Copyright by Nysha Chaderton 2009 - The University of Texas at ...

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COMPARISON WITH LARUE’S RADIAL FAN MODEL In Larue’s 1985 paper, five principal units of turbidite successions were described on Barbados and interpreted in the context of the classic “radial fan model” of Mutti and Ricci-Lucchi (1972). Progradational and rejuvenational sequences of the basin plain and lobe, channelized successions of the mid-fan and inner fan; retrogradational and abandonment sequences were identified. The Breedy’s (Walker’s Ridge Lower) outcrop was interpreted by Larue (1985) as an extensive abandonment sequence characterized by thick accumulations of basin plain mudstones. In this study, this succession has been reinterpreted as an extensive levee sequence, similar to that described by Mutti (1977), based on the presence of erosive based sand beds. The implication of the latter interpretation is that this sequence and the overlying sand-rich Breedy’s outcrop (Walker’s Ridge Upper) does not record an abandonment of the system followed by a rejuvenation as proposed by Larue, but is instead a system that experienced lateral shifts in the channel axis through time. The Scotland Formation as a whole does not record up and down system changes from mid- fan to basin plain, but more subtle lateral changes within the mid fan from the axis of the channel complex to the levees of the system. The most distal facies seen in outcrop is the channel mouth complex at Inner Turner’s Hall Ridge (Figure 2.36, 2.38a-e). This was the only shift of the system in the dip direction observed in the study area. This outcrop probably records a slight retrogradation of the system. 23
SUMMARY DEPOSITIONAL SETTING OF THE SCOTLAND FORMATION DEPOSITS The facies identified in the Scotland Formation outcrops range from conglomerates, coarse-grained sands with gravel and pebbles to laminated silty muds and fine grained sands. The facies and architectural components of the Scotland Formation fit into the mixed sand and mud submarine fan system of Reading (1991). The absence of slump deposits in outcrops, and the sand content of the system suggests a mid-fan depositional location for the Scotland as opposed to either a proximal, slope location or a distal basin plain location. Trace fossils can be locally well developed in submarine fans, particularly in mid to outer fan settings. Thalassinoides and Planolites were observed at the Mount All location. These trace fossils were locally abundant on the bases of mudstone beds. A similar assemblage of Thalassinoides, Scalarituba and Planolites were identified in the Nihoptupu and Tirikohua Formations of New Zealand that are comprised of deep water turbidites deposited in an inter-arc basin of the Northland volcanic arc (MacEachern et al., 2007). Middle fan environments often contain trace fossils along the soles of sandy turbidites that can suggest “shallow water” deposition (Crimes, 1977; Howell and Normark, 1982). Trace fossils, such as Diplocraterion habichi, that are rare in the Scotland Formation are generally shallow-water, high energy indicators ~ 200 m water depth (Pemberton and MacEachern, 1995). This anomalous trace fossil association is the result of the imitation of the high energy neritic environment in a mid fan setting. This occurs because fast flowing depositional currents result in short lived episodes of high oxygenation that, coupled with the slow build-up of organic detritus in the middle fan leads to an imitation of high energy neritic environments (Howell and Normark, 1982). 24
Page 1 and 2: Copyright by Nysha Chaderton 2009
Page 3 and 4: Sedimentation within the Tobago For
Page 5 and 6: Acknowledgements I would like to th
Page 7 and 8: Table of Contents List of Tables ..
Page 9 and 10: List of Tables Table 2.1: Latitudes
Page 11 and 12: Figure 2.14: Planar parallel lamina
Page 13 and 14: Figure 2.42: Coarse, cobble and peb
Page 15 and 16: Figure A.3a: Chalky Mount Ridge mea
Page 17 and 18: 1. Development history of the south
Page 19 and 20: Formation. This interpretation requ
Page 21 and 22: DATA AND METHODOLOGY Extensive work
Page 23 and 24: DESCRIPTIVE METHODOLOGY Each sectio
Page 25 and 26: Two or more channel complexes stack
Page 27 and 28: These poorly sorted sands are later
Page 29 and 30: East Coast Road Although the East C
Page 31 and 32: succession of interlaminated siltst
Page 33 and 34: Mount All The beds of the Mount All
Page 35 and 36: Lobes are non-channelized bodies, 3
Page 37: Sandy units are the most resistant
Page 41 and 42: Chapter Three: Petrographic Analysi
Page 43 and 44: had not been buried deeply or long
Page 45 and 46: Feldspars Calcium Plagioclase Felds
Page 47 and 48: Authigenic Minerals Authigenic mine
Page 49 and 50: amounts of chlorite and kaolinite c
Page 51 and 52: Sample: WRA 16 This sample was take
Page 53 and 54: cementation is observed. A number o
Page 55 and 56: COMPARISON WITH PREVIOUS WORK Punch
Page 57 and 58: K feldspar preservation to slightly
Page 59 and 60: CONCLUSIONS 1. No quartz cementatio
Page 61 and 62: The highest point of the island, is
Page 63 and 64: STRATIGRAPHIC FRAMEWORK ONSHORE TO
Page 65 and 66: STRUCTURAL FRAMEWORK OF THE BARBADO
Page 67 and 68: Sandy material is primarily quartz
Page 69 and 70: esult of extension caused by flexur
Page 71 and 72: 1994). The origin of the Oceanic Fo
Page 73 and 74: Oligocene-age sediments are deposit
Page 75 and 76: The observation of channel geometri
Page 77 and 78: Pudsey, (1982) interpreted smectite
Page 79 and 80: The interpretation of the Scotland
Page 81 and 82: Figure 1.2: Convergent margins arou
Page 83 and 84: NSF Study Lines Grenada St. Kitts S
Page 85 and 86: Figure 2.2: Generalized vertical se
Page 87 and 88: Figure 2.4: Detailed Geological map
Page 89 and 90:
Figure 2.6: Photographs and illustr
Page 91 and 92:
Figure 2.8: Bedsets on the channel
Page 93 and 94:
S 50 m Figure 2.10: Photo-panorama
Page 95 and 96:
Figure 2.13: Laminated silt and mud
Page 97 and 98:
Figure 2.16a: Measured section at C
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Figure 2.16c: Measured section at C
Page 101 and 102:
Figure 2.18: Correlation of section
Page 103 and 104:
Figure 2.21: Parallel laminated sil
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Wach, Vincent and Chaderton March 2
Page 107 and 108:
Page 109 and 110:
Page 111 and 112:
Figure 2.24: Channel element identi
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WRB S N Fresh rock face exposed by
Page 115 and 116:
Figure 2.28: Photograph of Diplocra
Page 117 and 118:
Figure 2.31: Conglomerate with eros
Page 119 and 120:
Figure 2.33: Thalassinoides trace f
Page 121 and 122:
Figure 2.35: Mount All measured str
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Figure 2.37: Medium grained sand be
Page 125 and 126:
Figure 2.38b: Inner Turner’s Hall
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Figure 2.38d: Inner Turner’s Hall
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Figure 2.39: Spa Hill measured stra
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Juniper Ridge, California Scotland
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Figure 3.1: Fractured quartz grain
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SGRF 1C SGRF 9C Figure 3.5: Measure
Page 137 and 138:
Figure 3.8: Photo of sample SGRF 11
Page 139 and 140:
Figure 3.10: Photo of sample SGRF 1
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Figure 3.12: Photo of sample WRA 16
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Figure 3.14: Photo of sample WRB 8
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Figure 3.16: Photo of sample ITR 9
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Figure 3.19: Photo of sample CMRA s
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Figure 3. 23: Composition of Scotla
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Figure 4.1: Base map showing seismi
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Figure 4.3: Channels within Unit Fi
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Figure 4.5: Seismic reflection prof
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Figure 4.7 Isochron maps of the old
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Figure 4.9: Illustration of the Spe
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Figure 4.11: Illustration of Hypoth
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necessary to clear a path. Keep to
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2006 Figure A.2a: Lidar Ridge measu
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Figure A.3b: Chalky Mount Ridge mea
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2006 Figure A.4a: Chalky Mount Ridg
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2006 Figure A.4c: Chalky Mount Ridg
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2006 Figure A.6: Chalky Mount Ridge
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Figure A.7b: Measured Section of Ch
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2006 Figure A.8a: Sleeping Giant Ri
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2006 Figure A.9: Sleeping Giant Rid
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2006 Figure A.11: Sleeping Giant Ri
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Figure A.13a: Sleeping Giant Ridge
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2006 Figure A.14a: Coast Road Below
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2006 Figure A.14c: Coast Road Below
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2006 Figure A.14e: Coast Road Below
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2006 Figure A.14g: Coast Road Below
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2006 Figure A.15: Ermy Bourne Ridge
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2006 Figure A.17: Spa Hill Fold Mea
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2006 Figure A.19: Ermy Bourne Ridge
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Figure A.20b: Walkers Ridge Measure
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Figure A.21: Walkers Ridge Measured
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Figure A.22b: Walkers Ridge Measure
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2007 Figure A.23b: Inner Turner’s
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2007 Figure A.23d: Inner Turner’s
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Framework grains Quartz Feldspar Ro
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CRIMES, T.P., 1977, Trace fossils o
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MONTGOMERY, S.L., BARKER, C.E., SEA
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RICHARDS, M., BOWMAN, M., and READI
Page 217 and 218:
WEBER, J.C., DIXON, T.H., DEMETS, C
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