Compound quartz and feldspar overgrowths from the Helsby Formation (Triassic) of Cheshire, northwest England

✍ Scribed by L Macchi; C. J. Veltkamp

• Book ID: 102222666
• Publisher: John Wiley and Sons
• Year: 2007
• Tongue: English
• Weight: 408 KB
• Volume: 20
• Category: Article
• ISSN: 0072-1050
• DOI: 10.1002/gj.3350200308

✦ Synopsis

Abstract

A polycrystalline grain of granitic composition with compound feldspar and quartz overgrowths is described from the continental Helsby Sandstone Formation (Triassic; Sherwood Sandstone Group) of the Cheshire Basin, northwest England. Overgrown phases, as seen by thin section and scanning electron microscopy, are in crystallographic continuity with respective components of the host grain and have mutual relationships which indicate the quartz to be the later diagenetic phase. Energy dispersive spectrometry (EDS) of the grain surface and of the earlier formed overgrowths indicates the feldspar to have a potassium aluminosilicate composition which is in accordance with the adularia‐habit crystal form of the authigenic phase.