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Journal articles on the topic 'Mid-Proterozoic'

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Published: 10 December 2022

Last updated: 30 January 2023

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1

Hurley, Sarah J., Boswell A. Wing, Claire E. Jasper, Nicholas C. Hill, and Jeffrey C. Cameron. "Carbon isotope evidence for the global physiology of Proterozoic cyanobacteria." Science Advances 7, no. 2 (January 2021): eabc8998. http://dx.doi.org/10.1126/sciadv.abc8998.

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Ancestral cyanobacteria are assumed to be prominent primary producers after the Great Oxidation Event [≈2.4 to 2.0 billion years (Ga) ago], but carbon isotope fractionation by extant marine cyanobacteria (α-cyanobacteria) is inconsistent with isotopic records of carbon fixation by primary producers in the mid-Proterozoic eon (1.8 to 1.0 Ga ago). To resolve this disagreement, we quantified carbon isotope fractionation by a wild-type planktic β-cyanobacterium (Synechococcus sp. PCC 7002), an engineered Proterozoic analog lacking a CO2-concentrating mechanism, and cyanobacterial mats. At mid-Proterozoic pH and pCO2 values, carbon isotope fractionation by the wild-type β-cyanobacterium is fully consistent with the Proterozoic carbon isotope record, suggesting that cyanobacteria with CO2-concentrating mechanisms were apparently the major primary producers in the pelagic Proterozoic ocean, despite atmospheric CO2 levels up to 100 times modern. The selectively permeable microcompartments central to cyanobacterial CO2-concentrating mechanisms (“carboxysomes”) likely emerged to shield rubisco from O2 during the Great Oxidation Event.

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2

Slotznick, Sarah P., Samuel M. Webb, Joseph L. Kirschvink, and Woodward W. Fischer. "Mid‐Proterozoic Ferruginous Conditions Reflect Postdepositional Processes." Geophysical Research Letters 46, no. 6 (March 18, 2019): 3114–23. http://dx.doi.org/10.1029/2018gl081496.

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3

Derry, Louis A. "Causes and consequences of mid-Proterozoic anoxia." Geophysical Research Letters 42, no. 20 (October 24, 2015): 8538–46. http://dx.doi.org/10.1002/2015gl065333.

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4

Rast, N. "Mid-Proterozoic Supercontinent Rodinia: Its Basis and Extent." Gondwana Research 5, no. 1 (January 2002): 205. http://dx.doi.org/10.1016/s1342-937x(05)70903-5.

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5

Olson, Stephanie L., Christopher T. Reinhard, and Timothy W. Lyons. "Limited role for methane in the mid-Proterozoic greenhouse." Proceedings of the National Academy of Sciences 113, no. 41 (September 26, 2016): 11447–52. http://dx.doi.org/10.1073/pnas.1608549113.

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Pervasive anoxia in the subsurface ocean during the Proterozoic may have allowed large fluxes of biogenic CH4to the atmosphere, enhancing the climatic significance of CH4early in Earth’s history. Indeed, the assumption of elevatedpCH4during the Proterozoic underlies most models for both anomalous climatic stasis during the mid-Proterozoic and extreme climate perturbation during the Neoproterozoic; however, the geologic record cannot directly constrain atmospheric CH4levels and attendant radiative forcing. Here, we revisit the role of CH4in Earth’s climate system during Proterozoic time. We use an Earth system model to quantify CH4fluxes from the marine biosphere and to examine the capacity of biogenic CH4to compensate for the faint young Sun during the “boring billion” years before the emergence of metazoan life. Our calculations demonstrate that anaerobic oxidation of CH4coupled to SO42−reduction is a highly effective obstacle to CH4accumulation in the atmosphere, possibly limiting atmosphericpCH4to less than 10 ppm by volume for the second half of Earth history regardless of atmosphericpO2. If recentpO2constraints from Cr isotopes are correct, we predict that reduced UV shielding by O3should further limitpCH4to very low levels similar to those seen today. Thus, our model results likely limit the potential climate warming by CH4for the majority of Earth history—possibly reviving the faint young Sun paradox during Proterozoic time and challenging existing models for the initiation of low-latitude glaciation that depend on the oxidative collapse of a steady-state CH4greenhouse.

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6

Schieber, Jürgen. "Storm-dominated epicontinental clastic sedimentation in the Mid-Proterozoic Newland Formation, Montana, U.S.A." Neues Jahrbuch für Geologie und Paläontologie - Monatshefte 1987, no. 7 (July 1, 1987): 417–39. http://dx.doi.org/10.1127/njgpm/1987/1987/417.

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7

Corrigan, David, Nicholas G. Culshaw, and Jim K. Mortensen. "Pre-Grenvillian evolution and Grenvillian overprinting of the Parautochthonous Belt in Key Harbour, Ontario: U–Pb and field constraints." Canadian Journal of Earth Sciences 31, no. 3 (March 1, 1994): 583–96. http://dx.doi.org/10.1139/e94-051.

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The Parautochthonous Belt in the region of Key Harbour, Ontario, is composed of Early Proterozoic migmatitic para- and orthogneiss and Mid-Proterozoic granitoids, which were reworked during the Grenville orogeny. Grenvillian deformation is localized into anastomosing arrays of high-strain shear zones enclosing elongate bands and lozenges of rock subjected to lower and near-coaxial strain. Crosscutting relationships preserved in the low-strain domains document two pre-Grenvillian plutonic and tectonometamorphic events, which are bracketed in age by U–Pb zircon geochronology. A 1694 Ma leucogranite intrudes, and provides a minimum age for, high metamorphic grade gneisses formed during an earlier tectonometamorphic event (D1–M1). The leucogranite was intruded by mafic dykes, deformed, and metamorphosed at uppermost amphibolite facies during D2–M2, before the emplacement of Mid-Proterozoic granitoids at ca. 1450 Ma. Following the emplacement of gabbro dykes and pods at ca. 1238 Ma, the area was overprinted by granulite to uppermost amphibolite facies metamorphism (Grenvillian), for which monazites provide a minimum age of ca. 1035 Ma. Titanite U–Pb ages of 1003 – 1004 Ma record cooling through 600 °C. A regionally important swarm of east–west-trending posttectonic pegmatite dykes dated by U–Pb zircon at 990 Ma provides a minimum age for Grenvillian ductile deformation. The present data support the contention that the Parautochthonous Belt in the Key Harbour area consists in part of reworked midcontinental crust of Early to Mid-Proterozoic age.

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8

Wang, Haiyang, Chao Li, Meng Cheng, Zihu Zhang, and Thomas J. Algeo. "Redbed formation in the redox-stratified mid-Proterozoic ocean." Precambrian Research 379 (September 2022): 106815. http://dx.doi.org/10.1016/j.precamres.2022.106815.

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9

Gower, Charles F. "Mid-Proterozoic evolution of the eastern Grenville Province, Canada." Geologiska Föreningen i Stockholm Förhandlingar 112, no. 2 (June 1990): 127–39. http://dx.doi.org/10.1080/11035899009453170.

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10

JAVAUX, EMMANUELLE J., ANDREW H. KNOLL, and MALCOLM R. WALTER. "TEM evidence for eukaryotic diversity in mid-Proterozoic oceans." Geobiology 2, no. 3 (July 2004): 121–32. http://dx.doi.org/10.1111/j.1472-4677.2004.00027.x.

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11

Pilot, Joachim, Carl-Dietrich Werner, Frank Haubrich, and Nils Baumann. "Palaeozoic and Proterozoic zircons from the Mid-Atlantic Ridge." Nature 393, no. 6686 (June 1998): 676–79. http://dx.doi.org/10.1038/31452.

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12

Planavsky, Noah J., Peter McGoldrick, Clinton T. Scott, Chao Li, Christopher T. Reinhard, Amy E. Kelly, Xuelei Chu, Andrey Bekker, Gordon D. Love, and Timothy W. Lyons. "Widespread iron-rich conditions in the mid-Proterozoic ocean." Nature 477, no. 7365 (September 2011): 448–51. http://dx.doi.org/10.1038/nature10327.

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13

Tang, Dongjie, Xiaoying Shi, Xinqiang Wang, and Ganqing Jiang. "Extremely low oxygen concentration in mid-Proterozoic shallow seawaters." Precambrian Research 276 (May 2016): 145–57. http://dx.doi.org/10.1016/j.precamres.2016.02.005.

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14

Gower, Charles F. "Mid-Proterozoic evolution of the eastern Grenville Province, Canada." Geologiska Föreningen i Stockholm Förhandlingar 114, no. 3 (September 1992): 343–44. http://dx.doi.org/10.1080/11035899209454802.

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15

Yierpan, Aierken, Stephan König, Jabrane Labidi, and Ronny Schoenberg. "Recycled selenium in hot spot–influenced lavas records ocean-atmosphere oxygenation." Science Advances 6, no. 39 (September 2020): eabb6179. http://dx.doi.org/10.1126/sciadv.abb6179.

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Oxygenation of Earth’s oceans and atmosphere through time has consequences for subducted surface signatures that are now stored in the mantle. Here, we report significant mass-dependent selenium isotope variations in modern hot spot–influenced oceanic lavas. These variations are correlated with tracers of mantle source enrichment, which can only be explained by incorporation of abyssal pelagic sediments subducted from a redox-stratified mid-Proterozoic ocean. Selenium geochemical signatures of these sediments have mostly been preserved during long-term recycling and may therefore complement the global surface sediment record as ancient oxygen archives. Combined deep mantle and surface perspectives, together with emerging models for atmospheric oxygen based on selenium systematics, further imply a significantly oxygenated ocean-atmosphere system throughout the mid-Proterozoic.

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16

Hanmer, Simon, Michael Williams, and Chris Kopf. "Striding-Athabasca mylonite zone: implications for the Archean and Early Proterozoic tectonics of the western Canadian Shield." Canadian Journal of Earth Sciences 32, no. 2 (February 1, 1995): 178–96. http://dx.doi.org/10.1139/e95-015.

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Study of the northern Saskatchewan–District of Mackenzie segment of the Snowbird tectonic zone suggests that fragments of relatively stiff mid-Archean crust, possibly arc related, have controlled the localization, shape, and complex kinematics of the multistage Striding–Athabasca mylonite zone during the Archean, as well as the geometry of the Early Proterozoic rifted margin of the western Churchill continent. By the late Archean, the Striding–Athabasca mylonite zone was located in the interior of the western Churchill continent, well removed from the contemporaneous plate margins. Except for the Alberta segment, the Snowbird tectonic zone was not the site of an Early Proterozoic plate margin. We suggest that the geometry of the Archean–Early Proterozoic boundary in the western Canadian Shield represents a jagged continental margin, composed of a pair of reentrants defined by rifted and transform segments. These segments were inherited from Early Proterozoic breakup and controlled by the Archean structure of the interior of the western Churchill continent. The geometry of this margin appears to have strongly influenced the Early Proterozoic tectono-magmatic evolution of the western Canadian Shield.

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17

Dawes, P. R. "Etah meta-igneous complex and the Wulff structure: Proterozoic magmatism and deformation in Inglefield Land, North-West Greenland." Rapport Grønlands Geologiske Undersøgelse 139 (December 31, 1988): 1–24. http://dx.doi.org/10.34194/rapggu.v139.8021.

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A hitherto uninvestigated collection of crystalline rocks from north-eastem Inglefield Land (c. 79°N) allowanew interpretation of the Precambrian geology of the region. The majority of the samples - high-grade basic, intermediate and granitoid rocks - are referred to the Etah meta-igneous complex, which has been shown to be mid-Proterozoic in age in the type area in south-western Inglefield Land. In areas of high deformation there is a gradation from massive rocks of igneous aspect into folded and variably migmatised gneisses. Thus the magmatic complex provides a gauge of the nature and intensity of Proterozoic (Hudsonian) deformation and metamorphism. In Inglefield Land Proterozoic deformation produced different structural styles; thus in the north-east the Wulff structure - a large-scale refolded isoclinal structure - characterises a region that lacks an obvious preferred regional foliation direction, while in the south-west, linear E-W trending belts with steep dips dominate the structural pattem. The Proterozoic evolution is outlined from the formation of the Etah Group, a supracrustal sequence that pre-dates the Etah meta-igneous complex, to uplift, peneplanation, deposition and magmatism in the late Proterozoic. Inglefield Land is not part of the Rinkian mobile belt of West Greenland, and it is stressed that the obvious continuation of the Proterozoic geology is into Ellesmere Island.

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18

Roberts, Nick M. W., Johanna Salminen, Åke Johansson, Ross N. Mitchell, Richard M. Palin, Kent C. Condie, and Christopher J. Spencer. "On the enigmatic mid-Proterozoic: Single-lid versus plate tectonics." Earth and Planetary Science Letters 594 (September 2022): 117749. http://dx.doi.org/10.1016/j.epsl.2022.117749.

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19

Arnold, G. L. "Molybdenum Isotope Evidence for Widespread Anoxia in Mid-Proterozoic Oceans." Science 304, no. 5667 (April 2, 2004): 87–90. http://dx.doi.org/10.1126/science.1091785.

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20

Upton, B. G. J., and C. H. Emeleus. "Mid-Proterozoic alkaline magmatism in southern Greenland: the Gardar province." Geological Society, London, Special Publications 30, no. 1 (1987): 449–71. http://dx.doi.org/10.1144/gsl.sp.1987.030.01.22.

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21

Crockford, Peter W., Justin A. Hayles, Huiming Bao, Noah J. Planavsky, Andrey Bekker, Philip W. Fralick, Galen P. Halverson, Thi Hao Bui, Yongbo Peng, and Boswell A. Wing. "Triple oxygen isotope evidence for limited mid-Proterozoic primary productivity." Nature 559, no. 7715 (July 2018): 613–16. http://dx.doi.org/10.1038/s41586-018-0349-y.

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22

Parnell, John, and Paula Lindgren. "Anomalous supply of bioessential molybdenum in mid-Proterozoic surface environments." Precambrian Research 275 (April 2016): 100–104. http://dx.doi.org/10.1016/j.precamres.2015.12.016.

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23

Gilleaudeau, Geoffrey J., Stephen J. Romaniello, Genming Luo, Alan J. Kaufman, Feifei Zhang, Robert M. Klaebe, Linda C. Kah, et al. "Uranium isotope evidence for limited euxinia in mid-Proterozoic oceans." Earth and Planetary Science Letters 521 (September 2019): 150–57. http://dx.doi.org/10.1016/j.epsl.2019.06.012.

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24

Lowell, Gary R. "The Butler Hill Caldera: a mid-Proterozoic ignimbrite-granite complex." Precambrian Research 51, no. 1-4 (June 1991): 245–63. http://dx.doi.org/10.1016/0301-9268(91)90103-h.

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25

VAN BREEMEN, O., and A. DAVIDSON. "Northeast extension of Proterozoic terranes of mid-continental North America." Geological Society of America Bulletin 100, no. 5 (May 1988): 630–38. http://dx.doi.org/10.1130/0016-7606(1988)100<0630:neopto>2.3.co;2.

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26

Henriksen, N., J. D. Friderichsen, R. A. Strachan, N. J. Soper, and A. K. Higgins. "Caledonian and pre-Caledonian geology of the region between Grandjean Fjord and Bessel Fjord (75°–76°N), North-East Greenland." Rapport Grønlands Geologiske Undersøgelse 145 (December 31, 1989): 90–97. http://dx.doi.org/10.34194/rapggu.v145.8084.

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The area between Grandjean Fjord and Bessel Fjord was the focus in 1988 of regional geological investigations and 1:500000 mapping during the North-East Greenland project (Henriksen, 1989). The greater part of the area forms part of the East Greenland Caledonides and can be divided into three distinct rock groups: infracrustal gneisses and granites of possibie Archaean or early Proterozoic origin; a metasedimentary sequence which has probably suffered both mid-Proterozoic and Caledonian migmatisation and metamorphism; and the late Proterozoic Eleonore Bay Group, a thick sedimentary sequence which has undergone amphibolite facies Caledonian metamorphism in its lower parts and is intruded by Caledonian granites. Aspects of the stratigraphy and sedimentology of the Eleonore Bay Group are described by Sønderholm et al. (1989); only the structures affecting the sequence are described here.

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27

Ings, S. J., and J. V. Owen. "‘Decompressional’ reaction textures formed by isobaric heating: an example from the thermal aureole of the Taylor Brook Gabbro Complex, western Newfoundland." Mineralogical Magazine 66, no. 6 (December 2002): 941–51. http://dx.doi.org/10.1180/0026461026660069.

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Abstract Reaction textures including corona structures in granulites from the Proterozoic Long Range Inlier of western Newfoundland are spatially associated with a Silurian (0.34 Ga) mafic intrusion, the Taylor Brook Gabbro Complex. They comprise, in metabasites and tonalitic gneiss, coronal orthopyroxene and plagioclase on garnet and, in metapelites, cordierite and spinel formed at the expense of sillimanite, garnet and quartz. Although generally interpreted to indicate near-isothermal decompression (ITD) following regional metamorphism, which in the inlier occurred at ˜1.10–1.03 Ga, these features appear to be absent elsewhere. Therefore they are interpreted to be products of contact metamorphism (near-isobaric heating – IBH) within the thermal aureole of the gabbro. Thus, there is a ˜0.7 Ga difference (i.e. mid-Proterozoic vs. mid-Silurian) between the age of the regional metamorphic mineral assemblages and the contact aureole assemblages. The observation that classic ITD features occur in this aureole environment underscores the fact that P-sensitive reactions can progress during IBH as well as by pressure release.

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28

Whelan, J. F., R. O. Rye, W. F. Delorraine, and H. Ohmoto. "Isotopic geochemistry of the mid-Proterozoic evaporite basin; Balmat, New York." American Journal of Science 290, no. 4 (April 1, 1990): 396–424. http://dx.doi.org/10.2475/ajs.290.4.396.

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29

Diamond, Charles W., and Timothy W. Lyons. "Mid-Proterozoic redox evolution and the possibility of transient oxygenation events." Emerging Topics in Life Sciences 2, no. 2 (July 13, 2018): 235–45. http://dx.doi.org/10.1042/etls20170146.

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It is often assumed that rising environmental oxygen concentrations played a significant role in the timing of the first appearance of animals and the trajectory of their early proliferation and diversification. The inherent large size and complexity of animals come with large energy requirements — levels of energy that can best, if not only, be acquired through aerobic respiration. There is also abundant geochemical evidence for an increase in ocean–atmosphere O2 concentrations in temporal proximity with the emergence of the group. To adequately test this hypothesis, however, a thorough understanding of the history of environmental oxygenation in the time between the first appearance of eukaryotes and the eventual appearance of animals is necessary. In this review, we summarize the evidence for the prevailing long-term conditions of the Proterozoic Eon prior to the emergence of Metazoa and go on to highlight multiple independent geochemical proxy records that suggest at least two transient oxygenation events — at ca. 1.4 and ca. 1.1 billion years ago (Ga) — during this time. These emerging datasets open the door to an important possibility: while prevailing conditions during much of this time would likely have presented challenges for early animals, there were intervals when oxygenated conditions were more widespread and could have favored yet undetermined advances in eukaryotic innovation, including critical early steps toward animal evolution.

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30

Hegardt, Eric Austin, David H. Cornell, Fredrik A. Hellström, and Inger Lundqvist. "Emplacement ages of the mid-Proterozoic Kungsbacka Bimodal Suite, SW Sweden." GFF 129, no. 3 (September 2007): 227–34. http://dx.doi.org/10.1080/11035890701293227.

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31

Kalsbeek, F., P. N. Taylor, and R. T. Pidgeon. "Unreworked Archaean basement and Proterozoic supracrustal rocks from northeastern Disko Bugt, West Greenland: implications for the nature of Proterozoic mobile belts in Greenland." Canadian Journal of Earth Sciences 25, no. 5 (May 1, 1988): 773–82. http://dx.doi.org/10.1139/e88-072.

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Whole-rock Rb–Sr and Pb–Pb and zircon U–Pb isotope data yield an age of approximately 2800 Ma for the Atâ granite from northeastern Disko Bugt, West Greenland. Field observations and isotope data suggest that the surrounding gneisses were formed by deformation and recrystallization of granitoid rocks similar to the Atâ granite some 100 Ma after the emplacement of the granite. Rb–Sr whole-rock data on siltstones at low metamorphic grade give an age of 1760 ± 185 Ma, which is interpreted as the time of closure of the isotope systems after metamorphism. The initial 87Sr/86Sr ratio demonstrates that the sediments were probably deposited during the early Proterozoic.Field observations and isotope data show that Proterozoic (Hudsonian s.l.) deformation and metamorphism were weak in the investigated area. The Archaean basement is well preserved, and the metasediments have well-preserved sedimentary structures. The area lies between the Proterozoic Nagssugtoqidian and Rinkian mobile belts of West Greenland, which are thus separated by an area of Archaean rocks little affected by mid-Proterozoic tectono-thermal events. Thus the two belts form separate tectonic units and do not constitute a single contiguous vast area of Archaean rocks reworked by Proterozoic deforma-tion and metamorphism. It is suggested that the Proterozoic mobile belts of West Greenland are orogenic zones of restricted width (a few hundreds of kilometres) that may be interpreted in terms of modern plate tectonic processes.

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32

Soper, N. J., and A. K. Higgins. "Basement–cover relationships in the East Greenland Caledonides: evidence from the Eleonore Bay Supergroup at Ardencaple Fjord." Transactions of the Royal Society of Edinburgh: Earth Sciences 84, no. 2 (1993): 103–15. http://dx.doi.org/10.1017/s0263593300003436.

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AbstractThe Eleonore Bay Supergroup (EBG) is a 16 km-thick shallow-water sequence of Neoproterozoic age that is preserved within the East Greenland Caledonides in several tracts, surrounded by crystalline gneisses and schistose supracrustal rocks. The apparent downward transition from non-metamorphic EBG into gneiss gave rise to the classic ‘stockwerke’ hypothesis, in which all the metamorphism was regarded as Caledonian, and differences in grade were ascribed to the ascent of a migmatite front to different levels within the orogen. Field and isotopic studies in the 1970s however revealed that the underlying gneisses and schists had undergone orogenic reworking in mid-Proterozoic time; the EBG–basement contact was then interpreted as an approximately bedding-parallel décollement with apparent lag geometry, that is with EBG cover rocks in its hangingwall.Recent work in the northernmost EBG tract, at Ardencaple Fjord, has shed light on the problems posed by the basal relationships of the EBG, and together with regional structural and stratigraphic data leads to the following interpretation. There are two regionally important basement-cover interfaces within the East Greenland Caledonides. The earlier one is between Archaean/early Proterozoic gneisses and early Proterozoic supracrustal rocks, which were pervasively deformed in mid-Proterozoic time and form the basement to the Neoproterozoic Eleonore Bay cover sequence. This was deposited on a vast, continually subsiding shelf that is now preserved in East and NE Greenland and Svalbard, and contains Grenville detritus. EBG deposition was terminated by major extensional faulting of Vendian age; the succeeding Tillite Group is interpreted as a syn-rift sequence, presumably associated with the opening of Iapetus.The EBG–basement contacts that are not late faults are inferred to be extensional shear zones of Vendian age. These were reactivated in compression during the Caledonian orogeny in the Silurian, with metamorphic and fabric convergence, which accounts for the apparent downward transition from sedimentary rocks through schists into gneisses. Caledonian shortening was not large; inversion of the Vendian grabens was incomplete, so that the marginal shear zones retained their lag geometry and large tracts of low grade Eleonore Bay sediments are preserved at the present erosion level, surrounded by Proterozoic basement rocks, within the Caledonian belt of East Greenland.

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33

James, N. P., G. M. Narbonne, and A. G. Sherman. "Molar-tooth carbonates: shallow subtidal facies of the mid- to late Proterozoic." Journal of Sedimentary Research 68, no. 5 (September 1, 1998): 716–22. http://dx.doi.org/10.2110/jsr.68.716.

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34

Planavsky, N. J., C. T. Reinhard, X. Wang, D. Thomson, P. McGoldrick, R. H. Rainbird, T. Johnson, W. W. Fischer, and T. W. Lyons. "Low Mid-Proterozoic atmospheric oxygen levels and the delayed rise of animals." Science 346, no. 6209 (October 30, 2014): 635–38. http://dx.doi.org/10.1126/science.1258410.

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35

Shen, Yanan, Andrew H. Knoll, and Malcolm R. Walter. "Evidence for low sulphate and anoxia in a mid-Proterozoic marine basin." Nature 423, no. 6940 (June 2003): 632–35. http://dx.doi.org/10.1038/nature01651.

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36

Prevec, Stephen A. "Basement tracing using Mid-Proterozoic anorthosites straddling a palaeoterrane boundary, Ontario, Canada." Precambrian Research 129, no. 1-2 (February 2004): 169–84. http://dx.doi.org/10.1016/j.precamres.2003.10.009.

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37

Calver, Clive R., Kathleen Grey, and Martin Laan. "The ‘string of beads’ fossil (Horodyskia) in the mid-Proterozoic of Tasmania." Precambrian Research 180, no. 1-2 (June 2010): 18–25. http://dx.doi.org/10.1016/j.precamres.2010.02.005.

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38

Ling, H. F. "Comment on "Molybdenum Isotope Evidence for Widespread Anoxia in Mid-Proterozoic Oceans"." Science 309, no. 5737 (August 12, 2005): 1017c. http://dx.doi.org/10.1126/science.1108737.

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39

Smith, Diane R., Calvin Barnes, William Shannon, Robert Roback, and Eric James. "Petrogenesis of Mid-Proterozoic granitic magmas: examples from central and west Texas." Precambrian Research 85, no. 1-2 (November 1997): 53–79. http://dx.doi.org/10.1016/s0301-9268(97)00032-6.

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40

Ozaki, Kazumi, Christopher T. Reinhard, and Eiichi Tajika. "A sluggish mid-Proterozoic biosphere and its effect on Earth's redox balance." Geobiology 17, no. 1 (October 3, 2018): 3–11. http://dx.doi.org/10.1111/gbi.12317.

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41

Thomas, D. Neil, and John D. A. Piper. "A revised magnetostratigraphy for the Mid-Proterozoic Gardar lava succession, South Greenland." Tectonophysics 201, no. 1-2 (January 1992): 1–16. http://dx.doi.org/10.1016/0040-1951(92)90172-3.

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Jackson, Michael James. "Mid-proterozoic dolomitic varves and microcycles from the McArthur basin, Northern Australia." Sedimentary Geology 44, no. 3-4 (July 1985): 301–26. http://dx.doi.org/10.1016/0037-0738(85)90017-x.

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Donnelly, Terrence Henry, and Michael James Jackson. "Sedimentology and geochemistry of a mid-Proterozoic lacustrine unit from northern Australia." Sedimentary Geology 58, no. 2-4 (August 1988): 145–69. http://dx.doi.org/10.1016/0037-0738(88)90067-x.

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Bluck, B. J., W. Gibbons, and J. K. Ingham. "Terranes." Geological Society, London, Memoirs 13, no. 1 (1992): 1–4. http://dx.doi.org/10.1144/gsl.mem.1992.013.01.03.

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AbstractThe Precambrian and Lower Palaeozoic foundations of the British Isles may be viewed as a series of suspect terranes whose exposed boundaries are prominent fault systems of various kinds, each with an unproven amount of displacement. There are indications that they accreted to their present configuration between late Precambrian and Carboniferous times. From north to south they are as follows.In northwest Scotland the Hebridean terrane (Laurentian craton in the foreland of the Caledonian Orogen) comprises an Archaean and Lower Proterozoic gneissose basement (Lewisian) overlain by an undeformed cover of Upper Proterozoic red beds and Cambrian to early mid Ordovician shallow marine sediments. The terrane is cut by the Outer Isles Thrust, a rejuvenated Proterozoic structure, and is bounded to the southeast by the Moine Thrust zone, within the hanging wall of which lies a Proterozoic metamorphic complex (Moine Supergroup) which constitutes the Northern Highlands terrane. The Moine Thrust zone represents an essentially orthogonal closure of perhaps 100 km which took place during Ordovician-Silurian times (Elliott & Johnson 1980). The Northern Highlands terrane records both Precambrian and late Ordovician to Silurian tectonometamorphic events (Dewey & Pankhurst 1970) and linkage with the Hebridean terrane is provided by slices of reworked Lewisian basement within the Moine Supergroup (Watson 1983).To the southwest of the Great Glen-Walls Boundary Fault system lies the Central Highlands (Grampian) terrane, an area dominated by the late Proterozoic Dalradian Supergroup which is underlain by a gneissic complex (Central Highland Granulites) that has been variously interpreted as either older

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Nielsen, T. F. D., B. Chadwick, P. R. Dawes, R. A. Frith, and H. K. Schønwandt. "Project SUPRASYD 1992: opening season in the Ketilidian of South Greenland." Rapport Grønlands Geologiske Undersøgelse 159 (January 1, 1993): 25–31. http://dx.doi.org/10.34194/rapggu.v159.8203.

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Project SUPRASYD was initiated in summer 1992 with a helicopter-supported field programme carried out between the end of June and mid-August. As outlined in last year's Report of Activities (Dawes & Schønwandt, 1992) the major aim of SUPRASYD is to provide an economic assessment of the Proterozoic Ketilidian mobile belt that forms the southern tip of Greenland (Fig. 1). In particular focus are supracrustal rocks and later intrusions.

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Lemieux, Y., R. I. Thompson, P. Erdmer, A. Simonetti, and R. A. Creaser. "Detrital zircon geochronology and provenance of Late Proterozoic and mid-Paleozoic successions outboard of the miogeocline, southeastern Canadian Cordillera." Canadian Journal of Earth Sciences 44, no. 12 (December 1, 2007): 1675–93. http://dx.doi.org/10.1139/e07-048.

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The Kootenay Arc has been interpreted as the western limit of autochthonous continental margin strata, west of which occur Paleozoic to Mesozoic rocks of uncertain paleogeographic origin. Recent mapping has demonstrated stratigraphic linkage between the Kootenay Arc strata and rocks farther west. A U–Pb study of detrital zircons using laser ablation – multicollector – inductively coupled plasma – mass spectrometry (LA–MC–ICP–MS) was undertaken in the upper succession of the Monashee complex mantling gneiss and in mid-Paleozoic strata of the Chase Formation exposed in the northern Kootenay Arc area and adjacent outboard strata. The predominance of >1.75 Ga zircon matches well with basement domains of the western buried North American craton and indicates that most of the grains were derived from a source of North American affinity. Zircon between 1.00 and 1.30 Ga demonstrates a Neoproterozoic source of possible “Grenville” affinity. Additional populations in the Chase Formation are mid-Paleozoic, Ediacaran, 800–1000 Ma, and 1400–1750 Ma. We interpret them to have been derived from exposed sources of Proterozoic continental crust and (or) proximal late Neoproterozoic and middle Paleozoic magmatic sources. The investigated Proterozoic and Paleozoic successions confirm sedimentologic and depositional relationships with the ancestral North American margin, and as such are interpreted to represent outboard extensions of the Cordilleran miogeoclinal succession.

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Sims, John P., Paul H. G. M. Dirks, Chris J. Carson, and Chris J. L. Wilson. "The structural evolution of the Rauer Group, East Antarctica: mafic dykes as passive markers in a composite Proterozoic terrain." Antarctic Science 6, no. 3 (September 1994): 379–94. http://dx.doi.org/10.1017/s0954102094000581.

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Archaean gneisses in the Rauer Group of islands, East Antarctica, record a prolonged history of high-grade deformational episodes, many of which predate that identified in mid-Proterozoic gneisses. Eleven generations of mafic dykes, belonging to discrete chemical suites, have been used as relative time markers to constrain this deformational history. Based on the timing of intrusion with respect to structures, dykes in the Rauer Group have been correlated with largely undeformed and dated dyke suites in the adjacent Vestfold Hills. This has allowed absolute ages to be inferred for the early- to mid-Proterozoic mafic dyke suites in the Rauer Group, and a correlation of the interspersed structural events. Most structures in the Rauer Group, however, developed in response to high-grade progressive deformation at approximately 1000 Ma. During this deformational episode, strains were repeatedly partitioned into sub-vertical, noncoaxial, high-strain zones recording NW-directed sinistral transpression, that separated zones of lower strain dominated by coaxial folding with axes parallel to the shear direction. Three additional mafic dyke suites intruded during this deformation which was followed by three stages of brittle-ductile deformation and a final suite of lamprophyre dykes. Due to the numerous intrusive time markers, the Rauer Group serves as an excellent illustration of how complicated gneiss terrains may be.

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Oen, I. S., A. A. de Maesschalck, and W. J. Lustenhouwer. "Mid-Proterozoic exhalative-sedimentary Mn skarns containing possible microbial fossils, Grythyttan, Bergslagen, Sweden." Economic Geology 81, no. 6 (October 1, 1986): 1533–43. http://dx.doi.org/10.2113/gsecongeo.81.6.1533.

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Rossetti, D. d. F. "Molar-Tooth Carbonates: Shallow Subtidal Facies of the Mid- to Late Proterozoic: Discussion." Journal of Sedimentary Research 70, no. 5 (September 1, 2000): 1246–48. http://dx.doi.org/10.1306/021500701246.

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James, N. P., G. M. Narbonne, and A. G. Sherman. "Molar-Tooth Carbonates: Shallow Subtidal Facies of the Mid- to Late Proterozoic: Reply." Journal of Sedimentary Research 70, no. 5 (September 1, 2000): 1249. http://dx.doi.org/10.1306/021500701249.

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