Late Cretaceous (Santonian-Campanian) Stratigraphy of the Northern Sacramento Valley, California

Home , Campanian, Chico Formation, Late Cretaceous, Santonian

Late Cretaceous (Santonian-Campanian) stratigraphy of the northern Sacramento Valley, California

DcT^rf {Department of Geology, University of California at Davis, Davis, California 95616 rElbK L). WAKL) J

ABSTRACT INTRODUCTION METHODS

The Upper Cretaceous (Coniacian-lower Thick accumulations of Upper Cretaceous Strata of the Chico Formation dip gently to Campanian) Chico Formation of the north- sedimentary deposits are found on the western, the southwest. Sections were mejisured using eastern Sacramento Valley, California, includes northern, and eastern margins of the Great Val- either tape and compass or Jacob's staff. In some three newly defined members at the type local- ley of California (Fig. 1). The search for oil and areas, outcrop data were plotted on U.S. Geo- ity: (1) cobble conglomerate of the basal Pon- gas in northern California, as well as interest in logical Survey topographic quadrangles and derosa Way Member, (2) coarse-grained con- the processes of sedimentation in fore-arc re- stratigraphie columns were determined trigo- glomeratic sandstone of the overlying Musty gimes, has made the Great Valley seque nce, ex- nometrically. Paleontologic collections of mac- Buck Member, and (3) fine-grained silty sand- posed along the west side of the Sacramento rofossils were made during the measuring of stone of the uppermost Ten Mile Member. Valley, probably the best-studied fore-arc de- sections. Minor offset of bedding was observed Other outcrops of the Chico Formation exhibit posit in the world (Ojakangas, 1968; Dickinson, on more southerly exposures of the Chico For- the same three members plus an additional unit, 1971; Ingersoll, 1978, 1979). These workers in- mation, and such structural modification be- the Kingsley Cave Member, composed of mud- terpreted strata of the Great Valley sequence to comes more prominent farther north. These stone. The Chico Formation resulted from a be deep-marine slope and basin-plain deposits. disruptions are easily recognized and the offset transgression onto the Sierra Nevada basement Many of these rocks contain an abundant micro- can be compensated for, except on Antelope in the Late Cretaceous. The Kingsley Cave fauna that has been utilized for correlation of Creek, where severe folding has occurred at Member was deposited locally in quiet-water diverse lithologic types (Goudkoff, 1945; some localities. Such areas were treated as iso- conditions below wave base in an intrashelf Douglas, 1969). basin and may represent a marine connection In contrast, Upper Cretaceous strata on the with regions farther northeast. eastern side of the Great Valley, including lateral Macrofossils allow correlation of the Chico equivalents of the gas-producing strata of the Formation with marine deposits of the Great Sacramento Valley, have received only minimal Valley sequence exposed along the western attention. This is due, in part, to the relative Sacramento Valley. Strata of the Guinda and paucity of a microfauna, as well as to the re- Forbes Formations represent submarine fan- moteness of most exposures. Little is known, channel to outer-fan deposits of a shallowing consequently, of the depositional environments Late Cretaceous fore-arc basin. The Santonian of these proximal facies, and biostratigraphic re- Guinda Formation, a massive sand unit depos- lations have not been defined in most sections. ited in fan-channel to distal-fan turbidite envi- In this paper, we describe new sections with ronments, is correlative with the Musty Buck paleontologic collections from the Chic» For- and Kingsley Cave Members of the Chico For- mation in Tehama and Butte Counties. Meg- mation. The Dobbins Shale Member of the afossils now allow correlation between both Forbes Formation, a widespread mudstone unit margins of the Great Valley, thus uniting out- of hemipelagic outer-fan to basin-plain deposits, crops of this depositional system into a compre- is correlative with the Kingsley Cave Member of hensive littoral to bathyal sedimentologic the Chico Formation and reflects a Santonian framework. transgressive event in the northern fore-arc basin. Mudstones and turbidites of the middle of the Forbes Formation are equivalent to the shallow-marine strata of the Ten Mile Member Figure 1. Distribution of Map Area of the Chico Formation. Correlatives of younger Upper Cretaceous outcrop Forbes Formation strata have not been posi- along the margins of the tively identified from the Chico Creek region Sacramento Valley. Stippled but may be represented by unfossiliferous, cross- area represents outcrop of bedded, coarse-grained sandstones found above the Chico Formation. sections of the Chico Formation.

Geological Society of America Bulletin, v. 95, p. 618-627, 11 figs., May 1984.

618

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/95/5/618/3445089/i0016-7606-95-5-618.pdf by guest on 26 September 2021 CRETACEOUS STRATIGRAPHY, SACRAMENTO VALLEY, CALIFORNIA 619

of Chico "should be abandoned as a group or which traverses the higher elevations of the field series name, but that it might usefully be re- region. The member unconformably overlies tained as a formational name for the rocks at pre-Cretaceous metamorphic rocks, this contact and near the type locality on Chico Creek." Re- being obscured in most areas by a cover of ero- cent workers have, as a rule, followed this sional debris. In the extreme northeast corner of suggestion. sec. 1, T. 23 N., R. 2 E., exposures on Big Chico The overlying and extensive Tuscan Forma- Creek in the vicinity of the Ponderosa Way tion of Pliocene age, and locally the Eocene Bridge are thus arbitrarily defined as the lower- Lovejoy Basalt, limit exposures of the Chico boundary stratotype for the Ponderosa Way Formation to narrow outcrops along only the Member. The member is approximately 200 m most deeply incised drainages of the Lassen thick on Big Chico Creek, with the upper- foothills region (Fig. 2). The first investigations boundary stratotype located in the center of sec. of Chico strata were those of Trask (1856), who 1, T. 23 N., R. 2 E. The member is well exposed described ammonites from the Cretaceous de- along Butte Creek, 8 km to the southeast, both posits exposed along Big Chico Creek. Diller above and below the Helltown Bridge crossing; (1889, 1895) mapped additional Chico Forma- here the stratigraphic thickness is somewhat less tion outcrops on Deer, Mill, and Antelope than on Big Chico Creek, —180 m. Creeks and noted that Cretaceous fossils had The lower part of the member consists of been found in those areas. However, due to their cobble conglomerate with local sand lenses remoteness, these outcrops have never been stra- (Fig. 4). Cobbles are poorly sorted and moder- tigraphically measured or collected. ately well rounded, and they range in size from 6 North of the Chico region, Cretaceous stratig- to 20 cm in diameter, with some as much as 70 raphy and molluscan occurrences in the vicin- cm. Clasts are primarily matrix-supported and ity of Redding, California, were summarized by consist of chert, metavolcanics, quartzite, schist, Popenoe (1943), who recognized six lithologic and slate, suggesting that they were derived from members. On the basis of macrofossils, he the underlying metamorphics. Granitic clasts equated the youngest of these deposits with the from nearby Mesozoic Sierran intrusives are ab- Figure 2. Outcrops of the Upper Creta- base of the section exposed along Big Chico sent. Clasts are embedded in a medium- to ceous Chico Formation, Tehama and Butte Creek. Matsumoto (1959-1960, p. 4) proposed coarse-grained arkosic sandstone matrix. Rare Counties, California. the name Redding Formation for these strata, trough cross-stratification occurs within the whereas Jones and others (1978) suggested that sandstone lenses, and there are indistinct, normal lated sections. Additionally, infilling of topo- at least some of Popenoe's (1943) Members grading and cobble imbrication in some graphic lows in the Cretaceous surface by I-VI were of formational rank. sections. younger volcanics results in isolation of some of The type locality for the Chico Formation, The upper portions of the member become the outcrops from the rest of the section. These Big Chico Creek, was established by Taff and increasingly sandy through interbedding of exposures were placed into a composite section others (1940) and has been the principal field sandstone lenses within the massive cobble con- based on the structural attitudes of the sediments area for biostratigraphic and sedimentologic glomerate. On Big Chico and Butte Creeks, the bracketing them. By necessity, then, some seg- studies. Saul (1959,1961) outlined the sedimen- transition to the overlying Musty Buck Member ments of the stratigraphie sections are incom- tologic units and the molluscan succession ob- is gradational at the localities noted above. Ma- plete, resulting in local truncation of lithologie served at the type locality. She recognized three rine fossils (ammonites and other mollusks) and faunal ranges. distinctive lithologies and informally designated have been reported from only the uppermost them the Ponderosa Way Member, the Musty exposures of the Ponderosa Way Member on STRATIGRAPHY Buck Member, and the Ten Mile Member. This Big Chico Creek (Matsumoto, 1959-1960). paper follows her usage in formal presentation. Exposures of the member along Butte Creek East Side: Lithostratigraphy Further examination of Chico Formation out- lack a normal marine macrofauna. crop along Deer, Mill, and Antelope Creeks has In the 125 years since the introduction of the shown the presence of these same three mem- Musty Buck Member name Chico for Upper Cretaceous sedimentary bers, plus an additional unit, herein designated deposits of the Pacific Coast of North America, the Kingsley Cave Member. Stratigraphic rela- The Musty Buck Member rests conformably the term has been employed in a variety of litho- tions of Chico Formation outcrops are summar- on the underlying Ponderosa Way Member on logie contexts. Cretaceous strata from California, ized in Figure 3. Big Chico and Butte Creeks. We place the Oregon, and Vancouver Island were lumped lower-boundary stratotype of the Musty Buck within the Chico Group by Gabb (1869), and Ponderosa Way Member Member at the uppermost occurrence of cobble successive workers have argued series, group, or conglomerate on Big Chico Creek, in the center formational designations for the name (Ander- The name Ponderosa Way Member is of sec. 1, T. 23 N., R. 2 E. The upper-boundary son, 1938, 1943; Taff and others, 1940). In an adopted for the conglomeratic lower unit ob- stratotype is placed at the highest exposures of effort to eliminate the confusion associated with served at the base of the Chico Formation along the pebbly sandstone, along Big Chico Creek at usage of the term Chico, Peck and others (1956, Butte, Big Chico, and Deer Creeks. The name is the west margin of sec. 13, T. 23 N., R. 2 E. p. 1982) proposed that stratigraphie application taken from the foothills road, Ponderosa Way, More accessible exposures of the member are

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/95/5/618/3445089/i0016-7606-95-5-618.pdf by guest on 26 September 2021 620 HAGGART AND WARD

lii.'&S-j Mid to Upper Forbes Equiv. Figure 3. Correlation, based on macrofossils, of east-side Sacramento Valley outcrops.

Tenmile Member r500

fgSSj Kingsley Cave Member

co Ij^v^l Musty Buck Member ce Barren u [-300 |.'P;-dS»l Ponderosa Way Member

^tij^ Pre-Cretaceous Metamorphics -100 Zonal Boundary

•0

Base of

Chicoensis Zone Capensis

Venustum

BUTTE CREEK ANTELOPE CREEK V//&W BIG CHICO CREEK

wm NORTH MILL CREEK DEER CREEK SOUTH

found along Butte Creek. Here, the relative and cobbles. Pebbles vary in size to 4 cm in difficult to observe, but horizons of calcareous thickness of Musty Buck strata (110 m) is sub- diameter and include chert, quartz, and mud concretions appear to have developed along stantially less than found on Big Chico Creek to clasts with subordinate schist, moderately original bedding or at the base of crcss sets. To the northwest (215 m). rounded to subrounded, and decreasing in di- the north on Deer and Mill Creeks, shell beds Farther north, on Deer Creek, cobble beds of ameter and occurrence upsection. The pebbles and concretionary horizons are less abundant, the member are found directly onlapping the are enclosed in a medium- to coarse-grained and the sands are more massive and featureless. pre-Cretaceous metamorphic rocks. This is the sandstone matrix consisting of subangular to However, pebble beds and floating pebbles are only locality where we have actually observed subrounded quartz with associated feldspar and also common here. Fossils, principally bivalves the contact of the Chico with the underlying biotite. and gastropods, are generally well preserved basement rocks. Lithologies of the member Large-scale, low-angle planar cross-stratifica- throughout the Musty Buck Membei, either in stratotype as well as the exposures on Butte tion occurs in the Musty Buck Member along concretionary lag deposits or individually in the Creek, Deer Creek, and Mill Creek are essen- Butte and Big Chico Creeks, and the upper por- matrix. The abundance of mollusks ass ignable to tially identical. The unit consists of arkosic sand- tions contain local associated shell-lag de])osits. the families Veneridae, Mactridae, Tellinidae, stone, greenish-gray to tan in color, containing Bioturbation has apparently obscured many and Naticidae within the member on Big Chico extensive pebble beds as well as single pebbles primary sedimentary structures, making bedding Creek led Saul (1961) to infer a maximum water

within the sands, commonly in association with climbing ripples and load structures. The Ten Mile Member is quite fossiliferous, with excel- lently preserved wood and mollusks found both singly in the matrix or as lag deposits in concretionary horizons (Fig. 5). Saul (1961) suggested a maximum water depth of 90 m for the member, on the basis of its molluscan assemblages.

Kingsley Cave Member

The three lithologic units described above are readily observed along Big Chico and Butte Creeks and, to date, have been the only rock types recognized within the Chico Formation. Our work on drainages to the north has shown the existence of yet a fourth distinctive lithology, which is herein called the Kingsley Cave Member. Named for the site of the near-extermination of the Yana Indians who inhabited the Lassen foothills region in recent history (Kroeber, 1961), strata of the Kingsley Cave Member crop out along Deer, Mill, and Antelope Creeks. The proposed lower boundary of the stratotype is located at the extreme northward bend of Mill Creek in the NEVi of the NW* of sec. 20, T. 27 N., R. 2 E. Farther upstream, but separated by a covered interval, there are found extensive exposures of the Musty Buck and Ten Mile Members. The proposed upper boundary of the type section is located along Mill Creek at the stratigraphically highest exposures of the unit in Figure 4. Exposure of the Ponderosa Way Member along Butte Creek showing unsurveyed land of the Lassen National Forest. interfingering of coarse sandstone lenses within conglomerate. Two-pound sledge for This locality is just west of the SW'/4 of sec. 19, scale. T. 27 N., R. 2 E. Along Mill Creek, -350 m of strata in discontinuous outcrop was measured. depth of 35 m. On Butte Creek, the abundance Chico Creek. The full thickness of the member is The member consists typically of spheroidally of wood and plant debris and the lack of a nor- obscured on Big Chico as well as all other creeks weathered greenish-gray to bluish-gray, heavily mal marine fauna suggest nonmarine, perhaps in the region; the upper-boundary stratotype is bioturbated muddy siltstone and silty mudstone. brackish-water, deposition. thus defined as the uppermost occurrence of the Containing common angular quartz and biotite distinctive lithology making up the Ten Mile to 0.5 mm, these fine-grained clastics are locally Ten Mile Member Member on Big Chico Creek. The outcrop of interbedded with sandy horizons and lack dis- this member along Big Chico Creek is composed tinctive sedimentary structures. Pebble con- The stratigraphically highest deposits of the of -575 m of discontinuous exposures. glomerates as much as 1 m thick are rare but Chico Formation exposed along Big Chico and The member, typically forming tall bluffs, interspersed throughout the member. These are Butte Creeks constitute the third lithologic consists of fine-grained silty sandstone, greenish- typically associated with shell-lag deposits con- member recognized within the Chico Forma- gray to tan in color, moderately well sorted and taining an abundant molluscan fauna. Gastro- tion. The Ten Mile Member is named for the site compositionally similar to the subjacent Musty pods, cephalopods, and disarticulated bivalves of the "Ten Mile House" located along the old Buck Member. Pebbles are rarely noted and are found within these lags are generally broken; route of Highway 32, paralleling Big Chico quite small and rounded where found. Large- many are the same species observed in the other Creek. The lower boundary of the Ten Mile scale, low-angle planar cross-stratification is oc- fossiliferous members of the Chico Formation. Member is proposed as the last occurrence of casionally observed within the member and Additionally, abundant and well-preserved mol- common pebbles, either singly or in stringers, bioturbation is more common than in the Pon- lusks, primarily ammonites and inoceramids, are . within the sandstone exposed in the SWW of the derosa Way and Musty Buck Members. Exten- found weathering out of the matrix or in calcite- ' NWK of sec. 13, T. 23 N„ R. 2 E., along Big sively burrowed mud horizons occur at intervals cemented concretions.

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/95/5/618/3445089/i0016-7606-95-5-618.pdf by guest on 26 September 2021 622 HAGGART AND WARD

more distal fore-arc facies. Kirby (1943) described a formational succession for the west- side strata that is still in use. Ki/by's Upper Cretaceous succession included the Sites, Funks, Guinda, and Forbes Formations, in ascending stratigraphic order. Kirby (1943, p. 282-283) noted the existence of a distinctive mudstone facies characterized by calcareous nodules at the base of the Forbes Formation. Emerson and Roberts (1962) called these strata Ihe Dobbins Shale and Pessagno (1976) proposed member status for this unique Great Valley sequence unit. More recent workers (Ingersoll and others, 1977) proposed new formational nomenclature, based on petrofacies analysis, for the Great Val- ley sequence. As justification for this nomenclature revision, these workers maintained that lithofacies variations, in the absence of fossils, make field mapping of Kirby's (1943) original units difficult at best. This may be true for older Figure 5. Concretion development around shell lags and water-escape structures in portions of the Great Valley sequence, but it the Ten Mile Member, Big Chico Creek. does not hold for the Guinda and Forbes For- mations, which we believe are distinctly recog- On Big Chico, Deer, and Mill Creeks, expo- deposits but suggested additional, locally impor- nizable in the field, even without fossil data. We sures of coarse-grained planar- and trough- tant molluscan species to complement the am- therefore follow Kirby's (1943) nomenclature cross-stratified sandstones are found strati- monite and inoceramid distributions. for the upper portions of the Great Valley graphically above, but not continuous with, Recollecting classic outcrops in the western sequence. exposures of the Ten Mile and Kingsley Cave Sacramento Valley, Ward and Haggart (1981) Ojakangas (1968) and other workers (Dick- Members. These unfossiliferous, moderately showed that portions of the lower Campanian inson, 1971; Ingersoll, 1978) interpreted the well-sorted, organic-rich strata are interpreted as ammonite-inoceramid sequence proposed by western outcrop belt of the Great Valley se- deltaic to shallow-marine deposits of probable Matsumoto were in error. On the basis of de- quence as deep-marine deposits. Basin-plain to mid-Campanian age, on the basis of their strati- tailed stratigraphic collections from the highly slope environments, especially submarine-fan graphic proximity to older Campanian sedi- fossiliferous facies of the Chico Formation as facies, were comprehensively analyzed by Inger- ments. It is possible, however, that these strata well as other outcrops bordering the Sacramento soll (1978). This work emphasized older por- belong to the Kione Formation (upper Campan- Valley, the relative distribution of important tions of the sequence, Cenomanian through ian to Maastrichtian), a nearshore-deltaic unit ammonites and inoceramids in the Santonian Coniacian, and did not utilize younger strata due readily recognized in the subsurface of the east- and Campanian of California has been estab- to difficulty of access. Although detailed sedi- ern Sacramento Valley (Edmondson, 1962; lished (Haggart, in press). This distribution is mentologic analyses of Santonian aid Campa- Garcia, 1981). summarized in Figure 6. nian strata of the Sacramento Valley have not Recent sampling of the Chico Formation and been undertaken, deposition during the Late East Side: Biostratigraphy its time equivalents elsewhere in the Sacramento Cretaceous is considered to have occurred in a Valley has shown the presence of a magnetic shallowing basin. The first detailed stratigraphic study of Upper reversal corresponding to anomaly 33-34 ob- We have examined Santonian and Campa- Cretaceous ammonites of California, based on served at the base of the Campanian section at nian strata along the western Sacramento Valley modern taxonomy, was undertaken by Matsu- the type locality at Gubbio, Italy (Ward and outcrop belt. Exposures of the Guinda and moto and culminated in an extensive mono- others, 1983). This reversal appears to be wholly Forbes Formations, including the distinctive graph and revision of the fauna (1959-1960). within the zone of Baculites chicoensis TRASK Dobbins Shale, can be traced from Black Butte Matsumoto discussed the strong affinities of the and is thus an important correlation tool when on the north to Salt Creek and farther south (see California fauna with other regions of the North coupled with the fossil data. The presence; of the Fig. 1). The strata maintain a remarkably similar Pacific, notably western Canada, Alaska, and reversal firmly identifies the Chicoensis zone as and persistent facies pattern throughout most of Japan. On the basis of his field work and as- early Campanian in age. their exposure; stratigraphic relations are sum- sessment of museum specimens, he compiled a marized in Figure 7. suggested ammonite and inoceramid distribu- West Side: Lithostratigraphy The Guinda Formation consists of alternating tion for California (1959-1960, Pt. 3, PI. 1) and massive sands and thin-bedded siltstones and attempted correlation of Cretaceous outcrops Stratigraphic analysis of outcrops from the shales (Fig. 8). Some of the sand bodies reach within the region. Popenoe and others (1960) western margin of the Sacramento Valley, in- 3 m in thickness and are laterally persistent over essentially followed Matsumoto's scheme in itially prompted by the search for natural gas, distances of hundreds of metres. Gradsd bedding their correlation of Pacific Coast Cretaceous has resulted in a detailed understanding of these with successive horizontal laminations, indica-

tive of Bouma AB sequences, is locally capped stones in the Dobbins Shale Member. Through- ments of oysters are found in locally developed with ripple laminations. Most of the sands are out most of its exposure, this distinctive unit is basal conglomerates. These laminated siltstones typified by an irregular basal surface, and some characterized by poorly laminated to nonlami- and shales are typically associated with abun- sand bodies exhibit convoluted bedding in their nated mudstones with abundant calcareous con- dant plant debris and, locally, vertical burrows. uppermost portions. Calcareous concretions, lo- cretions, many fossiliferous (Fig. 9). Grazing traces and some vertical burrows are cally reaching 3 m in diameter, are quite com- Massive sands that locally exhibit graded also common in the massive sands. We interpret mon in the uppermost portions of the Guinda bedding, horizontal laminations, and, rarely, the middle portion of the Forbes Formation as Formation. ripple horizons, characterize the overlying mid- mid- to outer-fan deposition in a much shal- Interbedded with the massive sands, there are dle portion of the Forbes Formation (Fig. 10). lower marine setting. thin beds of siltstone and mudstone, generally These sands reach thicknesses of 1 m but are less than 5 cm in thickness. These, too, exhibit generally much thinner and are typified by ir- West Side: Biostratigraphy abundant horizontal laminations, rare ripple regular basal surfaces. Lower portions of the marks, and convoluted bedding. Such facies are sands commonly contain shale clasts derived Many workers have noted the difficulty of most prominent in the vicinity of Putah Creek, from the finer-grained interbeds. Large frag- correlating Cretaceous strata of the western out- are common at Black Butte, but notably absent in the Salt Creek region. We interpret this lower portion of the Guinda to reflect channel and proximal turbidite deposition in the mid-fan environment (Walker and Mutti, 1973). feet meters Uppermost portions of the Guinda Formation 100 are represented by a sequence of thin-bedded turbidite deposits. Characteristically, these flat- bottomed sand and silt interbeds rarely exceed 12 cm in thickness. Typically, Bouma A is missing, but B and, locally, C are well developed. Figure 7. Correlation, based Overlying these outer-fan facies (Walker and on macrofossils, of west-side Mutti, 1973), we recognize hemipelagic mud- Sacramento Valley outcrops. EUROPEA N STAGE S SANTONIAN CAMPANIAN chicoensis Baculites MATSUMOTO , Baculites Inornatus Zone

Pseudoschloenbachia inornatus sp. off. P. boulei Barren

Baculites capensis I96 0 ^ Chicoensis 1. Inoceramus ezoensis Zone schmidti Bostrychoceras Hyphantoceras chicoensis Inoceramus Baculites Baculites Baculites venustum capensis inornatus Schmidt —i ^ SAND •sie* elongatum cn CREEK ZX3 m i -TD o EUROPEA N 1 STAGE S MID- SANTONIAN | ^ CAMR 1

Figure 6. Comparison of ranges of important ammonite and inoceramid species in northern California, as suggested by SALT BLACK Matsumoto (1959-1960) and Haggart (in press). CREEK BUTTE

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/95/5/618/3445089/i0016-7606-95-5-618.pdf by guest on 26 September 2021 624 HAGGART AND WARD

Figure 8. Massive, mid-fan, proximal turbidites of the Guinda For- mation, Black Butte. Staff in upper center of photograph is 1.6 m long.

Figure 9. Exposure of the Dobbins Shale Member of the Forbes Formation along Salt Creek showing distinctive calcareous concretions.

crop belt of the Great Valley sequence. Due to the paucity of megafossils and their relatively poor preservational state, most studies have re- lied on microfossils, principally foraminifera and radiolaria, for age dating of lithologic units. Goudkoff (1945) established a foraminiferal zonation for Great Valley strata that is in use, with some modification, today. Trujillo (1960) showed that some of GoudkofFs foraminiferal assemblages were facies- rather than time- dependent and Douglas (1969) further refined the original zonation. Still, only two planktic foraminiferal zones are recognized within the Santonian and early Campanian (Douglas, 1969, Fig. 4). It is clear that, when available, the resolution of megafossils, particularly ammonites and inoceramid bivalves, is highly desirable and a valuable correlation tool. Although some mixing of distinct faunal assemblages might be expected in the submarine-fan environment, the presence of repeated unique fossil successions Figure 10. Interbedded sands and siltstones of the middle portion of the Forbes strongly suggests that displacement of faunas is Formation, Salt Creek. not an important problem here. Ward and Haggart (1981) showed that meg- has confirmed the ammonite and inoceramid Valley sequence and also recognize an addi- afossils can be successfully employed as biostra- sequence observed in the arenaceous east-side tional zone, that of Baculites inomatus MEEK, tigraphic tools in at least the upper portions of Chico deposits. We have identified the Capensis, superjacent to the youngest zone observed in the the Great Valley sequence. Further collecting at Elongatum, Schmidti, and Chicoensis zor.es in Chico outcrops (Haggart, in press). The recogni- additional localities in the western outcrop belt Santonian and Campanian strata of the Great tion of these zones allows detailed correlation

Corning Gas Field 12-24N-3W

er SE OF 500 m CHICOENSIS ZONE 20 km

0 BLACK BUTTE NORTHEAST

Figure 11. Fence dia- gram illustrating relationships of Santonian and Campanian lithostrati- graphic units, Sacramen- ANTELOPE to Valley. Surface sec- CREEK tions are equilibrated at the first occurrence of B. chicoensis. Well log sections correlated by lithologie units.

X XX O East Rice Creek Gas Field X 28-23N-2W

MILL CREEK

for the first time between the east-side Chico deposits and west-side Great Valley strata. PONDEROSA WAY MBR CORRELATION BIG CHICO SOUTHEAST CREEK Megafossil correlations indicate that the upper portion of the Chico Formation is time- equivalent to the Guinda and Forbes Forma- ered to represent Coniacian time in Japan An important implication of the ammonite tions of Kirby (1943). Figure 11 illustrates the (Matsumato and others, 1981). Additionally, succession shown in Figure 6 is the recognition relationships between the various lithologic LouEUa Saul (1983, personal commun.) noted a of a previously unknown stratigraphie disconti- units discussed above. species of Cymbophora from lowermost Musty nuity at the type section of the Chico Formation Oldest strata of the Ponderosa Way Member Buck strata on Big Chico Creek that may be as well as other nearby outcrops. Strata of the on Big Chico Creek are unfossiliferous. How- Coniacian in age. At this point, precise age as- Elongatum and Schmidti zones, straddling the ever, highest exposures of the member have signments of the uppermost Ponderosa Way and Santonian-Campanian boundary, are represent- yielded specimens of the Coniacian form, Bacu- lowermost Musty Buck members are difficult to ed by a very short unfossiliferous interval in out- liles schencki MATSUMOTO (Matsumoto, make. crops in the vicinity of Big ChicO' Creek. A 1959-1960, Pt. 3). Matsumoto suggested that Uppermost strata of the Musty Buck Member widespread unconformity of similar age is rec- oldest strata of the Musty Buck Member along contain Baculites capensis WOODS on Big ognized by microfossil workers in the subsurface Big Chico Creek are Santonian, on the basis of a Chico Creek. Unfortunately, unequivocal spec- of the Sacramento Valley (Chuber, 1962; Ed- few juvenile ammonite specimens. However, we imens of this ammonite are rare from the Great mondson, 1962) and is possibly correlative with have recovered a fragment of Barroisiceras Valley sequence, but a few occurrences indicate the missing interval on Big Chico Creek. (sensu Matsumoto and others, 1981) sp. from that rocks of the basal Guinda or underlying To the north, however, along Mill and Ante- lowermost exposures of the Musty Buck Mem- Funks Shale are probably correlative with lope Creeks, the Kingsley Cave Member repre- ber along Deer Creek. Barroisiceras is consid- youngest strata of the Musty Buck Member. sents deposition in the late Santonian, as

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/95/5/618/3445089/i0016-7606-95-5-618.pdf by guest on 26 September 2021 626 HAGGART AND WARD

indicated by the presence of the ammonite Bos- gressed through Late Cretaceous time (Ingersoll, throughout exposures of the Dobbins Shale trychoceras elongatum (WHITEAVES) and the 1979). Transgression could be related to local Member and lower portions of the middle of the overlying zonal index species Inoceramus basin subsidence or eustatic sea-level rise or, Forbes. These units are characterized by the oc- schmidti (MICHAEL). Uppermost exposures of most likely, a combination of the two. currence of the zonal indicators Bostrychoceras the Guinda Formation contain specimens of B. Within the Chico Formation, thickness varia- elongatum and Inoceramus schmidti. elongatum, and the species is well represented in tions (see Fig. 3) and common load structures, As transgression continued eastward, sedi- the lower half of the overlying Dobbins Shale scour surfaces, and climbing ripples in the mentation in the eastern fore-arc biisin was, at Member of the Forbes Formation. Uppermost coarser facies suggest unstable, perhaps episodic least locally, reduced. The depositional hiatus portions of the Dobbins Shale contain abundant sedimentation; some areas received abundant observed at the type locality of the Chico For- specimens of I. schmidti We thus can correlate detrital influx, whereas adjoining regions were mation spans the duration of both of these upper the uppermost Guinda beds and the overlying exposed to nondeposition or perhaps removal of Santonian zonal indices. However, shallow- Dobbins Shale with the depositional hiatus ob- briefly deposited sands. The few paleocurrent marine deposition was occurring to the north, served in southerly exposures of the Chico For- indicators obtained indicate westward transport, where silts and muds of the Kinsley Cave mation and also with the more northerly and the great thickness of accumulated clastics Member were accumulating. Apparently, Kings- exposures of Chico, represented by the Kingsley suggests a high rate of terrigenous input from the ley Cave deposition occurred in a localized in- Cave Member. adjoining source regions. trashelf basin, as outcrops of this un ique facies The zonal ammonite Baculites chicoensis al- Rapid sedimentation in the western fore-arc are restricted to a small geographic area. West of lows correlation of the thick upper sequence of basin accompanied by slower deposition in the the outcrops of the Kingsley Cave facies on the Chico Formation, the Ten Mile Member, east was documented for the early Late Creta- upper Antelope Creek, coarse-grained planar- with transitional beds between the Dobbins ceous by Ingersoll (1979). However, a compari- cross-stratified sands and pebble conglomerates Shale and the overlying sands of the middle por- son of relative zonal thicknesses from the «astern of the Musty Buck Member are noted along tion of the Forbes Formation. Ward and Hag- and western outcrop belts (Figs. 3 and 7) indi- lower Antelope Creek. These strata contain a gart (1981) demonstrated the presence of B. cates a reversal of this pattern by the Santonian. number of specimens of B. elongatum in addi- chicoensis in the stratigraphic succession at Sand For example, the combined thickness of Elonga- tion to numerous other molluscan species. We Creek in Colusa County, and we have since tum and Schmidti zones spans -140-200 m of postulate a topographic high to the west of the documented this index fossil in the same transi- section at Black Butte and 80 m at Salt Creek. upper Antelope Creek region in the I ate Santo- tional beds along Salt Creek to the south and at However, on Mill Creek, the same zones contain nian that acted to restrict circulation in the local Black Butte to the north. a minimum of 375, but less than 560 m of strata. basin to the east, allowing fine-grained near- In the western outcrop belt, the Chicoensis zone shore deposits to accumulate. Alternatively, DISCUSSION spans a maximum of 40 m at Salt Creek, 45 m these heavily faulted outcrops may be indicative at Sand Creek, and an indeterminate amount of of movement of fault blocks, juxtaposing highly contrasting facies and analogous to the younger Integration of megafossil correlation with strata at Black Butte; in contrast, on Big Chico California continental borderlands terrain (Nil- stratigraphic analysis of exposures of the Great and Butte Creeks, more than 400 m of strata sen and Clarke, 1975). The relatively deeper- Valley sequence and the Chico Formation al- occur within the zone. It is not possible at this marine nature of the Kingsley Cave Member lows the formation of hypotheses about Santo- time to confidently correlate the thick sequences may reflect marine deposition farther to the east nian and Campanian sedimentation across the of Inornatus zone strata in the western outcrop and north, the postulated Lassen strait of Diller Late Cretaceous fore-arc basin of northern Cali- belt with the unfossiliferous upper portions of (1889). The true areal extent of Cretaceous fornia. Facies reconstruction suggests a cross- the sections exposed along the east-side creeks. strata in this region is not now known because of shelf transect from shallow, fluvial-deltaic depo- The much thicker sedimentary sequences on the the extensive volcanic cover. sition on the east to basinal and slope environ- eastern margin of the Sacramento Valley sup- ments on the west. port Ingersoll's (1979) conclusion of a decrease At the close of the Santonian, the. trend of The lithologic succession of the Chico Forma- in sedimentation rate in the distal reaches of the deepening of depositional sites in the western tion is highly suggestive of a transgressive se- Cretaceous fore-arc basin due to basin widening. fore-arc basin reversed. Progradation of fan quence, from basal fluvial-deltaic deposition to Arc-derived detritus was quickly deposited in complexes occurring as mid-fan to outer-fan fa- offshore, but still shallow, marine sedimentation localized regions adjacent to the arc front. cies, containing the lower Campanian zonal in the higher portions of the section. Howard In earliest Santonian time, represented by the index Baculites chicoensis, are found supeijacent and Reineck (1981) discussed recent high- zone of Baculites capensis, deposition of the to basin-plain facies of the Dobbins Shale. energy shelf sedimentation off Southern Califor- Musty Buck Member was occurring in shallow- Along the eastern basin margin, the deepest and nia, and Bourgeois (1980) documented an marine shoreface environments. To the west, thickest deposits of the Chico Formation (Ten Upper Cretaceous transgressive sequence in fossil control is still poor, but deposition in Mile Member) were accumulating, at li:ast in the shallow-marine rocks of coastal Oregon. Litho- deeper-marine submarine-fan complexes was more southerly outcrop regions. Thick deposits logic successions discussed by these authors re- occurring to produce the mid-fan to outer-fan of Chicoensis zone strata on Big Chico Creek flect the facies pattern observed in the Chico deposits of the Guinda Formation. (595 m) suggest a return to relatively higher Formation. This transgressive sequence is com- The late Santonian deepening of the western sedimentation rates characteristic of the early patible with the eastward migration of both fore-arc basin is well documented by the trend Santonian. Farther north, uppermost exposures magmatism and strandline as subduction pro- to distal-fan and basin-plain facies observed of the Kingsley Cave Member along Mill and

Ingersoll, R. V., 1978, Submarine fan fades of the Upper Cretaceous Great Antelope Creeks contain specimens of B. chi- the western and eastern outcrop belts indicates a Valley Sequence, northern and central California: Sedimentary Geol- coensis, suggesting that localized, quiet-basin major transgressive event in the Santonian, fol- ogy, v. 21, p. 205-230. 1979, Evolution of the Late Cretaceous fore-arc basin, northern and deposition continued into the early Campanian. lowed by rapid shallowing of the depositional central California: Geological Sodety of America Bulletin, v. 90, p. 813-826. Unfortunately, strata containing the mid- basin on the west during the early Campanian. ingersoll, R. V., Rich, E. I., and Dickinson, W. R., 1977, Great Valley Campanian zonal index Baculites inornatus are The transgressive event appears to be of basin- Sequence, Sacramento Valley: Geological Sodety of America, Cordil- leran Section Annual Meeting Field Guide, 72 p. missing from the eastern outcrop belt north of wide distribution. Jones, D. L., Sliter, W. V., and Popenoe, W. P., 1978, Mid Cretaceous (Albian to Turonian) biostratigraphy of northern California: Annates du Mu- the latitude of Sacramento. However, as noted seum d'Histoire Naturelle de Nice, v. 4, p. XXH.2-XXII.9. above, an apparently shallow-marine-deltaic ACKNOWLEDGMENTS Kirby, J. M., 1943, Upper Cretaceous stratigraphy of west side of Sacramento Valley south of Willows, Glenn County, California: American Assoda- complex is represented in unfossiliferous strata tion of Petroleum Geologists Bulletin, v. 27, p. 279-305. Kroeber, T., 1961, Ishi in two worlds: A biography of the last wild Indian in at the top of the sections along Big Chico, Deer, We would like to thank Rodney Watkins and North America: Berkeley, California, University of California Press, and Mill Creeks. This trend to shallower deposi- Sarah Baum for fruitful discussion. LouElla 256 p. Matsumoto, T., 1959-1960, Upper Cretaceous ammonites of California: tion must have preceded the development of the Saul, David Jones, and Ray Ingersoll provided Memoirs of the Faculty of Sdence, Kyushu University, Series D (Geology); Part 1: v. 7, p. 91-171; Pan 2: Spedal Volume I, 172 p.; late Campanian to Maastrichtian Kione deltaic helpful reviews of the manuscript. This work Part 3: Spedal Volume II, 204 p. complex (Kione Formation), as discussed by was supported in part by Geological Society of Matsumoto, T., Muramoto, K., Hirano, H., and Takahashi, T., 1981, Some Coniadan ammonites from Hokkaido (Studies of the Cretaceous am- Garcia (1981). Western basin deposits, massive America Research Grants 263580 and 299682 monites from Hokkaido -40): Palaeontological Sodety of Japan Trans- actions, new series, no. 121, p. 51-73. mid-fan sands, and proximal turbidites of the to J. Haggart and National Science Foundation Nilsen, T. H., and Clarke, S. H., Jr., 1975, Sedimentation and tectonics in the middle Forbes indicate a continuation of fan Grant EAR 80-19696 to P. Ward, as well as by early Tertiary continental borderland of central California: U.S. Geolog- ical Survey Professional Paper 925, 64 p. progradation and basin shallowing into the mid- the Atlantic Richfield Company and the De- Ojakangas, R. W,, 1968, Cretaceous sedimentation, Sacramento Valley, Cali- fornia: Geological Sodety of America Bulletin, v. 79, p. 973-1008. dle Campanian. partment of Geology, University of California at Peck, D. L., Imlay, R. W., and Popenoe, W. P., 1956, Upper Cretaceous rocks Davis. of parts of southwestern Oregon and northern California: American Association of Petroleum Geologists Bulletin, v. 40, p. 1968-1984. SUMMARY Pessagno, E. A., 1976, Radiolarian zonation and stratigraphy of the Upper Cretaceous portion of the Great Valley Sequence, California Coast REFERENCES CITED Ranges: Micropaleontology Spedal Publication no. 2,95 p. Popenoe, W. P., 1943, Cretaceous: East side Sacramento Valley, Shasta and Anderson, F. M., 1938, Lower Cretaceous deposits in California and Oregon: The base of the Upper Cretaceous Chico Butte Counties, California: American Association of Petroleum Geolo- Geological Society of America Special Paper 16, 339 p. gists Bulletin, v. 27, p. 306-312. Formation onlaps steeply dipping pre-Creta- J 943, Synopsis of the later Mesozoic in California: California Division Popenoe, W. P., Imlay, R. W., and Murphy, M. A., 1960, Correlation of the of Mines Bulletin 118, p. 183-186. Cretaceous formations of the Padfic Coast (United States and north- ceous metamorphic rocks. Chico Formation Bourgeois, J., 1980, A transgressive shelf sequence exhibiting hummocky strati- western Mexico): Geological Sodety of America Bulletin, v.- 71, fication: The Cape Sebastian Sandstone (Upper Cretaceous), south- strata reflect a transgressive sequence from p. 1491-1540. western Oregon: Journal of Sedimentary Petrology, v. 50, p. 681-702. coarse, fluvial conglomerates at the base to fine- Chuber, S., 1962, Late Mesozoic stratigraphy of the Sacramento Valley: San Saul, L. R., 1959, Senonian (Cretaceous) moilusks from Chico Creek (Califor- nia) [M.A. thesis]: Los Angeles, California, University of California. Joaquin Geological Society Selected Papers, v. 1, p. 3-16. 1961, Stratigraphy and correlation of the Chico Formation (Upper grained sandstones and mudstone indicative of Dickinson, W. R., 1971, Clastic sedimentary sequences deposited in shelf, Cretaceous) at its type locality: Geological Sodety of Sacramento An- slope, and trough settings between magmatic arcs and associated deeper-water deposition at the top. As indicated nual Field Trip, 1961, p. 16-20. trenches: Pacific Geology, v. 3, p. 15-30. by macrofossils, deposition of Chico Formation Diller, J. S„ 1889, Geology of the Lassen Peak District: U.S. Geological Sur- Taff, J. A., Hanna, G. D., and Cross, C. M., 1940, Type locality of the vey, 8tb Annual Report, pt. 1, p. 401-432. Cretaceous Chico Formation: Geological Sodety of America Bulletin, v. 51, p. 1311-1328. sediments was sporadic, with depocenters shift- 1895, Description of the Lassen Peak sheet: U.S. Geological Survey Trask, J. B., 1856, Description of a new spedes of ammonite and baculite from Geologic Atlas, Folio 15. ing through time. The shallow-marine mud- the Tertiary rocks of Chico Creek: California Academy of Natural Douglas, R- G., 1969, Upper Cretaceous planktonic foraminifera in northern Sdences Proceedings, v. 1, p. 85-86. stones of the northerly Kingsley Cave Member California—Part I, Systematica: Micropaleontology, v. 15, p. 151-209. Trujillo, E. F., 1960, Upper Cretaceous foraminifera from near Redding, Shasta Edmondson, W. F., 1962, Stratigraphy of the Late Upper Cretaceous in the are indicative of quiet-water deposition below Sacramento Valley: San Joaquin Geological Society Selected Papers, County, California: Journal of Paleontology, v. 34, p. 290-346. v. 1, p. 17-26. Walker, R. G., and Mutti, E., 1973, Turbidite fades and fades assodations: wave base in a localized intrashelf basin. Alter- Turbidites and deep water sedimentation: Anaheim, Sodety of Eco- Emerson, D. O., and Roberts, R., 1962, Map 3. Geologic map of Putah Creek, nomic Paleontologists and Mineralogists Short Course, p. 119-158. natively, these strata may be indicative of a Late in Brooks, B. D., Rogers, D., Day, P., and Wooton, T., Field trip 1: Ward, P. D , and Haggart, J. W., 1981, The Upper Cretaceous (Campanian) Sacramento Valley: California Division of Mines and Geology Bulletin ammonite and inoceramid bivalve succession at Sand Creek, Colusa Cretaceous marine connection, around the 181, p. 368-380. County, California, and its implications for establishment of an Upper Gabb, W. M., 1869, Cretaceous and Tertiary fossils, in Geological Survey of northern Sierra Nevada, with regions to the east Cretaceous Great Valley Sequence ammonite zonation: Newsletters on California, Palaeontology, v. 2. Stratigraphy, v. 10, p. 140-147. and north. Garcia, R., 1981, Depositional systems and their relatioo to gas accumulation in Ward, P. D„ Verosub, K. L., and Haggart, J. W„ 1983, Marine magnetic Sacramento Valley, California: American Association of Petroleum anomaly 33-34 identified in the Upper Cretaceous of the Great Valley Strata of the Chico Formation are correlative Geologists Bulletin, v. 65, p. 653-673. Sequence of California: Geology, v. 11, p. 90-93. Goudkoff, P. P., 1945, Stratigraphie relations of Upper Cretaceous in Great with deeper-marine shelf and slope deposits of Valley, California: American Association of Petroleum Geologists Bul- the western Sacramento Valley outcrop belt. letin, v. 29, p. 956-1007. Haggart, J. W., in press, Upper Cretaceous (Santonian-Campanian) ammonite Outcrops of the Guinda Formation, the Dob- and inoceramid biostratigraphy of the Chico Formation, California: Cretaceous Research, 1984. bins Shale Member, and the middle Forbes Howard, J. D., and Reineck, H. E., 1981. Depositional fades of high-energy beach-to-offshore sequence: Comparison with low-energy sequence: MANUSCRIPT RECEIVED BY THE SOCIETY MARCH 18, 1983 Formation reflect mid-fan to basin-plain envi- American Association of Petroleum Geologists Bulletin, v. 65, REVISED MANUSCRIPT RECEIVED JULY 11,1983 p. 807-830. ronments. The succession of lithologies of both MANUSCRIPT ACCEPTED JULY 13,1983

Printed in U.S.A.

Downloaded from http://pubs.geoscienceworld.org/gsa/gsabulletin/article-pdf/95/5/618/3445089/i0016-7606-95-5-618.pdf by guest on 26 September 2021