A model to calculate the depth of the SMI in sediments of the northern South China Sea

作者：Zhang Jie; Lei Huaiyan^*; Wang Weiguo; Hao Saisai; Gong Chujun

来源：Earth Science Frontiers, 2015, 22(4): 290-298.

DOI：10.13745/j.esf.2015.04.029

• Anaerobic methane oxidations
• Eodiagenesis
• Methane oxidation
• Northern South China Sea
• Organic matter oxidation
• Resource potentials
• SMI
• Sulfate concentrations

As an acceptor of electrons, sulfate plays a significant role in eodiagenesis. A shallow methane-sulfate interface (SMI) suggests that there may be a mass of gas hydrate beneath it. The South China Sea is a typical gas hydrate occurrence zone. Knowing about the sulfate reduction model in this area will help us understand the eodiagenesis system and the resource potential of gas hydrate. On the basis of analysis of sediments from multiple places on the north continental slope of the South China Sea, we propose a model that uses sulfate concentrations at different levels to calculate the depth of SMI. Sulfate reduction from shallow to deep can be divided into three zones: the organic matter oxidation zone, the transition zone and the anaerobic methane oxidation zone. The anaerobic methane oxidation zone can be divided into two layers based on their vastly different sulfate reduction rates and sulfate gradients. The organic oxidation zone and the anaerobic methane oxidation zone occur throughout the region. Whether or not the central transitional zone exists depends on the methane flux under the methane oxidation zone. An increase in surface sulfate concentration may be caused by organic sulfur oxidation. Before calculating the SMI depth, we should eliminate the relevant data caused by the consumption of organic matter. If the anaerobic methane oxidation layer can be divided into two layers based on the rate of sulfate reduction, we should use the lower layer to determine the depth of the SMI.

• 出版日期2015
• 单位厦门大学