Distribution of overprinting metamorphic mineral assemblages in the Wissahickon group, southeastern Pennsylvania

Bosbyshell, Howell; Crawford, María Luisa; Srogi, LeeAnn

doi:10.1130/0-8137-2330-2.41

Cited by 3 publications

(1 citation statement)

References 0 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…[5] Bosbyshell et al [1998Bosbyshell et al [ , 1999 suggested the Loch Raven Formation experienced two main stages of Palaeozoic metamorphism; an earlier andalusite-sillimanite facies zone (4 -6 kbars; $480 Ma) was variably overprinted by a kyanite bearing, Barrovian sequence (550°-650°C, 7 -9 Kbars; $380 Ma). Generalized garnet, staurolite and kyanite isograds have been mapped around the entire Baltimore area [Doe et al, 1965], and the southwestern part of Harford county [Southwick and Owens, 1968].…”

Section: Geological Settingmentioning

confidence: 99%

Significance of dextral reactivation of an E‐W transfer fault in the formation of the Pennsylvania orocline, central Appalachians

Yeh¹,

Bell

2004

Tectonics

View full text Add to dashboard Cite

Three hypotheses for orocline development including (1) primary plate boundary shape, (2) arc rotation, and (3) arc overprinting were evaluated for the formation of the Pennsylvania orocline, Maryland, USA, using foliation intersection/inflection axes preserved within porphyroblasts (FIA). The distribution and the timing of sequences of FIA data measured from garnet porphyroblasts within the Loch Raven formation are statistically the same across the Pennsylvania orocline, suggesting that all subregions of the arc have experienced the same deformation history. This may suggest that the geometry of the paleocontinental margin controlled the basic shape of this orocline. However, if the orocline is treated as three separate regions, defined by the SW‐WE‐NE trending portions of its slightly staircase‐shaped outline, a much higher proportion of the NNE‐SSW trending FIAs (set II) are preserved in the W‐E trending region than those to either side. This geometric relationship could have resulted from WNW‐ESE directed bulk stress causing a zone of dextral shear along what is now the W‐E trending portion of this orogen. It appears that what could have been an early formed W‐E trending sinistral transform shear zone was preferentially dextrally reactivated during the Taconian orogeny.

show abstract

Section: Geological Settingmentioning

confidence: 99%

Significance of dextral reactivation of an E‐W transfer fault in the formation of the Pennsylvania orocline, central Appalachians

Yeh¹,

Bell

2004

Tectonics

View full text Add to dashboard Cite

show abstract

Further detrital zircon evidence for peri-Gondwanan blocks in the central Appalachian Piedmont Province, USA

Martin

Bosbyshell

2019

Can. J. Earth Sci.

View full text Add to dashboard Cite

Evidence for exotic terranes in the central Appalachian Piedmont Province is fragmented between central Virginia, northern Maryland, and southeastern Pennsylvania. Here we present laser ablation-inductively coupled plasma mass spectrometry data from detrital zircon that support the presence of an exotic terrane in this region. U–Pb dating of detrital zircon from new samples of the Storck quartzite (central Virginia) and the Hoods Mill rocks (northern Maryland) confirms the presence of a major peak at ca. 630–610 Ma in these units. These ages are consistent with derivation from Gondwana, but not Ediacaran Laurentia. Further, modern εHf values of five of the ca. 670–580 Ma grains in these samples are inconsistent with derivation from the few plutons of this age in Ediacaran Laurentia. The Loch Raven Schist and a metasedimentary xenolith in the Wilmington Complex contain a smaller proportion of ca. 670–580 Ma grains than the Storck quartzite and the Hoods Mill rocks, but more such grains than in sediment derived from Ediacaran Laurentia, so we tentatively conclude that these two units also received sediment from Gondwana. Detrital zircon ages from the Piney Run Formation, Pleasant Grove Schist, Prettyboy Schist, and Wissahickon Formation allow sediment provenance solely in Ediacaran Laurentia. We also present new zircon spot U–Pb and Lu–Hf isotopic data from western Newfoundland plutons for comparison with these types of data from the detrital zircon. Intrusion ages of the Steel Mountain Anorthosite, Disappointment Hill Tonalite, and Round Pond Granite are 608 ± 12, 600 ± 8, and 590 ± 9 Ma, respectively. None of these units was derived entirely from the depleted mantle.

show abstract

Monazite age constraints on the tectono-thermal evolution of the central Appalachian Piedmont

Bosbyshell

Srogi

Blackmer

2016

American Mineralogist

View full text Add to dashboard Cite

Distribution of overprinting metamorphic mineral assemblages in the Wissahickon group, southeastern Pennsylvania

Cited by 3 publications

References 0 publications

Significance of dextral reactivation of an E‐W transfer fault in the formation of the Pennsylvania orocline, central Appalachians

Significance of dextral reactivation of an E‐W transfer fault in the formation of the Pennsylvania orocline, central Appalachians

Further detrital zircon evidence for peri-Gondwanan blocks in the central Appalachian Piedmont Province, USA

Monazite age constraints on the tectono-thermal evolution of the central Appalachian Piedmont

Contact Info

Product

Resources

About