TY - JOUR
T1 - Construction and evolution of igneous bodies
T2 - Towards an integrated perspective of crustal magmatism
AU - Annen, Catherine
AU - Blundy, Jonathan D.
AU - Leuthold, Julien
AU - Sparks, R. Stephen J
PY - 2015/8/1
Y1 - 2015/8/1
N2 - Field, geochronological and geophysical studies show that many igneous bodies are emplaced incrementally, growing by accretion of successive magma sheets. The existence of melt reservoirs with a size that exceeds one single increment strongly depends on the sheet emplacement rate, whereas the total volumes of magma that accumulate depend on the volumetric magma flux. Integration of geochronological and field data with numerical simulations suggeststhat those rates can vary dramatically over the growth of an igneous body and that magmas accumulate to form melt-rich magma chambers only during episodes of high magma flux.Heat and mass balance considerations and the large volumes of mafic magma required to generate differentiated melts suggest that most crustal differentiation happens in deep hot zones in the lower crust wherein a wide diversity of melts are produced by crystallisation of mafic parents and concomitant partial melting of the crust. Melt composition is further modified during migration, segregation and ascent, and intermediate compositions can be generated when different types of melt mix. Magma fluxes and intrusion geometry play a fundamental role in igneous body evolution. Thus our knowledge of igneous processes depends ultimately on our understanding of the physics that control magma fluxes into the crust, magma emplacement within the crust and magma migration through the crust.
AB - Field, geochronological and geophysical studies show that many igneous bodies are emplaced incrementally, growing by accretion of successive magma sheets. The existence of melt reservoirs with a size that exceeds one single increment strongly depends on the sheet emplacement rate, whereas the total volumes of magma that accumulate depend on the volumetric magma flux. Integration of geochronological and field data with numerical simulations suggeststhat those rates can vary dramatically over the growth of an igneous body and that magmas accumulate to form melt-rich magma chambers only during episodes of high magma flux.Heat and mass balance considerations and the large volumes of mafic magma required to generate differentiated melts suggest that most crustal differentiation happens in deep hot zones in the lower crust wherein a wide diversity of melts are produced by crystallisation of mafic parents and concomitant partial melting of the crust. Melt composition is further modified during migration, segregation and ascent, and intermediate compositions can be generated when different types of melt mix. Magma fluxes and intrusion geometry play a fundamental role in igneous body evolution. Thus our knowledge of igneous processes depends ultimately on our understanding of the physics that control magma fluxes into the crust, magma emplacement within the crust and magma migration through the crust.
KW - Crustal differentiation
KW - Igneous bodies
KW - Incremental emplacement
KW - Magma chambers
KW - Magma fluxes
KW - Melt reservoirs
UR - http://www.scopus.com/inward/record.url?scp=84937930869&partnerID=8YFLogxK
U2 - 10.1016/j.lithos.2015.05.008
DO - 10.1016/j.lithos.2015.05.008
M3 - Article (Academic Journal)
AN - SCOPUS:84937930869
SN - 0024-4937
VL - 230
SP - 206
EP - 221
JO - Lithos
JF - Lithos
ER -