The Role of Magmatism in the Catalina Metamorphic Core Complex, Arizona: Insights from Integrated Thermochronology, Gravity and Aeromagnetic Data
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Syracuse University SURFACE Earth Sciences - Dissertations College of Arts and Sciences 5-2012 The Role of Magmatism in the Catalina Metamorphic Core Complex, Arizona: Insights from Integrated Thermochronology, Gravity and Aeromagnetic Data Jessica Terrien Syracuse University Follow this and additional works at: https://surface.syr.edu/ear_etd Part of the Earth Sciences Commons Recommended Citation Terrien, Jessica, "The Role of Magmatism in the Catalina Metamorphic Core Complex, Arizona: Insights from Integrated Thermochronology, Gravity and Aeromagnetic Data" (2012). Earth Sciences - Dissertations. 28. https://surface.syr.edu/ear_etd/28 This Dissertation is brought to you for free and open access by the College of Arts and Sciences at SURFACE. It has been accepted for inclusion in Earth Sciences - Dissertations by an authorized administrator of SURFACE. For more information, please contact [email protected]. ABSTRACT The footwall of the Catalina MCC located within the Basin and Range Province has been intruded by several magmatic suites. Samples were collected from the Wilderness suite sills, the most voluminous suite. U/Pb data from zircon indicate that the Wilderness suite sills were emplaced during two separate phases of magmatism, the first at ~55 Ma and the second at ~45 Ma with additional evidence of zircon growth at <40 Ma. 40Ar/39Ar data from the Wilderness suite sills indicate that the majority of the older 40Ar/39Ar apparent ages from both potassium feldspar and mica were obtained from the structurally higher sills in the main range, and the younger 40Ar/39Ar apparent ages were obtained on samples from structurally lower sills. The potassium feldspar samples yield 40Ar/39Ar age gradients which may be the result of cooling for ~5 million years or thermal resetting by the Catalina pluton prior to exhumation along the Catalina detachment fault. 40Ar/39Ar lower intercepts from potassium feldspar in the main range suggest that exhumation of the main range occurred ~25 to 23 million years ago. In the forerange, concordant AFT and ZFT data and 40Ar/39Ar potassium feldspar lower age intercepts suggest rapid cooling due to exhumation ~23 to 22 million years ago. The muscovite and biotite samples from the Wilderness suite sills yield relatively flat 40Ar/39Ar age spectra with ages ranging from ~28 to 23 Ma representing recrystallization below the closure temperature for muscovite and biotite. Forward modeling of aeromagnetic and gravity data from the Catalina MCC region indicates a shallow, felsic to intermediate subsurface pluton in sharp contact with the Wilderness suite sills. The age of the subsurface pluton is unknown. However, on the basis of the gravity and aeromagnetic properties of intrusions in the region, a Tertiary or Mesozoic age subsurface pluton is preferred. The age of the pluton relative to detachment faulting can help distinguish between differing models for MCC formation. A Mesozoic pluton suggests that crustal thickening influenced MCC development, and a preexisting zone of weakness may have controlled the emplacement of this body as well as the Wilderness suite sills. A Tertiary pluton suggests magmatism may have initiated low-angle faulting and MCC formation. THE ROLE OF MAGMATISM IN THE CATALINA METAMORPHIC CORE COMPLEX, ARIZONA: INSIGHTS FROM INTEGRATED THERMOCHRONOLOGY, GRAVITY AND AEROMAGNETIC DATA by Jessica J. Terrien A.B. Augustana College, 2001 M.S. University of Missouri-Rolla, 2003 Dissertation Submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in Geology Syracuse University May 2012 Copyright © Jessica J. Terrien 2012 All Rights Reserved TABLE OF CONTENTS Preface…………………………………………………………………………………….1 Chapter 1: The Wilderness suite sills of the Catalina Metamorphic Core Complex, Arizona: Evidence for zircon inheritance and multiple phases of magmatism ….......…2 Abstract……………………...…………………………………………………….3 Introduction………………………………………………………………………..4 Field and Microstructural Observations…………………...………………………6 Field observations………………...……………………………………….6 Petrographic observations………………………………..……………….7 Sample Preparation and Analysis…………………………………………..……10 Methods………………………………………………………………………….10 LA-ICPMS Results…………...……………………………………..….………..12 Discussion………………………………………………………………………..15 Inherited zircon cores……………………………………………………15 Intrusion at ~55 Ma and ~45 Ma………………………………...………16 Igneous or metamorphic zircon growth at <40 Ma? ………...………….17 <40 Ma zircon rims……………………………………………………...18 Emplacement of the Wilderness suite sills…………………....……….....19 Basin and Range magmatism………………………………….…………20 Conclusions……………………………...……...……………………….……….21 References ……………………………………………………………………….23 Figures………………………………...………………………………………….30 Tables…………………………………………………………………………….46 v Chapter 2: 40Ar/39Ar data from the Wilderness sills of the Catalina MCC: reheating vs. monotonic cooling of the footwall.............................……………………………..…49 Abstract…………………………………………………………………………..49 Introduction and Nature of the Problem…………………………………………51 Geology of the Catalina MCC………………………………………………...…52 Previous Data……………………………………………………………53 Wilderness suite sills………………………………………..……………………55 40Ar/39Ar Method ……………………………………………..…………………58 Results …………………………………………………..……………………….59 40Ar/39Ar data…………………………………………………………….59 MDD modeling…………………………………………………………...63 Discussion………………………………………………………………………..63 40Ar/39Ar potassium feldspar data and the timing of exhumation………..63 40Ar/39Ar Muscovite and Biotite data…………………………………….65 40Ar/39Ar and deformation of the Wilderness sills……………………….66 Fission track data………………………………………………………..67 Conclusions……………...……………………………………………………….68 References………………………………………………………………………..69 Figures……………………………………………………………………………74 Tables………………………………………………………………….....………97 Chapter 3: Aeromagnetic and Bouguer Gravity modeling of the Catalina Metamorphic Core Complex: the Role of Magmatism in Metamorphic Core Complex Formation………………………………………………………………………..…..…100 Abstract…………………………………………………………………………101 Introduction………………………………………….………………………….103 Geology of the Catalina MCC…………………………………....…………….104 Models for MCC Formation……………………………………………………105 vi Geophysical Data ……………..………………………………………………..107 Aeromagnetic Data……………………………………………..………107 Gravity Data………………………………………………….…..…….108 Geophysical Anomalies…………………………………………………...……109 Aeromagnetic Anomalies……………………………………………….109 Gravity Anomalies……………………………………………………...112 Modeling Results…..……...……………………………………………………112 Discussion………………………………………………………………………114 Thermochronologic Data………...………………………………..……114 Age of the Pluton………………………………………………………..116 Conclusions…………………………………………………………….……….118 References………………………………………………………………………120 Figures……………………………………………………………………….….132 Tables…………………………………………………………………………...144 Appendices……………………………………………………………………………..149 Vita……………………………………………………………………………………..232 vii LIST OF FIGURES CHAPTER 1 Figure 1 Simplified geologic map of the Catalina MCC, Arizona………………...33 Figure 2 Geologic map of the forerange of the Catalina MCC, Arizona showing detailed mapping of the Wilderness suite sills…………………………...34 Figure 3 Cross-section from A-A’ as shown in Figure 1 indicating the structural positions of the seven Wilderness sills.………………………………….35 Figure 4 Representative CL images of zircon grains from the Wilderness suite sills……………………………………………………………………….36 Figure 5 Concordia plots and weighted mean plots of LA-ICPMS zircon analyses for the Spencer, Wilderness and Shreve Pass sills….…………………...37 Figure 6 Concordia plots and weighted mean plots of LA-ICPMS zircon analyses for the Gibbon Mountain sill..….………………………………………..38 Figure 7 Concordia plots and weighted mean plots of LA-ICPMS zircon analyses for the Seven Falls sill. …………………………..….…………………...39 Figure 8 Probability density plots with zircon 206Pb/238U age populations for a) Gibbon Mountain sill and b) Seven Falls sill…..…………………….…..40 Figure 9 Precambrian LA-ICPMS zircon analyses. a) Concordia plots and weighted mean plots for the Oracle Granite. b) Weighted mean plots of Precambrian LA-ICPMS zircon analyses from the Wilderness suite sills……………..41 Figure 10 Weighted mean LA-ICPMS 208Pb/232Th monazite analyses from the Catnip Canyon sill.…………...…………………………………………..42 Figure 11 The Precambrian provinces including the location of the Catalina MCC.43 Figure 12 Schematic diagram showing the intrusive sequence of the Wilderness suite sills………………………………………………….……………………44 Figure 13 Location of migratory magmatism from ~60 to 30 Ma in the western United States……………………………………………………………..45 CHAPTER 2 Figure 1 Location of metamorphic core complexes across western North America……………………………………………………….………….77 viii Figure 2 a) Simplified geologic map of the Catalina MCC Arizona, b) Geologic map of the forerange of the Catalina MCC, Arizona showing detailed mapping of the Wilderness suite sills ……….……………………….78-79 Figure 3 Cross-section from A-A’ as shown in Figure 2a indicating the structural positions of the seven Wilderness sills………..…………………………80 Figure 4 40Ar/39Ar spectra and inverse isochron plots for potassium feldspar and muscovite from Spencer sill of the Wilderness suite sills…………...…..81 Figure 5 40Ar/39Ar spectra and inverse isochron plots for potassium feldspar and muscovite from the Wilderness sill (Windy Point locality) of the Wilderness suite sills………………………………………………….….82 Figure 6 40Ar/39Ar spectra and inverse isochron plots for potassium feldspar and muscovite from the Wilderness sill (General Hitchcock locality) of the Wilderness suite sills………………………………………………….….83 Figure