INSIGHTS INTO MAGMA EMPLACEMENT RATES INTO THE SHALLOW CRUST FROM THERMAL MODELING AND THE PALEOSECULAR VARIATION RECORD, HENRY MOUNTAINS, UTAH

2019 ◽  
Author(s):  
Scott Giorgis ◽  
◽  
Eric Horsman ◽  
Anthony F. Pivarunas ◽  
Michael Braunagel
2020 ◽  
Author(s):  
William McCarthy ◽  
Vincent Twomey ◽  
Craig Magee ◽  
Mike Petronis

<p>Volcano eruption forecasting typically links ground deformation patterns to sub-surface magma movement. Injection and inflation of magmatic intrusions in the shallow crust is commonly accommodated by roof uplift, producing intrusion-induced forced folds that mimic the geometry of underlying igneous bodies. Whilst such forced folds have previously been described from field exposures, seismic reflection images, and modelled in scaled laboratory experiments, the dynamic interaction between progressive emplacement of hot magma, roof uplift, and any associated fracture/fault development remains poorly understood. For instance, analysis of ancient examples where magmatism has long-since ceased only provides information on final geometrical relationships, while, studies of active intrusions and forced folding only capture brief phases of the dynamic evolution of these structures. If we could unravel the spatial and temporal evolution of ancient forced folds, we could therefore acquire critical insights into magma emplacement processes and interpretation of ground deformation data at active volcanoes.</p><p> </p><p>We put forth and aim to test a new hypothesis suggesting that thermoremanent magnetization (TRM) records progressive deflection of the host rock during incremental laccolith construction and that these measurements can be used to measure the rate of laccolith construction. Here, we integrate palaeomagnetic techniques with semi-automated, UAV-based photogrammetric structural mapping to test: (1) whether we can identify variations in Natural Remanent Magnetisation (NRM), TRM, and magnetic mineralogy across an intrusions structural aureole; and (2) whether measured magnetic variations can be related to deflection caused by incremental sheet emplacement. Our test site is located within the basaltic lava pile of the ~800 m wide structural aureole of the rhyolitic Sandfell Laccolith in SE Iceland, which intruded <1 Km below the palaeosurface at ~11.7 Ma. We discuss whether palaeomagnetic backstripping can be an effective resource to constrain the rate and magnitude of intrusion-induced forced fold evolution, and thus an effective tool in volcanic hazard assessment.</p>


2006 ◽  
Vol 428 (1-4) ◽  
pp. 1-31 ◽  
Author(s):  
Michel de Saint-Blanquat ◽  
Guillaume Habert ◽  
Eric Horsman ◽  
Sven S. Morgan ◽  
Basil Tikoff ◽  
...  

2021 ◽  
Author(s):  
William McCarthy ◽  
Vincent Twomey ◽  
Craig Magee ◽  
Michael Petronis ◽  
Tobias Mattsson

<p>Injection and inflation of magma in the shallow crust is commonly accommodated by uplift of the surrounding host rock, producing intrusion-induced forced folding that mimics the geometry of the underlying intrusion. Whilst such forced folds have previously been described from field exposures, seismic reflection images, and modelled in scaled laboratory experiments, the dynamic interaction between progressive emplacement of hot magma, roof uplift, and any associated fracture/fault development remains poorly understood. Analysis of ancient examples where magmatism has long-since ceased typically only provides information on final geometrical relationships, while studies of active intrusions and forced folding only capture brief phases of the dynamic evolution of these structures. If we could unravel the spatial and temporal evolution of ancient forced folds, we could therefore acquire critical insights into magma emplacement processes and interpretation of ground deformation data at active volcanoes.</p><p> </p><p>We put forth a new hypothesis suggesting that thermoremanent magnetization records progressive deflection of the host rock during laccolith construction where these measurements can be used to measure the rate and dynamics of the magma emplacement of. Our test site is located within the basaltic lava pile of the ~800 m wide structural aureole surrounding the rhyolitic Sandfell Laccolith in SE Iceland, which intruded <1 Km below the palaeosurface at ~11.7 Ma. Our results show heat from the laccolith resets the remanence from samples within 50 m of the contact. Several variations in thermoremanent vectors observed further outward along the structural aureole reflect stepwise folding from incremental injection of magma suggesting as and the laccolith develops, different sections of the host rock are incrementally tilted and possibly reheated. This procedure could be tested in other ancient structure aureoles to investigate whether single or multiple thermal [email protected] coupled with structural observations could be used a proxy for ground deformation patterns in volcanic hazard assessment.</p>


2018 ◽  
Author(s):  
Vedant Bhuyar ◽  
Shiv Ram Suthar ◽  
Mohit Vijay ◽  
Prodyut R. Chakraborty

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