Spectral analysis of gravity anomalies and the architecture of tectonic wedging, NE Venezuela and Trinidad

Tectonics - Tập 13 Số 3 - Trang 613-622 - 1994
R. M. Russo, R. C. Speed

Tóm tắt

We have analyzed the spectral content of free air gravity anomalies in the Caribbean‐South American plate boundary zone in order to determine better the near‐surface (0–120 km) distribution of crustal and upper mantle elements which give rise to the unusual gravity field of this region. The plate boundary zone in northeastern Venezuela and Trinidad is the site of the world's sea level continental minimum of Bouguer gravity anomalies, yet the region is also one of mild topography (mean value 43 m, maximum 1200 m). We find the mean depths to interfaces of significant density contrast at a variety of depths for portions of the plate boundary zone. We interpret interfaces at 30–35 km and 32 km beneath the Guyana Shield and the Aves Ridge, respectively, to be the Moho. Other shallow interfaces (5–14 km) are most likely sediment cover‐basement contacts in the Maturin foreland basin and southern Grenada Basin. Deeper interfaces (54–63 km) we associate with loaded and downwarped continental and oceanic South American lithosphere. The deepest boundaries, at depths of 89–120 km, may be related to detached or detaching oceanic lithosphere overridden by continental South America. We use our results to test the tectonic wedging model of the plate boundary zone recently published by Russo and Speed (1992). We find that the tectonic wedging model adequately describes many of the structural boundaries inferable from our analysis of gravity anomalies but that the model must be modified to include a thinner Guyana Shield crust.

Từ khóa


Tài liệu tham khảo

10.1130/0091-7613(1990)018<0950:ROETIE>2.3.CO;2

10.1111/j.1365-246X.1977.tb06927.x

Båth M. Spectral Analysis in Geophysics Dev. Solid Earth Geophys. 7 552 Elsevier New York 1974.

Bladier Y., 1979, Rocas verdes de la región de Carupano, Venezuela, plano de Despaque Corrimientos, Bol. Geodin., Comis. Int. Geodin., 2, 35

Bonini W. E., 1978, Anomalous crust in the eastern Venezuela Basin and the Bouguer gravity anomaly field of northern Venezuela and the Caribbean borderland, Geol. Mijnbouw, 57, 117

Bowin C. Caribbean gravity field and plate tectonicsSpec. Pap. Geol. Soc. Am. 169 79 1976.

10.1111/j.1365-246X.1979.tb01031.x

10.1111/j.1365-246X.1990.tb06579.x

10.1029/JB075i017p03357

10.1130/0016-7606(1957)68[897:GIITEC]2.0.CO;2

10.1130/MEM162-p175

Foland K. A., 1992, Geochronologic studies of the hinterland of the Caribbean Mountains orogen of Venezuela and Trinidad, Geol. Soc. Am. Abstr. Programs, 24, A148

10.1029/JB090iB14p12623

10.1130/0016-7606(1950)61[1173:GOTEVB]2.0.CO;2

Heiskanen W. A., 1958, Earth and Its Gravity Field

10.1029/JB088iB12p10449

10.1111/j.1365-246X.1974.tb05423.x

10.1029/JB075i017p03367

10.1029/GM051p0103

10.1130/0016-7606(1957)68[359:GIITEC]2.0.CO;2

Pereira J. G., 1986, Interpretacion sismo‐estratigrafica del sector oriental de la cuenca de Carupano, Proc. Congr. Venez. Geofis. 3rd, Caracas, 454

Pindell J. L., 1990, The Geology of North America, The Caribbean, 405

Press W. H., 1986, Numerical Recipes

Robertson P., 1989, Evolution of the southern Caribbean Plate boundary, vicinity of Trinidad and Tobago, AAPG Bull., 73, 490

10.2516/ogst:1987001

10.1130/0091-7613(1992)020<0447:OCATWO>2.3.CO;2

10.1029/93JB00507

Salvador A., 1968, Transactions of the Fourth Caribbean Geological Conference, Trinidad, 1985, 31

Snoke A. W., 1990, Transactions, Caribbean Geological Conference, 12th, St. Croix, 389

10.1029/TC004i001p00041

10.1029/90JB02558

Speed R. C., 1984, Atlas 10, Ocean Margin Drilling Program, Lesser Antilles and Adjacent Ocean Floor

10.1029/JB094iB03p02913

Speed R. C. P. L.Smith‐Horowitz K. V. S.Perch‐Nielsen J. B.Saunders A. B.Sanfilippo Southern Lesser Antilles Arc Platform: Pre‐Late Miocene Stratigraphy Structure and tectonic EvolutionSpec. Pap. Geol. Soc. Am. 277 98 1993.

10.4294/jpe1952.36.255

van derHilst R. D. Tomography with P PP and pP delay‐time data and the three‐dimensional mantle structure below the Caribbean region Ph.D. thesis 250 pp. Univ. of Utrecht Netherlands 1990.

Thông tin
Thông tin xuất bản

Tectonics

Tập 13 Số 3

613-622

Thông tin tác giả