TY - JOUR
T1 - Where did the Arizona-Plano Go? Protracted Thinning Via Upper- to Lower-Crustal Processes
AU - Jepson, Gilby
AU - Carrapa, Barbara
AU - George, Sarah W.M.
AU - Reeher, Lauren J.
AU - Kapp, Paul A.
AU - Davis, George H.
AU - Thomson, Stuart N.
AU - Amadori, Chiara
AU - Clinkscales, Christopher
AU - Jones, Sean
AU - Gleadow, Andrew J.W.
AU - Kohn, Barry P.
N1 - Funding Information:
Tim Carter is thanked for the contribution of AFT data for the UoM samples obtained under Australian Research Council Grant DP0345931. Barbara Carrapa would like to acknowledge US National Science Foundation grant EAR Tectonics 1,919,179. Paul Kapp would like to acknowledge US National Science Foundation grant EAR 2048656. Jon Spencer is thanked for his invaluable support and guidance about the geology during fieldwork and valuable insights on an early draft. Asaf Raza provided assistance with sample preparation. The University of Melbourne Thermochronology Laboratory receives operation support through the AuScope program of the National Collaborative Research Infrastructure Strategy (NCRIS). We thank editor Isabelle Manighetti, the associate editor, reviewer M. Odlum, and an anonymous reviewer for their thoughtful comments which improved this manuscript.
Funding Information:
Tim Carter is thanked for the contribution of AFT data for the UoM samples obtained under Australian Research Council Grant DP0345931. Barbara Carrapa would like to acknowledge US National Science Foundation grant EAR Tectonics 1,919,179. Paul Kapp would like to acknowledge US National Science Foundation grant EAR 2048656. Jon Spencer is thanked for his invaluable support and guidance about the geology during fieldwork and valuable insights on an early draft. Asaf Raza provided assistance with sample preparation. The University of Melbourne Thermochronology Laboratory receives operation support through the AuScope program of the National Collaborative Research Infrastructure Strategy (NCRIS). We thank editor Isabelle Manighetti, the associate editor, reviewer M. Odlum, and an anonymous reviewer for their thoughtful comments which improved this manuscript.
Publisher Copyright:
© 2022. American Geophysical Union. All Rights Reserved.
PY - 2022/4
Y1 - 2022/4
N2 - Mesozoic-Cenozoic subduction of the Farallon slab beneath North America generated a regionally extensive orogenic plateau in the southwestern US during the latest Cretaceous, similar to the modern Central Andean Plateau. In Nevada and southern Arizona, estimates from whole-rock geochemistry suggest crustal thicknesses reached ∼60–55 km by the Late Cretaceous. Modern crustal thicknesses are ∼28 km, requiring significant Cenozoic crustal thinning. Here, we compare detailed low-temperature thermochronology from the Catalina metamorphic core complex (MCC) to whole rock Sr/Y crustal thickness estimates across southern Arizona. We identify three periods of cooling. A minor cooling phase occurred prior to ∼40 Ma with limited evidence of denudation and ∼10 km of crustal thinning. Major cooling occurred during detachment faulting and MCC formation at 26–19 Ma, corresponding to ∼8 km of denudation and ∼8 km of crustal thinning. Finally, we document a cooling phase at 17–11 Ma related to Basin and Range extension that corresponds with ∼5 km of denudation and ∼9 km of crustal thinning. During the MCC and Basin and Range extension events, the amount of denudation recorded by low-temperature thermochronology can be explained by corresponding decreases in the crustal thickness. However, the relatively limited exhumation prior to detachment faulting at ∼26 Ma recorded by thermochronology is insufficient to explain the magnitude of crustal thinning (∼10 km) observed in the whole rock crustal thickness record. Therefore, we suggest that crustal thinning of the Arizona-plano was facilitated via ductile mid- to lower-crustal flow, and limited upper-crustal extension at 50–30 Ma prior to detachment faulting and Basin and Range extension.
AB - Mesozoic-Cenozoic subduction of the Farallon slab beneath North America generated a regionally extensive orogenic plateau in the southwestern US during the latest Cretaceous, similar to the modern Central Andean Plateau. In Nevada and southern Arizona, estimates from whole-rock geochemistry suggest crustal thicknesses reached ∼60–55 km by the Late Cretaceous. Modern crustal thicknesses are ∼28 km, requiring significant Cenozoic crustal thinning. Here, we compare detailed low-temperature thermochronology from the Catalina metamorphic core complex (MCC) to whole rock Sr/Y crustal thickness estimates across southern Arizona. We identify three periods of cooling. A minor cooling phase occurred prior to ∼40 Ma with limited evidence of denudation and ∼10 km of crustal thinning. Major cooling occurred during detachment faulting and MCC formation at 26–19 Ma, corresponding to ∼8 km of denudation and ∼8 km of crustal thinning. Finally, we document a cooling phase at 17–11 Ma related to Basin and Range extension that corresponds with ∼5 km of denudation and ∼9 km of crustal thinning. During the MCC and Basin and Range extension events, the amount of denudation recorded by low-temperature thermochronology can be explained by corresponding decreases in the crustal thickness. However, the relatively limited exhumation prior to detachment faulting at ∼26 Ma recorded by thermochronology is insufficient to explain the magnitude of crustal thinning (∼10 km) observed in the whole rock crustal thickness record. Therefore, we suggest that crustal thinning of the Arizona-plano was facilitated via ductile mid- to lower-crustal flow, and limited upper-crustal extension at 50–30 Ma prior to detachment faulting and Basin and Range extension.
KW - Arizona-plano
KW - crustal thickness estimates
KW - lower-crustal flow
KW - metamorphic core complex
KW - thermochronology
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U2 - 10.1029/2021JB023850
DO - 10.1029/2021JB023850
M3 - Article
AN - SCOPUS:85128729921
SN - 2169-9313
VL - 127
JO - Journal of Geophysical Research: Solid Earth
JF - Journal of Geophysical Research: Solid Earth
IS - 4
M1 - e2021JB023850
ER -