Origin and mineralogy of sepiolite and palygorskite from the Tuluanshan Formation, Eastern Taiwan
Journal
Clays and Clay Minerals
Journal Volume
57
Journal Issue
5
Start Page
521
End Page
530
Date Issued
2009-10-01
Author(s)
Ming Kuang Wang
Pao Chung Tseng
Shyun Sheng Chang
Dah Tong Ray
Yen Hong Shau
Yun Wei Shen
Ruey Chyong Chen
DOI
10.1346/CCMN.2009.0570502
Abstract
The Tuluanshan Formation of the eastern Coastal Range of Taiwan overlies an andesitic core complex presumed to be the source of hydrothermal fluids responsible for the Si- and Mg-rich mineralization of sepiolite and palygorskite (attapulgite) which are found in veins within fissures and in fracture zones of the volcanic rocks of the region. This study was undertaken in order to understand these relationships better by characterizing sepiolite and palygorskite in this Formation and by examining their occurrence and distribution in the Tungho (TH) and Chunjih (CJ) areas. Samples were analyzed using X-ray diffraction (XRD), thermal analysis, Fourier-transform infrared (FTIR) spectroscopy, and petrographic, scanning (SEM), and transmission (TEM) electron microscopic methods. Sepiolite and palygorskite are blocky and earthy-type materials that display fibrous characteristics when viewed using TEM and SEM and occurred alone or with chalcedony in veins. The fibers of blocky sepiolite are commonly intercalated with smectite but the earthy type of sepiolite and palygorskite observed in this study displayed precipitation fromfluid enriched in Si, Al, Mg, and minor Fe and depleted in other ions at an earlier stage of offset of the andesitic veins. Continuation of reverse faulting and high shearing stress caused the precipitation of a significant quantity of interlaminated sepiolite. Sepiolite and palygorskite were formed at an earlier stage of fluid interaction relative to smectite in the Tuluanshan Formation.
Subjects
Alteration
Andesite
SEM
Smectite
Taiwan
TEM
Tuluanshan formation
Type
journal article