scholarly journals Early Tertiary exhumation of the flank of a forearc basin, southwest Talkeetna Mountains, Alaska

2012 ◽  
Author(s):  
Heather A. Bleick ◽  
Alison B. Till ◽  
Dwight C. Bradley ◽  
Paul O’Sullivan ◽  
Joe L. Wooden ◽  
...  
Keyword(s):  
Forearc Basin ◽  
Early Tertiary ◽  
Talkeetna Mountains

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.

Wandel Sea Basin, eastern North Greenland

1998 ◽  
pp. 55-62 ◽  
Author(s):  
Lars Stemmerik ◽  
Finn Dalhoff ◽  
Birgitte D. Larsen ◽  
Jens Lyck ◽  
Anders Mathiesen ◽  
...  
Keyword(s):  
Barents Sea ◽  
Fault System ◽  
Hydrocarbon Potential ◽  
Fold Belt ◽  
Related Field ◽  
Northern Margin ◽  
Late Mesozoic ◽  
Early Tertiary ◽  
Late Palaeozoic ◽  
North Greenland

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Stemmerik, L., Dalhoff, F., Larsen, B. D., Lyck, J., Mathiesen, A., & Nilsson, I. (1998). Wandel Sea Basin, eastern North Greenland. Geology of Greenland Survey Bulletin, 180, 55-62. https://doi.org/10.34194/ggub.v180.5086 _______________ The Wandel Sea Basin in eastern North Greenland is the northernmost of a series of fault-bounded Late Palaeozoic – Early Tertiary basins exposed along the eastern and northern margin of Greenland (Fig. 1). The basin and the surrounding shelf areas are located in a geologically complex region at the junction between the N–S trending Caledonian fold belt in East Greenland and the E–W trending Ellesmerian fold belt in North Greenland, and along the zone of later, Tertiary, continental break-up. The Wandel Sea Basin started to develop during the Carboniferous as a result of extension and rifting between Greenland and Norway, and Greenland and Spitsbergen (Håkansson & Stemmerik 1989), and was an area of accumulation during the Early Carboniferous – Early Tertiary period. Two main epochs of basin evolution have been recognised during previous studies of the basin fill: an early (late Palaeozoic – early Triassic) epoch characterised by a fairly simple system of grabens and half-grabens, and a late (Mesozoic) epoch dominated by strike-slip movements (Håkansson & Stemmerik 1989). The Mesozoic epoch only influenced the northern part of the basin, north of the Trolle Land fault zone (Fig. 1). Thus the northern and southern parts of the basin have very different structural and depositional histories, and accordingly different thermal histories and hydrocarbon potential. This paper summarises the results of a project supported by Energy Research Program (EFP-94), the purpose of which was to model the Wandel Sea Basin with special emphasis on hydrocarbon potential and late uplift history, and to provide biostratigraphic and sedimentological data that could improve correlation with Svalbard and the Barents Sea. It is mainly based on material collected during field work in Holm Land and Amdrup Land in the south-eastern part of the Wandel Sea Basin during 1993–1995 with additional data from eastern Peary Land (Stemmerik et al. 1996). Petroleum related field studies have concentrated on detailed sedimentological and biostratigraphic studies of the Carboniferous–Permian Sortebakker, Kap Jungersen, Foldedal and Kim Fjelde Formations in Holm Land and Amdrup Land (Fig. 2; Døssing 1995; Stemmerik 1996; Stemmerik et al. 1997). They were supplemented by a structural study of northern Amdrup Land in order to improve the understanding of the eastward extension of the Trolle Land fault system and possibly predict its influence in the shelf areas (Stemmerik et al. 1995a; Larsen 1996). Furthermore, samples for thermal maturity analysis and biostratigraphy were collected from the Mesozoic of Kap Rigsdagen and the Tertiary of Prinsesse Thyra Ø (Fig. 1).

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