Advances in Earth Science ›› 2017, Vol. 32 ›› Issue (7): 769-780. doi: 10.11867/j.issn.1001-8166.2017.07.0769

Special Issue: IODP

• Orginal Article • Previous Articles     Next Articles

A Study of Pretreatment Methods for Terrigenous Grain-Size Analysis of Marine Sediments

Shaohua Zhao( ), Zhifei Liu   

  1. State Key Laboratory of Marine Geology, Tongji University, Shanghai 200092,China
  • Received:2017-02-08 Revised:2017-06-28 Online:2017-07-20 Published:2017-07-20
  • About author:

    First author:Zhao Shaohua (1987-), male, Bozhou City, Anhui Province, Ph.D student. Research areas include marine sedimentoloy and

  • Supported by:
    Project supported by the National Natural Science Foundation of China “Deep-sea sedimentation process and mechanism in the South China Sea” (No.91528304) and “Deepwater sedimention since the miocene in the central basin of the South China Sea and its regional tectonic and environmental evolution significance” (No.41530964)

Shaohua Zhao, Zhifei Liu. A Study of Pretreatment Methods for Terrigenous Grain-Size Analysis of Marine Sediments[J]. Advances in Earth Science, 2017, 32(7): 769-780.

The prerequisite for obtaining variations of terrigenous grain-size of marine sediments is how to effectively remove non-terrigenous matters and preserve terrigenous particles synchronously. Combined with observations under biological microscope and scanning electron microscope, a comparative study of biogenic debris removal effect and terrigenous grain-size analysis under different pretreatment condition was performed on core sediments, which were retrieved in the South China Sea during the MD190 cruise. Our new results showed that the main three biogenic particles, namely, organic matter, carbonate, and opal in marine sediments could be removed effectively by 30% H2O2 in a stirring water bath at 60 ℃ for 3 h, 0.5% HCl for 1 h, and 2 mol/L Na2CO3 in a stirring water bath at 85 ℃ for 5 h, in turn. Such pretreatments achieved the goals of biogenic debris removal efficiency and relatively well-preserved terrigenous particles. Prior to selecting an appropriate pretreatment method, this study suggested that the actual effects of biogenic detritus on grain-size results of diverse marine sediment samples should be taken into account. If the laboratory data are ensured to be closer to the natural grain-size distribution of terrigenous particles, the removals of all biogenic debris are not always needed, and the less pretreatment processes the better. For example, opal particles have little effect on terrigenous grain-size distribution when their percentage is lower than 2%. Thus, there is no use to remove them from marine sediments before laboratory grain-size analysis of terrigenous particles. Additionally, ultrasonic is not suggested through the whole process of terrigenous grain-size analysis because the strong energy of ultrasonic can lead to the fragmentation of some fragile terrigenous particles.

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