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Home My WebLink About19970972 Ver 1_Geologic Map_20010120unedited draft t Open File Report Number 1-4 LEGEND TO ACCOMPANY GEOLOGIC MAP OF REGION H This geologic map was compiled from published reports, theses, dissertations, and original mapping conducted as a part of the North Carolina Geological Survey's regional geologic mapping program. Some of the previous mapping was used without modification. Other maps were modified to various degrees, partly as a result of reconnaissance mapping and partly for commonality. The use of previous work is gratefully acknowledged; however, the Geological Survey Section assumes responsibility for any errors, omissions, or revisions. For previous work, refer-to the Index of Geologic Mapping. To achieve conformity throughout the map and to make the map more useful to the public, similar rock types were combined into generalized units which could be extended over large areas. However, even though the map was generalized, certain areas may falsely appear more geologically complex than others because of the variety of different scale maps used during compilation. SEDIMENTARY ROCKS Floodplain alluvium Gray, buff to brown, unconsolidated sand, silt, and clay with some gravel beds. D:Tl Terrace Alluvium Both high and low terraces undivided, unconsolidated, gray, buff to brown gravel, sand, silt, and clay (T). Some terraces are mainly sand, silt, and clay, whereas others are conspicuously gravel rich. The highest terrace deposits (TI) in the Pee Dee River appears similar to but is not Middendorf Formation. uvial, cross-stratified sands with intercalated stringers of gravel. Gravel is mainly quartzite and is distinct from gravel in floodplains, terraces, and Cretaceous deposits. Deposits overlie Middendorf Formation. Several workers have assigned most outcrops to "Citronelle" Formation. Pinehurst Formation Buff to light brownish red, unconsolidated surficial sands. Primarily medium sand with small amounts of silt and clay. Planar cross bedding and horizontal bedding can be seen in some fresh cuts. Can be confused with soil formed on underlying Middendorf Formation. Eocene undivided Tan to reddish brown phosphatic sandstone,'glauconitic sandstone, fossiliferous sandy opal claystones. • Middendorf Formation Light-gray, buff to light-brown, fluvial, loose to poorly indurated, commonly cross-stratified silty sands with subordinate lenses of clay and pebbles; clay balls common in some sections. GL High-level Gravels Buff to tan fl _ I - - - \ , . .. -- - _. - - - '_ - - unedited draft rOpen File Report Number 1-4 LEGEND TO ACCOMPANY GEOLOGIC MAP OF REGION H This geologic map was compiled from published reports, theses, dissertations, and original mapping conducted as a part of the North Carolina Geological Survey's regional geologic mapping program. Some of the previous mapping was used without modification. Other maps were modified to various degrees, partly as a result of reconnaissance snapping and partly for commonality. The use of previous work is gratefully acknowledged; however, the Geological Survey Section assumes responsibility for any errors, omissions, or revisions. For previous work, refer to the Index of Geologic Mapping. To achieve conformity throughout the map and to make the map more useful to the public, similar rock types were combined into generalized units which could be extended over large areas. However, even though the map was generalized, certain areas may falsely appear more ,geologically complex than others because of the variety of different scale maps used during compilation. SEDIMENTARY ROCKS Floodplain alluvium Gray, buff to brown, unconsolidated sand, silt, and clay with some gravel beds. T 1, Terrace Alluvium 1 Both high and low terraces undivided, unconsolidated, gray, buff to brown gravel, sand, silt, and clay (T). Some terraces are mainly sand, silt, and clay, whereas others are conspicuously gravel rich. The hii-hest terrace deposits (Tl) in the Pee Dee River appears similar to but is not Middendorf Formation. uvial, cross-stratified sands with intercalated stringers of gravel. Gravel is mainly quartzite and is distinct from gravel in floodplains, terraces, and Cretaceous deposits. Deposits overlie Middendorf Formation. Several workers have assigned most outcrops to "Citronelle" Formation. GL High-level Gravels Buff to tan fl Pinehurst Formation Buff to light brownish red, unconsolidated surficial sands. Primarily medium sand with small amounts of silt and clay. Planar cross bedding and horizontal bedding can be seen in some fresh cuts. Can be confused with soil formed on underlying Middendorf Formation. Eocene undivided Tan to reddish brown phosphatic sandstone,'glauconitic sandstone, fossiliferous sandy opal claystones. Middendorf Formation Light-gray, buff to light-brown, fluvial, loose to poorly indurated, commonly cross-stratified silty sands with subordinate lenses of clay and pebbles; clay balls common in some sections. 1 r.; .. IV Intermediate Volcanic Rocks Medium- to dark-grayish-green tuffs and lithic and crystal tuffs with rare flows; possibly andesitic in composition. Mapped separately from mafic volcanic rock unit mainly by soil color. Soil is light to medium brown to medium red. Minerals present in major amounts are quartz, albite, epidote, chlorite, and sericite. Other minerals include magnetite, pyrite, calcite, tremolite, biotite, and leucoxene. Mafic Volcanic Rocks Medium- to dark-g ayisli-green tuffs, crystal tuffs, and flows; possibly basaltic in composition. Subordinate lithic tuffs. Soil deep brown to red. Major minerals are tremolite, epidote, chlorite, albite, and quartz. Other minerals include pyrite, leucoxene, sericite, and biotite. S p Phyllitic to Schistose Rocks Fine-grained, light-gray, silver-gray, greenish, and white phyllites and fine-grained schists with well developed cleavage. Includes horn-',,Is in metamorphic zones around intrusions, phyllites associated with pyrophyllite mineralization, sericite phyllite, and phyllites in what may be shear zones. Many small shear (?) zones not mapped at this scale. Principle minerals are sericite and muscovite %vith subordinate amounts of quartz, chlorite, feldspar, and hematite. El Felsic Tuffaceous Argillite Buff to medium-blue, thin bedded, fine-grained Felsic rock similar to thin-bedded argillite in texture and appearance but containing more quartz and possibly feldspar. This bedded unit is probably subaqueous in origin. EEI Mica Gneiss and Schist Gray, medium- to coarse-grained, well-foliated biotite gneiss and sericite schist. INTRUSIVE ROCKS Hl Diabase Dense, dark gray to black, fine- to medium-grai-;ed dikes and rare sills composed chiefly of augite, olivine, and plagioclase. Dikes range from 1 foot to 150 feet or more in width. Reinemund (1955) reports sills up to 400 feet thick from borehole data in the Deep River Coal Field, part of which crops out in northeastern Region H. GB Gabbro and Metagabbro Fresh, unmetamorphosed, massive, dark, coarse-Qrained gabbro composed chiefly of hornblende, pyroxene, olivine, and plagioclase crops out in Anson and Richmond Counties. Older(?) metagabbro sills crop out in Montgomery County. The principle mineral is hornblende. Other minerals include feldspar, sericite, epidote, calcite, pyrite, and leucoxene. El Granite Post-metamorphic granitic rocks, coarse-grained and porphyritic. The Lilesville Granite is compositionally zoned and consists of quartz monzonite, granodiorite, and quartz diorite. Characterized by porphyritic rapakivi texture with a matrix of plagioclase, quartz, and biotite (Waskom, 1970). The Millstone Lake Granite northeast of Rockingham is porphyritic but has not been studied in detail. N?l Quartz Quartz veins 3 l ?• ' t 13 Y If 4Q I ?Jr l Illp '14 ;QX g r` ?+ ?•? X0.1-? ? _ ??? , ? , a i ira - Q CL /-CL N ti Q lam. ,e,e?A 06, 17 cr. v ?/? ,tom • .'1 \ r i _ ; `+ j `I Q 1. i?. - T.. .i r fir' ? °? Q/ •"?' --1 c C` _ `,?! !' ...rte a CL? -N car* c it ( y a, j •17??? ?' a O. c. a 'cr F v a KrL p? 7t - ????j ? ? r a r ; ''L. ?p^2' c. '???T///(((???zy?Q/ ?a•A ,, \C i 1.?..?: ? , Q G) I to ?? D (` --1 / ?? ? '? ??'? oil' ,--' '1 ?.?.. +- r... • r?rl ? / J C 3 -? v , .`?. ,Q , . .....,. A 7D a CL Fr cu I GEOLOGIC MAP OF NORTH CAROLINA Compiled by Det),irtment of Conservation and Development William P. Saunders, Director Division of Mineral Resources Jasper L. Stuckey, State Geologist 49J"T J Y F E ,s i,jarad iew ar Inionyilie VV ir 4 :A' a d{?: e Y. Tu Undifferentiated Red, brown or purple claystone, siltstone, sandstone and con- glomerate; also gray and black claystone, shale and fine grained sandstone. y %J l fv /i i CAS i t1 JI T / ar Bedded argillites (volcanic slate) Bedded volcanic slate, containing lenses of acid and basic frag- mental and flow material. M M ln?r MM :__'c?3 Gti,7 i ..?.-? r C..' 2?