K-feldspar megacryst accumulations formed by mechanical instabilities in magma chamber margins, Asha pluton, NW Argentina
- Rocher, Sebastian
- Alasino, Pablo Horacio
- Macchioli Grande, Marcos Simón
- Larrovere, Mariano Alexis
- Paterson, Scott Robert
DOIAbstract
The Asha pluton, the oldest unit of the San Blas intrusive complex (Early Carboniferous), exhibits impressive examples of magmatic structures formed by accumulation of K-feldspar megacrysts, enclaves, and schlieren. Almost all recognized structures are meter-scale, vertically elongate bodies of variable shapes defined as fingers, trails, drips, and blobs. They preferentially developed near the external margin of the Asha pluton and generally are superimposed by chamber-wide magmatic fabrics. They mostly have circular or sub-circular transverse sections with an internal fabric defined by margin-parallel, inward-dipping concentric foliation and steeply plunging lineation at upper parts and flat foliation at lower parts. The concentration of m...
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