Índice de distorção, parâmetros celulares e composição química de cordierite de granitóides e corneanas da região de Tondela - Oliveira do Hospital (Portugal Central)

Abstract

Distortion index, cell parameters and chemical composítíon of cordíerites from granites and hornfelses of the Tondela-Oliveira do Hospital region (Central Portugal). Distortion index was measured and cell parameters calculated for cordierite samples from porphyritic granites (4 samples), pegmaplites (2) and contact peliiic hornfelses (13). Distortion index range is 0.14-0.26 with a low mean value 0.19 for granitic rocks; with one exception (distortion index 0.14), this index range between 0.22 and 0.26 in cordierite from hornfelses, with no apparent relation to the dista.nce from the contacto Cell parameters do not significantly discriminate the occurrences of cordierite, and the calculation fits orthorrombic sym.etry in ali samples, Electron microprobe chemical composition of 14 cordierite samples is presented; its probable relation to AI/Si order and rock type is discussed.