SEPM Core Workshop No. 15 Mixed Carbonate-Siliciclastic Sequences Edited by: A.A. J.J. LomandoLomando and Paul M. Harris ISBN 978-1-56576-269-5 , CD catalog 71015 Originally published in print as SEPM Core Workshop (CW) No. 15 ISBN 0-918985-87-0, catalog 70015 Tulsa, Oklahoma, U.S.A., 1991 www.sepm.org Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3801416/9781565762695_frontmatter.pdf by guest on 30 September 2021 kUsii Cvb©nats Scqustitss SILICICLASTIC CARBONATE Pond Eolian Dune . Marine Shoal III Ephemeral Stream 15,111...- IIIII8 VME e. IPINIUM,..... KollINMI w cmajwij WilIII8 Eri Irim_raraz If_,_ tillEl ..,.....,_:,iMffiginPliMIMO Muddy Shelf -1 .._..i... IMI mEt=1.mewl moniej,MINA , IMIMNI=11 MilIIIIII 111.18 is IIIMINI, e WW2= Iff"». 11.191111Wig u. GOIlreara a . Ume Mudstone and Largely Perlddel._ :- Dolomudstone INIIMESIENNI 111.11 ok. L.rgely Shale Ili ...... I. Sh. and Oahe _ - _ . _ NIIM ..... _ Sittsto- -Largely- Shale and _ p6, _ oISI ........v,......=._ .t, NI .and Gong, Q 0.-GR--60 2.5RHOB-3.0. SEA; SEPM Core Workshop No. 15 Dallas, April 7, 1991 1926 Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3801416/9781565762695_frontmatter.pdf by guest on 30 September 2021 MiNed Carbonate- 8111c1clastic Sequences Organized and Edited by Anthony J. Lomando and Paul M. Harris SEPM Core Workshop No. 15 Dallas, April 7 1991 Copyright 1991 by SEPM (Society for Sedimentary Geology) Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3801416/9781565762695_frontmatter.pdf by guest on 30 September 2021 SEPM gratefullyacknowledgesfinancialsupport from Reservoirs,Inc.,Houston, Texas for the publication of thisvolume. ISBN #0-918985-87-0 Additional copies of this publication maybe ordered from SEPM. Send your order to: SEPM Post Office Box 4756 Tulsa, OKlahoma 74159-0756 U.S.A. © Copyright 1991 by SEPM (Society for Sedimentary Geology) Printed in the United States of America Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3801416/9781565762695_frontmatter.pdf by guest on 30 September 2021 PREFACE The study of carbonate-siliciclasticmixed sequences hasseen an increase in the number of investigations that focus on mixed settings as part of the continuumbetween the carbonate and clastic end members. The level ofinterest in such mixedsequences has been reflected in recent years by sessions at national meetings that dealt specifically with the topic, and also byrecent publications (Doyle and Roberts, 1988;Budd and Harris, 1990).Cyclic deposition in mixed basins by reciprocal sedimentation has become one of the foundationblocks for sequence stratigraphy (Van Siclen, 1958; Wilson,1967; Meissner, 1972; Sarg, 1988).In addition, these mixed sequences have a variety of distinctive petroleum reservoir characteristics,important for both exploration and development programs. .The emphasis now is on reevaluatingancient sequences in the light of a more dynamic understandingof spatial and temporal variations and controls on these sequences. Mixtures of siliciclastic and carbonaterocks can occur due to lateral faciesmixing (spatial variability) or by sea-level changesand/or variations in sediment supply,causing a vertical variation in the stratigraphic succession (temporal variability) (Budd and Harris,1990). Mixing can occur through a wide range of scales, frommillimeters to kilometers, respondto a wide range of processes, and can be influenced by all ordersof cyclicity. Trends of mixingcan vary along both depositional strike and dip,ranging from coastal environmentsto deep basinal settings. Major basinwardtransport of siliciclastics is controlled byrates of change of sea level and subsidence that togethercreate accommodation space.Other significant factors include climate, supply volume andtransport mode, shelf width and paleobathymetry(ramp, distally steepened ramp, rimmed platform), andcurrent patterns. We have subdivided the papers within this volume (see Fig. 1) under the followingheadings: Shelf Wide, Coastal and Inner Shelf,Middle to Outer Shelf, Slope to Basin,and Paleokarst. In the Shelf Wide Sectionare two papers that are contrasting examples of thespectrum of mixing on a regional scale.Borer and Harris' present a Guadalupianexample from the Permian Basin that is a regionaltreatment of temporal mixing where siliciclasticsrepeatedly alternate with carbonatesacross the entire width of the shelf in environments rangingfrom inner shelf to shelf margin.The paper by Shew2 is a Jurassic examplefrom Mississippi that is dominated by spatial mixing where fluvial inputinto a coastal environment is reworked by shelf processes into a carbonate-dominated regime and addressesmixing processes from nearshore to outer-ramp environments. The Coastal and Inner Shelf Sectionis a group of five papers that describeenvironments ranging from fluvial and eolianto coastal marine. Dewet and others3present a Pennsylvanian example from the southern margin of theIllinois Basin where a terrigenous dominatedsystem contains periodic carbonate marine incursionsexemplifying both spatial and temporal mixing. Handford and Francka's'paper from the Mississippian of southwest Kansas isan example of shallow marine and carbonate eolian mixingand, in theory, would bea spatial mixing type. Lomando and Walkers presenta Cenomanian example from offshore Angola consistingof a spatially mixed sequence of shoreface, beach,and lagoonal environments. Cuzella and others' report on a Pennsylvanian example from the Cherokeegroup in west-central Kansas.Here temporal mixing dominates where transgressive-regressivecycles are characterized by widespread carbonate deposition during major transgressivepulses. The final paper in this section, by Shaw Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3801416/9781565762695_frontmatter.pdf by guest on 30 September 2021 /// . .. ... ... C. ° Shallow Deep Ramp Ramp Rimmed Margin 14 / Shallow Deep Ramp Ramp Rimmed Margin Fig. 1.--Block diagrams showing variety ofmixed settings across both ramp and rimmedmargin profiles (top) and settings described in papersof this volume (bottom). Numbers refer to preface text and also to table of contents. iv Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3801416/9781565762695_frontmatter.pdf by guest on 30 September 2021 and Schreiber,' is a middle Ordovicianexample from the Ancell Group of theIllinois Basin where shallow subtidal to supratidalenvironments contain a temporally mixedsequence controlled by both eustatic and tectonicprocesses. Papers in the Middle to Outer Shelf Sectionare dominated by examples of subtidal deposition. This group of fourpapers begins with Harwood and Sullivan' whopresent a Mississippian example from the Irish Midlands. Thissequence is an example of tectonically controlled spatial mixing. Tucker and Chalcraft9present a temporal mixing example driven by sea-level fluctuations during the Guadalupian in thePermian Basin. Bebouti°presents another example from the Guadalupian of the PermianBasin, where carbonate-dominated packagesare separated by siltstones and sandstones thatare introduced during lowstands and subsequently reworked during initial phases of transgressions.The final paper in this section by Bush"presents a modem example along the Puerto Rican shelfof a storm-dominated inner-shelfsystem typified by spatial mixingprocesses. The Slope to Basin Section containstwo examples of the deepest-water environments covered in this volume. Smosna and Patcheepresent an upper Ordovician example from the Trenton Limestone in the central Appalachian Basin.This basinal sequence is an example of temporal mixing during a tectonically driventransgressive phase of deposition.Foreman and others13 present an upper Cambrian example from eastern Tennessee.Spatial mixing occurs alonga distally steepened ramp-slope to basinsystem that is characterized by episodic input of shallow- water carbonate into a shale-dominated basinal setting. The final paper is an example of unconventionalmixing in the Paleokarst Section. Sieverding and Harris" present a Mississippian example fromthe southwest Wyoming thrust belt.In this temporal mixing example, the mixingprocess results from the downward percolation of siliciclastics into an underlying karstsystem during a major transgressive event. Many mixed sequences have been described in theliterature, but understanding the controls of these sequences from a process approach isnow in an adolescent stage. We have endeavored to compile examples from a broadrange of environments and ages in order to provide participants in the workshop, and subsequent readersof this volume, with a body of literature focused on mixing problems. We hope that this willaid and encourage both our academic and industrial colleagues to continue their effortsto understand the complexities of mixingprocesses and stimulate ideas and approaches to explore forand develop new oil and gasreserves. The core workshop was made possible with the helpof many people. The SEPM staff and continuing education committee supported theconcept of the workshop and handled the logistical preparations. We thank Chevron Overseas PetroleumInc. and Chevron Oil Field Research Company for supporting our efforts in organizing andpresenting the workshop, and editing and prepaiing this volume. A. J. LOMANDO P. M. HARRIS Downloaded from http://pubs.geoscienceworld.org/books/book/chapter-pdf/3801416/9781565762695_frontmatter.pdf by guest on 30 September 2021 REFERENCES BUDD, D. A., AND HARRIS,