Block and Their Implications for Mantle Plume Activity
FENG Di, LI Yanguang, SONG Shuguang
Acta Scientiarum Naturalium Universitatis Pekinensis    2025, 61 (3): 508-524.   DOI: 10.13209/j.0479-8023.2025.024
Abstract1242)   HTML    PDF(pc) (17467KB)(2729)       Save
This paper reports the layered mafic volcanic rocks formed in the Hongliuquan area of the North Altyn region at 843 Ma. This suite of volcanic rocks has relatively high TiO2 (1.18%–2.06%), low Zr/Hf (23.28–29.28) and low Nb/Ta (4.20–12.99), showing the trace element characteristics of E-MORB/OIB, like the typical low-Ti basalts in large igneous provinces. The analysis results of major and trace elements in the entire rock show that the magma of the basic rock has undergone a low degree of partial melting (<10%) of the asthenosphere source of garnet (<2%), and has been subject to varying degrees of crustal mixing during the uplift process. The occurrence, geochemical characteristics, age data and high mantle potential temperature (Tp=1479°C) of the northern Aljin layered basic volcanic rock indicate that this basic volcanic rock is a continental overflow basalt (CFB) originated from the Neoproterozoic mantle plume. Combined with the extended background magmatic activity developed in the region during the same period (850–750 Ma), we believe that the northern Alkinic volcanic rocks record the earliest magmatic activity during the supercontinent rifting process. In the Neoproterozoic era, it was discovered that the magmatic activities of Alkin and those of the Qilian, Chaibei Margin, Eastern Kunlun, South China and Qinling Mountains all had the diagenological characteristics of an intracontinental rift valley environment, which indicates that they are related to the mantle plume activities at 850–800 Ma. It further indicates that the formation of the Northern Altyn volcanic rock mass is closely related to the beginning of the rifting of the Rodinia supercontinent at approximately 850 Ma. 
Related Articles | Metrics | Comments0
Abiotic Methane Inclusions in Olivine from the Yushigou Peridotite and Their Forming Conditions
LIN Chiumei, SONG Shuguang, CUI Ying
Acta Scientiarum Naturalium Universitatis Pekinensis    2022, 58 (2): 241-248.   DOI: 10.13209/j.0479-8023.2022.013
Abstract2368)   HTML    PDF(pc) (5557KB)(767)       Save
The paper presents studies of the methane-rich fluid inclusions in the fresh peridotite from the Cambrian Yushigou ophiolite, the middle part of North Qilian Orogenic Belt. In situ analysis of laser Raman spectroscopy shows that these fluid inclusions are mainly composed of liquid or gaseous CH4+C (graphite) with minor components of N2, H2O, C2H6 and C3H8, representing the reductive C-H fluid speciation. Based on characteristic bands of graphite, the authors carry out fluid temperature estimates using the RSCM (Raman spectroscopy of carbonaceous materials). The calculated temperatures range from 430 to 590°C, which represents the minimum temperature for precipitation of graphite and indicates that CH4+C is abiotic origin and formed in the mantle environment.
Related Articles | Metrics | Comments0
Age and Tectonic Setting of the Aoyougou-Erzhihaladaban Ophiolite in the Western North Qilian Mountains, NW China
XIA Xiaohong,SUN Nan,SONG Shuguang,XIAO Xuchang
Acta Scientiarum Naturalium Universitatis Pekinensis   
Mg-Carpholite Metapelite and Its Implications for Ancient Oceanic Subduction in the North Qilian Suture Zone, NW China
YU Xiaoning,SONG Shuguang,WEI Chunjing,ZHANG Lifei
Acta Scientiarum Naturalium Universitatis Pekinensis   
Abstract1163)            Save
A typical Early Paleozoic oceanic suture zone, which consists of ophiolite, arc volcanic rocks and high-pressure low-temperature metamorphic rocks, occurs in the North Qilian Mountains, Northwestern China. Eclogite facies metapelites with index mineral assemblage of Mg-carpholite + garnet + chloritoid + phengite were studied in details in petrology and mineralogy. Using THERMORCAL (V3.23), the authors calculated the P-T conditions of the stability field for Carpholite (cr) + garnet (g) + chloritoid (ct) + phengite (ph) assemblage at P=2.2-2.5GPa and T=530-580℃. Based on the calculated stability fields of carpholite and chloritoid, the authors confirmed that the North Qilian suture zone was a “cold" oceanic subduction zone in Early Paleozoic time with geothermal gradients of 6.5-7.5℃/km, similar to Mesozoic-Cenozoic subduction zones. This study plays an important role in understanding the thermo-structure of the Early Paleozoic subduction zones and dehydration of HP metamorphic pelitic rocks.
Related Articles | Metrics | Comments0