Sandstone petrography and provenance of the Chubut Group (Cretaceous) in the Cañadón Matasiete (Golfo San Jorge Basin, central Patagonia): Implications for basin evolution and alluvial organization

Late Cretaceous sedimentary rocks assigned to the Santa Marta (Herbert Sound Member) and López de Bertodano (Cape Lamb and Sandwich Bluff members) formations of the Marambio Group, crop out on Cape Lamb, Vega Island. Although previous studies have recognized that these sedimentary rocks were derived from the northern Antarctic Peninsula region, the work presented here allows the provenance and palaeogeographical evolution of the region to be described in detail. On the basis of both sandstone petrography and clay mineralogy, the Herbert Sound and Cape Lamb members reflect sediment input from a low relief source area, with sand grade sediment sourced from low grade metasediments, and clay grade sediment ultimately derived from the weathering of an andesitic source area. In contrast, the Sandwich Bluff Member reflects a switch to a predominantly andesitic volcaniclastic source. However, this sediment was largely derived from older volcanic suites due to renewed source area uplift, with only a minor component from coeval volcanism. Regional uplift of both the arc terrane and the western margin of the James Ross Basin was likely during the Maastrichtian.

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Dickite in shallow oil reservoirs from Recôncavo Basin, Brazil: diagenetic implications for basin evolution

Clay Minerals ◽

10.1180/claymin.2008.043.2.06 ◽

2008 ◽

Vol 43 (2) ◽

pp. 213-233 ◽

Cited By ~ 10

Author(s):

J. De Bona ◽

N. Dani ◽

J. M. Ketzer ◽

L. F. De Ros

Keyword(s):

Fission Track ◽

Oil Reservoirs ◽

Basin Evolution ◽

Apatite Fission Track ◽

X Ray Diffraction ◽

Entire Region ◽

X Ray ◽

Deep Burial ◽

Uplift And Erosion ◽

Scanning Electron

AbstractFluvial and aeolian sandstones of the Sergi Formation are the most important reservoirs of the Recôncavo Basin, Brazil. Optical and scanning electron microscopy, X-ray diffraction and infrared spectroscopy revealed the occurrence of dickite, a clay mineral indicative of deep burial conditions (T >100ºC), in the shallow Buracica (630–870 m) and Água Grande (1300–1530 m) oilfields. Vermicular dickite replaces K-feldspar and plagioclase grains, and fills intra- and inter-granular pores. Its vermicular habit is a product of pseudomorphic kaolinite transformation during burial. The presence of dickite is in accordance with the intensity of compaction, post-compactional quartz cementation and δ18O values of calcite cements (T up to 109ºC). These petrological features of deep burial, as well as apatite fission-track analyses, indicate that uplift and erosion of at least 1 km, and probably >1500 m, affected the central part of the Recôncavo Basin and possibly the entire region. This uplift has not been detected previously by conventional structural and stratigraphic models.

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