Bedrock Geology of the Kingfield and Anson
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BEDROCK GEOLOGY OF THE KINGFIELD AND ANSON QUADRANGLES, FRANKLIN AND SOMERSET COUNTIES, MAINE by Kost A. Pankiwskyj Department of Geology and Geophysics University of Hawaii Table of Contents TABLE OF CONTENTS INTRODUCTION Location l Previous work l Regional geologic setting 3 STRATIGRAPHY OF THE METAMORPHOSED ROCKS 4 General Statement 4 Sangerville Formation (Ss) 4 Name 4 Internal stratigraphy and distribution 4 Lithology and mineralogy 6 Contacts and thickness 8 Perry Mountain Formation 11 Name 11 Internal stratigraphy and distribution 11 Lithology and mineralogy 11 Contacts and thickness 13 Parkman Hill Formation (Sph) 13 Name 13 Distribution 13 Lithology and mineralogy 13 Contacts and thickness 14 Smalls Falls Formation (Ssf) 15 Name 15 Distribution 15 Lithology and mineralogy 15 Contacts and thickness 17 Fall Brook Formation (DSf) 17 Name 17 Distribution 17 Lithology and mineralogy 17 Contacts and thickness 19 Madrid Formation (DSm) 19 Name 19 Distribution 20 Lithology and mineralogy 20 Contacts and thickness 20 Carrabassett Formation (De) 23 Name 23 Distribution 23 Lithology and mineralogy 23 Contacts and thickness 24 Hildreth Formation 25 Name 25 Distribution 25 Lithology and mineralogy 25 Contacts and thickness 28 Seboomook Formation 28 Name 28 Internal stratigraphy and distribution 28 Mount Blue Member (Dsm) 29 Name 29 Distribution 29 Lithology and mineralogy 29 Contacts and thickness 31 Temple Stream Member (Dst) 31 Name 31 Distribution 31 Lithology and mineralogy 31 Contacts and thickness 34 Day Mountain Member (Dsd) 34 Name 34 Internal stratigraphy and distribution 35 Lithology and mineralogy 35 Contacts and thickness 38 IGNEOUS ROCKS 39 General Statement 39 Sugarloaf Massif (Dga) 39 Lexington Batholith (Dqm and Ded) 39 Old Point Pluton (Dgr) 40 Age of the igneous rocks 40 STRUCTURAL· GEOLOGY 41 General Statement 41 Premetamorphic soft sediment slump faulting - S 41 Synmetamorphic major folding and associated thrust faulting - F 42 Intrusion of plutonic rocks accomapnied by second generation fotding - F2 44 Postmetamorphic faulting - F3 44 Intrusion of mafic dikes - D 44 METAMORPHISM 45 General Statement 45 Prograde metamorphism of calcareous rocks 45 Prograde metamorphism of non-calcareous rocks 48 REFERENCES CITED 49 Illustrations Figure 1 Locations of the 15' quadrangles referred to in the text 2 2 Correlation among the northwestern limb, the central part and the southeastern limb of the Merrimack Synclinorium 5 3 Modes of the Sangerville Formation 9-10 4 Modes of the Perry Mountain Formation 12 5 Modes of the Parkman Hill Formation and of the Smalls Falls Formation 16 6 Modes of the Fall Brook Formation and of the·Madrid Formation 21-22 7 Modes of the Carrabassett Formation and of the Hildreth Formation 26-27 8 Modes of the Mount Blue Member and of the Temple Stream Member of the Seboomook Formation 32-33 9 Modes of thP. Day Mountain Member of the Seboomook Formation 36-37 10 Mineral assemblages in calcareous metasediments 46 11 Mineral assemblages in non-calcareous metasediments 47 Plate 1 separate Plate 2 II Plate 3 II MAINE GEOLOGICAL SURVEY BEDROCK GEOLOGY OF THE KINGFIELD AND ANSON QUADRANGLES BY Kost A. Pankiwskyj Department of Geology and Geophysics University of Hawaii INTRODUCTION LOCATION The Kingfield and Anson 15' Quadrangles are located in the western part of Maine, both between 44045• and 45°00' north latitude, and respectively between 70°00' and 70015 1 west longtitude and 69°45' and 10°00• west longi tude. Beginning with the 1959 field season, I have been engaged with the detailed mapping of these two quadrangles and in addition of the Dixfield Quadrangle, the Farmington Quadrangle, and the Norridgewock Quadrangle, which are respectively southwest, south, and southeast of the Kingfield Quadrangle. The reader is referred to the index map, Figure 1, which shows the relationships among these quadrangles as well as others which are mentioned in this paper. PREVIOUS WORK Early mention of the geology in the Kingfield and Anson Quadrangles is in the reports of Jackson (1838, 1939) and of Hitchcock (1861, 1862, 1863) who note bedrock exposures on roads, in the rivers, and on prominent mountains. Emmons (1910) mentions a small mining operation in the north western corner of the Anson Quadrangle. The geology of this area is included in the map of the entire state by Keith (1933). Allen and Pratt (1959) and Allen (1955) note occurrences of limestone within the area. The first detailed studies are by Cariani (1958) of the Anson Quadrangle, and by Skapinski (1961) of the Kingfield Quadrangle, both unpublished Ph.D disserta tions at Boston University. Doyle (1967) shows the geQlogy of the areas on the 1: 500, 000 scale state map with information based in part on these theses and in part on reconnaissance work by the writer. Raabe (1969, 1970) discusses the structural relationships in the northern part of the Kingfield Quadrangle. Pankiwskyj and others (1976) include part of this area in a discussion of stratigraphic relationships on the southeastern limb of the Merrimack Synclinorium, 70°30 1 69°30 1 60°00 1 45°30' - Gr St LiB Bi Kb Gu DoF - 45°00' Ra Ph Kf An Sk Ru Di Fa No Wa 1 1 44°30 - - 44°30 BrP Bu Li Au Va 10°30' 69°30 1 69°00' An Anson Li Livermore Au Augusta LiB Little Bigelow Mountain Bi Bingham No Norridgewock BrP Bryant Pond Ph Phillips Bu Buckfield Ra Rangeley Di Dixfield Ru Rumford DoF Dover-Foxcroft Sk Skowhegan Fa Farmington St Stratton Gr Greenville Va Vassalboro Gu Guilford WA Waterville Ki Kingsbury Kf Kingfield FIGURE 1. Location of the 15' quadrangles referred to in the text. 2 REGIONAL GEOLOGIC SETTING The Kingfield and Anson Quadrangles are located respectively in the trough and on the southeastern limb of the Merrimack Synclinorium. This structural feature, originally defined in New Hampshire by Billings (1956), was extended into western Maine by Osberg and others (1968) and into central Maine by Pankiwskyj and others (1976). Stratigraphic sections were defined by a number of workers studying portions of the synclinorium in different localities, and as a result a complicated stratigraphic nomenclature has been inherited. On the northwestern limb, Moench (1971) defined the following post Ordovician section in the Rangeley and Phillips Quadrangles (see Index Map, Figure 1): Unnamed Devonian (?) rocks Hildreth Formation of Devonian and Devonian (?) age Seboomook (?) Formation Madrid Formation Smalls Falls Formation Perry Mountain Formation of Silurian (?) age Rangeley Formation Subsequently, on the nqrthwestei:n limb, Boone (1973), working in the Little Bigelow Mountain Quadrangle and the western part of the Bingham Quadrangle (see Index Map, Figure 1) redefined the Unnamed Devonian (?) rocks of Moench as the Seboomook Formation, and the Seboomook, (?) Formation of Moench as the newly defined Carrabassett Formation. On the far southeastern limb, Osberg (1968) defined the following section in the Waterville-Vassalboro area (see Index Map, Figure 1.): Vassalboro Formation of Silurian or Devonian age Waterville Formation of Silurian age Mayflower Hill Formation· In the interim, a number of geologists working with the Maine Geological Survey were mapping areas in between those covered by Moench and by Osberg. In this more central part of the Merrimack Synclinorium a new set of strati graphic names was informally established, The formations in this area are dated by means of graptolites from twelve localities found by A. Ludman in the Anson, Skowhegan, Kingsbury, and Guild£ord Quadrangles. To the east, J, Griffin has found eleven additonal graptolite localities in the same belt of rocks. In comparison, there are only three graptolite localities in the Waterville-Vassalboro area mapped by Osberg, and no fossil localities in the Phillips and Rangeley Quadrangles mapped by Moench. The formations in the central part of the Merrimack Synclinorium have not been traced physically into those on either of the two limbs because of intervening younger rocks and because of faults. However, the formations in the central part of the synclinorium are correlated with those on either limb by means of stratigra phic-lithologic similarity. The fossil ages from the Waterville-Vassalboro 3 area also strengthen the correlation. It was, however, decided by A. Ludman, J. Griffin, and myself (Pankiwskyj and others, 1976) to introduce new stratigraphic names, primarily because of the superior fossil data in the central belt and .because of pronounced sedimentary facies changes, The stratigraphic names of Osberg and of Moench are retained only: 1. in outcrop belts physically traceable into areas in which these older formation names have been used in published reports, and, 2. in outcrop belts adjacent to those in (1) above, in which are. present rock types of the same sedimentary facies as in (1). The stratigraphic nomenclature of this report is shown in column 3 of Figure 2. With but a few changes it follows that established by Pankiwskyj and others (1976). The nomenclature within the Devonian section has been not only confusing, but also inconsistant (cf. Moench, 1971,with Boone, 1973,as shown in Figure 2 of this paper). In this paper a scheme is followed in line with that to be described in Moench and others (in preparation). This is also shown in column 3 of Figure 2. STRATIGRAPHY OF THE METAMORPHOSED ROCKS GENERAL STATEMENT The stratigraphic section in the Kingfield and Anson Quadrangles is presented in Figure 2. In addition, there is a brief explanation column on each of the two geologic maps, plus a fuller description of the rock types in each formation on the sheet with the geologic cross sections. SANGERVILLE FORMATION (Ss) NAME. The formation was formally established and defined in Pankiwskyj and others (1976). One change is made here; viz., the Anasagunticook Formation of Pankiwskyj and others (1976) is made a member of the Sangerville Formation, Also the Patch Mountain Forll\ilt:J:Qn of Guidotti (.1965) is.