Geology of a Large Intact Extensional Oceanic Arc Crustal Section with Superior Exposures: Cretaceous Alisitos Arc, Baja California (Mexico)
Print publication date: 28/03/2023
Geological Society of America, GSA Special Papers, Earth Structure Processes and Tectonics, Volcanology
Type: Book (Paperback)
Binding: Paperback
ISBN: 9780813725604
Weight: 0.6kg
Number of pages: 0
£31.00
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Product code: USPE560
Edited by Cathy J. Busby, Rebecca A. Morris, Susan M. DeBari, Sarah Medynski, Keith Putirka, Graham D.M. Andrews, Axel K. Schmitt, and Sarah R. Brown
The Rosario segment of the Cretaceous Alisitos arc (Baja California, Mexico) is arguably the best-exposed structurally intact and unmetamorphosed oceanic arc crustal section on Earth. The gently tilted, 50-km-long section exposes the transition from upper-crustal volcanic rocks to mid-crustal plutonic rocks, formed in an extensional environment. This book presents a detailed geologic map, based on an exhaustive data set including geochemistry, geochronology, and annotated outcrop photos and photomicrographs. Subsegments within the Rosario segment include a subaerial edifice, a volcano-bounded basin, and a fault-bounded basin, each underpinned by separate plutons. The entire data set is integrated across these subsegments in a time slice reconstruction of arc evolution and the relationships between plutonism and volcanism. The data set provides constraints on the evolution of silicic calderas and tectonic triggers for caldera collapse, caldera resurgence by emplacement of sill complexes and by incremental growth of plutons, and comparison with velocity profiles in modern arcs.
Acknowledgments.v
Abstract.1
1. Introduction, setting, methods, and overview .3
Introduction.3
Geologic setting .5
Methods .15
Overview of the Rosario segment of the Alisitos arc.15
2. Analytical data.17
Geochronology.17
Whole-rock geochemistry.18
Hf isotopes in zircon.20
3. Central subaerial edifice.23
Stratigraphy.23
Central subaerial edifice hypabyssal intrusions .33
Central subaerial edifice plutonic rocks—La Burra pluton .34
4. Southern volcano-bounded basin.39
Stratigraphy.39
Southern volcano-bounded basin hypabyssal intrusions .54
Southern volcano-bounded basin plutonic rocks—San Fernando pluton.55
5. Northern fault-bounded basin.59
Stratigraphy.59
Northern fault-bounded basin hypabyssal intrusions.78
Northern fault-bounded basin plutonic rocks—Los Martires pluton.79
6. Time slice reconstruction.85
Introduction.85
Time slice 1.85iv Contents
Time slice 2.88
Time slice 3.89
Postmagmatic deformation.89
7. Discussion of processes in extensional oceanic arcs, with conclusions.91
Eruptive styles of oceanic arc ignimbrites.91
Tectonic triggers and controls for caldera collapse .91
Styles of caldera collapse.91
Caldera resurgence.92
Caldera plumbing systems and incremental growth of plutons.92
The caldera cycle .93
Magma storage levels and comparison with velocity profiles in modern arcs.95
Importance of silicic calderas in extensional oceanic arcs.95
Conclusions.96
References cited.99
