Mineral Resources On-Line Spatial Data
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|Geologic age||preCambrian-Proterozoic [Grenville]|
|Original map label||pCh|
|Comments||As orig. defined (Dumble, 1902), unit was named Hazel sandstone, describing only 500 ft of red ss. in Diablo Mtns. King and Flawn (1953) extended the unit to include conglomerate also, and renamed the unit Hazel Formation. Interbedded sandstone and conglomerate. Mostly indistinctly bedded ss. in northern outcrops, conglomeratic in basal part. Sandstone, mostly fine to very fine grained, mostly tightly cemented, brick red to maroon red. Conglomerate is poorly sorted, sl. rounded pebbles to angular blocks more than 6 feet across, derived mostly from Allamoore Formation. In places where conglo. beds are vertical, outcrop nearly a mile wide. North of Hazel mine on Sierrra Diablo escarpment, exposed thickness or red ss. is at least 2,000 ft, neither base nor top exposed. Thickness 5,000 +-ft. (from Geol. Atlas of Texas, Van Horn-El Paso Sheet, 1968). Unit deposited in arid-region alluvial-fan system that was shed north from a granitic and interbedded diabasic volcanic and carbonate rock source. Has three principal facies: 1) proximal, chiefly ls. clast conglo. of poorly sorted boulders and cobbles and thin horiz.-bedded granule-bearing arkosic ss.; 2) mid-fan alternating ls. clast conglo. and arkosic ss.; 3) distal, dominantly v.fine grained arkosic ss. Facies 1 grades north into facies 2. Upper more distal part is mainly red ss.; remainder is conglo. The thick, massive conglo. layers grade north into ss. Conglomerates are separated by increasingly thicker beds of red ss. Laminated algal stromatolites that crop out in an arcuate belt are interbedded with ss. and congl. in the mid- and distal-fan. These carbonates are green, delicately crenulated and laminated. Silt-size grains of quartz, feldspar, volcanic rocks trapped between algal laminations more than 1,700 m thick. (from Reid, J.C., 1989)|
|Primary rock type||sandstone|
|Secondary rock type||conglomerate|
|Other rock types||arkose; limestone|
Sedimentary > Clastic > Sandstone (Bed)mostly indistinctly bedded ss. in northern part of Van Horn area.
Sedimentary > Clastic > Conglomerate (Bed)Van Horn area.mostly conglomerate in southern (Van Horn area) outcrops. Ss inupper part. In northern Van Horn area, conglo. in basal part of mostly ss.
Sedimentary > Carbonate > Limestone (Bed)Laminated algal stromatolites that crop out in an arcuate belt are interbedded with ss. and congl. in the mid- and distal-fan. These carbonates are green, delicately crenulated and laminated.
Bureau of Economic Geology, 1992, Geologic Map of Texas: University of Texas at Austin, Virgil E. Barnes, project supervisor, Hartmann, B.M. and Scranton, D.F., cartography, scale 1:500,000
King, P.B., 1940, Older rocks of the Van Horn region, Texas: American Association of Petroleum Geologists Bulletin, v. 24, no. 1 p. 143-156.
|Geographic coverage||Culberson - Hudspeth|
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