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

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DISCUSSION General Depositional Model Mixed sand and mud systems submarine systems are defined as those that have sand to mud ratios of 30-70% (Reading, 1991; Richards et al. 1998). This type of submarine fan system is characterized by two main architectural elements; a channel- levee system and down-dip depositional lobes (Normark, 1978; Walker, 1978; Normark et al., 1979; Droz and Bellaiche, 1985). Channel sand bodies are offset stacked and bounded by levee fines. Down dip equivalents are stacked lobate sand bodies made up of mudstones and sandstones (Reading, 1991; Richards et al., 1998). Channel-levee systems form the conduits through which sediment is distributed to the main area of the fan. These systems may become mud-filled if fan abandonment is rapid or can contain a central core of coarse-grained, highly heterogeneous channel fill deposits, flanked by levee siltstones and mudstones if the fan is progradational (Walker, 1978; Winn and Dott, 1979; 1985 Tyler et al., 1984; Mutti et al., 1985a; Weuller and James, 1989; Schuppers, 1992; Richards et al., 1998). Channel facies in these systems vary from sandy conglomerates and pebbly sandstones with thick-bedded, high density turbidites to fine- grained thin bedded turbidites and hemipelagic mudstones (Richards et al., 1998). The Chalky Mount locality is a good example of this fan architecture. The Chalky Mount Ridge has channel-levee-overbank complex architectural elements. Sandy channel fill within the channel axes are deposits from individual channelized flows within the larger erosionally confined channel complex system. Silty mudstone intervals are out of channel levees, deposited after the individual abandonment of coarse-grained channels (Figure 2.40). It is believed by the author that this is a mud-rich fan system; however, The sand- mud ratio in the measured sections is skewed toward higher sand percentages by the fact that the thick sandy units are what more prevalently expose themselves for analysis. 21
Sandy units are the most resistant to weathering and generate poorer soils for the growth of vegetation. The muddier and siltier portions of the outcrop generate good soils for vegetation growth, and usually do not form extensive outcrops. Interpreting this system to be a mud-rich fan system has implications for the distribution of sands in the system. Mud-rich fans can be large systems (up to 1000s of km) dominated by well- developed channel-levee complexes with sand mostly restricted to axial channel fill within the channel levee complexes (Imperato and Nilsen, 1990; Weimer, 1990, 1995; Richards et al., 1998). Lobes Constructional lobes form layered sand bodies. The core of the lobe may be dominated by massive thick-bedded high density turbidites (Kleverlaan, 1989; Kulpecz and VanGeuns, 1990, Richards et al., 1998). Some lobes may display more classic turbidites and interbedded hemipelagic shales. Examples are the Stevens Fan, (MacPherson, 1978; Webb, 1981) and the Marenosa-Arenacea Fan, (Ricci-Lucchi and Valmori, 1980; Richards et al., 1998). Based on this definition of constructional lobes, it is thought that Inner Turners Hall Ridge locality is consistent with channel mouth or depositional lobe development and is interpreted as the most distal feature within the system (Figure 2.40). The Inner Turner’s Hall Ridge location has layered sandstone beds that vary from medium-grained to fine-grained and are thickest at the base of the section with a maximum thickness of 420 cm. Sand beds are capped with ripple-laminated, fine-grained sands and silts. Minor loading and planar lamination are observed throughout the section. There is no coarse- grained sand or conglomerate component and no erosive bases. 22
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: Lobes are non-channelized bodies, 3
Page 39 and 40: SUMMARY DEPOSITIONAL SETTING OF THE
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
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Figure 2.8: Bedsets on the channel
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S 50 m Figure 2.10: Photo-panorama
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Figure 2.13: Laminated silt and mud
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Figure 2.16a: Measured section at C
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Figure 2.16c: Measured section at C
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Figure 2.18: Correlation of section
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Figure 2.21: Parallel laminated sil
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Wach, Vincent and Chaderton March 2
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Page 109 and 110:
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Figure 2.24: Channel element identi
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WRB S N Fresh rock face exposed by
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Figure 2.28: Photograph of Diplocra
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Figure 2.31: Conglomerate with eros
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Figure 2.33: Thalassinoides trace f
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Figure 2.35: Mount All measured str
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Figure 2.37: Medium grained sand be
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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
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Figure 3.8: Photo of sample SGRF 11
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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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