Deciphering igneous and metamorphic events in high-grade rocks of the Wilmington complex, Delaware: Morphology, cathodoluminescence and backscattered electron zoning, and SHRIMP U-Pb geochronology of zircon and monazite

Bulletin of the Geological Society of America

Volumn 118, Issue 1-2, 2006, Pages 39-64

  Aleinikoff, John N ^a   Schenck, William S ^b   Plank, Margaret O ^b   Srogi, LeeAnn ^c   Fanning, C Mark ^d   Kamo, Sandra L ^e   Bosbyshell, Howell ^c  

^a DENVER FEDERAL CENTER   (United States)

^b Delaware Geological Survey   (United States)

^c WEST CHESTER UNIVERSITY   (United States)

^d AUSTRALIAN NATIONAL UNIVERSITY   (Australia)

^e UNIVERSITY OF TORONTO   (Canada)

Author keywords

Monazite; SHRIMP; U Pb geochronology; Wilmington Complex; Zircon

Indexed keywords

BACKSCATTERED ELECTRON ZONING; HIGH GRADE ROCKS; SENSITIVE HIGH RESOLUTION ION MICROPROBE (SHRIMP);

CATHODOLUMINESCENCE; GEOCHRONOLOGY; IGNEOUS ROCKS; METAMORPHIC ROCKS; MONAZITE; MORPHOLOGY; ZIRCON;

STRUCTURAL GEOLOGY;

IGNEOUS ROCK; ISLAND ARC; LAURENTIA; METAMORPHIC ROCK;

DELAWARE; NORTH AMERICA; UNITED STATES;

EID: 31444442645     PISSN: 00167606     EISSN: 00167606     Source Type: Journal    
DOI: 10.1130/B25659.1     Document Type: Article

References (94)

1. Aleinikoff, J.N., Fanning, C.M., Horton, J.W., Jr., Drake, A.A., Jr., and Sauer, R.R., 1997, The Baltimore Gneiss re-revisited: New SHRIMP (zircon) and conventional (titanite) U-Pb ages: Geological Association of Canada/Mineralogical Association of Canada Annual Meeting Abstract Volume 22, p. A-2.
2. Aleinikoff, J.N., Burton, W.C., Lyttle, P.T., Nelson, A.E., and Southworth, C.S., 2000, U-Pb geochronology of zircon and monazite from Middle Proterozoic (1.15-1.05 Ga) granitic gneisses of the northern Blue Ridge, Virginia: Precambrian Research, v. 99, p. 113-146, doi: 10.1016/ S0301-9268(99)00056-X.
3. Aleinikoff, J.N., Horton, J.W., Jr., Drake, A.A., Jr., and Fanning, C.M., 2002, SHRIMP and conventional U-Pb ages of Ordovician granites and tonalites in the central Appalachian Piedmont: Implications for Paleozoic tectonic events: American Journal of Science, v. 302, p. 50-75.
4. Aleinikoff, J.N., Horton, J.W., Jr., Drake, A.A., Jr., Wintsch, R.P., Fanning, C.M., and Yi, K., 2004, Deciphering multiple Mesoproterozoic and Paleozoic events recorded in zircon and titanite from the Baltimore Gneiss, Maryland, USA: SEM imaging, SHRIMP U-Pb geochronology, and EMP analysis, in Tollo, R.P., Corriveau, L., McLelland, J.M., Bartholomew, M.J., eds., Proterozoic tectonic evolution of the Grenville orogen in North America: Geological Society of America Memoir 197, p. 411-434.
5. Bascom, F., 1902, The geology of the crystalline rocks of Cecil County: Baltimore, Maryland Geological Survey, Cecil County Report, p. 83-148.
6. Bascom, F., Clark, W.B., Darton, N.H., Kummel, H.B., Salisbury, R.D., Miller, B.L., and Knapp, G.N., 1909, Description of the Philadelphia district, Philadelphia Folio: U.S. Geological Survey Geological Atlas of the US, Folio 162, 24 p. with maps, scale 1:62,500.
7. Berg, T.M., Edmunds, W.E., Geyer, A.R., Glover, A.D., Hoskins, D.M., MacLachlin, D.B., Root, S.I., Sevon, W.D., and Socolow, A.A., 1980, Geologic map of Pennsylvania: Pennsylvania Topographic and Geologic Survey Series 4, Map 1, scale 1:250,000.
8. 238U microprobe geochronology by the monitoring of a trace-element-related matrix effect; SHRIMP, ID-TIMS, ELA-ICP-MS, and oxygen isotope documentation for a series of zircon standards: Chemical Geology, v. 205, p. 115-140.
9. Blackmer, G.C., and Bosbyshell, H., 2002, The Wissahickon Formation - A persistent problem in the central Appalachian Piedmont: Geological Society of America Abstracts with Programs, v. 34, no. 1, p. A-77.
10. Bosbyshell, H., Sinha, A.K., Crawford, M.L., Fleming, P., Srogi, L., and Lutz, T.M., 1998, Thermal evolution of a convergent orogen; new U/Pb ages of monazite and zircon from the Central Appalachian Piedmont: Geological Society of America Abstracts with Programs, v. 30, no. 7, p. 125.
11. Bosbyshell, H., Crawford, M.L., and Srogi, L., 1999, Distribution of overprinting metamorphic mineral assemblages in the Wissahickon group, southeastern Pennsylvania, in Valentino, D.W., and Gates, A.E., eds., The Mid-Atlantic Piedmont: Tectonic missing link of the Appalachians: Geological Society of America Special Paper 330, p. 41-58.
12. Bosbyshell, H., Srogi, L., and Crawford, M.L., 2000, Geochemistry, petrogenesis, and tectonic significance of amphibolites in the Wilmington Complex, central Appalachian Piedmont, Delaware Co, PA: Geological Society of America Abstracts with Programs, v. 32, no. 1, p. A-7.
13. Bosbyshell, H., Srogi, L., Aleinikoff, J.N., Plank, M.O., Schenck, W.S., Crawford, M.L., and Williams, M.L., 2001, Tectonic synthesis of recent geochronological and geochemical data in the central Appalachian Piedmont of SE PA and N DEL: Geological Society of America Abstracts with Programs, v. 33, no. 6, p. A261-A262.
14. Carrigan, C.W., Miller, C.F., Fullagar, P.D., Bream, B.R., Hatcher, R.D., Jr., and Coath, C.D., 2003, Ion microprobe age and geochemistry of Southern Appalachian basement, with implications for Proterozoic and Paleozoic reconstructions: Precambrian Research, v. 120, p. 1-36, doi: 10.1016/S0301-9269(02)00113-4.
15. Cherniak, D.J., and Watson, E.B., 2001, Pb diffusion in zircon: Chemical Geology, v. 172, p. 5-24, doi: 10.1016/S0009-2541(00)00233-3.
16. Chester, F.D., 1890, The gabbros and associated rocks in Delaware: U.S. Geological Survey Bulletin, v. 59, p. 7-45.
17. Coler, D.G., Wortman, G.L., Samson, S.D., Hibbard, J.P., and Stern, R., 2000, U-Pb geochronologic, Nd isotopic, and geochemical evidence for the correlation of the Chopawamsic and Milton terranes, Piedmont Zone, southern Appalachian orogen: Journal of Geology, v. 108, p. 363-380, doi: 10.1086/314411.
18. Compston, W., Williams, I.S., and Meyer, C., 1984, U-Pb geochronology of zircons from lunar breccia 73217 using a sensitive high-resolution ion microprobe: Proceedings of the 14th Lunar Science Conference: Journal of Geophysical Research, v. 98B, p. 525-534.
19. Crawford, M.L., Bosbyshell, H., and Williams, M.L., 2001, Electron microprobe age mapping and dating of monazite: Deconvoluting polyphase Paleozoic tectonism in the central Appalachians: Geological Society of America Abstracts with Programs, v. 33, no. 1, p. A-82.
20. Faill, R.T., 1997, A geologic history of the north-central Appalachians; Part 1. Orogenesis from the Mesoproterozoic through the Taconic orogeny: American Journal of Science, v. 297, p. 551-619.
21. Fanning, C.M., and Aleinikoff, J.N., 1998, Complex zoning in monazite as revealed by backscatter imaging and SHRIMP analysis: Geological Society of America Abstracts with Programs, v. 30, no. 7, p. 214.
22. Foland, K.A., 1979, Limited mobility of argon in a metamorphic terrain: Geochimica et Cosmochimica Acta, v. 43, p. 793-801, doi: 10.1016/ 0016-7037(79)90219-9.
23. 39Ar incremental heating plateaus for biotites with excess argon: Chemical Geology, v. 41, p. 3-21.
24. Foland, K.A., and Muessig, K.M., 1978, A Paleozoic age for some charnockitic-anorthositic rocks: Geology, v. 6, p, 143-146, doi: 10.1130/ 0091-7613(1978)6<143: APAFSC>2.0.CO;2.
25. Grauert, B., and Wagner, M.E., 1974, Age of the granulite facies metamorphism of the Wilmington Complex, Delaware-Pennsylvania Piedmont: Carnegie Institute of Washington Yearbook, v. 73, p. 997-999.
26. Grauert, B., and Wagner, M.E., 1975, Age of the granulite facies metamorphism of the Wilmington Complex, Delaware-Pennsylvania Piedmont: American Journal of Science, v. 275, p. 683-691.
27. Grauert, B., Crawford, M.L., and Wagner, M.E., 1973, U-Pb isotopic analysis of zircons from granulite and amphibolite-facies rocks of the West Chester prong and Avondale anticline, southeastern Pennsylvania: Carnegie Institute of Washington Yearbook, v. 72, p. 290-293.
28. Grauert, B., Wagner, M.E., and Crawford, M.L., 1974, Age and origin of amphibolite-facies rocks of the Avondale anticline (southeastern Pennsylvania) as derived from U-Pb isotopic studies on zircon: Carnegie Institute of Washington Yearbook, v. 73, p. 1000-1003.
29. Hager, G.M., 1976, Petrologic and structural relations of the crystalline rocks in the Hoopes Reservoir area, Delaware [M.S. thesis]: Newark, Delaware, University of Delaware, 79 p.
30. Hanan, B.B., and Sinha, A.K., 1989, Petrology and tectonic affinity of the Baltimore mafic complex, Maryland, in Mittwede, S.K., and Stoddard, E.F., eds., Ultramafic rocks of the Appalachian Piedmont: Geological Society of America Special Paper 231, p. 1-18.
31. Hawkins, D.P., and Bowring, S.A., 1999, U-Pb monazite, xenotime and titanite geochronological constraints on the prograde to post-peak metamorphic thermal history of Paleoproterozoic migmatites from the Grand Canyon, Arizona: Contributions to Mineralogy and Petrology, v. 134, p. 150-169, doi: 10.1007/s004100050475.
32. Higgins, M.W., 1971, Depth of emplacement of the James Run Formation pillow basalts, and depth of deposition of part of the Wissahickon Formation, Appalachian Piedmont, Maryland: American Journal of Science, v. 271, p. 321-332.
33. Higgins, M.W., 1972, Age, origin, regional relations, and nomenclature of the Glenarm Series, central Appalachian Piedmont: A reinterpretation: Geological Society of America Bulletin, v. 83, p. 989-1026.
34. Higgins, M.W., 1990, The crystalline rocks of Cecil County, Maryland, in Higgins, M.W., and Conant, L.B., eds., The geology of Cecil County, Maryland: Maryland Geological Survey Bulletin, v. 37, p. 3-116.
35. Horton, J.W., Jr., Aleinikoff, J.N., Drake, A.A., Jr., and Fanning, C.M., 1998, Significance of Middle to Late Ordovician volcanic-arc rocks in the central Appalachian Piedmont, Maryland and Virginia: Geological Society of America Abstracts with Programs, v. 30, no. 7, p. A-125.
36. Hoskin, P.W.O., and Black, L.P., 2000, Metamorphic zircon formation by solid-state recrystallization of protolith igneous zircon: Journal of Metamorphic Geology, v. 18, p. 423-439, doi: 10.1046/ j.1525-1314.2000.00266.x.
37. Hoskin, P.W.O., and Schaltegger, U., 2003, The composition of zircon and igneous and metamorphic petrogenesis, in Hanchar, J.M., and Hoskin, P.W.O., eds., Zircon: Reviews in Mineralogy and Geochemistry, v. 53, p. 27-62.
38. Ireland, T.R., 1995, Ion microprobe mass spectrometry: Techniques and applications in cosmochronology, geochemistry and geochronology, in Hyman, M., and Rowe, M., eds., Advances in analytical geochemistry: Greenwich, JAI Press, v. 2, p. 1-118.
39. Ireland, T.R., Wooden, J.L., Persing, H.M., and Ito, B., 1999, Geological applications and analytical development of the SHRIMP-RG: Eos (Transactions, American Geophysical Union), v. 80, no. 46, Supplement, p. F1117.
40. 238U: Physical Review C, v. C4, p. 1889-1906, doi: 10.1103/PhysRevC.4.1889.
41. Karabinos, P., Samson, S.D., Hepburn, J.C., and Stoll, H.M., 1998, Taconian orogeny in the New England Appalachians; collision between Laurentia and the Shelburne Falls arc: Geology, v. 26, p. 215-218, doi: 10.1130/0091-7613(1998)026<0215:TOITNE>2.3.CO;2.
42. Kim, J., and Jacobi, R.D., 2002, Boninites: Characteristics and tectonic constraints, northeastern Appalachians: Physics and Chemistry of The Earth, v. 27, p. 109-147.
43. Krogh, T.E., 1973, A low-contamination method for hydrothermal decomposition of zircon and extraction of U and Pb for isotopic age determinations: Geochimica et Cosmochimica Acta, v. 37, p. 485-494, doi: 10.1016/0016-7037(73)90213-5.
44. Kröner, A., O'Brien, P.J., Nemchin, A.A., and Pidgeon, R.T., 2000, Zircon ages for high pressure granulites from South Bohemia, Czech Republic, and their connection to Carboniferous high temperature processes: Contributions to Mineralogy and Petrology, v. 138, p. 127-142, doi: 10.1007/s004100050013.
45. Ludwig, K.R., 1998, On the treatment of concordant uranium-lead ages: Geochimica et Cosmochimica Acta, v. 62, p. 665-676, doi: 10.1016/ S0016-7037(98)00059-3.
46. Ludwig, K.R., 2001, Squid, version 1.02: A user's manual: Berkeley Geochronology Center Special Publication 2, 21 p.
47. Ludwig, K.R., 2003, Isoplot/Ex version 3.00: A geochronological toolkit for Microsoft Excel: Berkeley Geochronology Center Special Publication 4, 73 p.
48. MacLachlan, K., and Dunning, G., 1998, U-Pb ages and tectonomagmatic relationships of early Ordovician low-Ti tholeiites, boninites and related platonic rocks in central Newfoundland, Canada: Contributions to Mineralogy and Petrology, v. 133, p. 235-258, doi: 10.1007/s004100050450.
49. Mac Niocaill, C., van der Pluijm, B.A., and Van der Voo, R., 1997, Ordovician paleogeography and the evolution of the Iapetus Ocean: Geology, v. 25, p. 159-162, doi: 10.1130/ 0091-7613(1997)025<0159:OPATEO>2.3.CO;2.
50. McKerrow, W.S., Mac Niocaill, C., and Dewey, J.F., 2000, The Caledonian orogeny redefined: Journal of the Geological Society of London, v. 157, p. 1149-1154.
51. McLelland, J., Hamilton, M., Selleck, B., McLelland, J., Walker, D., and Orrell, S., 2001, Zircon U-Pb geochronology of the Ottawan orogeny, Adirondack Highlands, New York; regional and tectonic implications: Precambrian Research, v. 109, p. 39-72, doi: 10.1016/ S0301-9268(01)00141-3.
52. Moench, R.H., and Aleinikoff, J.N., 2002, Stratigraphy, geochronology, and accretionary terrane settings of two Bronson Hill arc sequences, northern New England: Physics and Chemistry of The Earth, v. 27, p. 47-95.
53. 5: A minor element discriminant for basaltic rocks of oceanic environments and its implications for petrogenesis: Earth and Planetary Science Letters, v. 62, p. 53-62, doi: 10.1016/0012-821X(83)90070-5.
54. North American Commission on Stratigraphic Nomenclature (NACSN), 1983, North American stratigraphic code: American Association of Petroleum Geologists Bulletin, v. 67, p. 841-875.
55. Paces, J.B., and Miller, J.D., Jr., 1993, Precise U-Pb ages of Duluth Complex and related mafic intrusions, northeastern Minnesota; geochronological insights to physical, petrogenetic, paleomagnetic, and tectonomagnetic processes associated with the 1.1 Ga Midcontinent Rift System: Journal of Geophysical Research, ser. B, Solid Earth and Planets, v. 98, p. 13,997-14,013.
56. Pan, Y., 1997, Zircon- and monazite-forming metamorphic reactions at Manitouwadge, Ontario: Canadian Mineralogist, v. 35, p. 105-118.
57. Pearce, J.A., and Cann, J.R., 1973, Tectonic setting of basic volcanic rocks determined using trace element analysis: Earth and Planetary Science Letters, v. 19, p. 290-300, doi: 10.1016/0012-821X(73)90129-5.
58. Pickett, T.E., 1976, Generalized geologic map of Delaware (revised): Delaware Geological Survey Special Publication 9, scale 1:633,600.
59. Pidgeon, R.T., Macambira, M.J.B., and Lafon, J.-M., 2000, Th-U-Pb isotopic systems and internal structures of Complex Carajás Province, Brazil: Evidence for the ages of granulite facies metamorphism and the protolith of the enderbite: Chemical Geology, v. 166, p. 159-171, doi: 10.1016/S0009-2541(99)00190-4.
60. Plank, M.O., Schenck, W.S., and Srogi, L., 2000, Bedrock geology of the Piedmont of Delaware and adjacent Pennsylvania: Delaware Geological Survey Report of Investigations, no. 59, 52 p.
61. Plank, M.O., Srogi, L., Schenck, W.S., and Plank, T.A., 2001, Geochemistry of the mafic rocks, Delaware Piedmont and adjacent Pennsylvania and Maryland: Confirmation of arc affinity: Delaware Geological Survey Report of Investigations, no. 60, 39 p.
62. Pupin, J.P., 1980, Zircon and granite petrology: Contributions to Mineralogy and Petrology, v. 73, p. 207-220, doi: 10.1007/BF00381441.
63. Pyle, J.M., and Spear, F.S., 2003, Four generations of accessory-phase growth in low-pressure migmatites from SW New Hampshire: American Mineralogist, v. 88, p. 338-351.
64. Ratcliffe, N.M., and Aleinikoff, J.N., 2001, Pre-Ottawan deformation and transpressional faulting in the Hudson Highlands of New York based on SHRIMP zircon ages of the Storm King Granite and the syntectonic Canopus pluton: Geological Society of America Abstracts with Programs, v. 33, no. 2, p. A-5.
65. Rollinson, H.R., 1993, Using geochemical data: Evaluation, presentation, interpretation: Harlow, UK, Longman Scientific and Technical, 352 p.
66. Rubatto, D., Williams, I.S., and Buick, I.S., 2001, Zircon and monazite response to prograde metamorphism in the Reynolds Range, central Australia: Contributions to Mineralogy and Petrology, v. 140, p. 458-468.
67. Schaltegger, U., Fanning, C.M., Günther, D., Maurin, J.C., Schulmann, K., and Gebauer, D., 1999, Growth, annealing, and recrystallization of zircon and preservation of monazite in high-grade metamorphism: Conventional and in-situ U-Pb isotope, cathodoluminescence and microchemical evidence: Contributions to Mineralogy and Petrology, v. 134, p. 186-201, doi: 10.1007/s004100050478.
68. Schenck, W.S., 1997, Stratigraphic classification and nomenclature of the rocks in the Delaware Piedmont [M.S. thesis]: Newark, Delaware, University of Delaware, 106 p.
69. Schenck, W.S., Plank, M.O., and Srogi, L., 2000, Bedrock geologic map of the Piedmont of Delaware and adjacent Pennsylvania: Delaware Geological Survey Geologic Map Series, no. 10, scale 1:36,000.
70. Shervais, J.W., 1982, Ti-V plots and the petrogenesis of modern and ophiolitic lavas: Earth and Planetary Science Letters, v. 59, p. 101-118, doi: 10.1016/0012-821X(82)90120-0.
71. Southwick, D.L., and Fisher, G.W., 1967, Revision of the stratigraphic nomenclature of the Glenarm Series in Maryland: Maryland Geological Survey Report Investigation, no. 6, 19 p.
72. Speer, J.A., 1980, Zircon, in Ribbe, P.H., ed., Orthosilicates: Mineralogical Society of America Reviews in Mineralogy, v. 5, p. 67-112.
73. Srogi, E.L., 1988, The petrogenesis of the igneous and metamorphic rocks in the Wilmington Complex, Pennsylvania-Delaware Piedmont [Ph.D. thesis]: Philadelphia, Pennsylvania, University of Pennsylvania, 613 p.
74. Srogi, L., and Lutz, T.M., 1997, Chemical variation in plutonic rocks caused by residual melt migration: Implications for granite petrogenesis, in Sinha, A.K., Whalen, J.B., and Hogan, J.P., eds., The nature of magmatism in the Appalachian orogen: Geological Society of America Memoir 191, p. 309-335.
75. Srogi, L., Wagner, M.E., and Lutz, T., 1993, Dehydration partial melting and disequilibrium in the granulite-facies Wilmington Complex, Pennsylvania-Delaware Piedmont: American Journal of Science, v. 293, p. 405-462.
76. Stacey, J.S., and Kramers, J.D., 1975, Approximation of terrestrial lead isotope evolution by a two-stage model: Earth and Planetary Science Letters, v. 26, p. 207-226, doi: 10.1016/0012-821X(75)90088-6.
77. Steiger, R.H., and Jäger, E., 1977, Subcommission on geochronology, convention on the use of decay constants in geo- and cosmochronology: Earth and Planetary Science Letters, v. 36, p. 359-362, doi: 10.1016/ 0012-821X(77)90060-7.
78. Tera, F., and Wasserburg, G.J., 1972, U-Th-Pb systematics in three Apollo 14 basalts and the problem of initial Pb in lunar rocks: Earth and Planetary Science Letters, v. 14, p. 281-304, doi: 10.1016/ 0012-821X(72)90128-8.
79. Thomas, C.W., Miller, C.F., Fullagar, P.D., Meschter McDowell, S.M., Vinson, S.B., and Bream, B.R., 2001, Where is the arc? Discontinuities in Taconian arc magmatism in the southern Appalachians: Geological Society of America Abstracts with Programs, v. 33, no. 6, p. A-262.
80. Thompson, A.M., 1979, A summary of the geology of the Piedmont in Delaware, in Kraft, J.C., and Carey, W., eds., Selected papers on the geology of Delaware: Transactions of the Delaware Academy of Science, v. 7, p. 115-134.
81. Tollo, R.P., Aleinikoff, J.N., Borduas, E.A., Hackley, P.C., and Fanning, C.M., 2004, Petrologic and geochronologic evolution of the Grenville orogen, northern Blue Ridge province, Virginia, in Tollo, R.P., Corriveau, L., McLelland, J.M., and Bartholomew, M.J., eds., Proterozoic tectonic evolution of the Grenville orogen in North America: Geological Society of America Memoir 197, p. 647-677.
82. Tucker, R.D., and Robinson, P., 1990, Age and setting of the Bronson Hill magmatic arc; a re-evaluation based on U-Pb zircon ages in southern New England: Geological Society of America Bulletin, v. 102, p. 1404-1419, doi: 10.1130/0016-7606(1990)102<1404:AASOTB>2.3.CO;2.
83. van Breemen, O., Davidson, A., Loveridge, W.D., and Sullivan, R.W., 1986, U-Pb zircon geochronology of Grenville tectonites, granulites, and igneous precursors, Parry Sound, Ontario, in Moore, J.M., Davidson, A., and Baer, A.J., eds., The Grenville Province: Geological Association of Canada Special Paper 31, p. 191-208.
84. Vavra, G., 1990, On the kinematics of zircon growth and its petrogenetic significance: A cathodoluminescence study: Contributions to Mineralogy and Petrology, v. 106, p. 90-99, doi: 10.1007/BF00306410.
85. Vavra, G., Schmid, R., and Gebauer, D., 1999, Internal morphology, habit and U-Th-Pb microanalysis of amphibolite-to-granulite facies zircons: Geochronology of the Ivrea Zone (Southern Alps): Contributions to Mineralogy and Petrology, v. 134, p. 380-414, doi: 10.1007/s004100050492.
86. Villaseca, C., Martin Romera, C., De la Rosa, J., and Barbero, L., 2003, Residence and redistribution of REE, Y, Zr, Th, and U during granulite facies metamorphism: Behaviour of accessory and major phases in peraluminous granulites of central Spain: Chemical Geology, v. 200, p. 293-323, doi: 10.1016/S0009-2541(03)00200-6.
87. Wagner, M.E., and Srogi, L., 1987, Early Paleozoic metamorphism at two crustal levels and a tectonic model for the Pennsylvania-Delaware Piedmont: Geological Society of America Bulletin, v. 99, p. 113-126, doi: 10.1130/0016-7606(1987)99<113:EPMATC>2.0.CO;2.
88. Walsh, G.J., Aleinikoff, J.N., and Fanning, C.M., 2004, Geochronological constraints on the tectonic evolution of the eastern Hudson Highlands, western Connecticut, in Tollo, R.P., Corriveau, L., McLelland, J.M., and Bartholomew, M.J., eds., Proterozoic tectonic evolution of the Grenville orogen in North America: Geological Society of America Memoir 197, p. 729-753.
89. Ward, R.F., 1959, Petrology and metamorphism of the Wilmington Complex, Delaware, Pennsylvania, and Maryland: Geological Society of America Bulletin, v. 70, p. 1425-1458.
90. Williams, I.S., 1998, Chapter 1, U-Th-Pb geochronology by ion microprobe, in McKibben, M.A., Shanks, W.C., III, and Ridley, W.I., eds., Applications of microanalytical techniques to understanding mineralizing processes: Reviews of Economic Geology, v. 7, p. 1-35.
91. Williams, I.S., Buick, I.S., and Cartwright, I., 1996, An extended episode of early Mesoproterozoic metamorphic fluid flow in the Reynolds Range, central Australia: Journal of Metamorphic Geology, v. 14, p. 29-47, doi: 10.1111/j.1525-1314.1996.00029.x.
92. Woodruff, K.D., and Thompson, A.M., 1972 (issued 1975), Geology of the Newark area, Delaware: Delaware Geological Survey Geologic Map Series 3, scale 1:24,000.
93. Woodruff, K.D., and Thompson, A.M., 1975, Geology of the Wilmington area, Delaware: Delaware Geological Survey Geologic Map Series 4, scale 1:24,000.
94. Zartman, R.E., and Leo, G.W., 1985, New radiometric ages on gneisses of the Oliverian domes in New Hampshire and Massachusetts: American Journal of Science, v. 285, p. 267-280.