Virgil A. Frizzell, Jr, U.S. Geological Survey Msnlo Park, California
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UNITED STATES DEPARTMENT OF H7EERIOR GEOLOGICAL SURVEY PETROLOGY AND STRATIGRAPHY OF PALBOGENE NONMARINE SANDSTONES, CASCADE RANGE, WASHINGTON by Virgil A. Frizzell, Jr, U.S. Geological Survey Msnlo Park, California OiPEN-FIIE REPORT 79-1149 report is preliminary and has not been edited or reviewed for conformity with Geological Survey standards and nomenclature ACKNOWLEDGEMENTS I am indebted to the following workers for sharing both samples and edifying thoughts: Rowland W. Tabor (RWT, prefix for sample numbers); John T. Whetten (W); Charles W. Walker (most Roslyn samples); James D. Vine (V); Randall L. Gresens (all Wenatchee samples); James C. Yount (Y); Betsey L. Mathieson (BL); and David R. Pevear (DP). Without patient teaching from both Charles E. Meyer and Charles W. Naeser I would not have been able to learn the fission track dating technique. Likewise, I am indebted to William R. Dickinson, Jonathan C, Matti, Robert R. Compton, Robert J. McLaughlin, Kenneth Helmold, Henry N. Ohlin, and Bret F. Cox for aiding my petrographic abilities. Preliminary drafts of this dissertation benefited from scrutiny by various colleagues but Roland W. Tabor, in particular, fearlessly improved both form and content. I am grateful for the contributions of both time and thought by these and other workers because they aided substantially in the completion of this dissertation. iii TABLE OF CONTENTS Page LIST OF FIGURES. ........................ vi LIST OF PLATES ......................... vii LIST OF TABLES ......................... vii ABSTRACT ............................ viii INTRODUCTION .......................... 1 REGIONAL GEOLOGY AND TECTONIC SETTING. ............. 3 Regional Geology ...................... 3 Pre-Tertiary Stratigraphy of Selected Geologic Units .... 3 Plate Tectonic Setting ................... 10 STRATIGRAPHIC UNITS. ...................... 18 Introduction to Stratigraphic Units. ............ 18 Chuckanut Formation. .................... 22 Swauk Formation. ...................... 26 Isolated Arkosic Bodies. .................. 29 Manastash Formation. .................... 31 Puget Group. ........................ 32 Chumstick Formation. .................... 35 Roslyn Formation ...................... 37 Naches Formation ...................... 38 Wenatchee Formation. .................... 40 SANDSTONE PETROLOGY. ...................... 42 Introduction to Sandstone Petrology. ............ 42 Description of Basal Beds. ................. 50 Description of Subquartzose Sandstone Units. ........ 51 Description of Compositions .............. 52 Source Terrane and Tectonic Regimes .......... 52 Volcanic Rocks in Early Eocene Arkosic Sandstones. ..... 79 Volcanic Rocks in Young Units. ............... 80 Description of Isolated Arkosic Bodies ........... 82 Other Modal Analyses .................... 86 SIGNIFICANCE OF PALEOGENE SEDIMENTS TO THE STRAIGHT CREEK FAULT. 91 The Straight Creek Fault .................. 91 Swauk-Chuckanut Offset ................... 92 Discussion ......................... 95 iv TABLE OF CONTENTS Continued Page APPENDICES I. Methodology for producing fission track dates ..... 98 II. Methodology of point counting and calculating modal data. ...................... 101 III. Detrital modes of Paleogene sandstones, Cascade Range, Washington ............... 108 REFERENCES CITED ........................ 134 LIST OF FIGURES Page Figure 1. Map with place names, northwest Washington. ...... 2 2. Geologic sketch map, northwest Washington ....... 5 3. Inferred plate configuration of the northeast Pacific for late Cretaceous and early Tertiary after Dickinson (1979) and Coney (1978). ........ 12 4. Hypothesized late Cretaceous and early Tertiary plate geometry after Atwater (1970) and Fox (written conmun., 1979) .................. 15 5. Map showing generalized outcrop pattern for nonmarine Paleogene sandstones, Washington ......... 20 6. Correlation chart for Paleogene nonmarine arkoses and related rocks, Washington. ............ 24 7. QFL plot for modal data for Paleogene sandstones of Washington from literature sources ........ 43 8. Mean and standard deviations of framework grain parameters .................... 45-47 9. Triangular diagrams for detrital modes of Chuckanut Formation. ............... 54 10. Triangular diagrams for detrital modes of Swauk Formation ................ 56 11. Triangular diagrams for detrital modes of Manastash Formation. .................... 58 12. Triangular diagrams for detrital modes of Puget Group Arkoses. ..................... 60 13. Triangular diagrams for detrital modes of Chumstick Formation. .................... 62 14. Triangular diagrams for detrital modes of Roslyn Formation. ............... 64 15. Triangular diagrams for detrital modes of Naches Formation. ............... 66 16. Triangular diagrams for detrital modes of Wenatchee Formation. .................... 68 vi Page Figure 17. Triangular diagram comparing QFL plots. ........ 69 18. Triangular diagram comparing (^FL-p plots. ....... 70 19. Triangular diagram comparing Q|Y|QpL plots. ....... 71 20. Triangular diagram comparing QpLyl^ plots ....... 72 21. Triangular diagram comparing Q^PK plots ........ 73 22. Mean framework modes for Paleogene nonmarine sandstone units of Washington compared to provenance boundaries of Dickin son and Suczek ........ 78 23. Triangular diagrams comparing modes of four isolated Paleogene arkosic bodies ............. 84 24. Triangular diagrams comparing detrital modes of six sandstone units. ................. 88 25. Sketch map illustrating right lateral offset on Straight Creek Fault ............... 93 LIST OF PLATES Plate 1. Sample locality map, Victoria sheet .......... Pocket 2. Sample locality map, Wenatchee sheet, 3. Sample locality map, Seattle sheet. , LIST OF TABLES Table 1. Ternary and secondary ratios for nonmarine sandstone units from Washington. .............. 49 2. Typical values for grain parameters in subquartzose sandstones .................... 75 3. Ternary ratios and secondary parameters for two isolated arkosic bodies. ............. 85 4. Ternary and secondary ratios for six sandstone units. 89 vii ABSTRACT The Cascade Range of Washington north of 47° latitude is composed of probable Paleozoic and Mesozoic metamorphic rocks and Mesozoic and Tertiary plutonic rocks. Several Paleogene nonmarine arkosic sandstone units fringe and in part occur within the complex crystalline core. The early to middle Eocene Chuckanut Formation is present on the west side of the crystalline core in the western foothills of the Cascades. The early to middle Eocene Swauk Formation partially encircles the Mt. Stuart massif of the central Cascades. In the western foothills of the Cascades, between the main body of Chuckanut Formation near Bellingham and the main outcrop area of the Swauk Formation south of Mt. Stuart, many smaller bodies of arkosic sandstone have variously been referred to either the Swauk or Chuckanut Formations. The early Eocene Manastash Formation occurs locally in an area south of the Yakima River. The middle to late Eocene Chumstick Formation is mostly confined to the Chiwaukum graben within the crystalline core and is separated from the Swauk Formation on the southwest by the Leavenworth Fault. The Oligocene Wenatchee Formation unconformably overlies the Chumstick Formation near Wenatchee. The middle to late Eocene Roslyn Formation crops out north of the Yakima River and is underlain by the Teanaway Basalt which separates the Roslyn from the older Swauk Formation. The middle Eocene to early Oligocene Naches Formation forms a north-trending body that crosses the Yakima River and is in fault contact with both the Swauk and Manastash Formations. The middle to late Eocene Puget Group underlies the Quaternary deposits of the Puget Lowland southeast of Seattle on the western flank of the Cascades. viii The various formations are all composed predominantly of fine- to medium-grained sandstones with lesser amounts of interbedded shale, conglomerate and coal. Compositionally, the units are predominantly either feldspathic or litho-feldspathic subquartzose sandstones. Volcanic rocks are important constituents of the Puget Group, the Chumstick and Naches Formations, and the isolated arkosic bodies. The three older units, however, contain relatively less volcanic lithics to total lithics than do younger units, indicating perhaps the initiation of more widespread volcanic activity in middle Eocene time. Ratios of framework grain parameters show that the terrestrial sandstone units were derived from a mixed plutonic and tectonic source terrane of continental block tectonic provenance with an overprint of magmatic arc provenance. Modal analysis was performed on samples from the various sedimentary units to establish petrologic compositions, and to provide data with which to compare the different units and discuss clast provenance and tectonic regimen. Although the arkosic sandstones have generally uniform framework clast compositions, minor yet significant differences do exist between the units. Basal or basement-onlap portions of the units in particular are locally derived and differ markedly from the overall compositions of the individual units. Many coincidences of composition, age, structure, and bedrock indicate that the Chuckanut and Swauk may have originally been deposited as a single unit that since has been offset approximately 160 kilometers by right lateral strike slip motion starting about 48 Ma. If this hypothetical offset did occur, then major movement on the Straight Creek Fault