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Marc B. Edwards1
Search and Discovery Article #40063 (2002)
*Adapted for online presentation from article of the same title by the same author at the GCAGS 52nd Annual Convention, Austin, Texas, October 30-November 1, 2002. Appreciation is expressed both to the author and to GCAGS.
1Marc B. Edwards Consulting Geologists, Inc., Houston, Texas (www.marcedwards.com; [email protected])
Until the advent
of 
sequence
stratigraphy (late 1980s), geologists commonly subdivided the
siliciclastic units of the Gulf Coast Basin into regressive and transgressive
components. Sequence stratigraphy divided the regressive component into two
separate units: the highstand systems tract (HST) and the lowstand systems tract
(LST).
According to sequence stratigraphic theory, the HST and the LST are
separated by a sequence boundary, with two implications: (1) the LST of a
particular sequence is younger than the HST of the preceding sequence, and (2)
the two systems tracts contain facies that are not genetically related. In the
years following the introduction of sequence stratigraphy (early 199Os), it was
noted in several publications that in areas where sediment input was active
during a period of overall sea level fall, a single widespread sequence boundary
did not form. Since the model necessitated the existence of a sequence houndary,
stratigraphers argued over where the sequence boundary should he placed. To try
to deal with this problem, the concept of “forced regression” was introduced,
hut this did not resolve the fundamental problems.
Uncritical
application of the original (eustatically forced) sequence-stratigraphic
paradigm requires geoscientists to identify stratigraphic components without any
basis in fact or theory. Where analysis of the data indicates that updip and
downdip facies are genetically related, a sequence model may he inappropriate or
misleading. In these cases, the term regressive systems tract is preferred, as
it removes the need to identify a conceptual artifact: the
chronostratigraphically and geometrically significant sequence boundary.
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uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
uLate Pleistocene shelf to shelf margin
u uLate Pleistocene shelf margin to slope uTertiary depositional systems
|
Thumbnails with Abbreviated Captions
Click here for
Figure 1. Depositional elements and significant surfaces in a shelf to
shelf margin setting characterized by high sediment input and falling
sea level. A. Reconstruction of late Pleistocene shelf to shelf margin
Mississippi deltas showing depositional components and stratigraphic
boundaries, modified from Morton and Suter, 1996, their Figure 4D. B.
The dip section edge of the block in (A), showing the nomenclature of
Morton and Suter (1996). C. Same stratigraphic units as (B) hut with
additional designations for key surfaces. D. Strike view suggesting how
a depocenter, as emphasized in the above diagrams, would contrast with
the depoflank, where the sea level fall would yield a Figure 2. Strata1 patterns and chronostratigraphy according to the standard
Exxon
Figure 6. Depositional-environment map of a major regressive Building paleogeographic maps (which represent, by implication, a time
interval) requires the ability to delimit, both vertically and
laterally, a corresponding rock-stratigraphic interval. Another property of a The main purpose of this paper is to argue that the above assumptions do
not apply to regressive sequences formed in a high-sediment-supply
regime where sediment is delivered to the shoreline during sea level
fall. This argument applies as well to revised One of the most confusing aspects of This paper argues that fundamental tenets of the
Late Pleistocene Depositional Systems-Shelf to Shelf Margin Late Pleistocene depositional systems are a useful starting point for improving reconstructions of depositional and stratigraphic aspects of older systems. Several deltas along the northern Gulf Coast Basin shelf margin provide insights into key features and unresolved issues. Of particular note are studies of the late Pleistocene Mississippi deltas (Morton and Suter, 1996) and the late Pleistocene (Mobile River) Lagniappe delta (Kindinger, 1988; Sydow et al., 1992; Sydow and Roberts, 1994; Winn et al., 1998; Kolla et al., 2000). Another key area of progress has been the issue of how and when sediment is transported to the slope and basin floor. Recent studies have aimed at linking sands in slope minibasins to their updip sources (e.g., Winker and Booth, 2000, Beaubouef and Friedman, 2000). The first comprehensive regional database and interpretation of the
Pleistocene of the northern Gulf of Mexico is the landmark work of
Berryhill et al. (1986). Numerous seismic lines in this atlas illustrate
not only the incised fluvial systems on the shelf, but the widespread
distribution of packages of basinward dipping clinoforms that strongly
indicated that delta sediments were deposited (and preserved) while sea
level fell to the shelf margin during Pleistocene glacial periods. This
would counter the Studies of the late Pleistocene Mississippi deltas by Morton and Suter
(1996) were conducted to compare the development of these deltas to the
predictions of the The second key conclusion of Morton and Suter (1996) concerned the comparative properties of the highstand and lowstand deltas: “Strata1 patterns and lithologic relationships clearly demonstrate that potential reservoir facies of lowstand shelf-margin deltas include distributary mouth bars, channel fills, and reworked shoreline and shelf sands that are not constrained by an incised valley or former shelf margin and are comparable in stratigraphic position and paleogeographic location to sand bodies of the highstand systems tract model” (Morton and Suter, 1996, p. 529). Thus highstand and lowstand deltas can only be distinguished by their context with external phenomena, not by their internal properties. The third key conclusion reached by Morton and Suter (1996) involves the
placement of the lower boundary of the depositional
The discussion by Morton and Suter (1996) on the issues surrounding the
choice of surface to serve as a A problem arises when the correlative-conformity downlap surface is traced
updip to an area where the overlying section contains an incised fluvial
channel (Figure 1). A For the purpose of placing genetically related sediments in the same
stratigraphic unit, it would seem desirable to retain the lower boundary
along the correlative conformity, except where this is removed locally
by valley incision. But this essentially places the The above considerations do not apply in areas where sedimentation was shut off for a significant portion of the time during a sea level fall. These relationships can be illustrated in a strike section through a deltaic depocenter and a flank area, updip of the shelf margin (Figure 1D). This shows how the sandy deltaic package that is deposited during the sea level fall changes facies to marine mud overlain by the subaerial exposure surface. Farther along strike, this mud may be locally eroded by a true incised valley that was bypassing sediment across the exposed shelf. The absence of deltaic deposits fringing the incised valley suggests that the valley formed by headward gully extension on the emergent shelf, until an updip drainage was captured. Two diagrams are included to contrast the stratigraphic architecture and
chronostratigraphic interpretation of late Pleistocene deltas described
above according to the An alternative
Late Pleistocene Depositional Systems-Shelf Margin to Slope Just as the In general terms, Beaubouef and Friedman (2000) agree: “The southern limit of the Texas-Louisiana Shelf is rimmed by thick shelf margin deltas interpreted to have formed during the last Wisconsin glacial event These fluvio-deltaic systems provided the source for large volumes of sediment transported to the deep basin” (p. 41). However, referring to the minibasins in front of the Trinity-Brazos shelf margin delta, they stated “. the presence of an older, buried canyon beneath the deltas can not be precluded, as that region of the subsurface is not imaged by the high-resolution seismic data” (p. 52). These authors emphasized the uncertainties that remain: “although the source of sediment delivered to these basins is well known, the exact mechanisms of sediment gravity flow initiation and transport to the slope is not known” (p. 52). On the other hand, Morton and Suter (1996) emphasized that “. . . no incised valleys or submarine canyons breach the paleoshelf margin, even though incised drainages were present updip.. .” (p. 505), apparently implying that sediment gravity flows originated on shelf-margin-delta clinoforms (as shown in their Figure 4), and then continued downslope into minibasins. The late Pleistocene Mississippi canyon that strongly eroded a narrow corridor of the shelf and shelf margin did not form until after the Mississippi deltas had reached the shelf margin (Coleman et al., 1983). Additional work is required to resolve the important issues raised by Beaubouef and Friedman (2000), as cited above. The large-scale relationships between stratigraphy and structure in the Gulf of Mexico basin, where the depositional substrate is highly mobile salt and shale, are well established (Diegel et al., 1995). Prodigious stratigraphic thickening in the region of the shelf margin and upper slope is associated with regional extension associated with the displacement of salt, and in some cases, the downdip gliding of thick sediment layers (Figure 4). The outer shelf, shelf margin, and upper slope area can be defined in terms of two fundamental and complementary regimes that define the stratigraphic relationships around the important interface between shallow water (topset, or shelf) and deep water (foreset, slope) settings (Figure 4). The first regime is characterized by shelf-margin progradation associated with complex systems of growth faults (Winker and Edwards, 1983). Individual fourth-order regressive cycles expand by up to ten times across individual faults. The second regime is shelf-margin retrogradation caused by large-scale collapse that removes thousands of feet of section, truncating deeper structures, and tilling with a complex of slide blocks and gravity flows, capped with deltas (Morton, 1993; Edwards, 2000). Collapse events affect wide areas of the shelf margin along strike, unlike submarine canyons that excavate narrow dip-oriented erosional features. Retrogradational shelf-margin collapse is related to high rates of sediment supply, rapid progradation of the shelf margin and progradation over a buried shelf margin (see Ross et al., 1994). There is no clear evidence that these features form as a direct response to relative sea level fall, although there is abundant evidence for high-frequency sea-level falls manifested by incised valleys and other phenomena (e.g. Edwards, 1990, 1994). An important issue, but beyond the scope of this paper, concerns the relative importance and character of the delivery of sands to the slope via shelf-margin deltas (progradational) versus shelf-margin erosional features (retrogradational). In seismic data, the diagnostic features of the retrogradational collapse
are the basal collapse discontinuity, which truncates updip strata, and
the internal till, which commonly has an internal clinoform signature.
The features are similar in appearance, respectively, to the In the Gulf Coast Basin individual regressive pulses are stratigraphic
events that are commonly referred to as fourth-order sequences (e.g.
Mitchum and Van Wagoner, 1990). Several papers presented under the
“ Nevertheless, a number of regional stratigraphic studies conducted on the Gulf Coast Basin provide a basis for delineating several key features of depositional cycles or sequences in the region (e.g. Edwards, 1980, 1990, 1991, 1994; Galloway et al., 1982; Van Wagoner et al., 1990; Xue and Galloway, 1995). Unfortunately, relatively few of the published studies combine sufficient detail (correlation and mapping to at least “fourth-order” cycles), adequately dense well control (to encounter incised valleys and channels), and regional scope extending across an entire depocenter and flank system (or even a significant portion of a depocenter or flank). Marine flooding surfaces and their associated transgressive shales and “highstand” condensed sections are the best, and often only, regional markers for correlating depositional cycles (e.g. Van Wagoner et al.; 1990, their Figs. 22 and 33). The cycles formed in a range of waveto river-dominated coastal plains and shorelines, often in relation to well-defined depocenters and depoflanks (Fisher and McGowen, 1967; Galloway, 1989a, b; Edwards, 199 1; Morton et al., 1988, 1991). Depending on facies, cycles can be traced along dip for tens of miles. The downdip extensions of these cycles are either truncated by collapse erosional events or thickened dramatically by growth faulting. Cycle expansion is commonly associated with specific, predictable facies changes (Edwards, 1995a). Farther downdip, correlation usually breaks down in the slope environment. Regional studies illustrate examples of the distribution of lithofacies, depositional environments, and stratigraphic architecture for the various units mentioned above. These include the river-dominated depocenter and depoflank of the Yegua (Edwards, 1990, 1991), the wave-dominated interdeltaic bight of the Frio (Edwards, 1986; Galloway and Morton, 1989), growth-faulted river-dominated, wave-influenced Wilcox deltas (Edwards, 198 l), and the river-dominated lower Miocene (Edwards, 1994). A key element of depocenter versus depoflank setting is the rate of sediment supply. In a depocenter the sediment supply “hose” is on most of the time; small relative changes in sea level move the hose around, but do not shut it off. In contrast, in the depoflank, the hose is on only a small part of the time, and genetically unrelated sediment bodies may become juxtaposed. Another contrast is the subsidence rate, which in the depocenter has an average rate that may be several times that of the depoflank. The relationship between third- and fourth-order events is shown in a dip stratigraphic cross section in the lower Miocene of southwest Louisiana (Figure 5). This section connects 20 wells and is based on the integrated analysis of almost 2,000 wells in a 1,500-mi2 area (Edwards, 1994). In this section, the higher resolution stratigraphy is provided by flooding surfaces. Two shelf-margin collapse events are identified, of which the larger earlier one represents a third-order event, as does the group of regressive cycles that occur in this part of the lower Miocene. Sediment gravity flows locally overlie the collapse unconformities. I will selectively cite the literature in order to make several points
within the scope of this paper. These concern the distribution and
properties of channel-form features, and the delivery of sand to the
shelf margin. Typically, Although the study of the lower Miocene mapped and analyzed the section using fourth-order stratigraphic features, another example that may be more compelling is a regional study of the middle Eocene Yegua and Cook Mountain Formations that spans the entire depocenter and flanks (Edwards, 1990, 1991). This study was based on about 4,500 well logs and detailed fourth-order cycle mapping. A regional map of generalized paleoenvironments (Figure 6), based on net-sandstone and log-facies maps (Edwards, 1990,1991) illustrates several important features that are only apparent in large regional maps of tine-scale stratigraphy. The depocenter is characterized by an area of amalgamated and coalesced mouth-bar sands along the shelf margin, with mappable associated channels. Thus, many of the channels are surrounded by mouth bars. Some of the channels, however, appear to be associated with downdip shelf-margin deltas, without adjacent mouth-bar deposits (bays of Figure 6). In contrast, in the depocenter flanks, channels can be mapped across the shelf and are associated with downdip shelf-margin deltas. In several cases channels cannot be mapped across the entire shelf but only inferred from limited updip well control. The occurrence of shelf-margin deltas in the same depositional cycle is consistent with sand bypass across the shelf. These relationships are similar in many regards to the late Pleistocene shelf and shelf margin deltas described earlier in this paper. At times, science goes to great lengths to adapt new data to existing
explanations. Past examples include complex solar system models designed
to remain geocentric, and the original grouping of the Burgess Shale
invertebrate fauna in existing phyla (Gould, 1989). How important are
the underlying premises if the whole paradigm shifts as refinements are
introduced? Is an underlying principle effectively buried by subsequent
developments, or does it remain a permanent, integral property of the
paradigm? For example, the astronomical system based on the positioning
of the Earth at the center of the Solar system had to eventually be
swapped out, in its entirety, for a Solar-centric system (although
lessons learned about various orbital geometries could be retained for
use in different systems). What does
During relative sea-level fall, a high-sediment-supply delta will deposit a
single coherent, integrated deposit that can be considered a regressive
systems tract. There is no surface comparable to the It is possible that some degree of “forcing,” or sea-level fall, accompanied many Gulf Coast Tertiary high-frequency (“4th order”) cycles. In this case, “valley” features, difficult to identify in depocenters, would be important targets for exploration in depoflanks, where their detection would require time-scale stratigraphic analysis applied on a regional scale.
I would like to acknowledge Tucker Hentz’s careful review of the manuscript. Numerous oil and gas companies have supported the regional studies that underlie many of the observations made and conclusions reached in this paper. I appreciate the encouragement and support they have given to me.
Beaubouef, R. T., and S. J. Friedman, 2000, High
resolution seismic/ Berryhill, H. L., Jr., J. R. Suter, and N. S. Hardin, 1986, Late Quaternary facies and structure, northern Gulf of Mexico: American Association Petroleum Geologists Studies in Geology, 23, 289 p.
Coleman, J. M., D. B. Prior, and J. F. Lindsay, 1983,
Deltaic Influences of shelf edge instability processes, in D.J. Stanley
and G Moore, eds., The Shelf Break: Critical Interface on Continental
Margins: SEPM Special Publication 33, p. 121-137. Edwards, M. B., 1980, The Live Oak delta complex, an unstable shelf-edge delta in the deep Wilcox trend of South Texas. Gulf Coast Association of Geological Societies Transactions v. 30, p. 71-79. Edwards, M. B., 1981, Upper Wilcox Rosita Delta System of South Texas: growth faulted shelf edge deltas: American Association Petroleum Geologists Bulletin v.65, p. 54-73. Edwards, M. B., 1986, Sedimentary effects of differential subsidence in Frio shoreface-shelf sediments, Gulf Coast Tertiary: Houston Geological Society Bulletin v. 29, nr. 3, p. 10-14.
Edwards, M. B., 1990, Stratigraphic analysis and
reservoir prediction in the Eocene Yegua and Cook Mountain Formations of
Texas and Louisiana. Edwards , M. B., 1991, Control of depositional environments eustacy, and gravity and salt tectonics on sandstone distribution in an unstable shelf edge delta, Eocene Yegua formation, Texas and Louisiana: Gulf Coast Association of Geological Societies Transactions, v. 41, p. 237-252. Edwards, M. B., 1994, Enhancing sandstone reservoir prediction by mapping erosion surfaces, Lower Miocene deltas, southwest Louisiana, Gulf Coast Basin: Gulf Coast Association of Geological Societies Transactions, v. 44, p. 205-215. Edwards, M. B., 1995a, Differential subsidence and preservation potential of shallow water Tertiary sequences, northern Gulf Coast Basin, U.S.A., in A. G. Plint, ed., Sedimentary Facies Analysis: A Tribute to the Research and Teaching of Harold G. Reading. International Association of Sedimentologists Special Publication 22, p. 285-281.
Edwards, M. B., 1995b, A Journeyman’s Approach to
Edwards, M. B., 2000, Origin and significance of retrograde failed shelf margins; Tertiary northern Gulf Coast Basin: Gulf Coast Association of Geological Societies Transactions, v. 50, p. 81-93. Fisher, W. L., and J. H. McGowen, 1967, Depositional systems in the Wilcox Group of Texas and their relationship to occurrence of oil and gas: Gulf Coast Association of Geological Societies Transactions, v. 27, p.105-125. Fisk, H. N., 1944, Geological investigation of the alluvial valley of the lower Mississippi River: Vicksburg, Mississippi, U.S. Army, Corps of Engineers, Mississippi River Commission, 78 p. Frazier, D. E., 1974, Depositional episodes-their relationship to the Quaternary stratigraphic framework in the northwestern portion of the Gulf Basin: The University of Texas at Austin, Bureau of Economic Geology Circular No. 74-1,28 p. Galloway, W. E. 1989a, Genetic stratigraphic sequences in basin analysis I: architecture and genesis of flooding-surface bounded depositional units: American Association Petroleum Geologists Bulletin v.73, p.125-142. Galloway, W. E. 1989b, Genetic stratigraphic sequences in basin analysis II: application to northwest Gulf of Mexico Cenozoic basin: American Association Petroleum Geologists Bulletin v.73, p. 143-154. Galloway, W. E. and R. A. Morton, 1989, Geometry, genesis, and reservoir characteristics of shelf sandstone facies , Frio Formation (Oligocene), Texas coastal plain, Gulf Coast Section SEPM Seventh Ammal Research Conference, p. 89-115. Galloway, W. E., D. K. Hobday, and K. Magara 1982, Frio Formation of the Texas Gulf Coast Basin: Depositional Systems, Structural Framework, and Hydrocarbon Origin, Migration, Distribution, and Exploration Potential: The University of Texas at Austin, Bureau of Economic Geology Report of Investigation No. 122,78 p. Gould, S. J.,1989, Wonderful Life. W. W. Norton and Co. NY. 347 p. Hunt, D., and M. E. Tucker, 1992, Stranded parasequences and the forced regressive wedge systems tract: deposition during base-level fall: Sedimentary Geology, v. 81, p. l-9. Hunt, D., and M. E. Tucker, 1995, Stranded parasequences and the forced regressive wedge systems tract: deposition during base-level fall-reply: Sedimentary Geology, v. 95, p. 147-160. Kindinger, J. L., 1988, Seismic stratigraphy of the Mississippi-Alabama shelf and upper continental slope: Marine Geology, v. 83, p. 79-94.
Kolla, V., P. Biondi, B. Long, R. and Fillon, 2000,
Kolla, F., H. W. Posamentier, and H. Eichenseer, 1995, Stranded parasequences and the forced regressive wedge systems tract: deposition during base-level fall-discussion: Sedimentary Geology, v.95, p. 139-145.
Mitchum, R. M., and J. C. Van Wagoner, 1990,
High-frequency sequences and eustatic cycles in the Gulf of Mexico
Basin: Gulf of Mexico:
Mitchum, R. M., Jr., and J. C. Van Wagoner, 1991,
High-frequency sequences and their stacking patterns:
Morton, R. A.,1993, Attributes and origins of ancient submarine slides and filled embayments: examples from the Gulf Coast Basin: American Association Petroleum Geologists Bulletin, v. 77, p. 1064-1081. Morton, R. A., L. A. Jirik, and W. E. Galloway, 1988, Middle-Upper Miocene Depositional Sequences of the Texas Coastal Plain and Continental Shelf: Geologic Framework, Sedimentary Facies, and Hydrocarbon Plays: The University of Texas at Austin, Bureau of Economic Geology Report of Investigation 174, 40 p. Morton, R. A., R. H. Sams, and L. A. Jirik, 1991, Plio-Pleistocene Depositional Sequences of the Southeastern Texas Continental Shelf and Slope: Geologic Framework, Sedimentary Facies, and Hydrocarbon Distribution: The University of Texas at Austin, Bureau of Economic Geology Report of Investigation 200, 80 p.
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Posamentier, H. W., and P R. Vail, 1988, Eustatic
controls on elastic deposition II-
Posamentier, H. W., G. P. Allen, D. P. James, M. Tesson,
1992, Forced regressions in a Prather, B. E., J. R. Booth, G. S. Steffens, and P. A. Craig, 1998, Classification, lithologic calibration, and stratigraphic succession of seismic facies of intraslope basins, deep-water Gulf of Mexico: American Association Petroleum Geologists Bulletin, v. 82, p. 701-728. Pulham, A. J., 1993, Variations in slope deposition, Pliocene-Pleistocene, offshore Louisiana, northeast Gulf of Mexico: American Association Petroleum Geologists Memoir 58, p. 1999233. Ross, W. C., B. A. Halliwell, J. A. May, D. E. Watts and J. P. M. Syvitski, 1994, Slope readjustment: a new model for the development of submarine fans and aprons: Geology, v. 22, p. 5 1 l-5 14. Suter, J. R., and H. L. Berryhill, Jr., 1985, Late Quaternary shelf-margin deltas, northwest Gulf of Mexico: American Association Petroleum Geologists Bulletin, v. 69, p. 77-91. Sydow, J., and H. H. Roberts, 1994, Stratigraphic framework of a late Pleistocene shelf-edge delta, northeast Gulf of Mexico: American Association Petroleum Geologists Bulletin, v. 78, p. 1276-1312.
Sydow, J., H. H. Roberts, A.H.
Van Wagoner, J. C., H. W. Posamentier, R. M. Mitchum, P.
R. Vail, J. F. Sarg, T. S. Loutit, and J. Hardenbol, 1988, An overview
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D. Rahmanian, 1990, Siliciclastic Vail, P. R., R. M. Mitchum, and S. Thompson, 1977, Seismic stratigraphy and global changes of sea level, part 3: relative changes of sea level from coastal onlap, in C. W. Payton, ed., Seismic stratigraphy applications to hydrocarbon exploration: American Association Petroleum Geologists Memoir 36, p. 129-144. Winker, C. D., and J. R. Booth, 2000, Sedimentary dynamics of the salt-dominated continental slope, in P. Weimer, R. M. Slatt et al., eds., Deep-Water Reservoirs of the World, Gulf Coast Section SEPM Twentieth Research Conference, p. 1059-1086. Winker, C.D. and Edwards 1983: Unstable progradational elastic shelf margins, in D.J. Stanley and G. Moore, eds., The Shelf Break: Critical Interface on Continental Margins, SEPM Special Publication 33, p.139-157.
Winn, R. D., Jr., H. H. Roberts, B. Kohl, R. H. Fillon,
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Winn, R. D., Jr., H. H. Roberts, B. Kohl, R. H. Fillon,
J. A. Crux, A.H. Xue, Liangqing, and William E. Galloway, 1995, High-Resolution Depositional Framework of the Paleocene Middle Wilcox Strata, Texas Coastal Plain: American Association Petroleum Geologists Bulletin, 79, p. 205-230. |
Figure
1. Depositional elements and significant surfaces in a shelf to shelf
margin setting characterized by high sediment input and falling sea
level.
Figure
2. Strata1 patterns and chronostratigraphy according to the standard
Exxon 
Figure
3. Strata1 patterns and chronostratigraphy for the regressive systems
tract described in this paper, modified from the concepts of Morton and
Suter (1996).
Figure
4. Schematic cartoon to illustrate the large-scale (third-order) phases
of shelf-margin progradation and slope-minibasin initiation, alternating
with phases of shelf-margin retrogradation.
Figure
5. Stratigraphic dip section hung on the Lower Miocene S. davisi
marker.
Figure
6. Depositional-environment map of a major regressive 
