A Field Trip to Ancient Plate Tectonics Structures in Massachusetts and New York October 10-12, 2014 12.001: Introduction to Geology Led by Profs. Oliver Jagoutz and Taylor Perron Paleogeographic map of North America removed due to copyright restrictions. 1 Equipment Checklist Boots or sturdy shoes Change of clothing for two days Sweater or sweatshirt Warm hat Raincoat Pens and pencils Water bottle Camera Sunscreen Notebook Colored pencils Brunton compass* Hand lens* Hammer* *We will provide these for you 2 Keeping a Field Notebook (for this trip you can use the blank pages in the back of this guide for a field notebook): As practicing geologists, your field observations provide all of your data once you are back in the lab. Your memory is not as good as you think it is. It is therefore important that you take complete, organized, and neat notes. At each site you should make a series of notations about the site, the characteristics of the outcrop, and the individual rock units. 1. Setting the stage a. Your name, date, name of site, companions, and coordinates b. Formation name, probable stratigraphic level/age of rocks 2. Outcrop description a. Step back and look over the outcrop. Note its gross features. Are there any folds, faults, or unconformities evident? Are there any stratigraphic subdivisions that are visible at this scale? b. Make a sketch of the outcrop, including on it your observations from above. Be sure to include an estimated scale and compass orientation of the view (e.g. ‘looking towards the NE’). If you take a picture, note the picture number. 3. Rock description a. General appearance: Note bedding character, the thickness and lateral continuity of the beds; color of weathered and fresh surfaces; weathering characteristics (does it fall to bits, turn to mud, or remain blocky, etc.?), response to hammering (does it ring or thud, crumble, or is it tough, how does it fracture, etc.). b. Rock Type: Describe features encompassed by i. Grain size and shape. ii. Mineralogy. iii. Sedimentary structures. iv. Fossils. 4. Integration a. Suggest the probable paleoenvironments represented at each stop. 3 Introduction The purpose of this field trip is to introduce you to geologic evidence for the past action of plate tectonics. We will see various rocks from different tectonic settings that have been used to reconstruct the complex Paleozoic history of the eastern United States and Canada. The geology of the eastern U.S. is dominated by multiple rifting and collision events related to at least two complete sequences of the Wilson cycle, the hypothesized cyclical opening and closing of ocean basins that accompanies the formation and breakup of supercontinents. In particular, we will see evidence for the assembly and disassembly of the supercontinent Rodinia from ~0.5-1.3 billion years (Ga) ago, the subsequent collision of two volcanic islands arcs with Laurentia (proto-North American continent that rifted from Rodinia) between 440-350 million years ago (Ma), and the disassembly of the supercontinent Pangea after 250 Ma. We will not see any geologic evidence for the assembly of Pangea (the Allegheny orogeny), which occurred between ~350 and 250 Ma, since most of the affected rocks were rifted away during its breakup. We will begin the trip in the West, on the passive margin sequences of Laurentia, and work our way towards the East through a complex arc-continent collision zone. We will visit rocks formed or metamorphosed during the following events, listed in order of time of occurrence (see Fig. 1). 1. The Grenville orogeny associated with formation of the supercontinent Rodinia (Proterozoic eon ~1 Ga): Stop 1 2. Rift deposits associated with breakup of Rodinia (Ediacaran period): Stop 1 3. Passive margin of Laurentia (Cambrian to Ordovician periods): Stop 1 4. Taconic Orogeny associated with collision of Laurentia with the Shelburne Falls island arc (Middle Ordovician epoch): Stops 2-10 5. The Acadian orogeny associated with the collision of Laurentia with Avalon island arc (Early Devonian epoch) 6. Rifting from opening of the Atlantic Ocean associated with breakup of supercontinent Pangea (Jurassic to Triassic periods): Stop 11 An overview of the geologic structures in our field area is shown in Fig. 2. 4 Fig. 1. The geologictimescale. GSA GEOLOGIC TIME SCALE v. 4.0 Courtesy of The America.The SocietyGeological ofpermission.of Used with Courtesy CENOZOIC MESOZOIC PALEOZOIC PRECAMBRIAN CHRON . MAGNETIC MAGNETICHIST . BDY. AGE POLARITY PICKS AGE POLARITY PICKS AGE PICKS AGE PERIOD EPOCH AGE PERIOD EPOCH AGE PERIOD EPOCH AGE EON ERA PERIOD AGES (Ma) (Ma) (Ma) (Ma) (Ma) (Ma) (Ma) NAR Y HIST ANOM. (Ma) ANOM. CHRON. HOLOCENE 1 C1 QUATER­ 0.01 30 C30 66.0 541 CALABRIAN PLEISTOCENE* 1.8 31 C31 MAASTRICHTIAN 252 2 C2 GELASIAN 70 CHANGHSINGIAN EDIACARAN 2.6 Lopin­ 254 32 C32 72.1 635 2A C2A PIACENZIAN WUCHIAPINGIAN PLIOCENE 3.6 gian 33 260 260 3 ZANCLEAN LA TE CAPITANIAN NEOPRO­ 5 C3 CAMPANIAN Guada­ 265 750 CRYOGENIAN 5.3 80 C33 WORDIAN TEROZOIC 3A MESSINIAN lupian 269 C3A 83.6 ROADIAN 272 850 7.2 SANTONIAN 4 86.3 KUNGURIAN C4 280 279 TONIAN CONIACIAN VA N I A N 4A Cisura­ C4A TORTONIAN 90 89.8 1000 1000 PERMIAN ARTINSKIAN 10 5 1 1.6 TURONIAN lian C5 93.9 290 SAKMARIAN STENIAN CENOMANIAN 296 SERRAVALLIAN 34 C34 ASSELIAN 299 5A 100 100 300 GZHELIAN 1200 C5A 13.8 LATE 304 KASIMOVIAN 307 1250 MESOPRO­ 15 LANGHIAN ECTASIAN 5B C5B ALBIAN MIDDLE MOSCOVIAN TEROZOIC 16.0 ACEOUS 5C C5C 110 315 PENNSYL­ 1400 EARLY 5D C5D MIOCENE 113 320 BASHKIRIAN 323 5E C5E NEOGENE BURDIGALIAN SERPUKHOVIAN 1500 CALYMMIAN 6 C6 APTIAN LATE 20 120 331 20.4 6A C6A CHA TTIAN EARLY 1600 M0r 126 6B C6B AQUITANIAN M1 340 MIDDLE VISEAN MISSIS­ M3 BARREMIAN SIPPIAN STATHERIAN C6C 23.0 6C 130 M5 CRET 131 347 1750 HAUTERIVIAN 7 C7 CARBONIFEROUS EARLY TOURNAISIAN 1800 M10 134 25 7A C7A 359 8 C8 VALANGINIAN M12 360 140 M14 139 FAMENNIAN OROSIRIAN 9 C9 M16 28.1 M18 BERRIASIAN 2000 PROTEROZOIC 10 C10 LATE PALEOPRO­ M20 145 372 2050 30 11 C11 TEROZOIC 150 M22 TITHONIAN FRASNIAN 12 380 5 RUPELIAN 152 C12 LATE 383 RHYACIAN M25 KIMMERIDGIAN GIVETIAN OLIGOCENE MIDDLE 388 2250 M29 157 EIFELIAN 2300 13 C13 33.9 160 6 4 393 OXFORDIAN DEVONIAN 35 15 C15 1 400 EMSIAN SIDERIAN 16 C16 CALLOVIAN 166 PRIABONIAN BATHONIAN 408 17 168 EARLY PRAGIAN C17 170 MIDDLE BAJOCIAN 411 2500 2500 37.8 170 AALENIAN LOCHKOVIAN 18 174 419 40 C18 BARTONIAN CHANGES 420 PRIDOLI 423 19 LUDLOW LUDFORDIAN 426 NEOARCHEAN C19 TOARCIAN GORSTIAN 41.2 180 HOMERIAN 427 WENLOCK SHEINWOODIAN 430 2750 20 183 433 2800 LLANDO­ TELYCHIAN C20 PLIENSBACHIAN AERONIAN 439 EARLY 440 VERY 441 LUTETIAN SILURIAN RHUDDANIAN 45 190 444 JURASSIC 191 HIRNANTIAN 445 KATIAN MESO­ RAPID POLARITY CHANGES RAPID POLARITY RAPID POLARITY 3000 21 SINEMURIAN LATE 453 C21 SANDBIAN ARCHEAN EOCENE 47.8 200 199 458 HETTANGIAN 201 460 ALEOGENE DARRIWILIAN 22 MIDDLE 50 C22 RHAETIAN 467 3200 P DAPINGIAN 470 3250 23 C23 YPRESIAN 210 209 FLOIANAGE 1 0 EARLY 478 480 24 ORDOVICIAN TREMADOCIAN PALEO­ 485 C24 LATE 55 NORIAN FURON­ 490 ARCHEAN 220 JIANGSHANIAN 56.0 GIAN 494 3500 25 PAIBIAN ARCHEAN C25 497 THANETIAN 500 GUZHANGIAN 501 3600 26 228 Epoch 3 DRUMIAN 230 AGE 5 505 C26 59.2 509 60 SELANDIAN CARNIAN AGE 4 3750 Epoch 2 514 237 AGE 3 EOARCHEAN 27 61.6 520 C27 LADINIAN 521 240 MIDDLE 241 AGE 2 28 TRIASSIC C28 CAMBRIAN 529 DANIAN ANISIAN TERRE­ 4000 4000 ALEOCENE 65 29 247 NEUVIAN C29 P FORTUNIAN EARLY OLENEKIAN 250 HADEAN 66.0 250 INDUAN 30 C30 252 540 541 *The Pleistocene is divided into four ages, but only two are shown here. What is shown as Calabrian is actually three ages—Calabrian from 1.8 to 0.78 Ma, Middle from 0.78 to 0.13 Ma, and Late from 0.13 to 0.01 Ma. Walker, J.D., Geissman, J.W., Bowring, S.A., and Babcock, L.E., compilers, 2012, Geologic Time Scale v. 4.0: Geological Society of America, doi: 10.1130/2012.CTS004R3C. ©2012 The Geological Society of America. The Cenozoic, Mesozoic, and Paleozoic are the Eras of the Phanerozoic Eon. Names of units and age boundaries follow the Gradstein et al. (2012) and Cohen et al. (2012) compilations. Age estimates and picks of boundaries are rounded to the nearest whole number (1 Ma) for the pre-Cenomanian, and rounded to one decimal place (100 ka) for the Cenomanian to Pleistocene interval. The numbered epochs and ages of the Cambrian are provisional. REFERENCES CITED Cohen, K.M., Finney, S., and Gibbard, P.L., 2012, International Chronostratigraphic Chart: International Commission on Stratigraphy, www.stratigraphy.org (last accessed May 2012). (Chart reproduced for the 34th International Geological Congress, Brisbane, Australia, 5–10 August 2012.) Gradstein, F.M, Ogg, J.G., Schmitz, M.D., et al., 2012, The Geologic Time Scale 2012: Boston, USA, Elsevier, DOI: 10.1016/B978-0-444-59425-9.00004-4. Fig. 2a. Overview of rocks and structures to be visited on this field trip (after Bradley and Kidd 1991). Courtesy of the Geological Society of America. Used with permission. Source: Bradley, D. C., and W. S. F. Kidd. "Flexural Extension of the Upper Continental Crust in Collisional Foredeeps." Geological Society of America Bulletin 103, no. 11 (1991): 1416-38. 6 Fig. 2b. Overview of rocks and structures to be visited on this field trip (Suppe 1985). © source unknown. All rights reserved. This content is excluded from our Creative Commons license. For more information, see http://ocw.mit.edu/help/faq-fair-use/.