首页|Morphological and Sulfur-Isotopic Characteristics of Pyrites in the Deep Sediments from Xisha Trough,South China Sea

Morphological and Sulfur-Isotopic Characteristics of Pyrites in the Deep Sediments from Xisha Trough,South China Sea

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Pyrite is one of the common authigenic minerals in marine sediments.Previous studies have shown that the morphological and isotopic characteristics of pyrite are closely related to the geochemical environment where it is formed.To better understand the for-mation mechanism of authigenic pyrite,we analyzed the isotopic composition,morphology,and distribution of pyrite in the sediment at 500 m below the seafloor from Xisha Trough,South China Sea.Mineral morphologies were observed by scanning electron micros-copy and Raman spectrography.X-Ray computed tomography was applied to measure the particle size of pyrite.The size of pyrite crystals in the matrix sediment mainly ranged between 25 and 65 µm(av.ca.40 µm),although crystals were larger(av.ca.50 μm)in the veins.The pyrites had a fine-grained truncated octahedral shape with occasionally well-developed growth steps,which implies the low growth rate and weak anaerobic oxidation of methane-sulfate reduction when pyrite was formed.The δ34S values of pyrites ranged from +20.8‰ Vienna-defined Canyon Diablo Troilite(V-CDT)to +33.2‰ V-CDT and from +44.8‰ V-CDT to +48.9‰,which suggest two growth stages.In the first stage,with the continuous low methane flux,the pyrite possibly formed in an environment with good access to seawater.In the second stage,the pyrites mainly developed in sediment fractures and appeared in veins,probably due to the limited availability of sulfate.The less exposure of pyrite to the environment in the second stage was probably caused by sediment accumulation or perturbation.In this study,an episodic pyritization process was identified,and the paleoenvironment was reconstructed for the sediment investigated.

pyritesulfur isotopeAOMmethane fluxXisha TroughSouth China Sea

CHANG Jingyi、LIU Yujia、LU Hailong、LU Jing'an、SU Xin、YE Jianliang、XIE Wenwei

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College of Engineering,Peking University,Beijing 100871,China

Beijing International Center for Gas Hydrate,School of Earth and Planetary Sciences,Peking University,Beijing 100871,China

School of Marine Science,Nanjing University of Information Science and Technology,Nanjing 210044,China

MLR Key Laboratory of Marine Mineral Resources,Guangzhou Marine Geological Survey,Ministry of Land and Resources,Guangzhou 510075,China

School of Ocean Sciences,China University of Geosciences,Beijing 100083,China

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Guangdong Major Project of Basic and Applied Basic Research

2020B03 01030003

2024

10.1007/s11802-024-5521-4

中国海洋大学学报(自然科学英文版)
中国海洋大学

中国海洋大学学报(自然科学英文版)

CSTPCD
影响因子：0.268
ISSN：1672-5182
年,卷(期)：2024.23(1)
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