The plutonism in the North Chilean Coast-Range and its geodynamic significance

1981 ◽  
Vol 70 (3) ◽  
pp. 1054-1076 ◽  
Author(s):  
Klaus-Werner Damm ◽  
Siegfried Pichowiak ◽  
Werner Zeil
Keyword(s):  
Coast Range ◽  
Chilean Coast ◽  
The North

The North-Chilean Coast Range — an example for the development of an active continental margin

1983 ◽  
Vol 72 (2) ◽  
pp. 715-731 ◽  
Author(s):  
Karsten Berg ◽  
Christoph Breitkreuz ◽  
Klaus -Werner Damm ◽  
Siegfried Pichowiak ◽  
Werner Zeil
Keyword(s):  
Continental Margin ◽  
Active Continental Margin ◽  
Coast Range ◽  
Chilean Coast ◽  
The North

Volcanic dykes in the north Chilean Coast Range

1984 ◽  
Vol 73 (3) ◽  
pp. 853-868 ◽  
Author(s):  
Siegfried Pichowiak ◽  
Christoph Breitkreuz
Keyword(s):  
Coast Range ◽  
Chilean Coast ◽  
The North

General characteristics of active andean volcanoes and a summary of their activities during recent centuries

1963 ◽  
Vol 53 (6) ◽  
pp. 1415-1433
Author(s):  
Lorenzo Casertano
Keyword(s):  
Volcanic Activity ◽  
Central Valley ◽  
Mountain Range ◽  
Historical Account ◽  
The South ◽  
Chilean Coast ◽  
The North ◽  
The Andes ◽  
Transverse Fractures ◽  
Coastal Mountain

ABSTRACT An oceanic deep lies off the Chilean coast, bordered on the east by a coastal mountain range, a discontinuous central valley, and the high cordillera of the Andes. The Chilean volcanoes are found on lineaments that in general coincide with, or are sub parallel to, axis of the Andes. In north Chile they lie along en echelon fractures and, in some cases, along transverse fractures. In the south, the alignment of the volcanoes lies west of the axis of the Andes. Where the Central Valley is not well developed, active volcanoes are scarce. Recent lavas range from basalt in the south to rhyolite in the north. Volcanic activity appears to be decreasing. Details are given of individual volcanoes, and a list of active Andean volcanoes south of Volcan Misti is presented with a historical account of their activity.

Field and petrographic reconnaissance of Franciscan complex rocks of Mount Diablo, California: Imbricated ocean floor stratigraphy with a roof exhumation fault system

2021 ◽  
Author(s):  
John Wakabayashi
Keyword(s):  
Fault System ◽  
Normal Faults ◽  
Coast Range ◽  
Franciscan Complex ◽  
The North ◽  
Tectonic Window ◽  
Coast Range Ophiolite ◽  
Great Valley Group ◽  
Clastic Sedimentary ◽  
Great Valley

ABSTRACT Franciscan subduction complex rocks of Mount Diablo form an 8.5 by 4.5 km tectonic window, elongated E-W and fault-bounded to the north and south by rocks of the Coast Range ophiolite and Great Valley Group, respectively, which lack the burial metamorphism and deformation displayed by the Franciscan complex. Most of the Franciscan complex consists of a stack of lawsonite-albite–facies pillow basalt overlain successively by chert and clastic sedimentary rocks, repeated by faults at hundreds of meters to <1 m spacing. Widely distributed mélange zones from 0.5 to 300 m thick containing high-grade (including amphibolite and eclogite) assemblages and other exotic blocks, up to 120 m size, form a small fraction of exposures. Nearly all clastic rocks have a foliation, parallel to faults that repeat the various lithologies, whereas chert and basalt lack foliation. Lawsonite grew parallel to foliation and as later grains across foliation. The Franciscan-bounding faults, collectively called the Coast Range fault, strike ENE to WNW and dip northward at low to moderate average angles and collectively form a south-vergent overturned anticline. Splays of the Coast Range fault also cut into the Franciscan strata and Coast Range ophiolite and locally form the Coast Range ophiolite–Great Valley Group boundary. Dip discordance between the Coast Range fault and overlying Great Valley Group strata indicates that the northern and southern Coast Range fault segments were normal faults with opposite dip directions, forming a structural dome. These relationships suggest accretion and fault stacking of the Franciscan complex, followed by exhumation along the Coast Range fault and then folding of the Coast Range fault.

Tectonics and paleogeography of a post-accretionary forearc basin, Coos Bay area, SW Oregon, USA

2021 ◽  
pp. 187-243
Author(s):  
John M. Armentrout
Keyword(s):  
Sediment Transport ◽  
Middle Eocene ◽  
North American Plate ◽  
Coast Range ◽  
Forearc Basin ◽  
Oregon Coast Range ◽  
Susceptibility Data ◽  
Bay Area ◽  
The North ◽  
Coos Bay

ABSTRACT This field guide reviews 19 sites providing insight to four Cenozoic deformational phases of the Cascadia forearc basin that onlaps Siletzia, an oceanic basaltic terrane accreted onto the North American plate at 51–49 Ma. The field stops visit disrupted slope facies, prodelta-slope channel complexes, shoreface successions, and highly fossiliferous estuarine sandstones. New detrital zircon U-Pb age calibration of the Cenozoic formations in the Coos Bay area and the Tyee basin at-large, affirm most previous biostratigraphic correlations and support that some of the upper-middle Eocene to Oligocene strata of the Coos Bay stratigraphic record represents what was differentially eroded off the Coast Range crest during ca. 30–25 Ma and younger deformations. This suggests that the strata along Cape Arago are a western “remnant” of the Paleogene Tyee basin. Zircon ages and biostratigraphic data encourages the extension of the Paleogene Coos Bay and Tyee forearc basin westward beyond the Fulmar fault and offshore Pan American and Fulmar wells. Integration of outcrop paleocurrents with anisotropy of magnetic susceptibility data from the middle Eocene Coaledo Formation affirms south-southeast to north-northwest sediment transport in current geographic orientation. Preliminary detrital remanent magnetism data show antipodal directions that are rotated clockwise with respect to the expected Eocene field direction. The data suggest the Eocene paleo-shoreline was relatively north-south similar to the modern shoreline, and that middle Eocene sediment transport was to the west in the area of present-day Coos Bay. A new hypothesis is reviewed that links the geographic isolation of the Coos Bay area from rivers draining the ancestral Cascades arc to the onset of uplift of the southern Oregon Coast Range during the late Oligocene to early Miocene.

Upper plate deformation during blueschist exhumation, ancestral western California forearc basin, from stratigraphic and structural relationships at Mount Diablo and in the Rio Vista Basin

2021 ◽  
Author(s):  
Jeffrey Unruh
Keyword(s):  
San Francisco ◽  
Late Cretaceous ◽  
Normal Faults ◽  
Coast Range ◽  
Forearc Basin ◽  
Bay Area ◽  
The North ◽  
Early Tertiary ◽  
Local Equivalent ◽  
Structural Relief

ABSTRACT Late Cenozoic growth of the Mount Diablo anticline in the eastern San Francisco Bay area, California, USA, has produced unique 3D exposures of stratigraphic relationships and normal faults that record Late Cretaceous uplift and early Tertiary extension in the ancestral California forearc basin. Several early Tertiary normal faults on the northeast flank of Mount Diablo have been correlated with structures that accommodated Paleogene subsidence of the now-buried Rio Vista basin north of Mount Diablo. Stepwise restoration of deformation at Mount Diablo reveals that the normal faults probably root into the “Mount Diablo fault,” a structure that juxtaposes blueschist-facies rocks of the Franciscan accretionary complex with attenuated remnants of the ophiolitic forearc basement and relatively unmetamorphosed marine forearc sediments. This structure is the local equivalent of the Coast Range fault, which is the regional contact between high-pressure Franciscan rocks and structurally overlying forearc basement in the northern Coast Ranges and Diablo Range, and it is folded about the axis of the Mount Diablo anticline. Apatite fission-track analyses indicate that the Franciscan rocks at Mount Diablo were exhumed and cooled from depths of 20+ km in the subduction zone between ca. 70−50 Ma. Angular unconformities and growth relations in the Cretaceous and Paleogene stratigraphic sections on the northeast side of Mount Diablo, and in the Rio Vista basin to the north, indicate that wholesale uplift, eastward tilting, and extension of the western forearc basin were coeval with blueschist exhumation. Previous workers have interpreted the structural relief associated with this uplift and tilting, as well as the appearance of Franciscan blueschist detritus in Late Cretaceous and early Tertiary forearc strata, as evidence for an “ancestral Mount Diablo high,” an emergent Franciscan highland bordering the forearc basin to the west. This outer-arc high is here interpreted to be the uplifted footwall of Coast Range fault. The stratigraphic and structural relations exposed at Mount Diablo support models for exposure of Franciscan blueschists primarily through syn-subduction extension and attenuation of the overlying forearc crust in the hanging wall of the Coast Range fault, accompanied by (local?) uplift and erosion of the exhumed accretionary prism in the footwall.

Structural styles, deformation, and uplift of the Olympic Mountains, Washington: Implications for accretionary wedge deformation

2021 ◽  
Author(s):  
M. James Aldrich
Keyword(s):  
Accretionary Wedge ◽  
Coast Range ◽  
Block Rotation ◽  
Oregon Coast Range ◽  
Shallow Level ◽  
The North ◽  
Structural Style ◽  
Olympic Mountains ◽  
Competing Models ◽  
Axial Surface

The Olympic subduction complex is the exposed subaerial Cascadia accretionary wedge in the Olympic Mountains of Washington State. Uplift of the mountains has been attributed to two competing models: margin-normal deformation from frontal accretion and underplating, and margin-parallel deformation from the clockwise rotation and northward movement of the Oregon Coast Range block compressing the Olympic Mountains block against the Canadian Coast Range. East-northeast−oriented folds and Quaternary thrust faults and paleostress analysis of faults in the Coastal Olympic subduction complex, west of the subduction complex massif, provide new evidence for north-south shortening in the Coastal Olympic subduction complex that fills a large spatial gap in the north-south shortening documented in prior studies, substantially strengthening the block rotation model. These new data, together with previous studies that document north-south shortening in the subduction complex and at numerous locations in the Coast Range terrane peripheral to the complex, indicate that margin-parallel deformation of the Cascadia forearc has contributed significantly to uplift of the Olympic Mountains. Coastal Olympic subduction complex shallow-level fold structural style and deformation mechanisms provide a template for analyzing folding processes in other accretionary wedges. Similar-shaped folds in shallow-level Miocene turbidite sediments of the Coastal Olympic subduction complex formed in two shortening phases not previously recognized in accretionary wedges. Folds began forming by bed-parallel flow of sediment into developing hinges. When the strata could no longer accommodate shortening by flexural flow, further shortening was taken up by flexural slip. Similar-shaped folds in the deeper accretionary wedge rocks of the subduction complex massif have a well-developed axial-surface cleavage that facilitated shear folding with sediment moving parallel to the axial surface into the hinges, a structural style that is common to accretionary wedges. The pressure-temperature conditions and depth at which the formation of similar folds transitions from bed-parallel to axial-surface−parallel deformation are bracketed.

Economic Organization and Social Dynamics of Middle-Holocene Hunter-Gatherer-Fisher Communities on the Coast of the Atacama Desert (Taltal, Northern Chile)

2020 ◽  
pp. 74-100 ◽  
Author(s):  
Diego Salazar ◽  
Carola Flores ◽  
César Borie ◽  
Laura Olguín ◽  
Sandra Rebolledo ◽  
...  
Keyword(s):  
Social System ◽  
Social Dynamics ◽  
Atacama Desert ◽  
Economic Organization ◽  
Northern Chile ◽  
Middle Holocene ◽  
Chilean Coast ◽  
The North ◽  
The Social ◽  
Maritime Adaptations

Chapter 3 summarizes research on maritime adaptations at Middle Holocene (~7,500 to 4,500 cal BP) occupations of the southern extreme of the Atacama Desert, centered around Taltal on the north Chilean coast. Through this period, the authors see increasing population, complexity, and sedentism, but the social system comes to an abrupt end at 4,500 cal BP. In this hyperarid region, marine resources were always extremely important.

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