8.9.07 Treasure Bailley Georef Data 2006-010959 TI Isotope provinces in Laramide and mid-Tertiary igneous rocks of northwestern Mexico (Chihuahua and Sonora) and their relation to basement configuration AU "Housh, Todd B; McDowell, Fred W" AF "University of Texas at Austin, Department of Geological Sciences, Austin, TX, United States (USA)" AF "California State Polytechnic University, United States (USA); University of Wisconsin, United States (USA); University of Wyoming, United States (USA)" MT "The Mojave-Sonora Megashear hypothesis; development, assessment, and alternatives" ED "Anderson, Thomas H; Nourse, Jonathan A; McKee, James W; Steiner, Maureen B" AF "University of Pittsburgh, Department of Geology and Planetary Sciences, Pittsburgh, PA, United States (USA)" SO "Special Paper - Geological Society of America, vol.393, pp.671-692, 2005" IS 0072-1077 CD GSAPAZ DE absolute age; alkaline earth metals; Arizona; basement; Cenozoic; Chihuahua Mexico; Cretaceous; dates; deformation; faults; geochemistry; Grenvillian Orogeny; igneous rocks; intrusions; isotope fractionation; isotope ratios; isotopes; Jurassic; K/Ar; Laramide Orogeny; lead; magma contamination; magmatism; Mesozoic; metals; Mexico; Mojave-Sonora Megashear; Nd-144/Nd-143; neodymium; Oligocene; orogeny; Paleogene; Pb-206/Pb-204; Precambrian; Proterozoic; radioactive isotopes; rare earths; Rb/Sr; shear zones; Sierra Madre Occidental; Sonora Mexico; Sr-87/Sr-86; stable isotopes; strontium; systems; tectonics; Tertiary; Texas; U/Pb; United States; Upper Cretaceous; upper Precambrian AB "We have identified five distinct isotope provinces in northwestern Mexico in a study of the Sr, Nd, and Pb isotope geochemistry of Laramide and mid-Tertiary igneous rocks in Sonora and Chihuahua as well as adjacent portions of southwestern United States. Province A, in northern Sonora, is characterized by very unradiogenic Nd and Pb isotopic compositions and radiogenic Sr isotopic compositions. Unradiogenic Nd and radiogenic Sr and Pb isotopic compositions characterize Province B, in central Sonora. Provinces A and B are flanked to the east and south by Provinces C, D, and E, which are characterized by more radiogenic Nd and less radiogenic Sr isotopic compositions than observed in Provinces A and B. Rocks from Provinces C, D, and E have similar Sr and Nd isotopic compositions, although the variation observed in rocks from Province E is more restricted than in Provinces C and D. These provinces are unique, however, in their Pb isotopic compositions; rocks from Province C are the least radiogenic whereas those from Province E are the most radiogenic. The identified isotope provinces correlate well with the constraints imposed by the geology of the southwestern United States and northwestern Mexico. The primary factor controlling the geographic distribution of isotope provinces in northwestern Mexico appears to be the age of the crust that the magmas passed through and with which they interacted. Provinces A and B are interpreted to reflect the area underlain by old, early Proterozoic basement in northwestern Sonora; the significance of the difference in Pb isotopic compositions between rocks in Provinces A and B is not clear. We interpret Province C, located in northern Chihuahua and adjacent regions of Texas, to reflect the distribution of mid-Proterozoic crust of the North American craton that has been overprinted by Grenvillian deformation. Province D is located in a belt running from central Chihuahua into southwestern Texas and is interpreted to reflect the distribution of exotic crust that was accreted to the southern margin of the North American craton during Ouachita convergence; this crustal block consists of a Paleozoic arc sequence developed on Proterozoic basement. Lastly, we interpret Province E, located in southern Sonora and Chihuahua, as exotic Jurassic-Cretaceous arc crust accreted during the late Mesozoic. The observed distribution of isotope provinces in northwestern Mexico is not consistent with the Mojave-Sonora megashear hypothesis. In particular, the NNE-trending eastern boundary of the two western isotope provinces (Provinces A and B) does not show the 700-800 km of left-lateral offset that would be expected if this boundary was intersected by the Mojave-Sonora megashear." LA English FE "References: 110; illus. incl. 1 table, sketch maps" PY 2005 PT Serial; Analytic CP United States (USA) LL "Latitude:N263000,N323000 Longitude:W1083000,W1150500; Latitude:N254500,N320000 Longitude:W1030000,W1080000" CL 16 Structural geology; 02D Isotope geochemistry CY "GeoRef, Copyright 2006, American Geological Institute." UD 200604 DO 10.1130/2005.2393(25) AN 2006-010959 JV 393 JP 671-692 Sample Data Item Age Age Age Age Age Age Age Age Age Age Age Age Age Age LongDD LatDD Loc_prec Nd143_Nd144 Sr87_Sr86 Nd143_Nd144 Sr87_Sr86 Pb206_Pb204 Pb207_Pb204 Pb208_Pb204 Pb206_Pb204 Pb207_Pb204 Pb208_Pb204 ROCK_TYPE ROCK_CLASS SAMPLE_COMMENT MATERIAL FORMATION STATE Unit Ma Ma Ma Ma Ma Ma Ma Ma Ma Ma Ma Ma Ma Ma DD DD Method 1 2 3 4 5 6 7 8 9 10 11 12 13 14 18 18 15 15 16 16 16 16 16 17 17 17 Sample Name 3--25--3 32 -108.266 28.2696 0.0001 18.638 15.596 38.607 VOLCANIC ANDESITE AGGLOMERATE MINERAL CHIHUAHUA C1 30 -108.33 28.1932 0.0001 18.664 15.583 38.558 VOLCANIC UNKNOWN LAVA DOME MINERAL CHIHUAHUA C2 30 -108.4076 28.1875 0.0001 18.645 15.583 38.543 VOLCANIC UNKNOWN LAVA DOME MINERAL CHIHUAHUA 11--14--1 32 -108.566 28.4295 0.0001 18.636 15.579 38.506 VOLCANIC ANDESITE AGGLOMERATE MINERAL SONORA MA-1 63 -108.6506 28.3877 0.0001 18.608 15.6 38.615 INTRUSIVE GRANODIORITE MINERAL SONORA 3--21--2 23 -108.8615 28.3551 0.0001 18.728 15.609 38.597 VOLCANIC RHYOLITE LAVA MINERAL SONORA SAD-6 68 -106.381 28.8568 0.0001 18.587 15.591 38.451 VOLCANIC UNKNOWN MINERAL Penas Azules Fm CHIHUAHUA CM-38 53 -106.366 29.041 0.0001 18.462 15.546 38.335 VOLCANIC ANDESITE MINERAL CHIHUAHUA CM-636 37 -106.641 29.5415 0.0001 18.432 15.535 38.426 VOLCANIC DIORITE MINERAL CHIHUAHUA SGD 2 37.9 -106.2342 29.6957 0.0001 18.297 15.522 38.369 VOLCANIC RHYOLITE MINERAL GALLEGO RHYOLITE CHIHUAHUA SGD 5 36.5 -106.1458 29.83 0.0001 18.615 15.557 38.57 VOLCANIC RHYOLITE MINERAL MESTENO RHYOLITE CHIHUAHUA SGC 4 36 -106.2271 29.7047 0.0001 0.512495 0.712171 VOLCANIC RHYOLITE WHOLE ROCK MESTENO RHYOLITE CHIHUAHUA SGC 5 29 -106.2523 29.6567 0.0001 0.512579 0.704553 18.081 15.511 38.01 VOLCANIC ANDESITE BASALTIC ANDESITE WHOLE ROCK MILAGRO BAS. ANDESITE CHIHUAHUA SGD 6 38.5 -106.237 29.84 0.0001 0.512518 0.706981 18.579 15.653 38.848 VOLCANIC ANDESITE WHOLE ROCK AGATE ANDESITE CHIHUAHUA SGD 12 29.4 -106.5722 29.8996 0.0001 0.512531 0.7046 17.677 15.501 37.679 VOLCANIC ANDESITE BASALTIC ANDESITE WHOLE ROCK MILAGRO BAS. ANDESITE CHIHUAHUA CM-44 29.6 -106.461 29.0815 0.0001 18.848 15.614 38.728 VOLCANIC TUFF CRYPTIC TUFF MINERAL CHIHUAHUA MEX-3 45.7 -106.3768 28.8487 0.0001 18.681 15.601 38.56 VOLCANIC TUFF MINERAL QUINTAS TUFF CHIHUAHUA CH97-3 46 -106.3738 28.8595 0.0001 0.512632 0.714163 VOLCANIC TUFF WHOLE ROCK QUINTAS TUFF CHIHUAHUA CH97-5 30 -106.4786 29.0886 0.0001 0.512546 VOLCANIC TUFF CRYPTIC TUFF WHOLE ROCK CHIHUAHUA CH97-6 30 -106.543 29.0707 0.0001 0.512616 0.704624 18.259 15.525 38.209 VOLCANIC ANDESITE BASALTIC ANDESITE WHOLE ROCK CHIHUAHUA CH97-9 30 -106.4592 29.4569 0.0001 0.512531 0.705109 18.16 15.517 38.06 VOLCANIC ANDESITE BASALTIC ANDESITE WHOLE ROCK CHIHUAHUA CH97-11 38.3 -107.1577 29.9202 0.0001 0.512434 VOLCANIC RHYOLITE RHYOLITE LAVA WHOLE ROCK CHIHUAHUA CH97-11d 38.3 -107.1577 29.9202 0.0001 18.287 15.615 38.713 VOLCANIC RHYOLITE RHYOLITE LAVA MINERAL CHIHUAHUA CH97-12 27 -107.675 29.7456 0.0001 0.512513 0.706025 18.456 15.55 38.424 VOLCANIC ANDESITE BASALTIC ANDESITE WHOLE ROCK CHIHUAHUA CH97-13 27.9 -107.7259 29.3315 0.0001 0.512577 0.705376 18.663 15.627 38.715 VOLCANIC ANDESITE BASALTIC ANDESITE WHOLE ROCK CHIHUAHUA CH97-14 27.2 -107.8628 29.2221 0.0001 0.512513 0.706068 18.601 15.564 38.486 VOLCANIC DACITE DACITE DOME WHOLE ROCK CHIHUAHUA CH97-15 30 -108.1284 29.3509 0.0001 0.512658 0.705425 18.674 15.574 38.426 VOLCANIC ANDESITE BASALTIC ANDESITE WHOLE ROCK CHIHUAHUA CH97-16 30 -108.1587 29.5969 0.0001 0.512519 0.709463 18.659 15.605 38.632 VOLCANIC RHYOLITE RHYOLITE LAVA WHOLE ROCK CHIHUAHUA CH97-17 30 -108.1922 29.6527 0.0001 0.512574 0.705669 18.593 15.574 38.504 VOLCANIC ANDESITE WHOLE ROCK CHIHUAHUA CH97-18 27.7 -108.2388 29.19 0.0001 0.512562 0.705668 18.545 15.554 38.414 VOLCANIC ANDESITE BASALTIC ANDESITE WHOLE ROCK CHIHUAHUA CH97-20 29.2 -107.8481 28.8012 0.0001 0.512731 0.704774 18.758 15.591 38.524 VOLCANIC ANDESITE BASALTIC ANDESITE WHOLE ROCK CHIHUAHUA CH97-21 26.2 -107.5898 28.8723 0.0001 0.512557 0.705977 18.75 15.592 38.542 VOLCANIC ANDESITE BASALTIC ANDESITE WHOLE ROCK CHIHUAHUA M21 10.1 -110.76 28.897 0.0001 0.512767 0.704587 18.973 15.643 38.718 VOLCANIC BASALT WHOLE ROCK TRINCHERAS BASALT SONORA M28 10.3 -110.8002 28.2391 0.0001 0.512691 0.70477 18.989 15.669 38.815 VOLCANIC BASALT WHOLE ROCK TRINCHERAS BASALT SONORA M35 22.7 -110.9093 28.2049 0.0001 0.512691 0.703987 18.872 15.633 38.562 VOLCANIC ANDESITE WHOLE ROCK LAESPUELA ANDESITE SONORA M38 12.2 -110.8199 28.0333 0.0001 0.512663 0.705468 18.975 15.626 38.696 VOLCANIC FELSIC FELSIC LAVA WHOLE ROCK VENTANA FELSIC LAVA SONORA M48 11.5 -110.8758 28.129 0.0001 0.512679 0.705543 19.026 15.608 38.646 VOLCANIC FELSIC FELSIC LAVA WHOLE ROCK VENTANA FELSIC LAVA SONORA M51 14.4 -110.832 28.129 0.0001 0.512603 0.705655 18.972 15.64 38.734 INTRUSIVE GRANITE WHOLE ROCK EL POPALOTE GRANITE SONORA M53 12.3 -110.775 28.0973 0.0001 0.51264 0.705604 18.988 15.626 38.682 VOLCANIC FELSIC FELSIC LAVA WHOLE ROCK VENTANA FELSIC LAVA SONORA M56 11.8 -110.8381 28.1362 0.0001 0.512681 0.705774 19.044 15.621 38.695 VOLCANIC FELSIC FELSIC LAVA WHOLE ROCK VENTANA FELSIC LAVA SONORA M58 18.8 -110.829 28.0676 0.0001 0.512633 0.705172 18.971 15.647 38.759 VOLCANIC DACITE WHOLE ROCK MEZQUITE DACITE SONORA M60 15.3 -110.895 28.204 0.0001 0.512576 0.705586 18.977 15.618 38.658 VOLCANIC DACITE WHOLE ROCK MEZQUITE DACITE SONORA M61 8.5 -110.8159 28.0125 0.0001 0.51271 0.704975 18.983 15.655 38.783 VOLCANIC BASALT WHOLE ROCK TRINCHERAS BASALT SONORA C-16 28 -107.9093 29.1192 0.0001 18.82 15.621 38.659 VOLCANIC ANDESITE BASALTIC ANDESITE MINERAL CHIHUAHUA D75A 32 -106.9923 28.2806 0.0001 18.843 15.65 38.716 VOLCANIC RHYOLITE MINERAL CHIHUAHUA I521 31.4 -106.6108 28.3985 0.0001 18.81 15.644 38.7 VOLCANIC RHYOLITE MINERAL BUENAVISTA RHYOLITE CHIHUAHUA Per 42.3 -106.3628 28.4003 0.0001 18.728 15.644 38.626 VOLCANIC INTERMEDIATE INTERMEDIATE LAVA MINERAL PERALES INTERMEDIATE LAVA CHIHUAHUA J369 30.6 -106.8138 28.2723 0.0001 18.769 15.597 38.53 VOLCANIC FELSIC FELSIC LAVA MINERAL CHIHUAHUA W 200 32.6 -106.7098 28.2086 0.0001 18.877 15.714 38.912 VOLCANIC FELSIC FELSIC LAVA MINERAL CHIHUAHUA W 300 35 -106.7964 28.2075 0.0001 18.367 15.571 38.24 VOLCANIC INTERMEDIATE INTERMEDIATE LAVA MINERAL CHIHUAHUA DZ 31 29.8 -106.5359 28.0907 0.0001 18.891 15.683 38.801 VOLCANIC RHYOLITE RHYOLITE LAVA MINERAL CHIHUAHUA PLM 31 -106.4334 28.3364 0.0001 18.764 15.636 38.648 VOLCANIC ANDESITE TRACHYANDESITE FLOW MINERAL CHIHUAHUA I 532 30 -106.6082 28.4337 0.0001 18.818 15.67 38.772 VOLCANIC ANDESITE MINERAL CHIHUAHUA RND 34.7 -106.0738 28.1889 0.0001 18.544 15.594 38.402 VOLCANIC RHYOLITE RHYOLITE LAVA MINERAL CHIHUAHUA C10 28 -107.1357 28.8216 0.0001 0.512545 0.706335 18.668 15.609 38.601 VOLCANIC MAFIC MAFIC LAVA WHOLE ROCK CHIHUAHUA D70D 28 -107.1653 28.3655 0.0001 0.512541 0.705227 18.73 15.605 38.547 VOLCANIC MAFIC MAFIC LAVA WHOLE ROCK CHIHUAHUA D76A 26 -107.0162 28.4662 0.0001 0.512643 0.70523 18.749 15.597 38.59 VOLCANIC MAFIC MAFIC LAVA WHOLE ROCK CHIHUAHUA D53D 27 -106.8316 28.3632 0.0001 0.512676 0.704678 18.839 15.622 38.61 VOLCANIC MAFIC MAFIC LAVA WHOLE ROCK CHIHUAHUA W176 26 -106.6762 28.2118 0.0001 0.704028 18.785 15.596 38.477 VOLCANIC MAFIC MAFIC LAVA WHOLE ROCK CHIHUAHUA I133 31 -106.5494 28.4596 0.0001 0.512667 0.704239 18.565 15.58 38.388 VOLCANIC MAFIC MAFIC LAVA WHOLE ROCK CHIHUAHUA PC-1 32 -106.3909 28.2908 0.0001 0.705816 18.868 15.631 38.649 VOLCANIC MAFIC MAFIC LAVA WHOLE ROCK CHIHUAHUA ECD 30.5 -106.1497 28.423 0.0001 0.512524 0.705256 18.316 15.545 38.23 VOLCANIC MAFIC MAFIC LAVA WHOLE ROCK CHIHUAHUA 4RSRB 31.5 -106.1328 28.5639 0.0001 0.512551 0.705236 18.618 15.585 38.513 VOLCANIC MAFIC MAFIC LAVA WHOLE ROCK CHIHUAHUA SO 106 28.7 -109.9217 28.4317 0.0001 18.814 15.631 38.676 VOLCANIC DACITE DACITE DOME MINERAL SONORA SO 35 62 -109.5349 28.3433 0.0001 18.891 15.655 38.783 INTRUSIVE GRANODIORITE/TONALITE MINERAL SONORA SO 15 53 -109.1073 28.4715 0.0001 18.872 15.621 38.65 INTRUSIVE GRANODIORITE MINERAL SONORA SO 2 65 -109.9065 28.6166 0.0001 0.512315 0.707885 19.616 15.693 39.303 INTRUSIVE GRANODIORITE WHOLE ROCK SONORA SO 7 66 -110.0998 28.6207 0.0001 0.51231 0.70804 19.456 15.66 39.15 INTRUSIVE UNKNOWN WHOLE ROCK SONORA SO 8 55 -110.408 28.7416 0.0001 0.51211 0.712823 19.481 15.733 39.151 INTRUSIVE GRANITE WHOLE ROCK SONORA SO 26 60 -110.8639 28.6841 0.0001 0.707435 19.272 15.69 39.007 INTRUSIVE GRANODIORITE WHOLE ROCK SONORA SO 64 63 -110.0681 28.3877 0.0001 0.707357 19.093 15.709 38.994 INTRUSIVE GRANODIORITE WHOLE ROCK SONORA SO 3 67 -109.7307 28.6034 0.0001 0.512217 0.707232 19.069 15.678 38.826 INTRUSIVE GRANODIORITE WHOLE ROCK SONORA SO 5 59 -109.6526 28.5593 0.0001 0.512411 0.706299 18.848 15.645 38.728 INTRUSIVE GRANODIORITE WHOLE ROCK SONORA SO 14 14.4 -109.27 28.4512 0.0001 0.512404 0.706319 18.927 15.634 38.707 VOLCANIC MAFIC MAFIC LAVA WHOLE ROCK SONORA SO 25 81 -111.1261 27.9774 0.0001 0.512434 0.706288 19.054 15.673 38.893 INTRUSIVE GRANODIORITE WHOLE ROCK SONORA SO 28 23.5 -110.8639 28.6841 0.0001 0.512443 0.705707 18.874 15.635 38.645 VOLCANIC MAFIC MAFIC LAVA WHOLE ROCK SONORA SO 40 17.1 -109.2648 28.3311 0.0001 0.512571 0.705629 18.928 15.641 38.708 VOLCANIC BASALT WHOLE ROCK SONORA SO 41 27.7 -109.3155 28.2225 0.0001 0.512548 0.705538 18.852 15.629 38.646 VOLCANIC BASALT WHOLE ROCK SONORA SO 48 27.5 -109.5329 28.4172 0.0001 0.512598 0.704636 18.593 15.585 38.464 VOLCANIC BASALT WHOLE ROCK SONORA SO 60 8.9 -110.4221 28.4257 0.0001 0.512918 0.703618 18.864 15.609 38.481 VOLCANIC BASALT WHOLE ROCK SONORA SO 63 45 -110.3559 28.3857 0.0001 0.512301 19.115 15.659 38.794 INTRUSIVE GRANITE BASALTIC ANDESITE WHOLE ROCK SONORA CH98-2d 38 -106.774 30.0044 0.0001 18.179 15.616 38.508 VOLCANIC RHYOLITE MINERAL CHIHUAHUA CH98-3 26.2 -107.582 30.0271 0.0001 0.512521 0.70599 18.613 15.58 38.567 VOLCANIC ANDESITE WHOLE ROCK CHIHUAHUA CH98-5d 30.9 -108.1254 30.1824 0.0001 18.444 15.561 38.518 VOLCANIC RHYOLITE BASALTIC ANDESITE MINERAL CHIHUAHUA CH98-5 30.9 -108.1254 30.1824 0.0001 0.512532 VOLCANIC RHYOLITE WHOLE ROCK CHIHUAHUA CH98-6 30 -108.1994 30.1353 0.0001 0.512388 0.705598 17.761 15.493 37.954 VOLCANIC ANDESITE WHOLE ROCK CHIHUAHUA CH98-7d 26.5 -108.1462 30.9639 0.0001 18.856 15.592 38.712 VOLCANIC RHYOLITE BASALTIC ANDESITE MINERAL CHIHUAHUA CH98-7 26.5 -108.1462 30.9639 0.0001 0.512372 VOLCANIC RHYOLITE BASALTIC ANDESITE WHOLE ROCK CHIHUAHUA CH98-8 25.8 -108.1245 30.9895 0.0001 0.512355 0.707635 17.796 15.498 38.18 VOLCANIC ANDESITE WHOLE ROCK CHIHUAHUA CH98-10 29.4 -109.609 30.6388 0.0001 0.705512 18.521 15.553 38.397 VOLCANIC ANDESITE WHOLE ROCK SONORA CH98-11d 56.9 -109.6954 30.2599 0.0001 18.601 15.585 38.546 INTRUSIVE GRANODIORITE MINERAL SONORA CH98-11 56.9 -109.6954 30.2599 0.0001 0.707377 INTRUSIVE GRANODIORITE WHOLE ROCK SONORA CH98-17d 63.6 -109.426 29.8806 0.0001 18.82 15.648 38.702 INTRUSIVE GRANODIORITE MINERAL SONORA CH98-17 63.6 -109.426 29.8806 0.0001 0.512406 0.707557 INTRUSIVE GRANODIORITE WHOLE ROCK SONORA Method Data 1 UNK 1981-018881 2 UNK 1978-029320 3 K-AR 1994-005955 4 K-AR 1982-036712 5 PER_COM 2006-010959 McDowell and Housh 6 K-AR 2001-040164 7 AR-AR 1998-057410 8 UNK 1984-040796 9 K-AR 1985-041838 10 UNK 1985-018618 Age is midpoint of range given in report (21-31Ma) 11 K-AR 1987-061304 12 K-AR 1997-072240 13 PER_COM 2006-010959 McDowell and Roldan-Quintana 14 REG_COR 1982-036712 15 PER_COM 2006-010959 Data from Gabriela Mora-Klepeis 16 MS:WR 472 17 MS:FSP 472 18 TABLE 2006-010959 Normalization Data Item Sr87_Sr86 Method Number 16 Standard Name NIST SRM 987 Value 0.710266 References Data 1981-018881 Method reference 1 MT "Reconnaissance geology of the Yecora-Ocampo area, Sonora and Chihuahua, Mexico" AU "Bockoven, Neil Thomas" LA English PY 1980 PT Thesis or dissertation; Doctoral; Monographic ON "University of Texas at Austin, Austin, TX, United States (USA)" CP United States (USA) LL "Latitude:N270000,N290000 Longitude:W1080000,W1090000" DE areal geology; basin range structure; calderas; Chihuahua Mexico; faults; igneous rocks; metal ores; Mexico; Ocampo; Sierra Madre Occidental; Sonora Mexico; volcanic features; volcanic rocks; Yecora CL "13, Areal geology" AV "University Microfilms, Ann Arbor, MI, United States (USA)" CY "GeoRef, Copyright 2006, American Geological Institute." UD 1981 AN 1981-018881 References Data 1978-029320 Method reference 2 MT "Reconnaissance geology of the Tomochic-Ocampo area, Sierra Madre Occidental, Chihuahua, Mexico" AU "Swanson, Eric Rice" LA English PY 1977 PT Thesis or dissertation; Doctoral; Monographic ON "University of Texas at Austin, Austin, TX, United States (USA)" CP United States (USA) LL "Latitude:N253000,N300000 Longitude:W1060000,W1090000" DE absolute age; age; calderas; cartography; Cenozoic; Chihuahua Mexico; data; dates; distribution; geomorphology; geophysical surveys; igneous rocks; K/Ar; lava; Mexico; Ocampo; Oligocene; Paleogene; petrology; plate tectonics; remote sensing; Sierra Madre Occidental; subduction; surveys; Tertiary; Tomochic; volcanic features; volcanic rocks; volcanism; volcanology CL "05A, Igneous and metamorphic petrology" AV "University Microfilms, Ann Arbor, MI, United States (USA)" CY "GeoRef, Copyright 2006, American Geological Institute." UD 1978 AN 1978-029320 References Data 1994-005955 Method reference 3 TI "K-Ar and U-Pb zircon chronology of Late Cretaceous and Tertiary magmatism in central Chihuahua State, Mexico; with Suppl. Data 9403" AU "McDowell, Fred W; Mauger, Richard L" AF "University of Texas at Austin, Department of Geological Sciences, Austin, TX, United States (USA)" AF "East Carolina University, Department of Geology, Greenville, NC, United States (USA)" SO "Geological Society of America Bulletin, vol.106, no.1, pp.118-132, Jan 1994" RL [URL:http://www.gsajournals.org/] IS 0016-7606 CD BUGMAF DE absolute age; Cenozoic; Chihuahua Mexico; Cretaceous; dates; histograms; igneous activity; igneous rocks; K/Ar; magmas; Mesozoic; Mexico; nesosilicates; orthosilicates; plutonic rocks; silicates; statistical analysis; Tertiary; U/Pb; Upper Cretaceous; volcanic rocks; zircon; zircon group AB "Magmatism in central Chihuahua occurred from at least 68 to 27.5 Ma, a duration that can be separated into two periods by an order of magnitude increase in the intensity of magmatism starting at 46 Ma. Activity prior to 46 Ma was volumetrically minor and possibly intermittent. The oldest rocks (68 Ma) are a localized, very thick, intermediate-composition sequence of lava flows, debris flows, and related sediments. From 62 until at least 52 Ma, numerous small intrusives and felsic tuffs were emplaced locally. Between 46 and 27.5 Ma, the area was inundated with a quasi-steady supply of volcanic products. The post-46 Ma activity evolved through four distinct stages that produced two sequences of felsic ash-flow tuffs separated by a sequence of massive coarsely porphyritic lavas and tuffs of intermediate to felsic composition. These three calc-alkaline stages were gradually succeeded at about 31 Ma by mildly alkaline basaltic andesite lavas and rhyolitic tuffs with peralkaline characteristics. All volcanic activity terminated abruptly at 27.5 Ma. The most significant events in the evolution of this magmatism are its onset, its termination, and the profound increase in activity beginning at 46 Ma. In its timing and subdued intensity, the pre-46 Ma magmatism fits a setting within the interior of the Laramide Cordilleran orogen. A convergent magmatic arc had advanced eastward to central Chihuahua by at least 68 Ma. The oldest rocks are tilted, but volcanic rocks 46 Ma and younger were not deformed. The abrupt increase in magmatism at 46 Ma may be a manifestation of diminished compressional stress related to a decrease in the rate of plate convergence along western North America. The regional stress field remained in compression until about 31 Ma, which corresponds approximately to the time of transition from calc-alkaline to mildly alkaline mafic and peralkaline felsic volcanism. Magmatism ended at 27.5 Ma, prior to extensional faulting in the area, but generally coincident with the end of plate convergence along part of the continental margin of western Mexico." LA English FE "References: 64; illus. incl. strat. cols., 2 tables, sketch maps" PY 1994 PT Serial; Analytic CP United States (USA) LL "Latitude:N280000,N300000 Longitude:W1060000,W1070000" CL 03 Geochronology; 05A Igneous and metamorphic petrology CY "GeoRef, Copyright 2006, American Geological Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States" UD 199403 DO 10.1130/0016-7606(1994)106<0118:KAAUPZ>2.3.CO;2 AN 1994-005955 References Data 1982-036712 Method reference 4 TI "Tertiary volcanic history of the Sierra del Gallego area, Chihuahua, Mexico" AU "Keller, Peter C; Bockoven, Neil T; McDowell, Fred W" AF "Univ. Tex. at Austin, Dep. Geol. Sci., Austin, TX, United States (USA)" SO "Geological Society of America Bulletin, vol.93, no.4, pp.303-314, Apr 1982" RL [URL:http://www.gsajournals.org/] IS 0016-7606 CD BUGMAF LA English FE "References: 30; illus. incl. 10 anal., 2 tables, sects., geol. sketch map" PY 1982 PT Serial; Analytic CP United States (USA) LL "Latitude:N293000,N301000 Longitude:W1054500,W1064500" DE absolute age; alkalic composition; andesites; ash-flow tuff; basalts; calc-alkalic composition; Cenozoic; Chihuahua Mexico; dates; evolution; feldspar group; framework silicates; geochemistry; igneous rocks; K/Ar; lava; major elements; Mexico; Paleogene; petrology; pyroclastics; rhyolites; Sierra del Gallego; Sierra Madre Occidental; silicates; Tertiary; volcanic rocks; volcanism; volcanology; whole rock CL "05A, Igneous and metamorphic petrology" CY "GeoRef, Copyright 2006, American Geological Institute." UD 1982 AN 1982-036712 References Data 2001-040164 Method reference 6 TI "Miocene volcanism during late subduction and early rifting in the Sierra Santa Ursula of western Sonora, Mexico" AU "Mora-Alvarez, Gabriela; McDowell, Fred W" AF "University of Texas at Austin, Department of Geological Sciences, Austin, TX, United States (USA)" AF "California Institute of Technology, United States (USA)" MT Cenozoic tectonics and volcanism of Mexico ED "Delgado-Granados, Hugo; Aguirre-Diaz, Gerardo J; Stock, Joann M" AF "Universidad Nacional Autonoma de Mexico, Instituto do Geofisica, Coyoacan, Mexico (MEX)" CF "Union Geofisica Mexicana symposium on Cenozoic tectonics and volcanism of Mexico, Puerto Vallarta, Mexico, 1994" SO "Special Paper - Geological Society of America, vol.334, pp.123-141, 2000" IS 0072-1077 CD GSAPAZ IB 1813723345 DE absolute age; calc-alkalic composition; Cenozoic; correlation; dates; geochemistry; igneous rocks; ignimbrite; K/Ar; lava; magmatism; major elements; Mexico; Miocene; Neogene; plate tectonics; pyroclastics; rifting; Sierra Santa Ursula; Sonora Mexico; subduction; Tertiary; tuff; volcanic rocks; volcanism AB "The emplacement of volcanic rocks between 23.5 and 8.5 Ma within the Sierra Santa Ursula and surrounding areas of west-central Sonora, Mexico, coincided with the development of two distinct tectonic settings. Arc magmatism produced medium to high-K calc-alkaline lava flows, lava domes, tuffs, and ignimbrites of intermediate to felsic compositions between 23.5 and 11.4 Ma. During part of this interval, subduction was still active to the west of the present-day Baja California peninsula. The arc-related rocks now form a moderately dipping (10 degrees -35 degrees E) structurally concordant section. Above these rocks and an angular unconformity, the volcanic section younger than 11.4 Ma dips less steeply than the older rocks below. The dips of the younger rocks progressively decrease toward the top of the section, where the upper part of a sequence of felsic ignimbrites is intercalated with subhorizontal (less than 5 degrees W), 10.3 to 8.5 Ma mafic lava flows of tholeiitic composition. The tholeiitic rocks were emplaced during the early stages of rifting that eventually led to opening of the Gulf of California. We interpret these two episodes of magmatic activity to reflect a change in tectonic setting from subduction to rifting along the adjacent western edge of North America. An increase of dacitic and rhyolitic eruptions from 15.3 to 12.3 Ma may signal a change from compressional to tensional stresses in the region. The history of Neogene volcanism in the Sierra Santa Ursula vicinity and our interpretation of its tectonic setting are similar to those given previously for areas of the southern Baja California peninsula and the coast of central Sonora, all of which place initial rifting between 15 and 11 Ma. In northern Baja California evidence for the time of initial crustal extension is between 11 and 6 Ma. Extension in interior Sonora includes the development of metamorphic core complexes from 25 to 18 Ma and linear, fault-bounded basins that accumulated continental clastic deposits from 27 to 12 Ma. On the basis of our data and regional correlations, we show that the Neogene geologic history of coastal Sonora more closely resembles that of Baja California than that of the Basin and Range province of interior Sonora." LA English NT Includes appendix FE "References: 43; illus. incl. 2 tables, geol. sketch map" PY 2000 PT Serial; Conference document; Analytic CP United States (USA) LL "Latitude:N280000,N282000 Longitude:W1104000,W1110000" CL 05A Igneous and metamorphic petrology; 03 Geochronology CY "GeoRef, Copyright 2006, American Geological Institute." UD 200112 AN 2001-040164 References Data 1998-057410 Method reference 7 TI Late Miocene felsic volcanism in west-central Sonora; an expression of rift or subduction-related magmatism? AU "Mora Klepeis, Gabriela; McDowell, Fred W; Ortega Rivera, Amabel" AF "CSIRO Minerals Research Laboratories, Center for Isotope Studies, North Ryde, N.S.W., Australia (AUS)" AF "University of Texas at Austin, United States (USA); Queen's University, Canada (CAN)" MT "Geological Society of America, 1997 annual meeting" AU Anonymous CF "Geological Society of America, 1997 annual meeting, Salt Lake City, UT, United States, Oct. 20-23, 1997" SO "Abstracts with Programs - Geological Society of America, vol.29, no.6, pp.481, 1997" IS 0016-7592 CD GAAPBC DE absolute age; Ar/Ar; Baja California; calc-alkalic composition; Cenozoic; dates; East Pacific; emplacement; felsic composition; granites; Gulf of California; igneous rocks; lava flows; magmatism; metals; Mexico; Miocene; Neogene; North Pacific; Northeast Pacific; Pacific Ocean; plate convergence; plate tectonics; plutonic rocks; rare earths; Sonora Mexico; subduction; tectonics; Tertiary; upper Miocene; volcanic rocks; volcanism AB "Emplacement of Neogene volcanic and plutonic rocks in west-central Sonora coincided with the development of two distinct tectonic settings in NW Mexico. Between 23.5 and 11.4 Ma arc magmatism produced medium to high-K calcalkaline lava flows and tuffs of intermediate to felsic compositions. Mafic lava flows of tholeiitic composition were emplaced between 10.3 to 8.5 Ma during the early stages of rifting that led to the opening of the Gulf of California. Changes in the composition of volcanic rocks around the Gulf of California record the transition from a convergent arc system to a rift system. However, a compositional break within the arc section signaling an end to subduction-related magmatism in west-central Sonora has not been recognized previously. An (super 40) Ar/ (super 39) Ar age obtained from a felsic subvolcanic granitoid within the volcanic section suggests that a compositional shift in volcanism with an increase in the proportion of felsic compositions initiated at 14.4 Ma. Dacitic rocks of 11.4 Ma contain large amounts of incompatible elements and pronounced negative anomalies in Ce-Sr. K (sub 2) O content and incompatible elements of the mafic lava flows are less concentrated than those of older rocks, reflecting their tholeiitic nature. Both suites of rocks display similar REE patterns characterized by enrichment of LREE over HREE. We interpret the differences between these two episodes of magmatic activity as reflecting a change in tectonic setting from subduction to rifting along the western edge of North America. On the basis of our data and regional correlations we suggest that arc volcanism persisted in west-central Sonora until 11.4 Ma. Mafic lava flows were emplaced when rifting was already established in the Gulf of California. This tectonic history is most similar to that of central Baja California than that of interior Sonora." LA English PY 1997 PT Serial; Conference document; Analytic; Abstract only CP United States (USA) CL "05A, Igneous and metamorphic petrology" CY "GeoRef, Copyright 2006, American Geological Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States" UD 199821 AN 1998-057410 References Data 1984-040796 Method reference 8 MT "Geology, geochemistry, and geochronology of volcanic rocks between Cuauhtemoc and La Junta, central Chihuahua, Mexico" AU "Duex, Timothy William" LA English PY 1983 PT Thesis or dissertation; Doctoral; Monographic ON "University of Texas at Austin, Austin, TX, United States (USA)" CP United States (USA) DE alkaline earth metals; ash flows; Basin and Range Province; block structures; carbonate rocks; central Chihuahua; clastic rocks; Cretaceous; crust; dacites; differentiation; fractional crystallization; genesis; geochronology; igneous rocks; isotopes; limestone; Lower Cretaceous; mafic composition; magmas; Mesozoic; metals; Mexico; North America; petrology; pyroclastics; Rb/Sr; rhyolites; sedimentary rocks; shale; Sierra Madre Occidental; Sr-87/Sr-86; stable isotopes; stratigraphic boundary; strontium; tuff; volcanic rocks CL "05A, Igneous and metamorphic petrology" AV University Microfilms CY "GeoRef, Copyright 2006, American Geological Institute." UD 1984 AN 1984-040796 References Data 1985-041838 Method reference 9 TI "Geology and geochronology of volcanic rocks of the Sierra Pastorias area, Chihuahua, Mexico" AU "Megaw, Peter K M; McDowell, Fred W" AF "Univ. Tex. at Austin, Dep. Geol. Sci., Austin, TX, United States (USA)" MT Geology and mineral resources of north-central Chihuahua ED "Clark, Kenneth F; Goodell, Philip C" AF "Univ. Tex. at El Paso, Dep. Geol. Sci., El Paso, TX, United States (USA)" CF "1983 field conference, El Paso Geological Society ; Geology and mineral resources of north-central Chihuahua, Oct. 7-9, 1983" PB "El Paso Geol. Soc., El Paso, TX, United States (USA)" LA English FE "References: 11; illus. incl. 2 tables, strat. col." PY 1983 PT Book; Conference document; Analytic CP United States (USA) DE absolute age; calc-alkalic composition; calderas; Cenozoic; Chihuahua Mexico; dates; geochronology; geomorphology; igneous rocks; K/Ar; major elements; Mexico; Oligocene; Paleogene; petrology; pyroclastics; rhyolites; Sierra Madre Occidental; Sierra Pastorias; Tertiary; tuff; volcanic features; volcanic rocks CL 05A Igneous and metamorphic petrology; 03 Geochronology CY "GeoRef, Copyright 2006, American Geological Institute." UD 1985 AN 1985-041838 References Data 1985-018618 Method reference 10 MT "Geology of the mid-Tertiary volcanic terrane at Buenos Aires, Chihuahua, Mexico" AU "Wark, David Austin" LA English FE References: 89; 19 plates PY 1983 PT Thesis or dissertation; Master's; Monographic ON "University of Texas at Austin, Austin, TX, United States (USA)" CP United States (USA) DE bimodal composition; block structures; Buenos Aires; calc-alkalic composition; Cenozoic; Chihuahua Mexico; Ciudad Cuauthtemoc; composition; dikes; displacements; faults; high-angle faults; igneous processes; igneous rocks; intrusions; magma chambers; magmas; Mexico; Paleogene; petrology; stocks; Tertiary; volcanic rocks CL "13, Areal geology" CY "GeoRef, Copyright 2006, American Geological Institute." UD 1985 AN 1985-018618 References Data 1987-061304 Method reference 11 MT "Geology of mid-Tertiary volcanic rocks in the Laboricita-General Trias area, central Chihuahua, Mexico" AU "Ide, Susan" LA English FE References: 63; 28 plates PY 1986 PT Thesis or dissertation; Master's; Monographic ON "University of Texas at Austin, Austin, TX, United States (USA)" CP United States (USA) DE Abajo Tuff; absolute age; Aguaje Granodiorite; calc-alkalic composition; Cenozoic; Chihuahua Mexico; composition; compression; dates; eruptions; extension; faults; Frijol Tuff; General Trias; geochronology; igneous rocks; intrusions; K/Ar; Laboricita; Laboricita Andesite; lava; Mexico; Ojo Blanco Andesite; Oligocene; Paleogene; Subia Fanglomerate; Tertiary; Trias Trachyandesite; unconformities; volcanic rocks CL 03 Geochronology; 05A Igneous and metamorphic petrology CY "GeoRef, Copyright 2006, American Geological Institute." UD 1987 AN 1987-061304 References Data 1997-072240 Method reference 12 TI "Interrelationship of sedimentary and volcanic deposits associated with Tertiary extension in Sonora, Mexico" AU "McDowell, Fred W; Roldan Quintana, Jaime; Amaya Martinez, Ricardo" AF "University of Texas at Austin, Department of Geological Sciences, Austin, TX, United States (USA)" AF "Universidad Nacional Autonoma de Mexico, Hermosillo, Mexico (MEX);Universidad de Sonora, Hermosillo, Mexico (MEX)" SO "Geological Society of America Bulletin, vol.109, no.10, pp.1349-1360, Oct 1997" RL [URL:http://www.gsajournals.org/] IS 0016-7606 CD BUGMAF DE absolute age; basins; Cenozoic; clastic rocks; conglomerate; dates; extension faults; extension tectonics; faults; geochemistry; grabens; half grabens; igneous rocks; K/Ar; lava; major elements; Mexico; Neogene; plate convergence; sandstone; sedimentary basins; sedimentary rocks; Sonora Mexico; structural controls; systems; tectonics; Tertiary; volcanic rocks AB "Clastic sedimentary deposits and associated volcanic rocks record the progress of Tertiary extension in the Mexican state of Sonora. These deposits accumulated within basins located throughout the eastern two-thirds of the state. The rocks are slightly indurated conglomerates and sandstones; clast types reflect the local highland exposures. Volcanic units that bound and are interlayered with the sedimentary rocks provide stratigraphic and time markers of basin evolution and, by inference, of marginal fault development. This record has been examined in an east-west belt across south-central Sonora. The volcanic rocks occur in three distinct associations. At the base and interbedded within the lower portions of the sedimentary sections are lava flows of dominantly basaltic andesite composition. In most localities the overlying clastic sedimentary strata are conformable with these lava flows, and we conclude that the magmatism was triggered by early faulting along the basin margins. A second association present near the base of the sections comprises massive lava domes and flows of intermediate composition that contain distinctive phenocrysts of dark brown amphibole. The domes apparently formed when viscous lava welled up along developing marginal basin faults. In one case a transition was observed over a short distance from a structureless dome to a thick lava flow that is conformably interbedded with, and sheds clasts laterally into, the sedimentary section. A third volcanic association comprises layers of rhyolitic lava flows and ignimbrites that overlie the coarsest and thickest lower portions of the sedimentary sections. K-Ar ages for volcanic rocks in the two oldest of these settings indicate that each Tertiary basin had a distinct history with no apparent regional geographic pattern. In the Rio Yaqui basin, where exhumation by the major river of Sonora has exposed a full section of the volcanic and clastic sequences, extension was possibly as old as 27 Ma. Elsewhere, deposition of sediments was underway in most basins by 24 Ma, and in all basins by 20 Ma. K-Ar ages of the younger rhyolitic volcanic rocks fall within a narrow range from 12.8 to 10.5 Ma. These ages provide a younger time limit to deposition of the coarser and thicker portions of the clastic sedimentary sections. The mafic lava flows, dominantly basaltic andesite, are similar in major-element composition to mafic lava flows that cap felsic sections within the Sierra Madre Occidental volcanic field of western Mexico and the mid-Tertiary Datil-Mogollon volcanic field in southwestern New Mexico. They are higher in silica and lower in total alkalies than younger capping mafic lava flows within the Gulf of California extensional province of western Sonora and Neogene basaltic lava flows in the Datil-Mogollon field. They are similarly distinct from basaltic dikes and lava flows that are clearly associated with Basin and Range faulting in Trans-Pecos Texas and in northern Durango state. A convergent-margin magmatic arc was active in the present-day Gulf of California region between 24 and 11.5 Ma. The earliest extension in south-central Sonora was therefore occurring in a back-arc setting. Continued sedimentation and rotation of volcanic strata indicate that extension continued throughout the region after 10 Ma with little coeval volcanism." LA English FE "References: 41; illus. incl. strat. cols., 2 tables, geol. sketch map" PY 1997 PT Serial; Analytic CP United States (USA) LL "Latitude:N280000,N284500 Longitude:W1090000,W1110000" CL 16 Structural geology; 05A Igneous and metamorphic petrology; 03 Geochronology CY "GeoRef, Copyright 2006, American Geological Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States" UD 199724 DO 10.1130/0016-7606(1997)109<1349:IOSAVD>2.3.CO;2 AN 1997-072240 References Data 1982-036712 Method reference 14 TI "Tertiary volcanic history of the Sierra del Gallego area, Chihuahua, Mexico" AU "Keller, Peter C; Bockoven, Neil T; McDowell, Fred W" AF "Univ. Tex. at Austin, Dep. Geol. Sci., Austin, TX, United States (USA)" SO "Geological Society of America Bulletin, vol.93, no.4, pp.303-314, Apr 1982" RL [URL:http://www.gsajournals.org/] IS 0016-7606 CD BUGMAF LA English FE "References: 30; illus. incl. 10 anal., 2 tables, sects., geol. sketch map" PY 1982 PT Serial; Analytic CP United States (USA) LL "Latitude:N293000,N301000 Longitude:W1054500,W1064500" DE absolute age; alkalic composition; andesites; ash-flow tuff; basalts; calc-alkalic composition; Cenozoic; Chihuahua Mexico; dates; evolution; feldspar group; framework silicates; geochemistry; igneous rocks; K/Ar; lava; major elements; Mexico; Paleogene; petrology; pyroclastics; rhyolites; Sierra del Gallego; Sierra Madre Occidental; silicates; Tertiary; volcanic rocks; volcanism; volcanology; whole rock CL "05A, Igneous and metamorphic petrology" CY "GeoRef, Copyright 2006, American Geological Institute." UD 1982 AN 1982-036712