The diorite at West Warren, south-central Massachusetts
Open-File Report
74-138
By: John S. Pomeroy
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Abstract
Follated, syntectonic, concordant intrusive bodies of mostly diorite and meladiorite with less abundant quartz diorite and norite have been mapped in the West Warren area of south-central Massachusetts. The rocks of the pluton range from a medium colored phase of diorite and quartz diorite to a dark colored phase of meladiorite and norite. Major minerals In the dioritic rocks are calcic andesine, green hornblende, brown biotite, and hypersthene. Igneous textures are dominant, and retrograde or deuteric effects are generally minor. Silica and alumina contents of the dioritic rocks are somewhat higher than for average diorites; conversely, the oxides of iron, magnesium, and calcium are generally lower. Normative quartz, albite, and anorthite are higher and orthoclase is lower in the samples than In the average diorite. Sizeable plutons of diorite-norite are uncommon in central Massachusetts. The West Warren body, roughly 26 km2 (10 square miles) in area, bears little petrochemical relation to adjacent rock units. The pluton can be construed as belonging to a belt of intrusive mafic rocks which stretches from southeastern New York to coastal Maine.
| Publication type | Report |
|---|---|
| Publication Subtype | USGS Numbered Series |
| Title | The diorite at West Warren, south-central Massachusetts |
| Series title | Open-File Report |
| Series number | 74-138 |
| DOI | 10.3133/ofr74138 |
| Edition | - |
| Year Published | 1974 |
| Language | ENGLISH |
| Publisher | U.S. Geological Survey, |
| Description | 32 leaves :ill. (some folded), maps ;27 cm.; (44 p. - PGS) |
| Google Analytic Metrics | Metrics page |