Abstract Seismic mapping indicates that Lasuen Knoll in the Inner Borderland, offshore southern California, is a pop-up structure associated with a restraining stepover of the Palos Verdes Fault. Dextral shear is apparently transferred southeast through a complex zone of faults that includes the Carlsbad Ridge and Coronado Bank faults. This model is supported by comparison with other pop-up structures in the Inner Borderland and analogs to published sandpack laboratory simulations. The Palos Verdes Fault along Lasuen Knoll has existed at least since the late Miocene Epoch (5 to 8 Ma) and is contemporaneous with the segment of the Palos Verdes Fault on San Pedro Shelf and adjacent to the Palos Verdes Peninsula. Isochore maps of stratigraphic intervals indicate that extension occurred locally along the Palos Verdes Fault adjacent to the present Lasuen Knoll pop-up during the Mohnian Stage and became more widespread during the Delmontian Stage (approximately 7.5 to 5 Ma). Repettian strata onlapping Lasuen Knoll indicate that the knoll began to form as a pop-up structure by the early Repettian (entire stage approximately 5 to 2.3 Ma) and has been active possibly until the Holocene. Transtensional zones occur along the Palos Verdes–Carlsbad Ridge–Coronado Bank Fault Zone north and south of Lasuen Knoll. The San Gabriel Transtensional Zone, north of Lasuen Knoll, separates the knoll from the Palos Verdes Anticlinorium, the other major uplift structure along the Palos Verdes Fault. The Lasuen Knoll basement high, the overall structural high that includes Lasuen Knoll, is similar in dimension and shape to the Palos Verdes Anticlinorium, which has been interpreted to be underlain by a low-angle ramp fault. Recent models of low-angle ramp faults as major causes of the uplift of Palos Verdes, however, cannot be readily applied to Lasuen Knoll.

Abstract Amino-acid and oxygen isotope data for fossils from terraces of the Palos Verdes Hills and San Pedro areas in Los Angeles County, California, shed new light on the ages of terraces, sea-level history, marine paleotemperatures, and late Quaternary tectonics in this region. Low terraces on the Palos Verdes peninsula correlate with the ∼80-ka and ∼125-ka sea-level highstands that are also recorded as terraces on other coasts. In San Pedro, the Palos Verdes sand (the deposit on what is mapped as the first terrace by Woodring and others, 1946) was previously thought to be a single deposit; amino-acid, oxygen isotope, U-series, and fauna] data indicate that deposits of two ages, representing the 80-ka and 125-ka highstands occur within this unit. Oxygen isotope data show that on open, exposed parts of the Palos Verdes peninsula, ocean waters during the 125-ka highstand were cooler than present (by about 2.3-2.6°C) similar to what has been reported for other exposed coastal areas in California. In contrast, in the protected embayment environment around San Pedro, water temperatures during the 125-ka highstand were as warm or warmer than present. During the 80-ka highstand, water temperatures were significantly cooler than present even in the relatively protected embayment environment of the San Pedro area. Late Quaternary tectonic-uplift rates can be calculated from terrace ages and elevations. Correlation of the lowest terraces around the Point Fermin area shows that the Cabrillo fault has a late Quaternary vertical-movement rate of 0.20 m/ka, based on the difference in uplift rates on the upthrown and downthrown sides of the fault. Elsewhere in the Palos Verdes Hills-San Pedro area, late Quaternary uplift rates vary from 0.32 m/ka to possibly as high as 0.72 m/ka. These rates, which reflect vertical movement on the Palos Verdes fault, are in broad agreement with estimated Holocene vertical rates of movement determined for offshore portions of the fault.

ABSTRACT The Los Angeles basin formed in late Neogene time on a continental margin previously shaped by Cretaceous and early Paleogene subduction, Paleogene terrane accretion, and mid-Miocene rifting and block rotation. During Neogene time, the boundary between the Pacific and North American plates shifted progressively eastward beneath the Los Angeles region, creating the broad San Andreas transform zone. As reviewed in this paper, structures and rocks within the Los Angeles basin document each stage of that Neogene evolution. The Los Angeles basin began to take its present shape in late Miocene time (ca. 7 Ma) by subsidence between the right-oblique Whittier and Palos Verdes fault zones and the left-oblique Santa Monica fault system. The principal phase of basin opening involved early Pliocene extension in a northwest direction, which accompanied the opening of the Gulf of California and the eastward shift of the southern San Andreas fault to its present position. Most of the structural traps that hold the basin's oil fields began to form during this latest Miocene-early Pliocene deformation. Since mid-Pliocene time, many of these traps have been altered and enhanced—and a few have been breached—by Pasadenan deformation, involving southward shortening, the uplift of the Transverse Ranges, and the propagation of blind thrusts beneath the northern Los Angeles basin. The rapid transition from early Pliocene extension to late Pliocene contraction was associated temporally with a change in relative plate motion dated at 3.9- 3.4 Ma. In analyzing Pasadenan deformation, the flake-tectonics model is more appropriate than the fold-and-thrust-belt model, although both models incorporate aseismic detachment at midcrustal depths. The flake-tectonics model is valid for all phases of Neogene deformation, both transtensional and transpressive, in the Los Angeles region. Fields discovered to date in the Los Angeles basin will yield an ultimate 10.4 billion oil-equivalent barrels (GOEB) of petroleum. Of this, approximately 73% is trapped in faulted anticlines, 12% in simple anticlines, 10% in fault traps, and 5% in stratigraphic traps. Folding has been controlled primarily by preexisting structural hingelines and sedimentary wedge belts and secondarily by en echelon folding associated with wrench faults. Oil seeps and Quaternary topographic uplifts led to most of the discoveries prior to 1925 along the Whittier and Newport−Inglewood fault zones and in the Coyote Hills. Most later discoveries, including the 3-billion-barrel Wilmington oil field, were in structures with little or no Quaternary expression.