Forty kilometers south of Tecate, Baja California Norte, is an extensive area of pre–medial Cretaceous, greenschist-facies flysch, poorly exposed, and of unknown thickness. These rocks are lithocorrelative with the Triassic(?) French Valley and Julian Schist Formations and the Upper Triassic-Middle Jurassic Bedford Canyon Formation, north of the international border. The flysch type strata of the area consist of tabular, thin- to thick-bedded subarkosic metasandstone interbedded with metapelite. Isotopic studies on detrital zircon suggest a mixed population of discordant Middle to Late Proterozoic zircon and late Paleozoic and Triassic zircon. The flysch strata, herein named the Rancho Vallecitos Formation, is divided into a predominantly sandstone lithofacies and a predominantly shale lithofacies. Vertical sequence patterns and associations of sedimentary structures (graded bedding, outsized clasts, meniscate and diffuse laminae, etc.) indicate that the sandstones of both lithofacies were deposited by high-density turbidity currents. Rare ripple-laminated contourites of the shale lithofacies indicate deposition by northerly and southerly oriented paleocurrents. Vertical sequence patterns of sandstone beds in the sandy lithofacies suggest deposition in the outer part of a submarine fan-like system. Features of the predominantly shale lithofacies suggest a basin-plain depositional environment. Subordinate pebbly mudstone and local olistostrome/mélange deposits of the shaly lithofacies indicate proximity to slope areas. The overall fine-grained, poorly sorted, and matrix-rich character of all the sandstones suggests deposition in a large submarine fan or cone system of unrestricted open ocean basins, characteristically fed by large river/delta systems. Modal analyses of the sandstone framework indicates sediment sources of recycled orogens and possibly craton interior.

“The hypothesis of cumulative right-lateral displacement on the San Andreas Fault of hundreds of miles since Jurassic has received very wide acceptance among earth scientists, even to the point of incorporation into a number of leading textbooks, as more-or-less qualified fact for the instruction of young geologists” –Gordon Oakeshott, 1965

The Paleogene Cantua Sandstone Member of the Lodo Formation was deposited primarily by sand-rich, high-density sediment gravity flows fed by a submarine canyon into a structurally controlled, relatively deep-marine, basin bounded to the north, south, and east by shallow-marine shelves. The Cantua Sandstone probably represents, at least in part, the deep-water equivalent of the deltaic-neritic Gatchell sandstone which is an important petroleum reservoir at the East Coalinga Extension Field (Ryall, 1974; Graham and Berry, 1979; Harun, 1984). Graham and Berry (1979) interpreted portions of the Cantua in the subsurface to be “supra-fan” deposits. Nilsen (1981) interpreted outcrops of the Cantua Sandstone as dominantly “supra-fan” and middlefan channel deposits. These general characteristics and interpretations serve as a basis for classifying the Cantua Sandstone as a sand-rich, point-sourced submarine fan (Reading and Richards, 1994). It is important to note, however, that the morphologic term fan is probably not applicable to the Cantua Sandstone system because it was deposited in a confined, rather than unconfined, basin.

“Unfortunately, large ranges of error are inherent in estimates of San Andreas displacements on cross fault correlations. Therefore, several alternative interpretations of San Andreas slip history are possible.” —Graham and others (1989)

Abstract In this classic segment, many tectonic processes, like flat-subduction, terrane accretion and steepening of the subduction, among others, provide a robust framework for their understanding. Five orogenic cycles, with variations in location and type of magmatism, tectonic regimes and development of different accretionary prisms, show a complex evolution. Accretion of a continental terrane in the Pampean cycle exhumed lower to middle crust in Early Cambrian. The Ordovician magmatic arc, associated metamorphism and foreland basin formation characterized the Famatinian cycle. In Late Devonian, the collision of Chilenia and associated high-pressure/low-temperature metamorphism contrasts with the late Palaeozoic accretionary prisms. Contractional deformation in Early to Middle Permian was followed by extension and rhyolitic (Choiyoi) magmatism. Triassic to earliest Jurassic rifting was followed by subduction and extension, dominated by Pacific marine ingressions, during Jurassic and Early Cretaceous. The Late Cretaceous was characterized by uplift and exhumation of the Andean Cordillera. An Atlantic ingression occurred in latest Cretaceous. Cenozoic contraction and uplift pulses alternate with Oligocene extension. Late Cenozoic subduction was characterized by the Pampean flat-subduction, the clockwise block tectonic rotations in the normal subduction segments and the magmatism in Payenia. These processes provide evidence that the Andean tectonic model is far from a straightforward geological evolution.

Abstract Since the comprehensive synthesis on the Argentine–Chilean Andes by Mpodozis & Ramos (1989) , important progress has been made on the stratigraphy, palaeogeographic evolution and tectonic development of the Andean Orogen in Chile. We present here an overview of this evolution considering the new information and interpretations, including some unpublished ideas of the authors. To enable the reader to delve further into the subjects treated here, we accompany the text with abundant references. In the interpretation of the stratigraphic and radioisotopic data we used the timescale of Harland et al. (1989) . During most of its history the continental margin of South America was an active plate margin. The Late Proterozoic to Late Palaeozoic evolution was punctuated by terrane accretion and westward arc migration, and can be described as a ‘collisional history’. Although accretion of some terranes has been documented for the post-Triassic history, the evolution during post-Triassic times is characterized more by the eastward retreat of the continental margin and eastward arc migration, attributed to subduction erosion, and therefore can be described as an ‘erosional history’. The intermediate period, comprising the Late Permian and the Triassic, corresponds to an episode of no, or very slow, subduction activity along the continental margin, during which a totally different palaeogeographic organization was developed and a widely distributed magmatism with essentially different affinities occurred. It is therefore possible to differentiate major stages in the tectonostratigraphic evolution of the Chilean Andes, which can be related to the following episodes of supercontinent evolution: (1) post-Pangaea

Abstract California has one of the largest reserves for heavy oil in the world, second only to Venezuela. Recent declines in conventional resources and reserves during the last decade have prompted other jurisdictions to examine their prospective unconventional resources, such as heavy oil and oil sands, in a more favorable technological and economic setting. However, this has not been done universally in the United States, where thermal enhanced oil-recovery technologies (mostly used to produce heavy oil) have experienced a decline in production, concomitant with the downturn in conventional production. In California, the seep and oil-sand deposits are mostly unconsolidated sands bound together by biodegraded bitumen. Source rocks for both modern seeps and oil sands and ancient heavy-oil deposits are mainly the Miocene Monterey diatomites and equivalent diatomaceous mudstones and organic shales. In California, most of the seeps and oil sands overlie or are updip from underlying heavy-oil reservoirs. The seep and oil-sand deposits occur in areas where cap-rock integrity was compromised for the underlying heavy-oil reservoirs, breeched mainly by faults or fractures. Hydrocarbons migrated updip into basin-marginal settings or in structural areas of compromised cap rock and then pooled to form the seeps, later hardening into oil-sand deposits. Hydrocarbons accumulated in a wide variety of depositional environments from deep-sea fans, lobes, and submarine channels to fluvial-lacustrine deltas and incised valleys and every other sedimentary environment in between. This makes it difficult to identify type examples for the California accumulations, although case examples are given. In the past, steam-flood, condensed water drive, cyclic steam stimulation (CSS), and fireflood were used to produce the California heavy-oil reservoirs. Currently, significant California CSS projects underway include Belridge, Cymric, and northern Midway Sunset fields to stimulate intermediate-gravity hydrocarbons in the Monterey, Reef Ridge, and Etchegoin diatomite lithologies. Elsewhere, for example, in Canada, in-situ bitumen and extra-heavy-oil sands are commonly developed using CSS or steam-assisted gravity drainage (SAGD). Combined application of CSS along with SAGD from horizontal wells may recover bypassed pay in heavy-oil reservoirs and may be used to recover bitumen from associated oil sands, and multistage multifracing technologies may recover oil from the deeper unconventional (Monterey) source rocks. These technological developments, along with improved computing techniques (i.e., three-dimensional [3-D] geologic modeling/visualization), allow for real-time exploration and development of unconventional reservoirs. A significant effort exists in California to improve recovery from Pleistocene, Pliocene, and Miocene heavy-oil deposits; for example, at present, 70 to 80% recovery from heavy-oil steam drives is seen in Pleistocene Tulare Formation fluvial and alluvial sands. Full 3-D models anchored by extensive coring and logging programs have reaped benefits in many older oil fields (e.g., South Belridge, Midway Sunset, Cymric, Lost Hills, Kern River). Bypassed pay and new production from associated shallow oil sands and deeper source rocks may ultimately be a key to attainment of increases in secure unconventional energy reserves in North America. In the future, full integration of new technologies, along with technology sequencing, may be applied to old California oil fields for production of bypassed pay in heavy-oil fields.

ABSTRACT We will embark on a five-day journey through northern, western, and central Sonora, in which we will see excellent examples of mostly Mesozoic to Cenozoic tectonics, sedimentation, and metallogeny. On Day 1, we will visit the porphyry copper deposit at Ajo, Arizona, and several Pleistocene cinder cones and maar craters in the Pinacate Biosphere Reserve. On Day 2, we will see L- and L-S tectonites at the type locality of the Mojave-Sonora megashear in Sierra Los Tanques, Noche Buena orogenic gold deposit, Ediacaran Gamuza beds in Caborca, and have an overview of the Carnero detachment fault on the south side of Sierra La Gloria. Day 3 will explore faults and related sedimentary and volcanic rocks associated with the late Miocene oblique opening of the Gulf of California rift and visit outcrops that record late Miocene timing constraints for flooding of the Gulf of California seaway, including several localities on southern Isla Tiburón accessible only by boat. Day 4 will visit exposures of Permian sedimentary to Paleogene igneous rocks in Hermosillo (Cerro La Campana); Puerto del Sol detachment fault zone; Aconchi batholith and a hot spring localized on a Basin and Range normal fault; Santa Elena low-sulfidation epithermal gold mine; and the Upper Jurassic Cucurpe Formation. On Day 5, we will visit several exposures of different crustal levels of the Magdalena-Madera metamorphic core complex, including the spectacular stretched pebble conglomerates in Arroyo Amolares.