Comparison of the Late Miocene Sediments and Early Quaternary Red Paleosols in the Penghu Islands, Taiwan and Zhangpu, Fujian

Abstract

This study aims to compare the clay mineralogy and whole-soil major chemistry of elements in late Miocene soil sediments and early Quaternary red paleosols in the Penghu Islands, (Pescadores), Taiwan, and Zhangpu Volcanic Park, Fujian. There were the late Miocene Chu Wan (CWI and CWII), Shiao Men Yu (SMY) and two intergrade red soils, Chu Wan (CW(irs)) and Shiao Men Yu (SMY(irs)), with three distinctive zones of different dominating kaolins in the profiles of the Penghu Islands. A Tong Wei (TW) paleosol of early Quaternary basaltic eruptions in the Penghu Islands was collected. The Anzei (AZ), Si Yu (HY) and Chianmei (CM) paleosols were sampled from the Penghu Islands and Yulinshi (YLS) paleosols near the Zhangpu Volcanic Park for this study. The CW and SMY paleosols erupted in the late Miocene, and the other paleosols erupted on the Penghu Islands. These paleosols were fractionated into clay fractions and subjected to soil physical and chemical analyses. Kaolin minerals were dominant in the CW(irs) and SMY(irs) paleosols. The top layer (layer one) in the CW(irs) was 7 Å-halloysite, and order/disordered kaolinites were present in layers two and three. The CW(irs) and SMY(irs) hexagonal-like, platy kaolinites (0.1–0.2 µm in diameter), spheroidal and hollow 7 Å-halloysite (layer 1) was determined with transmission electron microscopic (TEM) investigations. The early Quaternary red soil of TW consisted of kaolinite, illite, vermiculite and smectite clay assemblages. Late Miocene paleosols were classified as fine, kaolinite, hyperthermic and Typic Rhodic Paleudults, and the early Quaternary red paleosols were classified as fine, mixed, hyperthermic and Typic Rodistalf, respectively. Late Miocene paleosols contained more clays, lower SiO2/Al2O3 and higher chemical index of weathering (CIW) than early Quaternary paleosols. The kaolin, illite, smectite and vermiculite mineralogy, physical and chemical properties of paleosols and landscapes in the Zhangpu YLS, Fujian, were similar to those of late Miocene sediments and early Quaternary red paleosols in the Penghu Islands.