Composite layering of a gabbro-diorite association: evidence for periodic invasion of a magma chamber, Isle au Haut, Maine
Chapman M, Rhodes J, National Park Service, Acadia National Park. 1990. Composite layering of a gabbro-diorite association: evidence for periodic invasion of a magma chamber, Isle au Haut, Maine. Eos, Transactions. 71(43):1678
Coastal exposures of a mafic unit in the Coastal Maine Magmatic Province provide a cross-section of a near continuous sequence of 10 alternating gabbro and diorite layers (1.5 - 45 m thick). Field and textural evidence indicate that coexisting gabbro and diorite layers were liquid or largely liquid contemporaneously. Gabbro overlying diorite is chilled approximately 4-5 cm. from the contact and coarsens upwards. Beneath these contact, chilled pillow-like, lobate structures have separated from the gabbro. Also, pipes or fingers of diorite intrude up into the gabbro increasing in diameter. A diffusive border increases away from the pipes with height. Generally, the layers are asymmetric having a sharp lower contact and a more diffuse or intermingled upper contact. Four successive layers are examined in detail.' /STUDY LOCATIONS:/ /ISLE AU HAUT/
- Type
- Journal Article
- Authors
- Chapman, Marshall; Rhodes, J.M.; National Park Service, Acadia National Park
- Units
- ACAD
- Keywords
- Diorite, gabbro, Geology, Igneous Rocks, Isle Au Haut, Magma