the stratigraphy and structural history of the mesozoic and cenozoic ...

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$A marine wide angle reflection/refraction profile adjacent Nova ...$

By the latest Triassic, the North American and African plates in the Scotian region had drifted northward to approximately 10-20º paleo-latitude, a relatively arid sub- equatorial climatic zone (Kidston et. al, 2002). Renewed rifting to the north in the Grand Banks/ Iberia area breached topographic barriers to the proto-Atlantic ocean and permitted the first incursion of marine waters from the Tethys oceanic realm to flood the interconnected syn-rift basins. Restricted shallow marine conditions were established at this time. Due to the hot dry climate and sub-sea level elevation, these waters were repeatedly evaporated, resulting in the accumulation of extensive salt and anhydrite deposits of the Argo Formation. Estimations on the thickness of the Argo Formation range from two kilometers thick in central rift sub-basins (Kidston et. al, 2002) to in excess of five kilometers in parts of the Orpheus Graben and Abenaki Subbasin (MacLean and Wade, 1992). The Argo Formation overlies the Eurydice Formation in the basin center and interfingers with it near basin margins (MacLean and Wade, 1992). Renewed tectonism during the Sinemurian resulted in complex faulting and some erosion of Late Triassic and Early Jurassic sediments and older rocks (Wade and MacLean, 1990). This phase of erosion is known as the Break-Up Unconformity (BU) and marks a time of tectonic adjustment related to plate separation and associated ocean spreading. Within the study area the Breakup Unconformity forms an easily mappable seismic horizon that marks the top of Late Triassic-Early Jurassic synrift strata. The southwest-northeast trending series of platforms, ridges, and depocenters that were created on the Nova Scotia margin as a result of the Sinemurian breakup are defined by 24
the landward extensions of regularly spaced oceanic fracture zones rooted onto continental crust (Welsink et al., 1990). Shallow marine dolostones of the Iroquois Formation and tidally influenced siliclastics of the Mohican Formation overlie the Breakup Unconformity. The Iroquois Formation attains a maximum thickness of approximately 800 m on the LaHave platform where it is coeval with the lower Mohican Formation (Wade and MacLean, 1990) Siliclastics of the Mohican Formation form a very thick late-Early to early-Middle Jurassic molasse sequence that was deposited into an actively subsiding sub-basin (MacLean and Wade, 1992). The Mohican Formation is widespread on the Scotian Shelf. Over 400 m of Mohican section was drilled in the study area in the Glooscap C-65 and Moheida P-15 wells (MacLean and Wade, 1993, Figure 2-4). Seismic data indicates that the formation may be as much as 4 kilometers thick in the Abenaki Sub-Basin. In some areas, salt flow occurred coeval with deposition of the Mohican Formation resulting in formation thicknesses as great as 5.5 kilometers in salt withdrawal synclines (MacLean and Wade, 1992). The combination of sea-floor spreading, basin subsidence and global sea level rise in the Middle Jurassic caused the North Atlantic Ocean to become broader and deepen to approximately 1000 m (Kidston et. al, 2002). A complex suite of shelf carbonates of the Scatarie Member, Abenaki Formation formed along the basement hinge zone in the relatively stable marine environment. Equivalent deepwater deposits at this time are the marls and muds of the Verrill Canyon Formation. Continued subsidence and relative sea level rise during the Callovian resulted in flooding of the carbonate bank and deposition 25
Page 1 and 2: THE STRATIGRAPHY AND STRUCTURAL HIS
Page 3 and 4: The integration of seismic stratigr
Page 5 and 6: leaving his door open and helping m
Page 7 and 8: 3.3.4 Tr2 Sequence Boundary 57 3.3.
Page 9 and 10: List of Figures (Short Titles) 1-1
Page 11 and 12: 3-22 Time structure map of the T1 S
Page 13 and 14: 5-17 End member geometries of alloc
Page 15 and 16: Chapter 1 Introduction 1.1 Introduc
Page 17 and 18: developed in the western part of th
Page 19 and 20: Areomagnetic surveys of the North A
Page 21 and 22: y Mukhopadhyay and Wade (1990), Wil
Page 23 and 24: 9 Figure 1-2: Comparative stratigra
Page 25 and 26: Naskapi N-30 Figure 1-3: Map showin
Page 27 and 28: SE NW 0 6 12 Kilometers 13 Figure 1
Page 29 and 30: converted using velocity informatio
Page 31 and 32: to date the effects of salt tectoni
Page 33 and 34: A 19 A’ Figure 2-1: Bathymetry an
Page 35 and 36: Within the area of the Scotian Basi
Page 37: 23 Figure 2-3: Generalized lithostr
Page 41 and 42: marine shales of the Misaine Member
Page 43 and 44: and positive relief structures on t
Page 45 and 46: formation thickness consistently in
Page 47 and 48: 2.4 Structural Styles and Geometry
Page 49 and 50: and igneous rocks of the Meguma Ter
Page 51 and 52: approximately 6 to 7 kilometers bel
Page 53 and 54: 4.2.3 Halotectonics In addition to
Page 55 and 56: 41 Figure 2-10: Scotian Margin base
Page 57 and 58: NW SE 6126 m 43 Figure 3-1: Represe
Page 59 and 60: TGS Base Tertiary Unconformity 45 T
Page 61 and 62: 47 Figure 3-3: Lithoprobe seismic r
Page 63 and 64: (Member Good DS9 Good Good Excellen
Page 65 and 66: NW SE Onlap Downlap 0 6 12 Kilomete
Page 67 and 68: 3.3.1. Top Basement Marker Within t
Page 69 and 70: 3.3.2. Tr1 Sequence Boundary The Tr
Page 71 and 72: 3.3.3 Depositional Sequence 1 Depos
Page 73 and 74: Glooscap C-63 E Moheida P-15 D TWT
Page 75 and 76: NW SE D D’ Eurydice Figure 3-9: S
Page 77 and 78: Formation consists of a series of m
Page 79 and 80: These reflections may represent int
Page 81 and 82: Anomalous highs Sequence boundary i
Page 83 and 84: in shape, 1 to 12 kilometers in dia
Page 85 and 86: Intersection with salt structure Fa
Page 87 and 88: 62, also intersected the Abenaki Fo
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marker in a landward direction (Fig
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south (slope-parallel) direction. T
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3.3.13 Depositional Sequence 5 Depo
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Thickness TWT (ms) D D’ Thick Int
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NW SE Quaternary Miocene - Oligocen
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Due to the consistently high amplit
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Correlation with the Shubenacadie H
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Page 105 and 106:
3.3.18. T2 Sequence Boundary The T2
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Reflections within DS8 are commonly
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3.3.20 T3 Sequence Boundary The T3
Page 111 and 112:
Page 113 and 114:
3.3.22 Water Bottom The uppermost r
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4.1 Introductory Remarks Chapter 4
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A (TWT ms) Basin-Bounding Fault Fam
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A A’ NW SE 105
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4.2.1 Slope Basin-Bounding Fault Fa
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Figure 4-3: Seismic Profile B-B’
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Wernicke (1981) or “second-order
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a) 2.0 3.0 4.0 5.0 6.0 7.0 8.0 b) D
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T3 T2 T1 T0 K1 J2 J1 Tr2 Tr1 NW SE
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thickening, resulting in distinct w
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Tertiary. In the northwest some maj
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SE NW Minor Faults 3076 m Major Fau
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NE SW 3075 m Pock-Marks ? Erosion E
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Chapter 5 Salt Tectonics 5.1 Mechan
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as a pressurized fluid with differe
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shales related to rapid progradatio
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131 Figure 5-3: Tectono-stratigraph
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Shelf N 0 15 30 Kilometers Moheida
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Shelf N 0 15 30 Kilometers Upper Sl
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A) NW SE B) Swells Normal basement-
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Salt Detachment Association includi
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formed shortly after autochthonous
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and Vendeville (1994) shows that th
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Allochthonous Stock “Finger” Di
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A’ SE A Folding of strata from T0
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Diapirs commonly intersect the K1 S
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D’ SE NW D 0 3 6 Strata folded fr
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Figure 5-14: Diapir rejuvenation du
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5.3.4 The Secondary Weld Associatio
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NW SE 0 3 6 Kilometers Inclined Sec
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An allochthonous salt structure is
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Salt Stocks A salt stock is charact
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F’ NE SW F 0 6 12 Kilometers Coal
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G (A) (B) G’ Figure 5-20: (A) Nor
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Figure 5-21: Schematic evolution of
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listric fault, causing the developm
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egardless of depositional setting a
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growth will continue until the sour
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Salt structures with onlapping syn-
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the base of post-kinematic stratigr
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SE NW 4093 m 179 Offset of paleo-de
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NE SW 6 km 181 Turtle Structure Pos
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NE SW 183 0 3 6 Turtle Structure Ki
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Figure 6-1: Seismic profile from th
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Figure 6-2: Tectono-stratigraphic c
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Ordovician metasedimentary rocks of
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191 Figure 6-3: Schematic block dia
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etween the location of salt swells
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On the slope, the Late to Middle Ju
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Listric growth faults typically tip
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this diapiric region. However, it w
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characteristically concordant with
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typical of passive margins modified
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Slope Basin: Kidston et al. (2002)
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~ Present day 100 C ~ Present day 1
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area can be divided into three slop
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Pre-Mesozoic structures are not con
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eservoir. The well locations were c
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7.2 Key Conclusions Geological Evol
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exclusively deform Late Triassic to
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• A reservoir of Cretaceous to Te
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References Alsop, G. I., Brown, J.P
Page 237 and 238:
Gauley, B. J., 2001, Lithostratigra
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Keen, C. E., and Potter, D. P., 199
Page 241 and 242:
Scotian Rise, Geological Survey of
Page 243:
Welsink, H.J., Dwyer, J.D., and Kni
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