Martin H. Link

Seismic facies and sedimentary processes of submarine fans and turbidite systems

Part I: Techniques and Topics in Turbidite Research. Part II: Seismic Facies and Sedimentary Processes of Ancient Submarine Fans and Turbidite Systems. Part III: Seismic Facies and Sedimentary Processes of Modern Submarine Fans and Turbidite Systems. Appendix 1: Abstracts.

Global Petroleum Occurrences in Submarine Fans and Turbidite Systems

Submarine fans and turbidite systems are major petroleum reservoirs in many sedimentary basins worldwide. More than 80 sedimentary basins contain major petroleum-producing submarine fan deposits, and these reservoirs produce from a variety of structural, stratigraphic, and combined traps. To characterize these reservoir occurrences, tables were constructed for each continent and basin showing reservoir age, formation name(s), tectonic setting, and a field example, if appropriate. In addition, 23 major turbidite reservoirs from eight basins are discussed to illustrate the variability in these kinds of reservoirs. Turbidite reservoirs occur primarily as submarine fan deposits, with some occurrences in debris aprons, canyon-related features, and carbonate deposits of mass transport origin.

Modern lacustrine stromatolites, Walker Lake, Nevada

Abstract The Walker River drainage basin occupies about 10,000 km2 in western Nevada and parts of California and is essentially a closed hydrologic system which drains from the crest of the Sierra Nevada in California and terminates in Walker Lake, Nevada. Walker Lake trends north and is about 27.4 km long and 8 km wide with water depths exceeding 30.5 m. The lake is situated in an asymmetric basin with steep alluvial fans flanking the western shoreline (Wassuk Range) and more gentle but areally more extensive alluvial fans flanking the eastern shoreline (Gillis Range). Exposed lake terraces and the present shoreline of Walker Lake record a sequence of Pleistocene and Holocene stromatolitic and tufaceous carbonate deposits. Small generalized and columnar stromatolites, frequently encrusted on exposed coarse-grained clasts or bedrock, are present along parts of the nearshore margin of Walker Lake and at elevated lake stands. Columnar stromatolites as much as 4 cm high are subcylindrical to club shaped discrete, and laterally linked at the base with local branching. These digitate stromatolites start as wavy, generalized stromatolites which are vertically transitional to small, laterally linked cabbage heads with laminae which thicken over the crests. Although algal structures are not well preserved in the older stromatolites, recent precipitation of low magnesium calcite occurs as smooth encrustations and as tiny mounds which are consistently associated with a diverse, seasonally variable, green and blue-green algal community including Cladophora glomerata, Ulothrix (cf. aequalis), Gongrosira, Schizothrix, Amphithrix janthina, Calothrix, Homeothrix, Spirulina, Anabaena, Lyngbya, and Entophysalis. Cladophora glomerata and a species of Ulothrix, which are the two most abundant algae within the Walker Lake stromatolite community, are known to condition semi-alkaline lake water by the removal of CO2 from bicarbonate during photosynthesis. Such conditioning results in the precipitation of calcium carbonate, which is trapped and bound by an understory of green and blue-green algae. The occurrence of stromatolites in highly siliciclastic lakes seems to be restricted to shoreline and nearshore environments, and can be used to locate ancient lake margins.

Eocene Conglomerate Sedimentology and Basin Analysis, San Diego and the Southern California Borderland

ABSTRACT Eocene conglomeratic strata in the San Diego area were deposited as a narrow, west-trending progradational system that changed facies from fluvial channel, to alluvial fan, to coastal plain-fan delta, to paralic, to shelf and subsea channels. Continuing this system westward are the large Eocene subsea fan deposits that include inner, middle, and outer subfan and basin plain facies of the southern California borderland. In all environments, 81 to 96 percent of the conglomerate clasts are distinctive, well-rounded, siliceous metavolcanic stones (Poway clasts) that reach 60 cm in size and average 6 cm; 2 to 13 percent are quartzite; and 0 to 12 percent are locally derived (Peninsular Ranges) crystalline basement (granitic and volcanic) rocks. The composition, shape, and average size of t e metavolcanic and quartzite clasts are constant in all environments, while the less resistant granitic clasts show the effects of progressive abrasion by a decrease in size and abundance with increased transport distances. Three major sedimentologic trends characterize the Eocene conglomerate. (1) Conglomerate uniformly decreases, and finer grained rocks increase, in abundance and thickness from east to west. (2) The nonmarine and shallow marine conglomerate facies each contain disorganized and organized beds with no grading. Organized conglomerates are framework supported, and have imbricated clasts that dip up-current. The long axes of the clasts are oriented perpendicular or parallel to the paleoflow or are distributed randomly. Some nonmarine sandstone beds contain caliche horizons. (3) The subsea fan conglomerate is both disorganized and organized, and the beds are graded, or inversely graded. The clasts are matrix-supported, imbricated, and dip up-current. Long axes of clasts are oriented both par llel to and perpendicular to paleocurrent trends, and angular mudstone rip-up clasts and reworked marine fossils are present.

Slope and Deep-Sea Fan Facies and Paleogeography of Upper Cretaceous Chatsworth Formation, Simi Hills, California

The Upper Cretaceous Chatsworth Formation is a sand-rich deep-sea fan deposit consisting of thick channelized sequences and interchannel deposits typical of middle fan facies. It has poorly developed outer fan lobes and slope facies. Petrographic and x-ray diffraction (XRD) data indicate the arkosic deposits of the Chatsworth Formation were derived from an uplifted granitic terrane. Paleocurrent studies indicate northward sediment transport and an east-trending slope. Regional comparisons of the Simi Hills with the Santa Monica and Santa Ana Mountains suggest these terranes were once contiguous and covered part of a deep-sea fan system that comprised much of the southern California area. Subsequently, these terranes have been offset along the Malibu-Cucamonga and Elsinore faults, and rotated in response to the opening of the Los Angeles basin and to other adjustments in the tectonic framework of the area. The Chatsworth Formation is thought to be part of a forearc-basin deposit similar to the Great Valley sequence and not part of the Salinian borderland block. The original geographic position of the forearc basin was to the south of the Sierra Nevada Mountains and the Great Valley sequence.

The Rocks Sandstone, an Eocene Sand-rich Deep-sea Fan Deposit Northern Santa Lucia Range, California

ABSTRACT The Rocks Sandstone of Thorup (1941), which crops out in the northern Santa Lucia Range, was deposited as a deep-sea fan in a restricted Eocene continental borderland basin. It is as thick as 640 m and consists primarily of medium-grained sandstone with interbedded mudstone and conglomerate. The average grain size and bed thickness increase toward the east, where The Rocks Sandstone is overlain by the nonmarine to shallow-marine Berry Formation and underlain by the deep-marine Lucia Mudstone of Dickinson (1965). To the west, The Rocks Sandstone thins and is overlain by the deep-marine Church Creek Formation and is underlain by the deep-marine Lucia Mudstone. Foraminifers from underlying and overlying units indicate a late early Eocene (Ulatisian) to middle Eocene (Narizian) age for Th Rocks Sandstone and deposition in a moderately deep basin connected to the open ocean. Thick channelized sandstone sequences typical of a middle-fan facies association characterize The Rocks Sandstone. Beds consist primarily of facies B and locally facies A of Mutti and Ricci Lucchi (1972, 1975) and contain graded beds, sole marks, dish structures, and other sedimentary structures indicative of deposition by sediment gravity flows. Amalgamated sequences of thick-bedded sandstone form fining- and thinning-upward channel deposits. These sequences appear to form anastomosing bodies of sandstone that directly overlie basin-plain deposits of the Lucia Mudstone. The middle-fan channel sequences are commonly superposed upon one another, forming thick sections that have very high sandstone-to-shale ratios. Interchannel deposits are relatively rare within these sandstone sequenc s, but where present consist of repetitive, thin, alternating beds of fine-grained sandstone, siltstone, and mudstone dominantly of Multi and Ricci Lucchi facies D and E beds. The minimal development of the outer-fan facies association and difficulties in separating the middle- and inner-fan facies associations characterize this sand-rich borderland-type deep-sea fan deposit. Deposition of large amounts of sand abruptly at the base of slope apparently resulted in a fan characterized chiefly by the middle-fan facies association. Without sufficient clay-sized sediment, turbidity currents that travel long distances and deposit outer-fan and basin-plain turbidites apparently did not develop. The petrographic data indicate derivation mainly from felsic plutonic rocks, with a minor contribution from volcanic rocks. Paleocurrent, thickness, and stratigraphic data indicate primarily northward and westward sediment transport. A granitic source terrane, located to the east and southeast, and probably comprising parts of the Salinian block and possibly part of the present Mojave Desert area, is suggested by the petrography and paleocurrents.

Matilija Sandstone; a transition from deep-water turbidite to shallow-marine deposition in the Eocene of California

ABSTRACT The Matilija Sandstone (middle-upper Eocene), exposed in the Santa Ynez Mountains, California, records a major regressive event in the Eocene Santa Ynez Basin in which turbidites were deposited in the basin and subsequently covered by shallow-marine complexes. The Matilija Sandstone is underlain by the Juncal Formation and overlain by the Cozy Dell Shale. The Juncal Formation--a distal turbidite sequence--grades upward into a proximal turbidite sequence in the lower part of the Matilija Sandstone. This proximal turbidite sequence is overlain by a shallow-marine complex which is divisible into coastal and restricted-coastal lithofacies. Recognition and interpretation of these facies is based on fossil occurrences, petrography, biogenic and sedimentary features. Deposition of the Matilija Sandstone documents shoaling from outer neritic and/or bathyal depths in the Juncal Formation and basal part of the Matilija Sandstone to neritic and littoral depths in the upper part of the Matilija. It closed in a rapid transgression which culminated in the deposition of the Cozy Dell Shale (neritic to bathyal depths). The vertical sequence of sedimentary features, facies, and aerial distribution of the Matilija Sandstone suggest that it was deposited as a progradational deltaic complex. Progradation resulted in deposition by traction currents on the shelf, high-concentration sediment gravity flows initiated by slumping and sliding of material on the slope to upper basin, and deposition by lower concentration sediment gravity flows in the basin. As the delta prograded and filled the basin, it covered the deeper-water sediments derived from it.

Fluvial facies of the miocene ridge route formation, Ridge Basin, California

Abstract The upper Miocene nonmarine Ridge Route Formation consists of more than 9000 m of fluvial rocks deposited along the northeast margin of Ridge Basin, California. Five major fluvial tongues of the Ridge Route Formation cross the basin to interfinger with the Violin Breccia on the southwest. Two styles of fluvial sedimentation are inferred: (1) deposition in small braided channels on fan deltas resulting from streamflow and sheet-flood processes on the northeast side of the basin; and (2) deposition on large meandering-channel complexes in the lower parts of fan deltas and in elongate deltas which formed by point-bar accretion and overbank flooding near the center of the basin. These fluvial strata are composed of crossbedded and laminated sandstone interbedded with mudstone. The braided-channel deposits have a high sandstone-mudstone ratio (10:1), and contain lenticular beds averaging 1 m thick and 20 m long. These channels are small and of low relief (

Sedimentology and Reservoir Potential of Matilija Sandstone: An Eocene Sand-Rich Deep-Sea Fan and Shallow-Marine Complex, California

The Matilija Sandstone of the Santa Ynez Mountains of southern California records a major regressive event in the Eocene Santa Ynez basin in which turbidites were deposited and subsequently covered by shallow-marine deposits. Despite thick, favorable source beds and generally good initial reservoir characteristics, the Matilija Sandstone is not a productive unit in the basin. Low reservoir permeability (generally less than 1 md) and porosity (1 to 10%) are interpreted to be the result of early compaction, cementation, and diagenesis. The lower part of the Matilija Sandstone is a 1,300 ft (400 m) thick sand-rich deep-sea fan complex, which overlies basin plain turbidite deposits of the Juncal Formation. The Matilija Sandstone consists of anastomosing outer fan lobes, lobe fringe, and interlobe deposits overlain by channelized middle and inner fan deposits. The upper Matilija Sandstone consists of shallow-marine cross-bedded sandstone, red beds, and carbonate-evaporite-lignite sequences which overlie the turbidites. Deposition of the Matilija Sandstone was terminated by a rapid basin deepening event which culminated in deposition of basin plain, slope, and turbidite deposits of the Cozy Dell Formation. The lower Matilija Sandstone deep-sea fan deposits have a high sandstone to shale ratio (4:1 to 10:1) and consist of submature arkoses (Folk, 1980). The depositional lobes consist of facies B, C, and D turbidites and a channelized sequence of facies A and B turbidites. The average sandstone is medium grained, moderately sorted, subangular to subrounded, and massive, containing 40% quartz, 35% feldspar (about equal amounts of plagioclase and potassium feldspars), 10% lithic fragments (mostly volcanic and metamorphic types), and minor amounts of detrital clay (illite), mica, chert, and heavy minerals. Early compaction, carbonate cementation, and authigenic pore-lining and pore-filling chlorite, albite, potassium feldspar, quartz, and localized laumontite have reduced the initial porosit and permeability. The only remaining porosity is secondary, resulting from the dissolution of detrital feldspars, and minor fracture porosity.

Seismic Facies and Sedimentary Processes of Submarine Fans and Turbidite Systems: An Overview

The geologic community’s understanding of submarine fans and turbidite systems has grown considerably during the past two decades. The geologic literature has proliferated with contributions addressing primarily the sedimentology and stratigraphy of ancient turbidites exposed in outcrops, and of modern submarine fans, as imaged with high-resolution, shallow-penetration seismic, and side-looking imaging systems and piston cores. A disparity has emerged in our understanding of how fan systems evolve because of the differing perspectives afforded by different data bases. Interpretations based on large-scale stratal geometries defined by seismic-reflection data sometimes conflict with interpretations based on fine-scale outcrop features such as bedding geometries and sedimentary structures (Bouma et al., 1985b). Multifold seismic-reflection data provide an important link in comparing the outcrop-scale and modern submarine fan-scale features. These type of data are best used in a regional context to describe both ancient and modern submarine fans, but they have been generally underrepresented and underutilized in the development of submarine fan models, primarily because much of the available data is proprietary.