enn- n e. sions in . for for ania ., and the Taconic the Taconic Avalonia Avalonia Avalonia s from the Wissa- the s from igneous and igneous Avalonia 2 Ganderia ? Cores P-05-02 Rim domains Ge-06-33 Wilmington Complex Wissahickon Fm. References Wiss Fm. Salinic Orogeny B-22 End of Acadian orogeny End of Acadian Mt.Cuba Rosemont Shear Zone Rosemont Shear Zone Early stages of Acadian orogeny Early stages of Acadian Tectonic Speculation Tectonic Doe Run Street Road Fault Street Wilmington Complex is intra-Iapetan arc. Complex Wilmington then Mt. Cuba Wissahickon, metamorphism in low-P High-T Complex Wilmington metamorphism of Granulite Dextral transpression Burial and metamorphism of Doe Run Schist Fm. Wissahickon onset of crustal thickening in Deformation Barrovian metamorphism of Wissahickon Fm. Wissahickon metamorphism of Barrovian Street Road Fault Street Laurentia Iapetus Laurentia Laurentia Embreeville Thrust Embreeville and Gale Blackmer Blackmer, G. C., 2005, Preliminary bedrock geologic map of a portion of the Wilmington 30- by 60-minute quadrangle, southeaster quadrangle, 60-minute 30- by Wilmington map of a portion geologic bedrock G. C., 2005, Preliminary of the Blackmer, (PDF) fil Document Format Portable Report OFBM 05–01.0, 16 p., Open-File 4th ser., Survey, Geological Pennsylvania Pennsylvania: age 2012, Detrital zircon W.S., and Schenck, V., Valencia, M., R., Crawford, L., Mathur, G.C., Srogi, H., Blackmer, Bosbyshell, Society and northerntectonic implications: Geological Regional of America Delaware: southeast Pennsylvania hickon Formation, 87. 2, p. 44, no. v. Abstracts with Programs, map of a portion geologic Montgomery H., 2008, Bedrock P of the Philadelphia quadrangle, Bosbyshell, and Philadelphia Counties, (PDF). Document Format Portable Report OFBM 08–05.0, 21 p., Open-File 4th ser., Survey, Geological sylvania: Pennsylvania through history 1997a, A Geologic the Mesoproterozoic of the North-Central from 1. Orogensis Part Appalachians. T., R. Faill, 551-619. 297, pp. v. orogeny: American Journal of Science, complex, mafic and tectonic affinity of the Baltimore and Sinha, A. K., S. K Maryland: in B., 1989, Petrology Mittwede, Hanan, B. p. 1-18. Paper 231, Piedmont: Geological Society of America Special rocks of the Appalachian Ultramafic eds., E. F., Stoddard, Pennsylv tectonic G.C., 2006, Refining the metamorphic and history of the southeastern H., and Blackmer, Bosbyshell, J.M., Pyle, Excur ed., F.J., in Pazzaglia, and accessory-phase geochronology thermometry, and zircon monazite from results Recent Piedmont: 83-112. Guide 8, p. Society Geological in the Middle States: of America Field Atlantic Trips Geology and History: Field Evidence Formation: Wissahickon within the metamorphic histories H., 2007, Contrasting G.C. and Bosbyshell L., Blackmer, Srogi, 86. 1, p. 39, no. v. Societysubdivision and tectonic implications: Geological of America Abstracts with Programs, Ordovician - ~480 Ma Ordovician Silurian ~430 Ma ~410 Ma Early Devonian H., 2006, Deciphering S. L., and Bosbyshell, C. M., Fanning, Kamo, L. A., O., Srogi, S., Plank,W. M. J.L, Schenck, Aleinikoff, and backscattered cathodoluminescence Morphology, Delaware: Complex, Wilmington of the in high-grade rocks metamorphic events 39-64 118, p. Society Geological and monazite: of America Bulletin, v. of zircon and SHRIMP U-Pb geochronology electron zoning, Middle ~385 Ma Devonian 1
300 320 340 360 380 400 420 440 460 480 500 380 390 400 410 420 430 440 450 460 470 480
Age (Ma) Age (Ma) Age ± 12 ± Rims Cores (n = 24) = (n Outer core Outer core 388 ± 12 Ma 388 ± Pennsylvania Geological Survey Geological Pennsylvania 2 constrain the timing constrain CC-7205
) likely record the time but is included within M2 ± 7 Ma , LeeAnn Srogi , LeeAnn Mn 1 320 340 360 380 400 420 440 460 480 B22 Rosemont Shear Zone ± 14 Ma) and are included in high-Ca± 14 Ma) garnet and are 0.5 mm U Wilmington Complex (Aleinikoff et al., 2006). similar in age to zircon and monazite the adjacent Monazite cores record this earlier metamorphism and are Ma. The shear zone cuts high-T, low-P pelitic migmatite. (average, 415 Ca overgrowth. Monazite cores (433 of M1. Asymmetric high-U rims on monazite rims. Sample B-22 demonstrates the metamorphic and deformational the metamorphic and deformational Sample B-22 demonstrates Wissa- portion lower of the history probably of the western, which Garnet a low-Ca core, maps show hickon Formation. metamorphism (andalusite- low-P during M1, high-T formed during the formed with a high-Ca overgrowth grade), sillimanite fabric in this The kyanite-grade metamorphism. M2, higher-P, rock, S3 wraps the M1 garnet core, of S3
While complexly deformed, the eastern Wissahickon Formation Formation Wissahickon the eastern deformed, While complexly st-ky-sil metamorhpic field a classic Barrovian, is characterized by meta- of the Silurian high-T and exhibits little evidence gradient that this metamorphism is morphism. Monazite ages indicate 2008). 384 Ma(Bosbyshell, approximately Devonian, Wissahickon Formation Wissahickon
Above, syn-tectonic Above, garnet in ultramylonite CC- the RSZ (loc. from of estimates 7205). P-T ob- 600C at 8 kb were tained using the composi- tion of this garnet with recrystallized matrix pla- 388 is Devonian, monazite Syn-tectonic and biotite. gioclase West Chester University Chester West Zone Shear Rosemont 1 Howell Bosbyshell Howell WG-216 GW-05-154 C-207 WG-43b
Avondale Massif sillimanite
Mill Creek Nappe
340 360 380 400 420 440 460 480 Age (Ma) Age Monazite is complexly zoned and may contain contain and may zoned Monazite is complexly age populations: 419 ± 9.7 Matwo and 437 ± 11.0 contain Ma. Both inclusions and matrix grains domains which yield both ages. compositional con- are textures where instances are While there such examples are with this age difference, sistent it is not clear that these re- Thus not ubiquitous. distinct two sults indicate periods of monazite is 427 ± 14 Ma, of all analyses average The growth. TIMS and SHRIMP reported previously similar to 2006). Aleinikoff, (above, results The Embreeville Thrust places the West West the places Thrust Embreeville The and all struc- Metamorphic Suite Grove the green- above turally higher rocks Formation. Creek Peters schist grade
340 360 380 400 420 440 460 480 520 540 560
i n o m (Ma) Age o
D
-
k
a
T
i
h r
e
429
+ rutile + 850 - ilmenite -
WG-216 6mm for both photos 427
- biotite - - sillimanite - ≈ U
235
426
Pb/ -biotite 23.01.2012 - 10:53:11 CPU time: 5h 04m 32.46 207
Concordia Age = 424.9 ± 0.4 Ma Concordia
probability of concordance = 0.42 sillimanite 424 kyanite garnet 750
pl ilm grt bt
sil qtz liq qfm +cordierite 471 491 422 -H2O 427 Width of field
+liquid 418 420 44069 (monazite) Formation Wissahickon TIMS data 0.512 0.514 0.516 0.518 0.520 0.522 0.524 0.526 0.528 430
pl ilm grt bt sil qtz 0.0688 0.0684 0.0680 0.0676 0.0672
434
H2O qfm
U Pb/
-staurolite Temperature [C] 238 206 -staurolite
650
+kyanite +cordierite
+sillimanite
+ms West Chester Massif
m1
-muscovite staurolite -chl Monazite with young, low-Y, high- low-Y, Monazite with young, in the matrix and rims is present Th as inclusions in the high-Ca garnet metamor- WG-216. High-T rims in phism can be no older than 410 ± on considerations Textural 11 Ma. growth the timing of monazite the age of high-T similarly constrain in metamorphism and deformation 411 ± 11 Ma. C-207 to
i n o m
550
o
D
-
k
-biotite
a
T
i
h r
e
sillimanite sillimanite kyanite
7000 6000 8000 9000 5000
4000 10000 Pressure [Bar] Pressure alm
C-207 grs pl ilm +cordierite grt bt sil qtz liq qfm
pyr
+ rt + - ilm - -H2O
+liquid sps
-staurolite -chlorite +sillimanite st-bearing assemblages Temperature [C]
Street Road Fault
Mn -chloritoid +chlorite
Mill Creek Nappe
Embreeville thrust WG-216 400 500 600 700 800
2 mm 7000 6000 9000 8000 5000 4000 10000 [Bar] Pressure Ca x-ray map of garnet from WG-216. Low Ca rim is in- Ca WG-216. Low map of garnet from x-ray Ca during high garnet growth to correspond to terpreted garnet 2007). Late et al., (Srogi breakdown T staurolite post- is syn- to and sil after st (photomicrographs) inter- Isopleths of this garnet rim compositon tectonic. 700C and 5 kb. sect at approximately Ca Mt. Cuba Gneiss Gneiss in the Mill nappe, in Mt. Cuba Creek conditions P-T exceeded have to estimated 44069) are De (loc. Yorklyn, of perthitic at pres- 750°C, based on the presence feldspars, than 0.6 greater but stability in the sillimanite field, sures 2011). et al., (Bosbyshell based on a lack of cordierite GPa, 426 ± 3 Ma and 424.9 ± 0.4 ages, TIMS monazite SHRIMP and constrain the timing 2006), et al., (Aleinikoff, Ma, respectively metamorphism and deformation. of high-T Doe Run Schist Doe Run The dominant foliation in the Mount Cuba Gniess above the Street Road Fault (sample WG-43) (sample Road Fault the Street Gniess above in the Mount Cuba dominant foliation The foliation-parallel contains inclusions of Staurolite and biotite. sillimanite by aligned is defined as small crystals occurs which overprint Kyanite and cross-cuts fabrics. sillimanite sillimanite period of mineral suggests a second This on garnet. present are and high Ca-rims sillimanite peak temperatures. from during isobaric cooling growth Ca E n = 116 CC46-2 40º 41º 75º n = 139 n = 143 75º 75º P-05-02 S 42º N Wiss-1N DEL. Glen Riddle, Pa Glen Riddle, 76º 76º Wissahickon Fm. Wissahickon Fairmont Park Fairmont W Philadelphia, Pa Philadelphia, Pa P-05-02 Wissahickon Fm. Wissahickon Wiss-1N Wissahickon Fm. Wissahickon 77º Wissahickon Creek Wissahickon 77º 10 Km Ma Ge-06-33 78º 78º 1200 Ma 79º 79º 1195 Ma 1470 Ma D 80º 80º Stockton Fm. Stockton James Run arc/BMC Run James Wissahickon Fm Wissahickon Wilmington Complex Mesozoic Basin Schist Laurels & Doe Run Metasedimentary rocks Clastics and carbonates gneiss Grenville Coastal Plain Mt. Cuba Gneiss 895 Ma U 42º 41º 40º Amphibolite facies Granulite facies Granulite Sycamore Mills Fm. Undifferentiated gneiss Triassic rocks Triassic
610 Ma
White Clay Creek Amphibolite White Clay Ma
Mt. Cuba Gneiss Schist Laurels and Doe Run Kennett Square Amphibolite Kennett
525
Wissahickon Formation Wissahickon
A W
o 0 500 1000 1500 2000 2500 3000
Avondale massif Avondale West Chester Massif West
75
D
Cambrian Metamorphic Suite Grove West MAP AREA MAP
U
B-22
Legend
Z
o 30'N S
Precambrian
40
y
n = 90
Z C-207
e n = 124
S D
l
l
a GW-05-154
CC-7205
Chatham, Pa
U t
V Pa Unionville,
n
W Doe Run Schist Doe Run Schist
o
o
m
76
e
Ma
s
o
R
n
?
do
Modified from Faill (1997), Hanan and Sinha (1989). Modified from
? 1050 Ma
o N ofRocks and probable Laurentian affinity known
?
40
ing
t
? Wilmington Complex Wilmington
Pa.
Del.
n
960 Ma
Anorthosite Quartz monzonite gneiss and intermediate gneiss Felsic Graphitic felsic gneiss Octoraro Formation Antietam Fms. Harpers, Chickies, undifferentiated meta-clastic rocks Undifferentiated meta-carbonate rocks Peters Creek Schist Peters Glenarm Group
?
500 1000 1500 2000 2500
574 Ma 554 Ma
?
t
Hu
l
?
u
Metamorphic Grove West The part is no longer considered Suite Formation, Wissahickon of the tectono- in based on differences thermal history and detrital zircon et al, (Bosbyshell provenance. 2012).
a
Avondale Massif Avondale
2006. 2005; Pyle et al., Blackmer, Modified from
?
F
Pa.
?
Paleozoic Lower
d
Md.
D ? a
N
?
o
U ?
R
?
Massif Chester West
t
t
s
?
e
44069
u
o 30'N e
?
r
Coastal Plain Coastal
r
?
h t
39 ?
? T S
e
e Simplified Geologic Map of the Central Appalachian Piedmont Simplified Geologic Map of the Central n
i n = 49
0 km 25
l n = 95 n = 95
l 44069
c Bc21-b
Granite/ granodiorite
l
Bc21-b i
t Wg-101
i
n
v
Yorklyn, De Yorklyn, A e
De Ashland,
e k
Pa Grove, West
2006 Aleinikoff et al. r
e Mt. Cuba Gneiss Mt. Cuba Mt. Cuba Gneiss Mt. Cuba
Gneiss Mt. Cuba b
e
GW-05-54 r
m
Ma
E
C
l
l i Metamorphic Suite Grove West
M
e
Pa. Del.
Honey Brook Upland Brook Honey
n
i ofRocks arc affinity
ultramafic rocks
Wissahickon Fm Wissahickon Geologic Map of Southeastern Pennsylvania and Northern Delaware Volcanic Plutonic Gabbro Undifferentiated
L
Md.
1035 Ma
c Nappe
1020 Ma i
t
Advances in constraining the timing of deformation and metamorphism: the timing of deformation in constraining Advances
r
Woodville WG-43
a
WG-101
216
- 965 Ma 1050 Ma 945 Ma
M Silurian plutonic/metaplutonic rocks metaigneous rocks Ordovician Ordovician meta-clastic Ordovician rocks and meta-volcanic 960 Ma 547 Ma
546 Ma
Ridge Mine WG Salinic through Acadian transpressional tectonics in the Central Appalachians tectonics in the Central transpressional Acadian Salinic through
C-207 This poster focuses on focuses poster This Meta- Grove West the morphic Suite (WGMS)- the Mt. Cuba Gneiss and Doe Run Schist and the arc- Wissahickon related Formation. 0 500 1000 1500 2000 2500