Geochemistry of magnetite in beach sands, stream sediments, and in situ magnetites in surrounding rocks at north Taiwan island

• Published in: Acta geochimica 2022, Vol.41 (3), p.434-452
• Main Authors: Mitwally, Eslam Mohammed Ali, Yu, Bing-Sheng
• Format: Article
• Language: English
• Subjects: Ablation; Aluminum; Analytical methods; Andesite; Atomic properties; Beaches; Chemical composition; Chromite; Correlation; Earth and Environmental Science; Earth Sciences; Ecological aggregations; Emission analysis; Emission spectroscopy; Fluvial deposits; Geochemistry; Inductively coupled plasma mass spectrometry; Iron; Laser ablation; Lasers; Magnesium; Magnetite; Manganese; Mass spectrometry; Mass spectroscopy; Minerals; Molybdenum; Nickel; Niobium; Original Article; Rivers; Rock; Rocks; Scientific imaging; Sediments; Spinel; Trace elements; Water analysis; Water sampling; Zinc
• ISSN: 2096-0956; 2365-7499
• DOI: 10.1007/s11631-021-00521-y

The geochemistry of magnetite provides constraints on the source(s) of the magnetite and other ore minerals. In this study, we constructed a magnetite distribution map, compared the chemical composition of magnetite present in hard rocks with that present in sand beach and stream deposits to determine magnetite’s provenance, investigated relationships among different trace elements, examined variations in the concentrations of trace elements present in magnetite, and identified the type of studied magnetite. Laser ablation inductively coupled plasma mass spectrometry (LA-ICP-MS) and inductively coupled plasma mass spectrometry/inductively coupled plasma atomic emission spectroscopy was used to analyze samples available in small and large amounts, respectively. The average magnetite compositions of beach and river samples were substantially similar to those of andesite rocks, revealing that the magnetite samples may have originated from surrounding andesite rocks; this finding is consistent with the chemical composition of the samples analyzed using LA-ICP-MS. Some of the andesite rocks found in the study area were the primary source of magnetite aggregations in the beach sands and stream sands near or slightly away from these rocks. High Ti–V magnetites lie within the fields of Fe–Ti–V bearing magnetite and titanomagnetite (ulvöspinel). These titanomagnetites may be undergoing transformation to spinel minerals such as galaxite, gahnite, magnesiochromite, and chromite, which are characterized by the high concentrations of Al, Ti, Mg, Cr, Ni, Mn, and Zn. The positive correlation between Fe and Ti, Cr and Ni, and also the negative correlation between Fe and Mg, Mn and Zn can be attributed to various magnetite phases present in the study area. V, Co, Mo, Nb, Ga, Sn, and Ta exhibited a positive correlation with Fe and a negative correlation with Al. The positive correlation between Fe and these elements indicates the enrichment of these elements in the magnetite series. We observed a negative correlation between Fe and Li, Rb, Ca, Ba, Sr, Cu, Cd, Sb, As, Sc, Y, REE, U, and Th. A positive correlation between Al and these elements indicates the enrichment of these elements in the spinel series.