U.S. GEOLOGICAL SURVEY PETROLEUM GEOLOGY OF THE
U.S. DEPARTMENT OF THE INTERIORU.S. GEOLOGICAL SURVEYPETROLEUM GEOLOGY OF THESANTA MARIA BASIN ASSESSMENT PROVINCE, CALIFORNIAFOR THE1987 NATIONAL ASSESSMENT OFUNDISCOVERED OIL AND GAS RESOURCESbyCaroline M. Isaacs1Open-File Report 89-450 CThis report is preliminary and has not been reviewed for conformity with U.S. GeologicalSurvey editorial standards or with the North American Stratigraphic Code. Any use oftrade, product, or firm names is for descriptive purposes only and does not implyendorsement by the U.S. Government.XU.S. Geological Survey345 Middlefield Road, MS 999Menlo Park, California 940251992
CONTENTSIntroduction. 1Basin Ixx tion. 1Structural Setting . 1Stratigraphy. 2Source roclb. 3Burial history, thermal maturity, and timing of migration. 19Hydrocarbon occurrence. 20Geographic distribution. 20Stratigraphic and structural habitat of petroleum. 20Basis for play definition. 21Neogene Play .22Play definition. 22Reseivoirs.22Traps and seals. 22Oil characteristics. 23Depth of occurrence. 23Exploration status. 29History. 29Future potential. 30Acknowledgments. 30References. 38Figures1. Index maps. 4A. Assessment province and play boundary. 4B. Neogene basins. 5C. Oil and gas fields. 62. Contour map of base of Tertiary, Santa Maria basin. 73. Plate tectonic model of the Tertiary California margin. 84. Rotation tectonic model of the Santa Maria basin. 95. Cross-sections. 106. Structural interpretations. 11A. Wrench tectonics. 11B. Compresssional tectonics. 127. Terrane model for the pre-Eocene California margin. 138. Stratigraphic columns. 14A. Huasna district. 14B. Arroyo Grande district. 15C. Central Santa Maria district. 16D. Southwestern Santa Maria district. 17E. Southeastern Santa Maria district. 189. Trap types. A. Structural trap, Orcutt field. 24B. Stratigraphic trap, Santa Maria Valley field. 25C. Combination trap, West area of Cat Canyon field. 2610. Contour map of top of Monterey, onshore Santa Maria basin. 2711. Contour map of top of Monterey, offshore Santa Maria basin. 28Tables1. Field data for major fields (Nehring). 312. Oil production and reserves for minor fields. 323. Field data (California Division of Oil and Gas). 33
INTRODUCTIONThis report presents a summary of the geology used as a basis for the U.S. GeologicalSurvey's 1987 assessment of undiscovered oil and gas resources in the Santa Maria Basinassessment province. The petroleum geology was taken for the most part from publishedsources, principally Crawford (1971) and California Division of Oil and Gas (1974).The assessment was made on a baseline of discovered oil and gas resources (cumulativeproduction plus proved reserves) from the Nehring data base as of 12/31/83 (NRGAssociates, 1984) which includes only fields with resources exceeding 1 MMBOE (millionbarrels oil equivalent). The figures correspond to those in California Division of Oil andGas (1984) which includes fields of all sizes. Reserve additions due to field development ornew discoveries subsequently declared by the California Division of Oil and Gas were forassessment purposes regarded as undiscovered resources.Total cumulative production in the assessment province through 1983 was 762 MMbbl(million barrels) oil, 53 MMbbl NGL (natural gas liquids), and 705 Bcf (billion cubic feet)gas; proved reserves totalled 165 MMbbl oil, 9 MMbbl NGL, and 107 Bcf gas (NRGAssociates, 1984).BASIN LOCATIONThe Santa Maria Basin assessment province is located in central coastal California. Asdefined (Figure 1A), the province is bounded on the south approximately by the SantaYnez fault, on the east by the Santa Barbara-Ventura County line, and on the west(offshore) by the western limit of state waters within 3 miles of shore from Jalama (at thesouth) nearly to Monterey (at the north). On the northeast, the assessment province isgenerally bounded by the Sur-Nacimiento fault but extends beyond that fault north of 36 Nto include the approximate extent of exposed pre-Cretaceous metamorphic basementrocks.Geologically speaking, the assessment province mainly represents the Tertiary onshoreSanta Maria Basin, Pismo Basin ("Arroyo Grande district" in Figure 2), and Huasna Basin"Huasna district" in Figure 2). In addition, the assessment province also includes small unnamed Tertiary basins or basin fragments in the Coast Ranges west of the Sur-Nacimientofault, a piece of the Tertiary Salinas Basin northeast of the Sur-Nacimiento fault in the areanorth of 36 N, a wedge along the southern boundary that is regarded by some as part of theTertiary Santa Barbara-Ventura Basin, and slivers of the Tertiary Sur and offshore SantaMaria Basins in adjacent offshore state waters (Figure 2).STRUCTURAL SETTINGPrevailing views of the formation of west coast Neogene basins are based onmodifications of Atwater's (1970) and Atwater and Molnar's (1973) plate tectonic model
for the west coast of North America. In this model, Neogene basins were formed at a triplejunction (between the North American, Pacific, and Farallon Plates) that migrated northand south from the vicinity of southern California between 29 Ma and present (Figure 3).Various theories address the formation of basins within this setting (e.g. Blake and others,1978) including a model for the formation of the Neogene Santa Maria geologic basin as apull-apart basin during strike-slip tectonism (Hall, 198 Ib). Another theory about theNeogene Santa Maria geologic basin is that it formed as an area of thinned crust related toclockwise tectonic rotations of elongate crustal blocks bounded by more or less verticalfaults (Figure 4; Hornafius, 1985, Horaafius and others, 1986).The Miocene and younger structural style of the assessment province has generally beenregarded as dominated by wrench tectonics and associated vertical strike-slip faulting (e.g.,Howell and others, 1980; Figures 5,6A). However, compressional tectonics and associatedthrust and high-angle reverse faulting were more recently advocated as the dominantstructural style in the development of adjacent offshore areas (Crouch and others, 1984;Figure 6B). Subsequent to the assessment, major anticlinal structures throughout theassessment province have been related to fault-bend and fault-propagation folds in aPliocene and younger fold and thrust belt (Namson and Davis, 1990).STRATIGRAPHYThe Santa Maria Basin assessment province is mainly included in the Sur-Obispocomposite terrane of Vedder and others (1983), a composite of the San Simeon terraneand the Stanley Mountain terrane. Basement rocks in the San Simeon terrane consist ofpre-Jurassic, Jurassic, and Cretaceous Franciscan melange (Figure 7), and basement rocksin the Stanley Mountain terrane consist of Coast Range ophiolite and upper Jurassic (?)and Cretaceous sedimentary rocks of the Espada or "Knoxville" Formation.In most of the assessment area, an unconformity represents Late Cretaceous and most ofPaleogene time (Vedder and others, 1983). Between this unconformity and the widespreadpredominantly fine-grained Miocene strata of the Miocene Monterey Formation (and/orPoint Sal Formation), the stratigraphy varies from locality to locality. In the southernmostpart of the assessment area (Figures 8D, 8E) is an Eocene-Oligocene sequence overlainlocally by the Oligocene-Miocene Sespe Formation. Overlying the Sespe there, andoverlying the Late Cretaceous-early Paleogene unconformity in the Huasna (Figure 8A)and Pismo (Figure 8B) geologic basins and in coastal areas to the north that are west of theSur-Nacimiento fault, is a sequence that includes sandstones of the Oligocene-MioceneVaqueros Formation and shale and sandstone of the early Miocene Rincon Shale.Overlying the Rincon Shale are volcaniclastic and sedimentary rocks of the lower-middleMiocene Obispo Tuff in areas north of the Santa Maria geologic basin (Figures 8A, 8B),and the Tranquillon Volcanics locally in the southern part of the assessment province(Figures 8D, 8E; Dibblee, 1950, 1966). Locally in the Santa Maria geologic basin,especially in the northwestern part of the basin, the Late Cretaceous-Paleogeneunconformity is overlain by non-marine sandstones, conglomerates, and mudstones of the
Lospe Formation (Figure 8C). This unit, now dated as early Miocene in age (Stanley andothers, 1991), was at the time of the assessment presumed to be uncertainly of lateOligocene or early Miocene age.Overlying the Rincon Shale in the southernmost part of the assessment area (Figures8D, 8E), the Obispo Tuff in areas north of the Santa Maria geologic basin (Figures 8A,8B), the Lospe Formation locally within the Santa Maria geologic basin (Figure 8C), andFranciscan or Cretaceous sedimentary rocks within much of the Santa Maria geologicbasin, are the predominantly fine-grained strata of the Miocene Point Sal and MontereyFormations. These strata consist mainly of bathyal clay-bearing siliceous-calcareous,calcareous-siliceous, and siliceous mudstones and shales derived from diatom andcoccolith-foraminiferal oozes. Where sandstones are notably abundant in the lower part ofthese strata (as in the central part of the onshore Santa Maria basin) and by local custom inother areas (such as the Pismo and Huasna basins), the lower part of this sequence islocally included in the Point Sal Formation.Overlying the Monterey Formation are sequences of marine sedimentary rocks generallyrepresenting deposition in comparatively shallow environments. In the Santa Mariageologic basin (Figure 8C; Lagoe, 1987), the Monterey Formation is overlain (in placesdisconformably or with slight to significant angularity) by outer neritic clayey-siliceousmudstones (uppermost Miocene and lower Pliocene Sisquoc Formation, as much as 5000 ftthick), clayey mudstones (Pliocene Foxen Mudstone), and shallow marine sandstone andconglomerate (upper Pliocene Careaga Sandstone). In the Pismo basin (Figure 8B), theMonterey Formation is not defined equivalently in that a thick sequence of upper Miocenesiliceous mudstones and shales is locally included in the overlying Pismo Formation. ThePismo Formation also includes shallow marine sandstones and conglomerates of latestMiocene and Pliocene age (Figure 8B; see also Kablanow and Surdam, 1984). In theHuasna basin (Figure 8A), the Monterey Formation is overlain mainly by siltstone andsandstone of the Santa Margarita Formation.Overlying the marine Pliocene sequence in most areas of the assessment province areupper Pliocene and Pleistocene non-marine gravel, sand, and silt deposits of the PasoRobles Formation (Figure 8).Basic references for detailed stratigraphy in the assessment province are Canfield(1939), Woodring and Bramlette (1950), Dibblee (1950, 1966), Hall and Corbato (1967),Hall (1973a, 1973b, 1974, 1976, 1978, 1981a), Hall and Prior (1975), and Hall and others(1979).SOURCE ROCKSThe Monterey Formation is generally thought to be the only significant source rock inthe Santa Maria Basin assessment area, though other potential source rocks such as theRincon Shale are locally present in the area.Source-rock studies available at the time of the assessment that included samples fromwithin the assessment province were few, mainly Surdam and Stanley (1981) for the Pismo
Santa BarbaraAssessment province boundaryAssessmentprovince boundary(state-federal3-mile boundary)35*-" . * . Maria* .*.'."Pacific OceanVENTURA BASINASSESSMENT PROVINCE120'Figure 1 A. Location of the Santa Maria basin assessment province andNeogene play boundary.
122'124'120'42'40 (POINTARENACORDELL38 COUTERSANTA CRUZS A LI N A S C U Y A M A36COFFSHORESANTA MARIASANTA LUCIAONSHORESANTA MARIASANTA BARBARA-VENTURA34'LOS ANGELESFigure IB. Location of the Neogene basins of California (from Blake and others,1978, and McCulloch, 1987,1989). The lined area shows the assessment province.
PISMO-HUASNA BASINLOPEZ CANYONARROYO GRANDEHUASNASAN MIGUELSANTA MARIA VALLEYCASMALIAOFFSHORESANTA MARIABASINVMARIMARIAONSHORE} SANTA MARIAORCUTTJ/ESUS*)/POINT PEDERNALESCAT CANYONFOUR DEER ZACABASINLOMPOC BARHAM RANCHLOS ALAMOSBONITOPOINT ARGUELLOSWORDHONDOSANTA BARBARA CHANNELSANTA ROSA20 KMFigure 1C. Oil and gas fields in the assessment province and adjacent areas to thesouth (from California Division of Oil and Gas, 1974).
20 Ml.PTCONCEPTIONFigure 2. Generalized contour map of base of Tertiary, Santa Maria basinassessment province, California. Datum is sea level, contour interval is 1 mile.Black areas are Jurassic-Lower Cretaceous outcrops, hachured areas are UpperCretaceous outcrops. Cross-sections A-B", C-D, and E-F (shown in Figure 5)are located. Reprinted from Crawford (1971) by permission.
Figure 3. Schematic model of interaction of Pacific Farallonand North American plates for six Tertiary time intervals, showingtime of initial development, location, and general shape of Neogenebasins that formed (from Blake and others, 1978; based on Atwaterand Molnar, 1973). ER, Eel River basin; PA, Point Arena basin; B,Bodega basin; SC, Santa Cruz basin; OSC, Outer Santa Cruz basin;SM, Santa Maria basin; SCB, Southern California basin; SV, SebasianVizcaino basin; TB, Tortugas basin; and M, Magdalena borderland.S«Mi»ctloH IOMVVr. Melfte olata (notionC rotatiM t« HM WorthAmor Icon »lotoNorm American otato " ]CXPIANATIONTrontform faultOctonJc rld«oToctonieoMy 'toft* WMrtln ofFMif le - Norm Amortoan ptototoo
122*120*119*SOUTHERN CALIFORNIA-33'Figure 4.Present-daygeography(above)andpalinspastic reconstruction at 16Ma (below) showing preseritdayfaults and shorelines of southernCalifornia.Circular arrowsindicate the sense and amount oftectonic rotation suggested bypaleomagnetic data, with mostrotation in the interval 10-16 Ma.Straight arrows indicate theamount of displacement betweenpiercing points along majorstrike-slip faults. Reprinted fromHornafius and others (1986) bypermission.
10SOlHHS»t LtrtlWOO'14000'I WOOswFRANCISCAN (n-- 1 .OII--' "t 4 KM.Figure 5. Cross sections in the Santa Maria Basin assessment province. A-B'-B"through Santa Maria district (from Crawford, 1971; based on Krammes, Curran, andothers, 1959). C-D through Huasna district (from Crawford, 1971; based on Hall andCorbato). E-F across southeastern Santa Maria district (from Crawford, 1971; fromDibblee, 1966). Location of cross sections is shown in Figure 2. Reprinted from Crawford(1971) by permission.
BANKFigure 6A. An example of wrench tectonic interpretation of offshore Santa Maria basin (fromHowell and others, 1980).SANTA LUCIA
12Northeastern Santa Maria Basin0(SL)3.0sccNortheastern Santa Maria Basin3km0(SL)3.0 secFigure 6B. An example of compressional tectonic interpretation of offshore SantaMaria basin off Point Sal (reprinted from Crouch and others, 1984, by permission).
1350403020wSUTURED TERRANES10-10-20§wuB4080120TIME (myBP)SUR-OBISPO COMPOSITETERRANESALINIAN COMPOSITETERRANEFigure 7. Pre-Eocene geologic history of the Santa Maria and Santa BarbaraVentura basins. (A) Terranes of Southern California and northern Baja California showingthe Santa Lucia-Orocopia allochthon (diagonal lines) and the Baja Borderland allochthon(stippled pattern). From Howell and others (1987). (B) Proposed latitude trajectories ofthe allochthons (and their constituent terranes) shown in A. From Howell and others(1987). (C) Generalized pre-Eocene stratigraphic column for the Salinian compositeterrane, and the Sur-Obispo composite terrane (including the San Simeon terrane and theStanley Mountain terrane). Modified slightly from Vedder and others (1983).160
14i-?-DESCRIPTIONLITH.FORMATION' r- .\ J-?-SANTA MARGARITAm?!0-5000'oo f'-'ocMONTEREY0-4500'OCENE-coSiltstone; porceloneous, cherty,ond limy shole; ond chertNortheastern fine to mediumgroined sondstone fociesUI2Siltstone ond cloystoneFine to coorse groined sondstone\tr* Siltstone ond siliceous siltstoneFine to coorse groined sondstoneIll.trUJa.a.Fine to coorse groined sondstone ond sondy siltstone *»\coUJ - --- POINT SAL1 §3s-?-V /I- ! ' v-/i f-OBISPOa:Diotomoceous, tuffoceous siltstone ond cloystone.Grades laterally into Obispo fm to the southwest ond intomedium groined sondstone to the northeast A0-3000'AV -/1Tuff ond ash with siltstone interbedsUIV0-500'VAOUEROSO-600'TJT? 7 Vr v **«v v1ec-cpc0-600' - ' ' b o'. .'rTJ / TVlCloystoneFine to coorse groinedsondstone. conalomerote ond siltstone( non-marine ) n. . o . o . e 2o UJctoCARRIE CREEKFine to coorse groinedSondstone, siltstone ond conglomerate0 -5000'&0.*" a. ?T*."T:TTDSnOBOVJJOLLO-OISS ? 00O'Cloystone, conglomerate, sondstone. .0-0SwD ff 50JFRANCISCANM l\ V 1 1 1 p 4T/ o.e.Sondstone, siltstone, chert ondbosolt with serpentine intrusionsFigure 8A. Generalized stratigraphic section of Huasna district (reprinted fromCrawford, 1971, by permission).
15uLITH. "FORMATION!§aK-PASO ROBLESLUQ.!UJ1f! o6 .Grovel and sond(nan* marine )OUJo»i? 0 ?o arz.'. -. . a. ( 7-7.0-200'z rUJ iiio0lDESCRIPTIONo lFine to coarse grained sandstonewith shale and claystane interbeds'.'O TOo-?h-Conglomerate. o -oPISMO-. .-.:Fine to medium grained sandstonewith diotomite and diatomoceaus shale interbeds'.'.! '.'.'.*Tor sand0-5000'. ! .'. .Fine to coarse grained sandstone*Tor sond 'j -:(TUJQ.Q.0 ]KUJ r zLU UJK o.tt9Silty shale and siltstoneT rsondNorthern fine to medium grainedsandstone facie*Siliceous shaleTar sandDiatamoceaus shale, locally chertyfo\Oprz z nz2MONItHtYj cc.0-3000'!Z o P1oooEfLELJJO0Porceloneous and cherty shaleSiliceous and limy shale'.-i . . r -2?-rrLJ ojPOINT SALV 4J TV" ? "?"OBISPOSJ 3RINCON0-3000'VAQUEROS "-/i 1: ' 0 jr t .*r-FRANCISCANXv/rO-lOO1JURASSIC- CRET.L. b j'.rla-7 P-iTuff, agglomerate, ash, bentonitewith silty and cloy shale interbedsx Altered igneous rocks/I U' /I -r r A i' Figure 8B. Generalized stratigraphic section of Arroyo Grande district (reprintedfrom Crawford, 1971, by permission).
16LITH.FORMATION1-' 'PLEIST.PRODUCTIVE1DESCRIPTION.P.O.PASO ROBLESo0-4500'Grovel, sond, silt, cloy( non-morine )*oo.o . ee0' o ?:6CAREAGACoorse groined sondstone & conglomerote0-1500'Fine groined sondstone"j UPPERLOWERPLIOCENEFOXENMuds tone ond siltstoneEr-ErE0-3000'Silty tor sondzrErEDiotomoceous cloystone ond siltstone and diotomiteHISISQUOC0-4500'Northern and eastern marginal sondstone faciesV . . .iiitrti-UPPER UJ0.0.UJi-0-3500'3N300I2J:1Porceloneous shale generally ploty,\'gss1Jlocally cherty; ond laminated diotomiteSiliceous ond cherty shole ond chert11MIDDLEPhosphotic, silty, limy, ond siliceous sholeFine to coarse groined sandstone locally presentPOINT SAL0 - 2500' nMudstone ond siltstone withthin sandstonesZZT." ' ' ' \J8 [EOCENEMWloLIGOCENEILOSPEF7ii-r-r0-2600'o o o ' boo- oJ URASSI- C CRL.ETACEOUSKNOXVILLEGreenish ond reddish mudstone,siltstone, sondstone, conglomerateiEr.:.:Z . o '(non-marine)Cloy shole, sondstone ond conglomerote* VAN Vi.FRANCISCANAltered igneous rocks/l V l Figure 8C. Generalized stratigraphic section of central Santa Maria district(reprinted from Crawford, 1971, by permission).
DESCRIPTION0- . . . . e -oPASO ROBLES UJUJ0UT-2.Grovel, sand, silt, cloy(nan - marine):.v.'v.v:Pebbly sandstoneFine groined sandstoneL JtCfU)1EEEL ESISQUOCDiotomite and diotomoceous cloystone0 - 9fwV[Er-JEr-IE Ia:UceUJUJzUJ(C o o1- sa.nMONTEREYSiliceous and cherty shale and us shale, generally ploty - 0-2500'D (CUJ., .,, .,,. . ,0-I2OO'UJORINCON0-500'VAQUEROS0-400' T 3 ",v; cVV V V-.-.-.A V 1 A # 0«y A J1. «»» V V A -Ej EI-Ee ' 'o'- .o- ooooogSPhosphotic, silty, limy, and siliceous shalesMudstone and siltstoneRhyolite, agglomerate, tuffCloystoneMedium to coarse groined sandstone and conglomerateS2rtUJzUJu0UJJIFine to medium groined sandstone and cloy shaleEErEL- . . . .Cloy shaleANITA0-700'r -TZ Cloy shaleESPADA(KNOXVILLE)IIICarbonaceous shale withthin sandstone interbedswMwM 1 C.0-1200'a:UJa.a.- -?5HUJ(CUE;- wMV 1 w 1 MCOZY DELL0-700'MATILIJA0- TOO'1JURASSICFRANCISCAN*',/---Sandstone, sheared cloy shale,chert, basalt; serpentine intrusions g««Figure 8D. Generalized stratigraphic section of southwestern Santa Maria district(reprinted from Crawford, 1971, by permission).
18LITH.FORMATION oPLEIST.djQ.ftV-f*PASO ROBLESwViSGravel, sand, silt, clay-?-0-3000'.'-ZV.O- 'o- -00-0( nen -marine)Z)CAREA6A0-3O01JSISQUOCo-iooo1OO-- O.v.9-0Medium groined sandstoneFine to medium groined sandstone\Wjj?: si.a:UJo.a.UPPERMONTEREY0-2500'Porcelaneous shale, generally platy, locally chertyrio 2 2tr LOWERitrUlie -J*- z.- .TEMBLOR (PT SAL )0-6001Fine to medium grained sandstone, locally tuffaceousRINCONo-iooo'Cloy shale and silly shaleni'.rzirVAQUEROS0-600'/.TT. ' " TTSESPEO-I500'o-«0. 0O -0000- -0COLDWATERa:z -?oo UJUlUl-JooCOZY DELLo - 1000'E:' ". MATILIJA. .' .0 - 800'. .JUNCAL0 -1200'Err'-rEfE2JCRET.L.URASS1- Ct T-\.jro-io'ESPADA( KNOXVILLE )Fine to coarse sandstone, conglomerate,and reddish and greenish silty shale( non -marine)Cloy shale and silty shaleFine to coarse groined sandstonewith minor siltstone interbedsCloy shale and silty shale withthin sandstone interbedsSandy limestoneCarbonaceous shale withthin sandstone interbeds. . . .FRANCISCANFint to medium groined sandstone and sandy siltstoneFine to coarse grained sandstonewith siltstone interbeds0-600'SIERRA BLANCAOrganic, phosphatic, clay shalt" zr 0UlQ.Q.Z)Diatomite end diatomoceous siltstoneEastern sandstone (Tequepis) facie*Siliceous and silly shale, generally platy3i UlZUl0UlDESCRIPTIONO MBOQOQOQ * *.y.-rv.v'.-Sandstone, sheared cloy shale, chertFigure 8E. Generalized stratigraphic section of southeastern Santa Maria district(reprinted from Crawford, 1971, by permission).
19area, Kablanow and Surdam (1984) for the Huasna area, and Curiale and others (1985),Orr (1986), and a study later released as Isaacs and Tomson (1990) for the onshore SantaMaria area. Some data was also available for the Point Conception DST well in theoffshore Santa Maria basin (Claypool and others, 1979; King and Claypool, 1983; Petersenand Hickey, 1984,1987).Reported values for total organic carbon (TOC) are 1-5% (av 2-3%) for the MontereyFormation in the Pismo basin (Surdam and Stanley, 1981). In the Santa Maria basin,reported values for TOC are 0.7-8% (av 1%) for the Sisquoc Formation, 1-18% (av 6%) forthe Monterey Formation, and 1-4% (av 2%) for the Point Sal Formation (Isaacs andothers, 1989, 1990). In general, Monterey strata are classed as type n kerogen thought tohave derived mainly from marine algal sources with varying contributions from terrigenoussources (Surdam and Stanley, 1981; Kablanow and Surdam, 1984; Isaacs and Tomson,1990). Because of its sulfur richness, the kerogen type has come to be generally knownsubsequent to the assessment as type II-S (e.g., Heasler and Surdam, 1989).BURIAL HISTORY, THERMAL MATURITY, AND TIMING OF MIGRATIONThe main burial histories available at the time of the assessment were Pisciotto (1981)for the onshore Santa Maria basin, Heasler and Surdam (1983, 1985) for the Pismo basin,and Kablanow and Surdam (1984) for the Huasna basin. All these histories were limitedby lack of measured equilibrium thermal gradients (which have been published for onlyone well in each of the Santa Maria Valley, Orcutt, and Lompoc fields by French, 1940)and lack of empirical evidence about paleogradients.At the time of the assessment, models of maturation and thermal history in the SantaMaria Basin assessment province had been complicated by two newly discovered problems:(1) misleading and difficult-to-interpret maturity parameters; and (2) misleading anddifficult-to-construct thermal models.Maturity parameters are misleading and difficult-to-interpret probably because of bothcompositional characteristics of the kerogen (sparse vitrinite, high sulfur) and oilgeneration after comparatively short time-temperature histories (Milner and others, 1977;McCulloh, 1979; Walker and others, 1983; Petersen and Hickey, 1984, 1987; Heasler andSurdam, 1983, 1985, 1989; Orr, 1986). For most purposes, maturity parameters in theMonterey Formation are considered unreliable or of little value (for a summary, see Isaacsand Petersen, 1987).Thermal models are misleading and difficult-to-construct because of both unusualporosity and thermal conductivity characteristics of diatomaceous rocks and uncertaintiesin the thermal history (for a summary, see Isaacs and Petersen, 1987). Combined withunreliable maturity parameters, for most purposes thermal models are highly speculativeand of questionable value for predicting oil generation. However, ongoing research onthese topics subsequent to the 1987 assessment may be providing useful approaches topredictive understanding (e.g., Heasler and Surdam, 1989; King and Lillis, 1990).
20Potential deep hydrocarbon generation areas in the onshore Santa Maria basin lie in themajor synclinal areas between the Santa Maria Valley and Orcutt fields and between theOrcutt and Lompoc fields. In both these synclinal areas, the Monterey Formation showsgreater diagenetic grade and thermal maturity than in adjacent structurally high areas(Pisciotto, 1981; Isaacs and Tomson, 1990).On the basis of thickness differences in the Sisquoc Formation and younger strata acrossthe major anticlinal structures (see for example Figure 5, section A-B"), growth of thesestructures has long been regarded as having begun in the late Miocene about coincidentwith the boundary between the Sisquoc and Monterey Formations (Woodring andBramlette, 1950). Growth of these trapping structures has presumed to have preceded themigration of most generated hydrocarbons (Crawford, 1971). Subsequent to theassessment, a new structural interpretation suggested that the formation thicknessdifferences might be due to fault-repetitions in a later compressional tectonic regime(Namson and Davis, 1990). If this interpretation is correct, the majo
SANTA MARIA OUTER SANTA CRUZ S A LI N A S C U Y A M A OFFSHORE SANTA MARIA SANTA LUCIA SANTA BARBARA-VENTURA LOS ANGELES . SANTA ROSA 20 KM Figure 1C. Oil and gas fields in the assessment province and adjacent areas to
AER/AGS Special Report 101 (October 2015) 1 Introduction K.E. Maccormack1, L.H.Thorleifson2, R.C. Berg3, and H.A.J. Russell4 1 Alberta Geological Survey 2 Minnesota Geological Survey 3 Illinois State Geological Survey 4 Geological Survey of Canada Abstract The objective of this year’s 3D workshop is to
GEOLOGICAL SURVEY SELECTED GEOLOGICAL SURVEY, U.S. BUREAU OF MINES, AND ALASKA DIVISION OF GEOLOGICAL AND GEOPHYSICAL SURVEYS REPORTS AND MAPS ON ALASKA RELEASED DURING 1978, INDEXED BY QUADRANGLE BY Edward H. Cobb Open-file Report 79-706 1979 This report is preliminary and has not been edited or reviewed for conformity with
Illinois State Geological Survey Natural Resources Building 615 East Peabody Drive Champaign, IL 61820-6964 (217) 333-4747 Indiana Geological Survey
GEOLOGICAL SURVEY FOR THE FISCAL YEAR 1988-89 (JULY 1, 1988-JUNE 30, 1989) by Larry D. Fellows State Geologist Arizona Geological Survey Open-File Report 89-11 Arizona Geological Survey 416 W. Congress, Suite #100, Tucson, Arizona 85701 This report is preliminary and has not been edited
U.S. Geological Survey U.S. DEPARTMENT OF THE INTERIOR U.S. Geological Survey 10 Bearfoot Road Northborough, MA 01532 Water Resources Data Massachusetts and Rhode Island Water Year 2001 Prepared in cooperation with the States of Massachusetts and Rhode Island and with other agencies U.S. Geological Survey Water Resources Data Water-Data Report .
veys reports and maps on Alaska released during 1974, indexed by quadrangle: U.S. Geological Survey Open-file Report 75-128, 46 p. Cobb, E. H., 1976, Geological Survey and selected U.S. Bureau of Mines and Alaska Division of Geological and Geophysical Sur veys reports and maps on Alaska released during 1975: U.S. Geological Survey Open-file .
Geological mapping is a step-by-step process, which culminates in a compilation of a geological map. Up on completion of the geological map, applied maps of various . to identify geological hazards. 1) IntroductIon to estim
hydrogeological and engineering geological mapping) o Detailed geological mapping of the direct area of the route (structural geological, hydro-geological and engineering geological mapping) o Test pits, test shafts and outcrops (exc
