UNITED STATES DEPARTMENT OF THE INTERIOR Harold L. Ickes, Secretary GEOLOGICAL SURVEY W. C. Mcndenhull, Director Professional Paper 190 LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM THE LOS ANGELES BASIN, CALIFORNIA AND THEIR INFERRED ENVIRONMENT BY W. P. WOODRING UNITED STATES GOVERNMENT PRINTING OFFICE WASHINGTON : 1938 For sale by the Superintendent of Documents, Washington, D. C. ------ Trice 30 cents CONTENTS Page Abstract._____________----______-_-_-- Inferred environment of larger fossils Continued. Introduction __________-_-___-___---_-_ Inferred depth range of larger fossils______________ 13 New systematic names proposed_______-_ Interpretation of fossils of deep-water facies----.... 15 General features of Los Angeles Basin____ Distribution of fossils of different depth facies...... 16 Repetto formation of Los Angeles Basin __ Paleogeographic implications_____________________ 16 General features.___________________ Bearing on geologic history of Los Angeles Basin.__. 17 Outcrop localities._-_--____-_-_____ Comparison between Los Angeles Basin during Subsurface section.________________ Repetto time and modern deep-water basins on Larger fossils from Repetto formation____ Continental Shelf of southern California._________ 18 Outcrop localities._________________ Age relations of larger fossils.__________________'______ 18 Subsurface localities.---______.__-_- Fossils of deep-water facies__-____________________ 18 Fossils. _ _-____-____---___-_-______. Fossils of intermediate and shallow-water facies.____ 20 Inferred environment of larger fossils..... Descriptions of species_____-___--__-_-____-__-_.____ 22 Depth range of allied modern species. Index.______.________________________ 65 ILLUSTRATIONS Page Page PLATE 1. Relief map of California showing principal areas PLATE 7. Pliocene mollusks from Los Angeles Basin_____ 62 of marine Pliocene formations._____________ 2 8. Pliocene mollusks from Los Angeles Basin and 2. Generalized geologic map of Los Angeles Basin Miocene mollusks from Colorado Desert. 63 and borders._----------------_-__----_-_ 2 9. Pliocene mollusks and echinoids from Los 3. Depth frequency graphs of modern Pacific Angeles Basin___________________________ 64 coast mollusks and echinoids allied to Re­ FIGURE 1. Bathymetric map of Continental Shelf along petto fossils.-----------.-.-------------- 14 part of coast of southern California. _______ 19 4. Map of Los Angeles Basin showing distribution 2. Hinge of Phreagena, Calyptogena, and Ec- of Repetto fossils of different depth facies. _ _ _ 14 lenagena. _________-_____-________----__ 50 5, 6. Pliocene and Miocene mollusks from Los Ange­ les Basin___----_-____-_____-_-____.___ 60,61 it LOWER PLIOCENE MOLLUSKS AND EG^INOIDS FROM THE LOS ANGELES BASIN, CALIFORNIA, AND THEIR INFERRED ENVIRONMENT By W. P. WOODRING ABSTRACT depth facies during Pliocene and Pleistocene time was a factor The Repetto formation, which is considered of lower Pliocene in the accumulation of the 6,000 to 10,000 feet of Pliocene and age, embraces the principal oil-bearing strata in most of the major Pleistocene sediments in the basin. Unless, however, the depth oil fields of the Los Angeles Basin. Twenty-six forms of mollusks. of the Repetto sea was much greater than now appears probable, and one echinoid are described from the Repetto formation of subsidence also was a factor. this region, and other larger fossils are recorded. These fossils, The inferred deep-water environment of the Repetto formation were collected from outcrops and from cores representing 56 wells supports the comparison, also already made, of the Los Angeles distributed widely over the basin. Imperfect remains from 10 Basin during Repetto time with the modern deep-water basins additional wells are undetermined or undeterminable. on the Continental Shelf of southern California. These modern The fossils are assigned to three depth-range groups on the basins have depths of 300 to 1,000 fathoms. According to recent assumption that they represent essentially the same depth range investigations, sand is being deposited on the ridges between the as modern species from the eastern Pacific, to which the}7, are modern basins regardless of depth, and the fine-grained sediments closely allied. These groups are (J) fossils of shallow-water in the basins are relatively rich in organic matter. facies; (2) fossils of intermediate-depth facies, inferred to repre­ The age relations of the fossils are briefly discussed. Most of sent a range from shallow water into deep water; (3) fossils of the fossils of deep-water facies closely resemble modern species, deep-water facies. and many are similar to Miocene and Oligocene forms. The The fossils of deep-water facies consist of at least 8 species, shallow-water species have a middle Pliocene aspect in terms of possibly .1.2 species, embracing mollusks, an echinoid, a sponge, current age assignments. and doubtfully a coral. The first fossil representatives of the echinoid family Echinothuriidae found in America are included INTRODUCTION in this group. Inasmuch as the fossils of deep-water facies belong to genera or subgenera that, with one exception, have not been The Repetto formation, which is assigned to the found in California Pliocene formations characterized by a lower Pliocene, embraces the principal oil zones in most shallow-water facies, it is inferred that they represent deep water of the major oil fields of the Los Angeles Basin. The or cool water. The hypothesis that they represent upwelling extensive foraminiferal fauna of this formation^ tjas cool water is considered and rejected, and the probability that been exhaustively studied on account of its value in pil|- they lived in deep water is considered reasonably certain. Most of the deep-water fossils are closely allied to species dredged by field correlations, but the results of these studies have the Albatross off the coast of Oregon arid California, but some not yet appeared in print aside from a few brief accounts closely resemble species that have not yet been found north of dealing with single species or local areas. Apparently Central America, and allies of one species of probable deep-water only one record of a Repetto larger fossil* from core facies are unknown in the eastern Pacific. material in the basin has been published.2 The fossils of deep-water facies are widely distributed through­ out the basin. They suggest that during Repetto time the Los I am greatly indebted to Dr. W. S. W. Kew, of the Angeles Basin sea had depths of 300 to 600 fathoms (roughly Standard Oil Co. of California, and to Mr. S. G. Wissler, 2,000 to 4,000 feet). of the Union Oil Co. of California, for the opportunity Fossils of shallow-water .facies have so far been found near the .to study Repetto larger fossils from 60 wells distributed northern border of the basin and near the western margin. The over the-basin. These fossils have accumulated in the fossils of intermediate-depth facies are more widely distributed than those of shallow-water facies. Some evidence points to Standard and Union micropaleontology laboratories areas of shallow water near the northern border of the basin. during the last few years. The officials of these com­ The association of fossils of deep-water, intermediate, and shallow- panies and of other companies whose wells are repre­ water facies and of land fossils in part of this region, however, sented in the core collections kindly gave permission to suggests proximity to land and transportation of the shallow- publish the data on the fossils. Mr. Wissler also per­ water and land fossils by unknown agencies. The source of a shallow-water fossil from a locality near the western margin of mitted publication of records of Lima hamlini and the basin is not known but may have been an area of shallow Hyalopecten aff. H. randolphi tillamookensis based on water farther south. specimens in his laboratory from six additional wells. The widespread distribution of fossils of deep-water facies in the Repetto formation and the depth facies of the overlying Plio­ 1 The term "larger fossils" is used to contrast mollusks, echinoids, and other rela­ tively large fossils with microscopic ones; it corresponds to the term "rnegafossils." cene and Pleistocene formations support the interpretation, 8 Hertlein, L. G., New species of marine fossil Mollusca from western North already suggested, that the deposition of sediments of decreasing America: Southern California Acad. Sci. Bull., vol. 24, p. 43, pi. 4, flg. 6,1925. LOWER PLIOCENE MOLLUSKS AND ECHINOIDS FROM LOS ANGELES BASIN Dr. Kew presented to the National Museum the ma­ Mortensen kindly permitted use of his identification and terial accumulated under his direction. Mr. Wissler comments on the echinothuriids. I prepared the de­ donated to the Museum the types, other figured speci­ scription of the echinothuriid material under the super­ mens, and additional material from his collection; the vision of Dr. A. H. Clark. Mr. H. L. Driver, of the Stand­ other specimens from his collection have been returned ard Oil Co. of California, verified the stratigraphic data to the Union Oil Co.'s laboratory. Mr. Alex Clark, of for the specimens in the Standard collection. Mr. Wissler the Shell Oil Co., donated to the Museum the specimen prepared a chart showing the stratigraphic distribution of Lunatia cf. L. caurina from the Inglewood field; of the larger fossils with reference to foraminiferal permitted publication of the record of Lima hamlini, zones. Though the data on this chart are cited only based on the specimen in his collection from the exca­ in general terms, they were very useful in attempting vation for the Times Building in Los Angeles; and guided to interpret the significance of the fossils. Dr. L. G. me to collecting localities in the Repetto Hills. Hertlein, of the California Academy of Sciences, loaned It is to be hoped that additional material will be specimens for comparison. Mr. D. D. Hughes, of the collected as cores are sampled, for almost any Repetto Texas Co.