GJBX-1 0(82)
National Uranium Resource Evaluation A GEOLOGIC REPORT ON THE OAKVILLE-GOLIAD DRILLING PROJECT
Field Engineering Corporation
Grand Junction Operations Grand Junction, CO 81502
March 1982
PREPARED FOR THE U.S. DEPARTMENT OF ENERGY Assistant Secretary for Nuclear Energy Grand Junction Area Office, Colorado GJBX-10(82)
A GEOLOGIC REPORT ON THE OAKVILLE-GOLIAD DRILLING PROJECT
JON ALAN BENFER
BENDIX FIELD ENGINEERING CORPORATION Grand Junction Operations Grand Junction, Colorado 81502-1569
December 1981
Prepared for the U.S. Department of Energy Grand Junction Area Office Under Contract No. DE-AC07-76GJ01664 CONTENTS
Page
Acknowledgments • • • • • • • • • • • • • • • • • • • • • • • • 5 Introduction • • • • • • • • • • • • • • • • • • • • • • • • • • 7 Project objective • • • • • • • • • • • • • • • • • • • • • 7 Past and present activity • • • • • • • • • • • • • • • • • 8 Geologic summary • • • • • • • • • • • • • • • 8 Summary of uranium genesis • • • • • • • • • • • • • • • • • • • • 17 Drilling activities and results •••••••••••••••••• 18 Drill-hole descriptions •••••••••••••••••••• 19 Hole OG-2 • • • • • • • • • • • • • • • • • • • • 19 Hole OG-3 • ...... • • ...... 20 Hole OG-5 • • • • • • . . • • ...... 20 Hole OG-6 • • ...... • • • • 20 Hole OG-10 • • • • • ...... 21 Hole OG-12 •••••• ...... 21 Hole OG-16 ••• ...... 21 Hole OG-17 ...... • • ...... • • 22 Hole OG-17A •••••••••• . . • • ...... • • • 22 Hole OG-18 ...... • • 22 Hole OG-20 • • • • • • • • • • • • • ...... 23 Hole OG-22 ...... • • . . • • 24 Conclusions of uranium favorability and resources ...... 24 Recognition criteria • • • • • • • • • ...... 24 Procedures for scoring favorability • • ...... 24 Limitations to the scoring • • • • • • • • ...... 29 Uranium favorability of project area ...... 32 References • • • • • • • • • • • • • • • • • • • • • • • • • • • • • • 35 Selected bibliography • • • • • • • • • • • • • • • • • • • • 37 Appendix A. Assay results of individual elements, OG-2 and OG-17 39 Appendix B. Petrographic descriptions • • • ••••••••• 43 Appendix c. Geophysical and lithologic logs ••••••• 89
TABLES
Table 1. Drill-hole summary • • • • • • • • • • • • • • • • • 12 2. Recognition criteria for South Texas-type deposits and associated numerical values • • • • • • • • • • • • • • • • 26 3. Favorability criteria • • • • • • • • • • • • • • • • • • 30
ILLUSTRATIONS
Figure 1. The South Texas mineral trend • • • • • • • • • • • • • 9 2. Potential uranium resource areas and project drill holes, 1979 •• • • ...... • • • • ...... 11 3. Map of South Texas coastal plain showing project area and major structural features • • • • • • • • • • • • • • • • • 13 4. Generalized stratigraphic column for South Texas gulf coast 14 5. Generalized geologic map of project area • • • • • • • • • 15 6. Recognition-criteria for the South Texas-type uranium deposits • • • • • • • • • • • • • ••••••••••• 25 7. Schematic relation between calculated favorability for South Texas-type deposits and the chances of a deposit being present within the area evaluated • • • • • • • • • • 31 8. Favorability scores by hole and formation ••••••••• 33
3 ACKNOWLEDGMENTS
The author expresses appreciation to BFEC geologists Mike Freeman and John Rundle for their assistance in the field, and to W. E. Galloway and D. A. Morton (University of Texas at Austin, Bureau of Economic Geology) for use of their core-log data. Additional thanks is also extended to John Rundle for his assistance in final preparation of this report.
5 INTRODUCTION
The Oakville-Goliad drilling project was conducted in support of the National Uranium Resource Evaluation (NURE) Program, administered by the Grand Junction, Colorado, Area Office of the u.s. Department of Energy (DOE). Bendix Field Engineering Corporation (BFEC), prime con tractor for the Grand Junction Area Office of the Department of Energy, performed the investigation. The project consisted of 12 drill holes having a cumulative depth of 28,646 feet. These holes tested the stratigraphy and uranium favorability of the Goliad Formation, the Oakville Formation, and in some cases the Catahoula Fonnation. The project area is largely coincident with Brooks County, located near the southern tip of Texas (Fig. 1), and it is situated in the gulf coastal region about 60 miles southwest of Corpus Christi. Falfurrias, located at the northern end of Brooks County, is the only town of any size within the 1350-square-mile project area. The project area lies within the Laredo and McAllen 2° Quadrangles.
David L. Norton, DOE regional geologist in Austin, proposed in April 1978 that a NURE drilling program be conducted in the Brooks County area to obtain subsurface data to be used to improve uranium resource estimates. At that time, the Department of Energy estimated that 22,500 tons U308 of possible potential resources, in the $50-per-pound forward-cost category, were contained in the Goliad and Oakville Formations within the resource areas (Fig. 2).
This report presents geologic data generated by the drilling, coring, and logging conducted in 1979 and 1980. Included herein are interpretive lithologic and geophysical logs of each hole. Selected drill cuttings from holes OG-2 and OG-17, only, were analyzed petrographically and chemically by the BFEC petrology and chemistry laboratories with the results appended. All core obtained, totaling approximately 700 feet, was studied and described by William Galloway and colleagues at the Texas Bureau of Economic Geology (Galloway and Morton, in preparation). Table 1 is a summary of drill-hole data obtained.
As part of the NURE program, aerial radiometric and magnetic surveys have been performed on the Laredo Quadrangle area [(GJBX-99(79)] and the Brownsville-McAllen Quadrangle areas [ (GJBX-118(78)]. Hydrogeochemical and stream sediment reconnaissance reports have also been published on the Laredo [(GJBX-14(80)] and the Brownsville-McAllen Quadrangle areas [(GJBX-249(80)]. Uranium resource evaluation reports are being prepared on these same areas.
PROJECT OBJECTIVE
Project objective was to obtain subsurface data by drilling and logging to improve the estimate of uranium resource potential for the Goliad and Oakville Formations in and around Brooks County. This objective was achieved by performing the following tasks:
1. Integrating available subsurface data (Quick and others, 1977) and selected electric logs.
2. Determining stratigraphy and petrology encountered in drilling by studying drill cuttings and core and geophysical logs.
7 3. Assessing the uranium favorability of each stratigraphic section penetrated by applying the criteria observed at relevant known deposits.
PAST AND PRESENT ACTIVITY
The South Texas mineral trend occurs along the strike of the Tertiary coastal plain sediments. The project area is downdip about 10 miles to the southeast of the main trend (Fig. 1) in an area that has been a major producer of petroleum for many years, but until very recently has been considered a frontier for uranium exploration. About 1970, Hecla Mining Company drilled several uranium exploratory holes in the vicinity of the Alta Verde Dome (Fig. 1). About that same time, Exxon investigated the Gyp Hill area, another domal structure. In the last two years or so, Exxon has been drilling in the vicinity of Falfurrias, Chevron has been testing the Kelsey Field area, and Conoco has been exploring for uranium on their lease properties in the northwestern portion of Brooks County.
Currently, exploration is actively being conducted by several uranium producers near Hebbronville, located in southern Duval County {Fig. 1). This area has been described as a subsidiary mineral belt oriented perpendicular to the main trend and is projected to the southeast through Brooks County (Adams and Smith, 1981).
GEOLOGIC SUMMARY
The project area is situated on the broad, flat coastal plain of Texas and within the Rio Grande Embayment, which has accumulated a complex sequence of Tertiary marine and nonmarine sediments exceeding 50,000 feet in thickness. Figure 3 shows the position of the project area in relation to the main structural features of the coastal plain.
The south coastal plain is cut by several strike-oriented normal faults, which were active during Tertiary deposition (Fig. 3). These high-angle "growth faults" have caused thickening of the sedimentary units on the downthrown, normally southeast, block.
Figure 4 illustrates the generalized stratigraphic section and nomenclature of Tertiary units of the South Texas gulf coast. Depositional environments represented include fluvial, flood plain, deltaic, lagoonal, strand plain/longshore bar, and open shelf. Sediments consist principally of sandstone, siltstone, and claystone deposited as a series of wedges which gently dip and generally thicken to the southeast toward the gulf coast.
Formational units within the Rio Grande Embayment which host uranium deposits include, in ascending order, the Jackson Group, the Frio Clay, the Catahoula Formation, the Oakville Formation, and the Goliad Formation. Only the Goliad crops out in the project area (Fig. 5).
Uranium was first discovered in Karnes County, Texas, in 1954, in rocks assigned to the Jackson Group (Fig. 4). The Jackson, comprised of several formations, is of Eocene age and is the oldest known uranium host rock in
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I I LEGEND 30' IS' gao 5 0 5 10 MILES Possible Potential Re~o!.!:-~e Area 5 0 5 10 KILOMETERS Probable Potentia I ~M~~-~--~~~~~1 Resource Area l..--- .... _... I Goliad Potential Resource Area ,-. '-. . ..) Oakville Potential Resource Area
FIGURE 2. 1979 potential uranium resource areas and project drill holes
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I I / ' \ I \ I \ I \ II ' \ I \ I N \ ' Hous,.o ' v ~I I \ ~ OAustin I ' L,Y I ,I \_ ' , '\ \ vc,O~~,z, ~-? \ 0 50 MILES Modified from Quick, et al (1977} Oakville -Goliad Project Area FIGURE 3. Map of South Texas coastal plain showing project area and major structural features 13 ERA SYSTEM SERIES GROUP FORMATION LITHOLOGY DESCRIPTION t-"aerr-rAri~1df.f:!§f~~8~~0:~::~~ Clay, silt, sand, gr• and organic matter 81 RECENT Beach ridge, sand dunes, de.. >a: 1 'a~·~~~~~~~si~sitlsanlnd-i~-~-.r.~·-:~,.,~~ lrDo~;its c::[ r 1 - - z deposits dunes a: w Fluviatil• .... river deposits ~:::;:.=-'.'·'·'· :;•:·~:_:: c::[ ::!) PLEISTO ~~~~~~~~iiiW Sand, silt clay, and gravel; iron oxide and caliche in Cl CENE r weathered zones ,...... ,,, ..... ,,, __ ,.. _. :-:~:;: Y.;J,!. - Uvalde Gmvel .. "·"·' PliO 1- ~,: -']Calcitic, medium· to very coarse-grained sandstone and CENE Gohad* 1::.• , ·._::;:-·~.- ::~:; conglomerate; marL limestone, clay, and caliche ~l~:.:.. _:_. :__,_,__ :.t£· ~~:;;-:<:>;...;; t-_ .:._ __ :.:.:._ _·:.:..- -:-_ -,:c-_-,_- _-- ~;~~1;1~8~-f?~T:~i .. Subsurface only; calcitic mudstone, thick-bedded medium Fleming tW:lTI=i.[0"'-'~~=lB !lli=i.~"'"~-flli=~-~,"'~~.:..:..t MIOCENE FLEMING Oakville" t..,..,~-,--_:_-_:_ _:_--::'..,.."'--:--:~:..:. grained sanstone, and intermittent volcanic ash; caliche in ~jfiJ?tqt;{f~~i:;f,}tj[Jj weathered zones __ ,::::: ::::::;~:;_:;:~ .: ~ ~:. ._..:.::·.:~; - --~----~------~~~~~~~~~~-~=~:~~;:-~~~:-~~.;·~~------~ (,.) c ~b·,~?~9;o. ·":Jr'):~ N 0 CATA catahoula- I- :-_--'_~ Varicolored, massively bedded tuff and tuffaceous z HOULA Frio* mudstone, sandstone, clayey sandstone, and clay; loosely L&.l OLIGO (,.) CENE ===f~:::;~~~= ~ ~e~~~~~:d ~~~r:se volcanic conglomerate; caliche in :.. ::.:.::.:...:·..:..:: .. :::..:..·_ >a: c::[ i= VICKS :_--'-'--~-:;: Subsurface only; greenish-gray clay and sandstone, volcanic a: BURG ~ --__ : rock fragments w ....::- .... ·.. -: .... Whitsett* F - ~c- :~}=Jf),:,;i Fine- to coarse-grained, fossiliferous, laminated, and ~-;:;=~-~['.~'@':-:'--g:·.-~~~~.~~ crossbedded sandstone; sandy, calcitic clay with abundant ::·:~!~ ·"·.!··~~-~ fossil wood; some volcanic ash beds ..::·: .,_".:..'..··: :'[;ijV? __..:..·::::... -= :c-.-= f\Xi:f:}ii{iii)Hi!i!!@ Lignitic, bentonitic, silty, brown clay and fine-grained, :~:?::;:~~:§~ calcareous, glauconitic sandstone with some fossil wood ~~~~~~~~~~~~ Thin-bedded, fine-grained sandstone overlain by clay and ~sandstone .-:-...,-----~~ Subsurface only; clay, fine-grained sandstone, and coal, interfingering to the northeast with fine-grained sandstone --- and shale overlain by clay Reklaw s. ____"!!!!'!!!!'!!! Subsurface only; calcareous, ;iferous clay and - clay, thin- to thick-bedded vua•::.c-~1 a111cu sandstone; lig~nite CARRIZO ~ -""'- ...:..: . Subsurface only; thin-bedded, fine-grained, carbonaceous WILCOX $i0'\~~'W?;:::~-: :·:;::fj sandstone; sandy shale; !ignite .___ _.__ ___...__ ___...______. _____---<:.:.~::::;:-::::. '(. ! *Contams uramum deposits. murh/11.'1/ from C!wrr!JHIII FTGURE 4. Generalized stratigraphic column for the South Texas gulf coast 14 30' 15' se• LEGEND 5 0 Geology modified from 5 10 MILES Galloway ( 1981) appended. Pliocene Age Goliad [!!] Formation 5 _,0 5 10 KILOMETERS Ia!~ll5iii~iiiiiiiiiiiiiiiiiiiiiiiiiiiiii~' ~~I ~~ Growth Fault 0 Project Dri II Hole OG-2 FIGURE 5. Generalized geologic map of project area 15 South Texas. The Jackson is also the only known marine host, consisting of sand bodies deposited in strand-plain/longshore-bar environments with associated lagoonal muds and lignites (Adams and Smith, 1981). Besides hosting at least 30 uranium orebodies, the Jackson sediments are also important producers of oil and gas. The Frio Clay is a thin (<200 feet) clay unit containing minor sandstone and siltstone that conformably overlies the Jackson Group. Only one uranium deposit has been mined from the Frio. In Live Oak County, a fluvial-channel sandstone at the base of the unit contains podlike deposits. However, the presence of scattered radioactive anomalies throughout South Texas may yield additional uranium deposits in the Frio (Quick and others, 1977). The Catahoula Formation of Miocene age underlies the Oakville Formation and overlies the Frio Clay. The formation consists of a series of continental tuffaceous sediments interbedded with fluvial sediments which merge with marine deposits toward the coast. Regionally, the majority of the Catahoula is comprised of tuffaceous clay; however, in the Rio Grande Embayment, thick accumulations of channel and crevasse splay sandstones predominate. Here the formation attains its maximum thickness of approximately 2700 feet (Quick and others, 1977). The Soledad Conglomerate is designated as the middle member of the Catahoula Tuff. This unit consists of a series of volcanic conglomerates, sandstones, and tuffs cemented by a white opaline matrix. The Soledad member lies approximately 1000 feet below the base of the Oakville Formation. The Catahoula Formation contains some of the largest uranium deposits in South Texas. It is probable that the high tuff content of the formation is responsible for supplying uranium found in deposits of other formations as well. Principal uranium deposits hosted in the Catahoula occur as classic roll-front. deposits in the south Duval County mineral belt along the flanks of fluvial channels. Most of these deposits appear to be related to faulting (Galloway and Kaiser, 1979). The Oakville Formation of Miocene age locally displays a basal conglomerate which lies unconformably on the Catahoula Formation. The upper contact with the overlying Fleming Formation is conformable and usually gradational. Poorly consolidated sand, bentonitic clay, marl, and gravel comprise the Oakville. Sands. are generally light gray, medium grained, extensively cross laminated, and friable. Regionally, much of the formation is characterized by thick (up to 200 feet), massive, multistoried channel sand bodies which can be traced laterally for several miles. l.Jithin the study area, the formation varies between 400 and 1400 feet thick due to regional thickening to the southeast because of variable subsidence during deposition. Known uranium deposits within the Oakville Sandstone oc.cur along major channel systems where permeable sands, deposited in crevasse splay and point-bar environments, are interbedded with less permeable fine-grained flood-plain deposits. The resulting sequence of alternating sandstones and shales influenced patterns and rates of uraniferous ground-water movement. Uranium may he preferentially deposited where sandstone/shale ratios range between 1:1 and 4:1, n.nd where five to ten "stacked" sandstone units ranging between 20 and 50 feet in thickness are present (Quick and others, 1977). Zones of mineralization occur most frequently in the basal, coarse-grained sand unit and are commonly associated with hydrogen sulfide and hydrocarbon seeps along faults. 16 The Fleming Formation overlying the Oakville Sandstone is also of Miocene age. The Fleming is gradational with the Oakville and often the two units are not subdivided by workers. The Fleming contains a much higher percentage of clay than does the Qakville and displays minor interbedded sand lenses. ·The formation becomes especially sandy in the southern portion of Brooks County. No significant uranium deposits have been found in the Fleming. The Goliad Formation of Pliocene age unconformably overlies the Fleming Formation and is the only formation which crops out in the project area. It often consists of a basal zone of semiconsolidated, interbedded coarse grained sand and gravel which is overlain by a sequence of alternating sand and clay units with abundant caliche. Regionally, the average sand content of the formation is about 80 percent. Goliad sediments are stream and flood plain deposits which attain a maximum thickness on the order of 1000 feet. The largest and best documented Goliad orebody is a deposit atop the Palangana Salt Dome in east-central Duval County (Fig. 1). It ~s thought that the uranium deposit was localized by the reducing properties of hydrogen sulfide gas emanating from the caprocks of the dome. The uranium deposits appear to overlie sulfur deposits in the caprock (Weeks and Eargle, 1960). Radioactive anomalies associated with OLner saiL domes capped by the Goliad Sand suggest that similar deposits may be pres.ent elsewhere. Uranium is known to occur atop the Sejita Dome in southeast Duval County and the Alta Verde Dome in Brooks County (Fig. 1). As the stratigraphy and provenance of the Goliad and Oakville strata are very similar, it is thought that the Goliad is also prospective for nonsalt-dome-associated zones of uranium mineralization. SUMMARY OF URANIUM GENESIS Uranium in South Texas deposits is presumed to have been leached from tuffaceous, bentonitic and volcaniclastic sediments associated with the Jackson Group and the Catahoula and Oakville Formations. Volcanism was active during deposition of these formations in the area of west Texas and northern Mexico. Deposits in other than these formations are down the hydrologic gradient from these source rocks. Leached uranium was carried downflow by oxidizing ground waters~and was precipitated upon encountering a chemically reducing environment. Favorable host rocks consist of permeable sandstones varying in composition from quartz arenites to arkoses. These sandstones were deposited as point bars, lateral bars, and crevasse splays marginal to fluvial channels, and as longshore bars and barrier beaches in shallow marine environments. Galloway (1977) and Galloway and Kaiser (1979) thoroughly describe the hydrologic complexities of uraniferous ground-water movement. All uranium-bearing formations except the Jackson lack sufficient carbonaceous material to serve as reductants. Diagenetic pyrite, originating from hydrogen sulfide, appears to be the principal reductant in the formation of South Texas uranium deposits (Adams and Smith, 1981). Hydrogen sulfide migrated upward along faults from hydrocarbon reservoirs at depth and entered the aquifers, establishing a reducing environment. This scenario appears likely considering that the coastal plain is extensively fractured by growth faults as well as 17 tension faults in the vicinity of salt domes. Additionally, Galloway (1977) estimates that one-third of the region is underlain by closely spaced petroleum reservoirs which are largely fault controlled. Most South Texas uranium deposits display the typical C-shaped roll-type geometry occurring at well-developed oxidation-reduction boundaries. Many deposits, however, occur wholly within reduced rock which suggests re-reduction after ore formation (Adams and Smith, 1981). Permeable sandstone hosting the ore is commonly bounded above and below by less permeable shale. The elements selenium, vanadium, uranium, and molybdenum are zoned across many of the deposits. Iron-titanium oxides are found well updip of the deposit but have been completely leached from downdip sediments. DRILLING ACTIVITIES AND RESULTS A 20-hole drilling program was authorized by the Department of Energy in April 1979, to test uranium favorability of the Oakville and Goliad Formations in an area largely coincident with Brooks County (Fig. 2). Prior to actual drilling, the 20-hole program was reduced to 12 holes due to budgetary constraints. Nine holes were drilled in Brooks County and one each in Starr, Jim Hogg, and Jim Wells Counties. In many cases, holes were sited in areas where little subsurface information was available. Rotary drilling commenced in September 1979, with holes OG-3 and OG-17A. The contractor on these two holes was HMC Drilling. Hole OG-3 was drilled to 217 feet by a Gardner-Denver 1500 drill rig, and casing was set to that depth. Hole OG-17A was drilled with a Gardner-Denver 2000 to a depth of 1400 feet. In late September, the contractor was released due to contractual problems and neither hole was completed. Hole OG-3 was not logged but hole OG-17A was logged to a depth of 990 feet where the hole had apparently bridged. The remaining 10 holes were drilled with a Failing 2500 rig by Stewart Brothers Drilling Company. Drilling began in March 1980, and was completed in June 1980. The 12 holes totaled 28,646 feet and ranged in depth from 217 feet to 3110 feet. All holes except OG-3 and OG-5 were cored, for a total of 1049 feet of which approximately 700 feet were recovered. In general, an attempt was made to core the basalp50 feet of the Oakville and Goliad Formations. In addition, the Soledad Member of the Catahoula Formation was cored in OG-2. Core points were estimated by projecting formation picks from logs of adjacent holes drilled for petroleum. All core obtained was studied and described by W. E. Galloway and D. A. Morton of the Texas Bureau of Economic Geology (1981). An attempt was made to obtain an accurate representation of stratigraphy penetrated by using drilling methods which would provide reliable drill cuttings. To this end, an effective mud program was maintained and the mud was circulated through steel tanks. A shale shaker was employed as well as desilters to reduce solids in the recirculated mud. Even so, hole walls sloughed and bottom hole cuttings were contaminated with uphole lithologies. Cuttings were collected at 10-foot intervals, washed, and described in the field. For additional technical drilling details, surveyed plats of hole locations, and tricrofiche of complete geophysical logs, see GJBX-19(81) (Abramiuk, 1981). 18 All drilling permits were obtained from private landowners. Difficulty was encountered in obtaining drilling permits for several areas; therefore, less desirable alternate locations had to be substituted. In most cases, a full suite of geophysical logs was obtained from each hole by BFEC logging units or Century Geophysical. When a significant gamma anomaly was encountered, a KUT spectral-gamma log was run over that interval whenever possible. The KUT log was run on six holes. All gamma anomalies were shown to be due to uranium only. An archaeological survey was performed at each hole location prior to drilling. The projected total depth of drill holes as well as core points was established from data modified from Quick and others (1977) and from review of over 350 electrical logs of petroleum wells in and around Brooks County. The base of the Goliad is relatively easy to pick from logs; however, the top and bottom of the Oakville is arbitrary at best. Contacts established for this report differ markedly in some cases from those established by Galloway in his study of the project core. Such variations are co~uon among South Texas subsurface workers and represent a difference in interpretation. Galloway's formation picks are based on a regional study while picks used in this report represent a localized detailed study. It should be mentioned that if Galloway's picks are appropriate, then most holes did not penetrate the entire Oakville section. Readers are therefore urged to make their own interpretations. DRILL-HOLE DESCRIPTIONS HOLE OG-2 Hole OG-2 was positioned in an area where the Soledad Member of the Catahoula Formation appeared to be well developed and sufficiently shallow. Nearby petroleum wells provided accurate core intervals. In this hole, the basal units of the Goliad and Oakville and the upper Soledad were cored. Formation contacts established for this hole are considerably shallower than picks used by some workers. Several conglomeratic zones, representing bed-load channel-fill sequences were encountered in the Oakville and Catahoula Formations (see lithologic log for descriptions). A weak radioactive anomaly occurs at the base of the Oakville, and a significant anomaly registering 4.5 times background occurs in a channel sand of the Catahoula (see geophysical log). Petrographic and chemical analyses were performed on selected drill cuttings from OG-2. Lithologically the cuttings are primarily micrite and sandy carbonate with minor amounts of calcareous sandstone and gypsum. Clastic grains are generally texturally submature and consist mostly of quartz with lesser amounts of feldspars, chert, volcanic rock fragments, and less than 1 percent heavy minerals. Autoradiographs of cuttings from radioactive zones did not indicate the presence of uranium. This is probably a result of lag and contamination associated with uphole travel of drill cuttings and probably suggests that cuttings analyzed did not originate from the radioactive interval. Chemical analyses of drill cuttings did not reveal any anomalous values (see Appendix A). 19 HOLE OG-3 Hole OG-3 was sited on the western flank of the Alta Verde Dome to test for the presence of suspected uranium occurrences (Fig. 1). The hole was abandoned at 217 feet because of contractual problems with the drilling company. When the project's second drilling phase began, the land situation had changed and a drilling permit was no longer available in the vicinity of the dome. No data were obtained from the hole. HOLE OG-5 Hole OG-5 was offset approximately one-fourth of a mile from a petroleum well, the log of which displayed a significant gamma anomaly near the base of the Oakville Formation. In OG-5, a 3-foot-thick anomaly registering 3 times background was encountered at the base of the Oakville. Additionally, about 200 feet above the base~ a 10-foot-thick zone~ 2.5 times background 7 was recorded. Approximately 700 feet of the upper portion of the Catahoula Formation were penetrated, revealing two thin anomalies of about twice background (see geophysical logs). Both the Goliad and Oakville Formations observed in this hole consist of approximately 50 percent sandstone with lesser amounts of siltstone and claystone. A gypsiferous zone conspicuously marks the base of the Goliade The majority of sediments encountered in drilling this hole are oxidized . except for portions of the Catahoula which are pyritic. Hole OG-5 was not cored nor were any petrographic or chemical analyses performed on the drill cuttings. HOLE OG-6 Hole OG-6 was positioned less than 1 mile updip from the mapped location of the Vicksburg Fault (San Fordyce-Vanderbilt Fault of Quick and others, 1977). Lack of reduced rock encountered in the hole suggests the absence of a nearby fault, or that reducing fluids did not migrate upward along ·the Vicksburg Fault and into permeable sediments. The location of OG-6 was also chosen to test an area marginal to Baluarte Creek, a current major drainage of Brooks County. It was thought that Baluarte Creek might follow a paleodrainage course which could be a favorable uranium environment. This thought was somewhat verified by the presence of many channel sandstones stacked throughout the stratigraphic section. A weak gross-gamma anomaly of twice background was encountered within a claystone at the base of the Fleming Formation. A spectral-gamma KUT uranium anomaly of 18 ppm (3 times background) occurs within sandstone of the Oakville (see lithologic and geophysical logs). After completion of drilling~ log correlations indicated that OG-6 was terminated too shallow and that the base of the Oakville Formation was about 200 feet below the bottom of the hole. 20 HOLE OG-10 The location of hole OG-10 was chosen to test the stratigraphy of target formations in the southern portion of Brooks County. Here, the Fleming Formation changes facies and becomes much sandier than farther north. In this area, the Fleming is virtually indistinguishable from the underlying Oakville, both in lithology and in electrical log characteristics. Petroleum wells in the vicinity of OG-10 are cased to depths of about 2000 feet, making accurate log correlations difficult in the shallow formations. Formation contacts established for this hole are therefore arbitrary. The Goliad, the Fleming, and the Oakville Formations are all sand-rich in this area. Reduced, pyritized rock is scattered throughout the hole (see lithologic log). Four radioactive anomalies were encountered in drilling OG-10 (see geophysical logs). A 5-foot-thick section having a 3.5 times background anomaly occurs in the bottom one-third of the Fleming Formation. Three thin, separate anomalies registering 2.5 times background occur in the upper part of the Catahoula Formation. All anomalies are found in sandstone and probably represent minor concentrations of uranium. The KUT log was not available to run in this hole. HOLE OG-12 Hole OG-12 was drilled on the eastern flank of Gyp Hill, a salt dome structure suspected by previous workers to have uranium occurrences (Fig. 1). Correlation of nearby petroleum logs suggests that a fault having approximately 450 feet of displacement lies about 500 feet west of the hole. The hole is situated on the upthrown block of the fault which may be associated with the McAllen Fault or with a tensional feature associated with dome emplacement (Figs. 1 and 3). Basal portions of both the Goliad and Oakville Formations were cored in this hole (see lithologic log). The Goliad contains considerable gypsum and is typically sandy, whereas the Oakviile Formation is deficient in sand. Sediments are at least partially reduced throughout the section penetrated and contain diagenetic pyrite estimated in amounts upwards of 10 percent. The source of pyrite reductants is presumed to be hydrogen sulfide which migrated along the nearby fault. The presence of hydrogen sulfide in the vicinity is substantiated by sulfur deposits associated with the dome cap rock. A 3 times background gamma anomaly was encountered in the bottom one-third of the Fleming Formation, and a twice background anomaly near the top of the Catahoula. HOLE OG-16 The location of hole OG-16 was chosen to test an area which lacked sufficient subsurface information. Correlation with logs from distant petroleum wells is difficult and it is possible that OG-16 was terminated about 100 feet above the base of the Oakville Formation. The estimated basal portion of the Oakville was cored in this hole, but the Goliad was not. An arsenic (262 ppm) and molybdenum (29 ppm) anomaly was found in a coaly, reduced sandstone observed in the core of the Oakville (see lithologic log). 21 Associated with these geochemical anomalies is a 2.5 times background gamma anomaly. Near the base of the Fleming Formation is a 60-foot-thick sandy interval which produced three thin ((10 feet) gamma anomalies registering 3, 2, and 2.5 times background radiation~ A KUT log was not run in this hole, however, the anomalies are probably a result of weak uranium mineralization. HOLE OG-17 Like hole OG-16, hole OG-17 was spotted to test an area which has little nearby subsurface information. After hole completion, additional correlation with distant petroleum logs suggests that OG-17 was terminated approximately 250 feet above the base of the Oakville Formation. The lower portion of the hole was the only section cored (see lithologic logs). Petrographic and chemical analyses were performed on selective drill cuttings from OG-17 and are virtually the same as those described previously for OG-2. A radioactive anomaly was encountered in a 22-foot-thick sandy zone near the middle of the Goliad Formation. An analysis of the KUT log indicates the zone averages about 24 ppm uranium with a maximum of 57 ppm over a 3-foot interval. This is one of the largest anomalies recorded in any of the holes drilled for the project. The Oakville Formation penetrated in OG-17 consists of several thick silty sandstone beds which display mostly syndepositional oxidation (hematitic) although some weak epigenetic oxidation (limonitic) was observed in the core. Approximately one-third of the Goliad Formation consists of fine-grained sandstone containing finely disseminated pyrite. HOLE OG-17A Hole OG-17A was one of two holes drilled in September 1979, during the first phase of the project. The hole was terminated at 1400 feet due to contractual problems with the drilling company and was not completed. Geophysical logging was performed on the upper 990 feet only because of hole bridging. A core was cut at the estimated base of the Goliad Formation. However, the log suggests that the cored interval was too deep and correlates with the upper Fleming (see lithologic log). The Goliad Formation in hole OG-17A appears to consist of well-developed stacked, fluvial-channel sandstones. Also, the upper portion of the Fleming Formation appears to be relatively sandy. An interesting anomaly was encountered in the Fleming core consisting of the elements potassium, magnesium, copper, nickel, vanadium, zinc, lead, lithium, and strontium [(see App. C of Galloway's report, GJBX-9(82)]. The anomaly occurs in a clay which contains oxidized carbonaceous material and oxidized pyrite. Associated with the zone are relatively low iron and titanium values suggesting strong alteration. No gamma anomalies were encountered in the hole. HOLE OG-18 Hole OG-18 was positioned to investigate the uranium favorability of the Oakville and Goliad Formations in the vicinity of the McAllen Fault 22 (Figs. 3 and 5). Correlation by electrical logs from nearby petroleum holes suggests that OG-18 was drilled within a mile of the fault and on the downdropped, eastern block. Fault displacement on the top of the Catahoula Formation appears to be about 100 feet. Basal units of both the Goliad and Oakville Formations were cored. The Oakville Formation, represented by the lower half of the hole, is primarily reduced and pyritic, possibly a result of reducing fluids which emanated along the ~ault from depth. The basal Goliad sediments are likewise reduced. Both the Goliad and Fleming Formations contain considerable gypsum, indicative of a unique coastal playa-lake environment (Galloway and Morton, 1981). The lower portion of the Fleming contains several well-developed sandstones. The Oakville is silty and clayey except for the uppermost part which is sandy (see lithologic log). Two thin radioactive anomalies occur in fine-grained rocks of the Goliad; one registering 3 times background near the top of the formation and the second, 2.5 times background near the base. In a sandstone near the base of the Fleming are two gamma anomalies of 2 and 3 times background, totaling about 10~5 feet in thickness (see lithologic and geophysical logs). No anomalies were encountered in the Oakville Formation. KUT logging was not performed on OG-18. HOLE OG-20 Hole OG-20 was drilled in the extreme northeastern portion of Starr County and updip from the interpreted location of the Vicksburg Fault (Fig. 5). It is an area of limited subsurface data, and correlation of existing electrical logs is difficult. Adding to this uncertainty is a relatively sandy Fleming Formation which causes an arbitrary pick for the base of the Goliad and the top of the Oakville. One core was cut in OG-20 which is sufficiently deep to be correlated with the Fleming Formation. Both the Goliad and Oakville Formations have a relatively high sandstone content in hole OG-20. Much of the sandstone in both these units, however, appears to be silty or thinly interbedded with shaly sediments. Partially reduced sediments associated with diagenetic pyrite and occasional carbonaceous material are scattered throughout the hole. Several radioactive anomalies were encountered in drilling hole OG-20. A 3 times background total gamma anomaly was recorded 50 feet above the base of the Goliad. Slightly higher in the Goliad, the KUT log revealed a 10-foot thick clayey section having 27 ppm eU303. Two more anomalies occur near the base of the Fleming. The deeper of these registered 20 ppm eU303 from the KlJT log, also in a clayey zone. Near the bottom of the hole, within a silty sand of the Catahoula Formation, the KUT log detected a significant 4-foot-thick zone of 78 ppm eU308 (see lithologic log). No gamma anomalies were observed in the Oakville Formation. 23 HOL.E OG-22 Hole OG-22, located in Jim \Jells County, was drilled in the Seeligson oil field to test for the presence of residual hydrocarbons which could serve to precipitate uranium. Scattered remnants of what appeared to be dessicated oil and other minor amounts of organic carbonaceous material was observed in drill cuttings. Pyrite, as so cia ted with reduced sediments, occurs in relatively large anounts, especially in the deeper portion of the hole. The hole is situated about 4 miles updip (west) of the Vicksburg Fault (Figs. 3 and 5). Cores were cut at the base of the Goliad and Oakville Formations. The Goliad Formation drilled, typically consists of sandstone bodies 10 to 50 feet thick with interbedded silt and clay. A spectral gamma anomaly registering 22 ppm eU303 occurs near the base of the unit. The Fleming Formation observed in hole OG-22 is thicker (1000 feet) than in other holes but is typical in lithology to other sections drilled in the northern portion of the project area. It consists primarily of claystone and siltstone with minor interbedded sandy units especially near the base of the forr.tation. A gamma anor.1aly of twice background occurs near the middle of the Fleming. The . Oakville Formation contains several thick (SO+fee t) channel sandstone bodies bounded by thick, finer grained units. A spectral gamma reading of 19 ppm eu3o8 was encountered near the top of the Oakville. The Formation contains considerable pyrite associated with reduced rock, especially in the basal portion (see li tholo gi c log). CONCLUSIONS ON URANIUM FAVORABILITY AND RESOURCES RECOGNITION CRITERIA Criteria used to estimate uranium f avorabili ty of drilled sections in the project area have been taken from a scheme developed by Adams and Smith ( 1981 ). Shown as Figure 6 are their criteria which proceed fror.t a regional to a local extent fror.t left to right. Included are criteria which are considered diagnostic to South Texas uranium deposits. Table 2 shows the choices to be selected for each criteria and the numerical values assigned to the various criteria. To arrive at a favorability score, these values are summed, then divided by the maximum possible points which could be achieved, and finally multiplied by a weighting factor. This weighting factor reflects the relative importance of the presence or absence of the various criteria. The final score is expressed as a percent of a possible 100 percent. All the project drill holes scored the maximum possible points allowed under the two criteria headings of "Tectonic, Structural, and Regional Geologic Setting" and "Sedimentary Sequence" (Fig. 6). This is not surprising, as these headings consist of criteria which are regional in extent. PROCEDURES FOR SCORING FAVORABILITY Uranium favorability of both the Goliad Formation and Oakville Formation was evaluated separately in each drill hole. Additionally, the Catahoula Formation was analyzed in holes OG-2 and OG-5; two holes in which the Catahoula was penetrated to significant depths. The Fleming Formation was not 24 FIGURE 6. Recognition criteria for the South Texas-type uranium deposits 25 Table 2. Recognition Criteria for South Texas-Type Deposits and Associated Numerical Values (modified from Adams and Smith, 1981) I. Tectonic, Structural, and Regional Geologic Setting (weighting factor +30) Tectonic Setting Coastal Plain (+80) Miogeosyncline (+15) Eugeosyncline (-70) Continental Basin (-95) Structural Setting f ..J..I, f'l \ Contemporaneous Growth Faults \'"""VJ Possible Growth Faults (+20) No Growth Faults (-50) Sediment Dip oo-5o (+ 5) 5°-10° (--10) 10°-20° (-40) 20° (-70) II. Sedimentary Sequence (weighting factor +50) Age Tertiary (+20) Mesozoic (+ 5) Paleozoic ( 0) Proterozoic (-70) Basin Thickness )20,000 ft (+15) 5,000 to 20,000 ft ( 0) 1,000 to 5,000 ft (-30) 1,000 ft (-70) Basin Area )10, 000 mi 2 (+15) 1,000 to 10,000 mi2 ( 0) 1,000 mi2 (-50) Host Sediments Volcaniclastics Abundant (+50) Absent (-95) 26 Table 2. Recognition Criteria for South Texas-Type Deposits and Associated Numerical Values (continue d) Color 30%-70% oxidized (+30) <30% oxidized (-30) )70% oxidized (-SO) Depositional Environment Mixed fluvial-shallow marine (+50) Fluvial (-40) Deep marine (-90) III. Host Sandstone (weighting factor +60) Thickness 25 to 100 ft (+20) Area Large (+15) Medium (-10) Small (-60) Permeability High (+15) Medium (-20) Low (-7 5) Uncertain ( 0) Depositional Environment Abundant fluvial (+60) Mixed fluvial-shallow marine (+30) No fluvial (-50) Composition Clastics Arkose (+20) Subarkose (+10} Quartz arenite (+ 5) Unstable (-70) 27 Table 2. Recognition Criteria for South Texas-Type Deposits and Associated Numerical Values (continued) Volcaniclastics Trace to 15% (+60) / 1"\, \ U) )30% (-80) Reductants Plant trash (+40) Iron sulfides (+30) Structure and hydrocarbon resvoirs (+10) None (-95) Sand-shale Proportions 40%-60% sand (+35) 60%-75% sand (+20) )75% sand ( 0) (40% sand (-30) IV. Alteration and Mineralization (weighting factor 75) Alteration Strong epigenetic oxidation plus pyrite (+60) Weak epigenetic oxidation plus pyrite (+20) Syndepositional oxidation plus pyrite ( 0) Syndepositional oxidation with no pyrite (-10) None (-80) Mineralization Several anomalies (+80) Some anomalies (+40) No anomalies (-50) 28 evaluated. Only the Goliad section from below hole casing to the top of the Fleming was considered in favorability determinations (see casing depths on lithologic logs). Table 3 shows- the distribution of favorability scores for each hole and each criteria category. All holes scored equally in clastics, volcaniclastics, thickness, area, and depositional environment. The meaning of each criterion should be self explanatory except for possibly area, which refers to the spatial distribution of potential host sandstone bodies. Areas of large extent are host sandstones which have a width measured in thousands of feet and length measured in miles. All holes were scored "some anomalies" under the mineralization criteria if there was at least one anomaly in the hole, regardless of the formation in which it occurred. In order to better evaluate available project data, minor modifications were made to the Adams and Smith criteria. These changes were implemented essentially due to lack of strong data, specifically in the "host sandstone permeability" and "alteration" criteria. Sandstone permeability was difficult to assess in several drill holes. Primarily, permeability of the sandstone was scored high (+15) if lithologic logs and core descriptions suggested that the drilled sandstones were texturally mature with relatively large grain size. Sandstone permeability was scored zero in holes in which permeability was difficult to evaluate. This modification was made to avoid significantly downgrading permeability solely because of uncertainty. Alteration criteria were modified significantly to better fit available data. Adams and Smith suggest that the most important alteration concern is the presence or absence of iron-titanium oxides. These data were not available for evaluation. Therefore, the following alteration types and associated scores were considered in evaluating alteration criteria. The presence of: 1. Strong epigenetic oxidation and pyrite +60 2. Weak epigenetic oxidation and pyrite +20 3. Syndepositional oxidation and pyrite 0 4. Syndepositional oxidation with no pyrite -10 Had the original Adams and Smith alteration criteria been used, virtually all holes would have been scored "some alteration types" (-10) simply due to lack of good data. Because of the high weighting factor (75) used in computing alteration, final scores would have been severely lowered, probably unjustifiably, again due solely to uncertainty. Evaluation of alteration criteria was made from core descriptions included in Galloway and Morton, 1981. Formations which were not cored were scored zero. LIMITATIONS TO SCORING Figure 7 shows the relation between calculated favorability and the actual chance of a deposit being present within the area evaluated. Notice that as favorability declines, the chance of a deposit being present declines even 29 Table 3. Favorability Criteria Alteration and ~------Host Sandstone ------~-- Mineralizationl Composition 1 F OOL()O 0 0 0 OOOL() L()OOO OL()O L()OO L()OL()O 000 00000 0 0 0 C\1~ a r ~ 00 ~r<)~ 30 +100- +75- ,..,.,,.,- / - +50- // 4»~ / ~ +25- I f., I ~ I ~:; 0-N·~------I ~ 0 I ; -25-1 ..c c ~ 0 I > c 1L -50-1I I -75-1 I -100~~------.1 1 1 0 25 50 75 100 Chance of a deposit beino present (Percent) FIGURE 7. Schematic relation between calculated favorability for South Texas-type deposits and the chances of a deposit being present within the area evaluated 31 more. This figure, devised by Adams and Smith (1981), assumes a high confidence in geologic observations and complete geologic data. This of course is not the case in evaluating most of the project drill holes. Two criteria had to be rated zero based on uncertainty. However, it is felt that had better data been available, most of the zero-rated criteria would have been elevated in value. Therefore, it is believed that the calculated project favorability scores are in reality overly conservative, that is, uranium favorability of the area of the drill holes is actually higher than. the numerical values suggest. Hole OG-17A represents a disparity in scoring which should be mentioned. It was possible to log this hole only to 990 feet and no gamma anomalies were detected. Had the hole been drilled and logged to an average project hole depth of 2500 feet, at least one gamma anomaly would probably have been encountered. This would have resulted in a mineralization criteria score of +40 (some) instead of -50 (none), elevating the favorability of OG-17A from 65 percent to 88 percent. By increasing this criteria one step, OG-17A would have increased in overall favorability from the least favorable hole drilled to within one point of the most favorable hole. Hole OG-20 suggests another potential inequity between the numerical score and uranium favorability. The Goliad scored 76 percent and the Oakville 67 percent in this hole, yet the highest uranium anomaly detected in the drilling project occurs near the bottom of the hole in the Catahoula Formation. The Catahoula here was not evaluated because only 300 feet of the formation was penetrated. A total of five radioactive anomalies are scattered throughout the drilled ~tratigraphic section suggesting that the area is more favorable than the scores indicate. Had the mineralization score been increased from +40 (some) to +80 (several), the final favorability score would have been unjustifiably high for a hole which has zero scores (uncertain) for two . important criteria. URANIUM FAVORABILITY OF PROJECT AREA Figure 8 shows the geologic favorability scores by drill hole and formation. The drill holes plot into three basic locations which allows for assigning the relative qualitative geologic favorabilty as shown in the figure. Favorability scores for the majority of holes are rated as moderately low geologic .favorability. Favorability of the Goliad Formation appears to be slightly lower than that of the Oakville and Catahoula Formations, due in general to less pyrite in the Goliad and also to a greater than 40 percent sand content relative to the Oakville and Catahoula Formations. Based on results of the favorability study, there appears to be a slight correlation between the geographic location of holes within the project area and hole favorability (Fig. 8). The most favorable hole, OG-2, possibly A1,...~ reflects a dowi.1dip extension of the south Duval County mineral trend. 1'\. .LU\1, in general holes located in the southern portion of the project area are morP favorable than those in the northern portion. Only holes OG-17 and OG-20 are exceptions to this generality. In hole OG-17, favorability of the Goliad Formation scored significantly less than the Oakville due to a lower 32 Qualitative Geologic Gol Oak Cat Favorability 90- 89 - 2 2 88 - 2 87 - MODERATELY 86 - 85- HIGH 84 - 83- 82- 81- 80 - 79 - 10 18 78 - 77 - 17 MODERATE cJ\0 76 - 20 <1) w 75- 10 w """0 74 - 18 0 (/) 73 - 72 - 71- 12 16 22 .MODERATELY 70 - 6 6 69 - LOW 68 - 67 - 5 12 16 17 22 5 20 5 66 - 65 - 17A ------X = 71 X = 74 X = 78 Anomalous Holes - (holes which show disparity in scoring) 17 - Gol <40% sand, no Gol core so no alt. data, therefore, 0. 20 - Oak <40% sand, no Oak core so no alt. data, therefore, 0. FIGURE 8. Favorability scores by hole and formation sand-shale proportion score in the Goliad and to a zero alteration score because the formation was not cored, resulting in a lack of data. These same situations occur in hole OG-20, except here, the Oakville was downgraded significantly relative to the Goliad. Overall, it is concluded that the project area has a moderate potential for SIJall- to medium-sized uranium deposits. Currently, the Department of Energy (1980) estimates probable potential resouces in the project area in the $50-per-potmd forward-cost category to be 6947 tons U303 for the Oakville and 18,456 tons U308 for the Goliad. Possible potential resources are 1780 tons U30g for the Oakville and 4576 tons U308 for the Goliad. 34 REFERENCES Abramiuk, I. N., 1981, Engineering report on drilling in the Oakville-Goliad project, Laredo-McAllen quadrangles, Texas: U.S. Department of Energy Report, GJBX-19(81), 62 P• Adams, S. S., and Smith, R. B., 1981, Geology and recognition criteria for sandstone uranium deposits in mixed fluvial-shallow marine sedimentary sequences, South Texas: U.S. Department of Energy Report, GJBX-4(81), 143 p. Galloway, W. E., 1977, Catahoula Formation of the Texas Coastal Plain: depositional systems, compositions, structural development, gronnd-water flow history and uranium distribution: University of Texas at Austin, Bureau of Economic Geology Report of Investigations 87, 59 p. Galloway, W. E., and Kaiser, W. R., 1979, Catahoula Formation of the Texas Coastal Plain: origin, geochemical evolution, and characteristics of uranium deposits: u.s. Department of Energy Report, GJBX-131(79), 139 p. Galloway, W. E., and Morton, D. A., in preparation, Description and interpretation of test cores - Brooks and adjacent counties, South Texas: University of Texas at Austin, Bureau of Economic Geology, 62 p. Quick, J. v., Thomas, N. G., Orogdon, L. D., Jones, C. A., and Martin, T. s., 1977, Uranium favorability of late Eocene through Pliocene rocks of the South Texas Coastal Plain: u.s. Energy Research and Development Administration Report, GJBX-7(77), 48 p. U.S. Department of Energy, 1980, An assessment report on uraniun in the United States of America: u.s. Department of Energy Report, GJD-111(80), 150 p. ~eeks, A. D., and Eargle, D. H., 1960, Uranium at Palangana salt dome, Duval County, Texas: U.S. Geological Survey Professional Paper 400-B, p. B48-B52. 35 SELECTED BIBLIOGRAPHY Austin, s. R., and D'Andrea, R. F., Jr., 1978, Sandstone-type uranium deposits, in Mickle, D. G. and Mathews, G. W., editors, r~ologic characteriStics of environments favorable for uranium deposits: U.S. Department of Energy Report, GJBX-67(78), p. 87-119. Bornhauser, M., 1958, Gulf coast tectonics: American Association of Petroleum Geologists Bulletin, v. 42, p. 339-370. Cherepon, A. J., and Stauber, A. J., 1980, Uranium resource evaluation, Laredo quadrangle, Texas: u.s. Department of Energy Report, PGJ-069(81), 116 p. -----1981, Uranium resource evaluation, McAllen and Brownsville quadrangles, Texas: U.S. Department of Energy Report, PGJ-134(81), 97 p. Eargle, D. H., Dickinson, K. A., and Davis, B. 0., 1975, South Texas uranium deposits: American Association of Petroleum Geologists Bulletin, v. 59, p. 766-779. Eargle, D. H., Hinds, G. W., and Weeks, A.M. D., 1971, Uranium geology and mines, South Texas: University of Texas at Austin, Bureau of Economic Geology Guidebook 12, 59 p. Eargle, D. H., and Weeks, A.M. D., 1961, Possible relation between hydrogen sulfide-bearing hydrocarbons in fault-line oil fields and uranium deposits in the southeast Texas Coastal Plain: u.s. Geological Survey Professional Paper 424-D, p. 7-9. Flawn, P. T., 1967, Uranium in Texas: University of Texas at Austin, Bureau of Economic Geology Geological Circular 67-1, 16 p. Galloway, W. E., 1978, Uranium mineralization in a coastal-plain fluvial aquifer system: Catahoula Formation, Texas: Economic Geology, v. 73, p. 1655-1676. Galloway, W. E., Finley, R. J., and Henry, C. D., 1979, South Texas uranium province-geologic perspective: University of Texas at Austin, Bureau of Economic Geology Guidebook 18, 81 p. Geodata International, Inc., 1978, Aerial radiometric and magnetic survey, Brownsville-McAllen national topographic map, Texas gulf coast: u.s. Department of Energy Report, GJBX-118(78), 2 volumes. -----1979, Aerial radiometric and magnetic survey, Corpus Christi-Laredo national topographic map, Texas gulf coast: u.s. Department of Energy Report GJBX-99(78), 2 volumes. Mickle, D. G., and Mathews, G. W., editors, 1978, Geologic characteristics of environments favorable for uranium deposits: u.s. Department of Energy Report, GJBX-67(78), 250 p. Myers, B. N., and Dale, O. C., 1967, Ground-water resources of Brooks County, Texas: Texas Water Development Board Report 61. 37 Oak Ridge Gaseous Diffusion Plant, 1980, Hydrogeochemical and stream sediment reconnaissance basic data for Laredo Quadrangle, Texas: u.s. Department of Energy Report, GJBX-14(80), 39 p. -----1980, Hydrogeochemical and stream sediment reconnaissance basic data for Brownsville-McAllen NTMS Quadrangle, Texas: U.S. Department of Energy Report, GJBX-249(80), 39 p. Sandifer, D. F., 1969, Dip cross section from Mirando City, Webb County, to Baffin's Bay, Kleberg County, Texas: U.S. Atomic Energy Commission Report, AEC-RD-5. Texas Bureau of Economic Geology, 1975, Geologic Atlas of Texas, McAllen Brownsville Sheet: University of Texas at Austin, Bureau of EconoMic Geology, scale 1:250,000. -----1976, Geologic Atlas of Texas, Laredo sheet: University of Texas at· Austin, Bureau of Economic Geology, scale 1:250,000. 38 APPENDIX A Assay Results of Individual Elements, OG-2 and OG-17 39 APPENDIX A Assay Results of Individual Elements OG-2 ppm % ppm ppm ppm Sample no. Lab no. Depth U308 Org-C Cs Li Se % s MKL 201 71604 250 1 .07 4 12 2 .04 MKL 202 71605 500 1 .05 4 14 3 .09 MKL 203 71606 650 1 .06 5 24 2 .03 MKL 204 71607 840 1 .11 4 14 2 .03 MKL 205 71608 860 1 .06 5 20 3 <.01 MKL 206 71609 890 1 .07 5 18 1 <.01 MKL 207 71610 1080 4 .06 4 12 <1 .01 MKL 208 71611 1170 4 .07 4 12 <1 .01 MKL 209 71612 1220 4 .07 3 10 2 .02 MKL 210 71613 1260 1 .10 3 10 1 <.01 MKL 211 71614 1380 1 .16 4 20 <1 <.01 MKL 212 71615 1550 1 .28 6 28 2 .37 MKL 213 71616 1820 1 .09 6 28 1 .10 MKL 214 71617 1860 <1 .07 6 26 1 .05 MKL 215 71618 1870 1 .07 6 26 <1 .03 MKL 216 71619 1980 2 .07 5 24 <1 .06 MKL 217 71620 2270 2 .06 6 26 2 .10 MKL 218 71621 2280 2 <.01 6 24 1 .07 MKL 219 71622 2420 <1 .05 7 30 6 .12 MKL 220 71623 2710 2 .07 6 22 5 .08 MKL 221 71624 2920 2 .19 4 20 3 .15 MKL 222 71625 2960 2 .71 7 28 4 .06 MKL 223 71626 340 <1 .03 3 12 5 <.01 41 APPENDIX A Assay Results of Individual Elements OG-17 ppm ppm ppm ppm Sample no. Lab no. Depth U308 % Org-C Cs Li Se % s MKL 351 71690 110 <1 .05 2 8 3 <.01 MKL 352 71691 360 <1 .06 4 14 4 .17 MKL 353 71692 430 1 .05 6 16 5 <.01 MKL 354 71693 440 1 . 05- 6 18 5 .03 MKL 355 71694 450 <1 .07 6 18 6 .01 MKL 356 71695 520 1 .04 4 10 3 .21 MKL 357 71696 700 1 .06 4 12 4 .28 MKL 358 71697 740 1 .09 4 12 3 1.16 MKL 359 71698 1120 1 .18 6 18 4 .55 MKL 360 71699 1350 2 .06 7 26 3 .41 MKL 361 71700 1370 1 .06 7 . 26 4 .39 MKL 362 71701 1410 1 .07 6 24 4 .48 MKL 363 71702 1450 1 .06 5 31 3 .71 MKL 364 71703 1520 1 .02 6 31 4 .72 MKL 365 71704 1550 2 <.01 6 25 2 .37 MKL 366 71705 1670 2 .05 6 27 4 .21 MKL 367 71706 2050 2 .34 6 32 3 .04 MKL 368 71707 2204 2 .05 5 20 2 <.01 MKL 369 71708 2230 3 .21 3 8 6 .20 MKL 370 71709 2250 2 .16 6 30 6 .16 MKL 371 71710 2300 3 .11 7 33 5 .OS APPENDIX B Petrographic Descriptions 43 PETROG~~PHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-201 DEPTH: 250 Mineral/Component Percent Size/Texture Characterist:lcs Other Important Features Fragments Clay Analysis Carbonate 5 micritic and sparitic montmorillonite - dominant illite.- minor Sandy/Carbonate 93 vf-c/ang-subrnd quartz, chert, feld kaolinite - minor spar, SRF mixed layer - minor Grains Quartz 1 single-grain variety Opaques <1 iron oxides, ilmenite, pyrite PETROGRAPHIC DESCRIPTION PROJECT; Oakville--Goliad REQUEST: 600139. FIELD NO.: MKL-202 DEPTH: 500 Mineral/Component--~------· ______Percent Size/Texture _.______Characteristics Other Important Features Fragments Clay Analysis Carbonate 28 micritic and sparitic; montmorillonite - dominant some could be calcareous illite - subdominant claystones kaolinite - minor mixed layer - minor Sandy Carbonate 35 f-c/ sub-sub quartz, chert, feldspar, VRF, SRF H.M. Analysis Calcareous SS 5 f-c/sub-sub quartz, chert, feldspar, mostly magnetite; SRF lesser ilmenite, hematite, sphene, biotite, epidote, Chert 2 typical microcrystalline zircon, pyrite, anhydrite texture Chalcedony 1 feathery texture Volcanic RF 's <1 altered flow rocks Claystones 2 Grains Quartz 19 single and polycrystalline varieties Feldspar K P 7 microcline, perthite~ plagioclase, tr. sanidine Opaques 4 iron oxides~ ilmenite, pyrite PETROG~~PHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-203 DEPTH: 650 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 17 micritic and sparitic; montmorillonite - dominant some could be calcareous illite - subdominant mudstones kaolinite - minor mixed layer - minor Sandy Carbonate 69 f-med/sub-sub quartz, SRF, feldspar, chert, PRF Calcareous SS 3 med/sub-sub Q, SRF, chert, feldspar Chert <1 some remnant carbonate Grains Quartz 8 single-grain variety dominant Feldspar K P 2 plagioclase, microcline, perthite Opaques <1 iron oxides, ilmenite PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: 7>.1KL-204 DEPTH: 840 Mineral/Component Percent Size/Texture Characteristics Other Important Features ~------~------~------Fragments Clay Analysis Carbonate 10 micritic and sparitic; montmorillonite - dominant some could be calcareous illite - minor mudstones kaolinite - minor mixed layer - minor Sandy Carbonate 75 f-m/sub-sub quartz, chert, feldspar, SRF, VRF(?) Grains Quartz 14 single-grain variety dominant Feldspar K P <1 plagioclase and microcline Opaques <1 iron oxides; pyrite, ilmenite PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-205 DEPTH: 860 Mineral/Component Percent Size/Texture Characteristlcs. Other Important Features Fragments Clay Analysis Carbonate 6 mostly fine sparitic; montmorillonite - dominant a few micritic illite - subdominant kaolinite - minor mixed layer - minor Sandy Carbonate 86 vf-f/sub-sub Q, feldspar, SRF ,. chert, VRF(?), chal. Chert <1 Chalcedony <1 Grains Quartz 6 single-grain variety dominant Feldspar K P <1 plagioclase and microcline Opaques <1 iron oxides, pyrite, ilmenite PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-206 DEPTH: 890 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonat~= 16 micritic and sparitic; montmorillonite - dominant a few might be illite - subdominant calcareous claystones kaolinite - minor mixed layer - minor Sandy Carbonate 80 f-m/sub-sub Q, feldspar, SRF, VRF, chert H. M. Analysis mostly magnetite; lesser Grains ilmenite, hematite, sphene zircon, epidote, pyrite Quartz 3 single grain V1 0 Feldspar K p Opaques <1 iron oxides, pyrite, ilmenite PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-207 DEPTH: 1080 Mineral/Component Percent Size/Texture Characteristics Other Important Featu~es Fragments Clay Analysis Carbonate 14 micritic and sparitic; montmorillonite - minor some could be illite - subdominant calcareous mudstones kaolinite - minor mixed layer - dominant Sandy Carbonate 18 vf-m/sub-sub with quartz and feldspar Calcareous SS 1 vf-m/sub-sub with Q, feldspar, SRF, VRF, chert, chal. Chert 28 remnant carb. and chal. present Chalcedony 11 typical feathery texture Volcanic RF' s 17 flow rocks; some porphyries, altered tuffs Grains Quartz 7 single and polycrystalline varieties Feldspar K P 3 sanidine, plagioclase, microcline Opaques <1 iron oxides, ilmenite PETROGRAPHIC DESCRIPTION PROJECT: Oakville~Goliad REQUEST: 600139, FIELD NO.: MKL-208 DEPTH: 1170 Mineral/Component Percent Size/Texture Characteri~tics Other Important Features ~------~------~--~~--~~------~~~~------~~-- Fragment~~ Clay Analysis Carbonate 18 micritic and sparitic; montmorillonite - subdominant some -could be i lli t.e - minor calcareous claystones; kaolinite - minor some cha.l. and mixed layer - dominant secondary macro quartz associated H.M. Analysis Sandy Carbonate 31 vf-c/sub-sub Q, feldspar, chert, VRF, mostly magnetite; SRF, chalcedony lesser hematit,e, ilmenite zircon, epidote, sphene, 1..11 Calcareous SS 10 vf~/sub-sub with Q, feldspar, chert, pyrite N VRF, SRF, chal. Chert 9 typical microcrystalline texture Chalcedony 1 typical feathery texture; some gyp. Volcanic RF's 6 flow rocks and tuffs (or tuffaceous rocks?) Plutonic. RF 's 4 "granitic" Grains Quartz 17 single and polycrystalline; some secondary overgrowths Feldspar 7 sanidine, microcline, plagioclase Opaques <1 iron oxides, ilmenite, pyrite PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-209 DEPTH: 1220 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 35 sparitic; some w:l th montmorillonite - subdominant fossils illite - minor kaolinite - minor mixed layer - dominant Sandy Carbonate 3 f/sub-ang with Q, chert, feldspar Calcareous SS 3 f/sub-ang with Q, chert, feldspar, SRF Chert 40 some remnant carbonate l..n w Chalcedony 9 some gypsum assoeiated Volcanic RF's 7 porphyritic flow rocks and altered tuffs Grains Quartz 2 single-grain variety Opaques <1 iron oxides, ilmenite PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-211 DEPTH: 1380 Mineral/C<>_m~p,_o_n_e_n_t____ P_e_r_c_e_n_t_-.:....·S_i_z_e....;/_T_e_x_t_u_r_e ______C_h_a_r __~a_c_t_e_r_i_s_t __ i_c_s ______O_t_h_e_r __ Im_p.,__~•rtant Features Fragments Clay Analysis Carbonat'e 14 micrites and sparites; montmorillonite - minor some calcareous illite - minor claystones(?) kaolinite - minor mixed layer - dominant Sandy Carbonate 60 vf-m/sub-sub with Q, feldspar, VRF ,, SRF, chert, chal., gyp. Calcareous SS 10 vf-c/ sub-sub with Q, feldspar, VRF ,, chert, SRF Chert 2 typical microcrystalline texture Chalcedony 3 with secondary macroquartz Volcanic RF's 1 flow rocks Grains Quartz 5 single and polycrystalline grains Feldspar K P 4 sanidine, plagioclase, microcline Opaques <1 ilmenite, iron oxides PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-212 DEPTH: 1550 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 42 micrites, sparites, and montmorillonite - dominant possible calcareous illite - subdominant siltstones; some kaolinite - minor chal~edony, secondary mixed layer - minor quartz, and gypsum present Sandy Carbonate so vf-med/sub-sub Q, feldspar, SRF, chert chalcedony Chert 1 typical microcrystalline texture V1 V1 Chalcedony 2 typical feathery texture Gypsum 1 some secondary quartz associated Grains Quartz 3 single-grain variety Opaques <1 iron oxide-stained grains, ilmenite PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-213 DEPTH:. 1820 Mineral/Component Percent Size/Texture Characteristics Other Important Features ~------~------·------~------Fragments Clay Analysis Carbonate 57 micritic and sparitic montmorillonite - dominant fragments; some could illite - subdominant be calcareous kaolinite - minor claystones; gypsum and mixed layer - minor chalcedony on some Sandy Carbonate 27 vf-f/sub-sub Q, feldspar, chert, VRF Calcareous ss 3 with Q, feldspar, chert Chert 2 lr1 0\ Chalcedony 2 Volcanic RF's 1 flow rocks Fossils <1 portion of shell fragments Claystones 1 with some sand-sized detritus Grains Quartz 5 single and polycrystalline grains Feldspar K P 1 plagioclase and sanidine present Opaques <1 ilmenite, iron oxides, pyrite PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-214 DEPTH: 1860 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 52 with clay~ could be montmorillonite - minor either micrite or illite - subdominant calcareous claystones; kaolinite - minor positive distinction mixed layer - dominant could not be made; some sparitic fragments Alpha-tracking of a polished thin section of this sample Sandy Carbonate 37 vf-f/sub-sub Q, feldspar, chert for 28 days revealed no anomalous sources of Chert 1 some with remnant radioactivity. U1 carbonate '-J Chalcedony 1 Volcanic RF's 1 flow rocks Fossils <1 shell fragments(?) Grains Quartz 5 single and polycrystalline grains Feldspar K p 2 plagioclase, sanidine, trace microcline Opaques <1 ilmenite, iron oxides PETROGRAPHIC DESCRIPTION PROJECT: Oakville--Goliad REQUEST: 600139 FIELD NO.: MKL-215 DEPTH: 1870 Mineral/Component Percent Size/Texture Characteristics Other Important Features ~~------~~------Fragments Clay Analysis Carbonate 36 some might be montmorillonite - dominant calcareous claystones; illite - subdominant mostly micritic (clayey) kaolinite - minor mixed layer - minor Sandy Carbonate 18 vf -f I su b-ang with Q, VRF, chert, SRF, feldspar Alpha-tracking of a polished thin section of the Chert 1 typical microcrystalline sample for 28 days revealed texture no anomalous sources of radioactivity. 1..11 Chalcedony 7 typical feathery texture 00 Volcanic RF's 3 flow rocks; porphyries Silty Carbonates or 22 Silty Calcareous Clays tone~ s Grains Quartz 9 single and polycrystalline grains Feldspar K P 3 sanidine and plagioclase; trace microcline, perthite Opaques <1 ilmenite, iron oxides PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-216 DEPTH: 1980 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 27 some might be calcareous montmorillonite - dominant claystones, some fossil illite - subdominant fragments present i.n kaolinite - minor some; micritic (1;vi th mixed layer - minor clay) and sparitic H. M. Analysis Sandy Carbonate 30 vf -f I su b-ang quartz, feldspar, chert, chalcedony mostly magnetite; lesser pyrite, ilmenite, Chert 21 some with remnant hematite, zircon, carbonate hornblende(?), epidote, sphene, anhydrite Chalcedony 3 feathery texture Volcanic RF's 15 flow rocks; some porphyries Sandy/Silty Claystones 1 with quartz and feldspar Grains Quartz 2 single-grain variety Opaques PROJECT: Oakville-Goliad REQUEST: &00139 FIELD NO.: MKL-217 DEPTH: 2270 Mineral/Component Percent Size/Texture Characteristics Other Important Features .~------~------ Fragment~~ Clay Analysis Carbonate 40 some might be calcareous montmorillonite - dominant claystones; micritic and illite - subdominant sparitic; gypsum mafic kaolinite - minor with varying amounts mixed layer - ·minor of clay Sandy Carbonate 49 vf -f I su b-ang Q, feldspar, chert, chalcedony Chert 2 microcrystalline texture Chalcedony 3 typical feathery texture Volcanic RF' s 2 flow rocks and altered tuffs Fossils <1 one unidentified fragment Grains Quartz 2 single-grain variety Feldspar K P <1 plagioclase and sanidine Opaques <1 ilmenite, iron oxide, pyrite PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-218 DEPTH: 2280 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 43 some are very clayey montmorillonite - dominant (calcareous claystones?); illite - subdominant a few with fossil kaolinite - minor fragments; some "\i~i th mixed layer - minor gypsum; micritic and sparitic Sandy Carbonate 42 med sand/sub-ang Q, chert, VRF Calcareous ss (1 f-med/ sub-sub· Q, SRF, feldspar Chert 7 typical microcrystalline 0'. texture 1-' Chalcedony 2 feathery texture Volcanic RF's 3 mostly flow rock fragments; some tuffs Anhydrite <1 one fragment observed Sandy Claystone (1 Q, K, P Grains Quartz 1 single-grain variety Feldspar K p <1 plagioclase and sanidine; some microcline Opaques (1 pyrite, ilmenite, iron oxide PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: ~KL-219 DEPTH: 242.0 Mineral/Component Percent Size/Texture Characteristics Other Important Features ·~------~------~------Fragments_ Clay Analysis Carbonate 38 might be calcareous montmorillonite - dominant claystones; mostly illite - subdominant very clayey (micritic); mixed layer - minor some with fossils Sandy Carbonate 50 vf-med/ sub-ang Q, K, P, SRF, chert, chalcedony Chert 2 typical microcrystalline texture Chalcedony 2 feathery texture Volcanic RF's <1 flow rocks and altered tuffs Graip.s Quartz 6 single-grain variety; a few polycrystalline Feldspar K P 1 sanidine and plagioclase Opaques <1 iron oxides, pyrite, ilmenite PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-220 DEPTH: 2710 Mineral/Comp6nent Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 28 might be calcareous montmorillonite - dominant claystones; clayey and illite - subdominant fine sparitic varieties kaolinite - minor mixed layer - minor Sandy Carbonate 64 f-med/sub-sub Q, chert, SRF, gypsum, K, P, VRF, opaques Chert 1 microcrystalline texture Chalcedony (1 feathery texture 0'\ w Volcanic RF's 5 flow rocks and tuffs Grains Quartz (1 single-grain variety dominant; some polycrystalline Opaques (1 ilmenite, iron oxides PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: ·MKL-221 DEPTH: 2920 Mineral/Component Percent Size/Texture Characteristics Other Important Features --~------~------~------Fragments Clay Analysis Carbonate 40 some carbonate fragments montmorillonite - dominant might be calcareous illite - subdominant claystones; some fossil kaolinite - minor fragments present ·mixed layer -minor Sandy Car1bonate 35 f-med/sub-sub Q, K, P:P VRF, SRF, H. M. Analysis chert, chalcedony mostly anhydrite; less magnetite, pyrite Chert 10 typical texture; remnant ilmenite, zircon, biotite, carbonate present epidote Chalcedony 6 feathery texture; trace gypsum Volcanic RF's 3 flow rocks and altered tuffs Anhydrit·e (1 one "clast" observed <1 Grains Quartz 4 single-grain variety; some polycrystalline Feldspar K P <1 plagioclase and sanidine Opaques <1 pyrite, iron oxides, ilmenite, carbonaceous matter (as inclusive and loose grains) PE!ROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-222 DEPTH: 2960 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 71 some might be calcareous montmorillonite - dominant claystone; mostly clayey illite - subdominant (micritic); some sparitic mixed layer - minor Sandy Carbonate 5 vf-f/ang-sub-ang Q, K, P, chert, opq. muse., chlor. Chert <1 typical microcrystalline texture Volcanic RF' s <1 altered flow rocks and tuffs(?) Clay Fragments 13 red; iron staine!d; some carbonaceous material present Silty Carbonate 7 quartz; others too small for positive ID Grains Quartz 2 single-grain variety dominant Feldspar K P <1 sanidine and plagioclase Mica B M Chl <1 muscovite, biotite Opaques <1 pyrite, ilmenite, iron oxides PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600139 FIELD NO.: MKL-223 DEPTH: 340 Mineral/Component Percent Size/Texture Characteristics Other Important Features ~~------~------~------ Fragmentf~ Clay Analysis CarbonatE! 35 some might be calcareous montmorillonite - dominant claystones; clayey illite - minor (micritic) and sparitic kaolinite - minor forms mixed layer - iminor Sandy Carbonate 53 f-med sand/ contains Q, K, P, opq., Some predepositional sub-sub chert, sparitic secondary quartz overgrowths were Chert 1 f-med sand/ typical microcrystalline observed; some quartz sub-ang. texture appears to be of volcanic origin. Volcanic RF's (1 flow rocks--mostly 0'\ plagioclase H. M. Analysis 0'\ mostly magnetite; lesser ilmenit,a, hematite, epidote, zircon, biotite, sphene, pyrite Grains Quartz 8 vf-m; sub-ang; mostly single-grain variety Feldspar K P 1 microcline, plagioclase, sanidine Mica B M Chl (1 muscovite Opaques (1 ilmenite, iron oxides, pyrite PETROG~~PHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-351 DEPTH: 110 Mineral/Component Percent Size/Texture Characteristfcs Other Important Features Fragments Clay Analysis Carbonate 35 vfg micrite, some with very little clay found fossils kaolinite - trace chlorite - trace mixed layer(?) - trace Sandy Carbonate 32 fs/sr quartz and chert in micrite Chert tr Chalcedony 1 Grains Quartz 30 Feldspar®® 1 altered cleavage fragments; K)P Mica B ® Chl tr trace B Opaques tr hematite - limonite PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-352 DEPTH: 360 Mineral/Component Percent Size/Texture Characteristics Other Important Features ~------~------~------~------~------~----- FragmentE~ Clay Analysis ·carbonate 60 vfg mostly micritic; a very little clay found little sparite montmorillonite - trace mixed layer - trace Sandy Carbonate 25 fs-vfs/sa-sr micrite w/qtz, K, H. M. Analysis trace P magnetite - dominant Chert tr anhydrite - subdominant ilmenite - modE~rate rutile - minor zircon - tr epidote - tr biotite - tr tourmaline - tr. 0.72% -heavy portion Grains Quartz 15 many are quite rounded and undulose Feldspar K ® · tr Mica@ M Chl tr Opaques tr relatively coarse Resistates Ap ® Sp Tm tr Anhydrite tr clasts of mats PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-353 DEPTH: 430 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 50 vfg clayey micrite; elay montmorillonite - dominant clasts mixed layer - minor kaolinite - trace Sandy Carbonate 40 fs-cs/sa-wr clayey U-Mineral Analysis Calcareous SS 10 silt-vfs/a-sr clayey No alpha-tracks in the Volcanic RF's tr cs/sr clast in sandy carbonate autoradiograph corresponding to discernable phases. PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-354 DEPTH: 440 Mineral/Component Percent Size/Texture Characteristics Other Important Features ~------~------·------~--·------ Fragments~ Clay Analysis Carbonate 65 vfg micrite, microsparite, very little clay clayey montmorillonite - dominant chlorite - minor Sandy Carbonate 15 fs/sa-sr kaolinite - trace Chert tr U-Hineral Analysis Chalcedony tr No alpha-tracks in the autoradiograph Mudstone 5 vfg few clasts; calcareous corresponding to and iron stained discernable phases. -.....! 0 Grains Quartz 10 Feldspar ~:&:~ ® 5 K)P Mica® M €~ tr Opaques tr Resistates Ap@ Sp Tm tr Carbonate tr crystals PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-355 DEPTH: 450 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 20 minor sparite; clayey montmorillonite - dominant micrite; few fossils kaolinite - moderate mixed layer - trace Sandy Carbonate 34 fs/sa-r clayey illite - trace Calcareous ss 10 ms-cs/sr-sa U-Mineral Analysis Chert 1 some with rims of No alpha-tracks in the iron oxide autoradiograph corresponding to Fossils tr possibly shell fragments discernable phases. ...... Clay 20 1--' Grain.s Quartz 15 Opaques tr PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-356 DEPTH: 520 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 20 minor sparite mostly montmorillonite - dominant micrite kaolinite - moderate rriixed layer - minor Sandy Carbonate 20 fs/a-sr quartz and feldspar H. M. Analysis Chert 15 vfg some iron stained magnetite - dominant Chalcedony 5 feathery texture pyrite - subdom:inant anhydrite - subdominant Volcanic RF's 5 vfg/aphanitic ilmenite - moderate rutile - minor Quartzite (meta RF) tr sheared, with muscovite zircon - tr flakes epidote - tr ....._, N sphene - tr Clay 5 0.68% - heavy portion Grains Quartz 30 rounded, medium-to-coarse sand size Feldspar~)(!') tr cleavage fragments Calcite(?) tr rounded cleavage fragments PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-357 DEPTH: 700 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 25 vfg micrite and sparite montmorillonite - dominant common kaolinite - minor mixed layer - minor Sandy Carbonate 15 silt to ms/ sa-r H. M. Analysis Chert 5 vfg magnetite - dominant pyrite - subdominant Chalcedony tr ilmenite - moderate anhydrite - minor Volcanic RF's 5 vfg/aphanitic composed of laths; hematite - tr basaltic ? epidote - tr ...... rutile - tr w Quartzite (meta RF) 1 some strongly rutilated sphene - tr zircon - tr Clay Clasts 3 vfg garnet(?) - tr 0.94% -heavy portion Mudstone tr silt to vfs Grains Quartz 45 fine-to-medium sand size; rounded; rneta texture Feldspar K® tr altered Mica B ® Chl tr Opaques tr altered iron oxide; aggregates of cubic euhedra Glauconite tr rounded medium sand size Carbonate 1 .rounded coarse sand size PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-358 DEPTH: 740 Mineral/Component Percent Size/Texture Characteristics Other Important Features .~~------~~------ Fragment:~ Clay Analysis Carbonate 30 vfg micrite and sparite no clay Sandy Carbonate 35 fs-cs/sa gypsiferous Calcareous SS tr fs-ms/sa-sr sparry cement Chert 1 vfg Chalcedony tr feathery Sandy Gypsum Rock 2 fs-ms clasts of chert, quartz, carbonate, K-spar in coarse gypsum cement Mudstone 2 silt-vfs/sa iron stained GlauconitE~ tr vfg chalcedony core Hematite SS(?) 1 ms/sa Grains Quartz 20 some well rounded Feldspar®® 3 K)P; microcline, trace P Opaques 1 Gypsum 3 flakes and cleavage fragments Hornblende~ (?) tr cleavage fragments Epidote tr PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-359 DEPTH: 1120 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 34 vfg micrite Too little sample for clay analysis. Sandy Carbonate 5 vfs-fs/a-sa Note: Thick section makes it very difficult to Chert tr vfg distinguish between the very fine-grained Calcareous Mudstone 40 iron stained phases. Grains ...... 1..11 Quartz 20 undulose grains, some look metamorphic Opaques tr Anhydrite tr matted flakes; probably mixed with gypsum Gypsum tr PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-360 DEPTH: 1350 Min~ral/Compbnent Percent Size/Texture Charactetist~cs dth~t Impottant F~~ture~ ~------~------~------·------~------ Fragments~ Clay Analysis Sandy Carbonate 5 montmotillonite - domihant kaolinite - tr~:ic~ Anhydrit e:-Gyps urn 1 illite - minor mixed layer - minor Calcareous Claystone 94 some angular sand and silt Grains Quartz tr few rounded grains PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-361 DEPTH: 1370 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 25 very litle clay mixed layer - minor Calcareous Claystone 70 few quartz clasts Grains Quartz 5 '-J Gypsum tr flakes '-J PETROGRAPHIC DESCRIPTION PROJECT: Oakville~Goliad REQUEST: 600140 FIELD NO •. : MKL-362 DEPTH: 1410 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments. Clay Analysis Carbonate· 65 micrite and sparite montmorillonite - dominant kaolinite - moderate Chert tr illite - minor mixed layer - minor Gypsum Rock 1 Calcareous Mudstone 30 Mudstone 1 iron oxide stained -....,J 00 Grains Quartz 2 Resistates Ap@ Sp Tm tr Glauconite tr Gypsum 1 elongate flakes up to 4 mm PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-363 DEPTH: 1450 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fra~ments Clay Analysis Carbonate 25 clayey micrite montmorillonite - dominant kaolinite - moderate Sandy Carbonate 5 silt-vfs/sa illite - trace mixed layer - minor Chert tr vfg Anhydrite-Gypsum 1 Calcareous Claystone 5 Calcareous Mudstone 60 -...... ! \0 Grains Quartz 3 sub rounded grains; stained and undulose PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-364 DEPTH: 1520 Mineral/Component Percent Size/Texture Characteristics Othet Important Fe~tures ~------~------~------Fragments Clay Analysis Carbonate 35 silty micrite - micrite montmorillonite - dominant kaolinit~ - minor Sandy Carbonate tr silt-vfs/sa illite - minor mixed layer - minor Chert tr H. M. Analysis Anhydri te-·Gyps urn 1 anhydrite - dominant Calcareous Claystone 60 some dark with iron stain ilmenite - moderate magnetite - minimum pyrite - trace 00 0 rutile - trace epidote - trace 0.12% -heavy portion Grains Quartz 2 rounded to' subangular grains; slightly undulose 'Gypsum tr PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQLmST: 600140 FIELD NO.: MKL-365 DEPTH: 1550 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 45 vfg microsparite; micrite montmorillonite - dominant kaolinite - minor Sandy Carbonate 2 fs-ms/sr-sa microsparite cement mixed layer - trace illite - trace Chert tr Chalcedony tr Calcareous Mudstone •45 few with strong :lron stain 00 ...... Anhydrite-Gypsum 1 Calcareous Claystone 1 Grains Quartz 5 up to coarse sand; generally rounded Feldspar K ® tr cleavage fragments PETROGRAPHIC DESCRIPTIO.N PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-366 DEPTH: 1670 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate 10 montmorillonite - dominant illite - minor Sandy Carbonate 1 ms-cs/sr large clasts o.f gypsum, kaolinite - trace chert, quartz mixed layer - minor Volcanic RF''s tr highly altered iron oxides (basalt ?) Gypsum Rock 2 Calcareous Claystone 85 00 N Grains Quartz 1 Resistates Ap(?) Sp Tm tr Gypsum tr arigular flakes PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-367 DEPTH: 2050 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragmen~s Clay Analysis Carbonate 10 vfg micrite and sparite montmorillonite - dominant illite - minor Sandy Carbonate tr vfs-fs/sa mixed layer - minor kaolinite - minor Chert 10 vfg and microcrystalline quartz H. M. Analysis Chalcedony 1 feathery magnetite - dominant Volcanic RF' s 10 vfg/porph. opaque replaced; anhydrite - moderate basaltic looking rutile - minor 00 Gypsum Rock tr fg ilmenite - moderate w hematite - trace Calcareous Claystone 2 zircon - trace sphene - minor Calcareous Mudstone 40 quartz silt garnet(?) - trace epidote - trace 0.26% - heavy portion Grains Quartz 25 Feldspar®® 1 trace of perthite, microcline, plag. PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 6001Lj.Q FIELD NO.: MKL-368 DEPTH: 2204 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragment~:~ Clay Analysis Carbonate 25 mostly sparite 1 less Too little sample for clay micrite analysis. Calcareous ss 2 fs-ms/sa-sr Chert 15 Chalcedotty 2 ferruginous Volcanic RF's 15 opaque replaced basaltic 00 +:-- Calcareous Claystone 3 Meta RF 2 recrystallized quartz and feldspars Grains Quartz 30 some look metamorphic Fe 1 ds par 1:X)(£) 5 cleavage fragments; rounded and altered Opaques tr hematite - limonite PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-369 DEPTH: 2230 Mineral/Component Percent Size/Texture Characteristics Other Important Features Fragments Clay Analysis Carbonate or 10 vfg and fs, mostly micrite, some montmorillonite - dominant Calcareous ss silt-fs/sa-sr sparite illite - minor mixed layer - trace Chert 2 vfg Chalcedony 1 /feathery Calcareous Claystone 60 Calcareous Mudstone 10 with silt of qua:rtz, 00 feldspars Ln Meta RF(?) tr vfg/sheared recrystallized quartz with sericite and epidote Quartz Wacke(?) 1 ms-cs/sr Grains Quartz 15 medium sand Feldspar®® 1 cleavage fragments Opaques tr Resistates Ap z@Tm tr medium sand-sized subrounded euhedra PETROGRl\PHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-370 DEPTH: 2250 Mineral/Component Percent Size/Texture Characteristics Other Important Fea,tures Fra~ments Clay Analysis Carbonate 10 vfg micrite; little sparite montmorillonite - dominant illite - minor Sandy Carbonate 5 fs/sa plag., qtz., mixed layer - minor chert ka,olinite - trace Chert 1 vfg iron stained Chalcedony tr Volcanic RF's tr vfg porphyritic silicified groundmass with plag. (X) pheno. 0'\ Meta RF's (?) tr vfg may be plutonic; mosaic undulose quartz Quartz Wacke (?) tr ms/r Calcareous :Mudstone 20 qtz., silt; little K&P Calcareous Claystone 60 iron stained Gl'a,ins Quartz 3 stained Feldspar (g)(l') 1 plag. laths with altered cores Opaques tr PETROGRAPHIC DESCRIPTION PROJECT: Oakville-Goliad REQUEST: 600140 FIELD NO.: MKL-371 DEPTH: 2300 Mineral/Component Percent Size/Texture Character is t :l c s Other Important Features Fragments Clay Analysis Carbonate 3 vfg micrite; trace Too little sample for glauconite clay analysis. Sandy Carbonate 1 ms/sr-sa quartz, plag. Volcanic RF's tr vfg/porphy. altered basalt(?) Fossils tr in the carbonate Calcareous Mudstone 30 o:> Calcareous '-I Claystone 65 Grains Quartz tr stained Feldspar K® tr cleavage fragment APPENDIX C Geophysical and Lithologic Logs 89 EI2J Sandstone u Siltstone []ill Claystone 0] Conglomerate Gypsum ~ Conglomeratic Sandstone ~ Silty Sandstone [ZJ Caliche D Pyritic Trace (P) to Abundant (PPP) OCM Organic Carbonaceous Material Hole Casing Intervals That are More Favorable for Uranium Cored Interval: Solid Where Recovered; Blank Where Lost Gamma 2x Background Gross-Gamma Radiation Down-Hole Log 20 PPM eU · Equivalent Parts per Million Uranium Calculated from Spectral Gamma (KUT) Log All Depths in Feet Core Descriptions by W. E. Galloway and D. A. Morton, Texas Bureau of Economic Geology Legend for Lithologic Logs 91 Hole OG-2 o- ········ ... Surficial O.!lC!!Ift-Holocene Mettly caliche and calcareous fine eond. Goliad Formation -Pliocene SANDSTONE, CARBONATE, and CLAYSTONE; stmlconsolldoted, pink to gray, colcareoue. Sandetone 11 very fine-to coaree-grolned, angular to tubrounded and moderately well sorted; containing claell of quartz, chert, feldspar and lldlmtntory and volcanic rock fragments. Carbonate is micritic and sparitlc. Claystone dominantly montmorillonite. Traces of iron oxidu, pyrite and organics. Unit mostly oxidized. Very fine-to fine-grained sandstone with lntersperud clay mottles. Syndeposltionol and some epigenetic (f) oxidation. Siltstone overlain by clay /mu'dstone. Siltetane contains clay mottles, caliche mottlll, caliche zone and organics. Mudatone contolna minor oroanlce. Syndeposltionol oxidation. Entire core represents on lntor -channel flood plain 11tting. 6~A'~s\g~f~ii~";~;ONE and SANDSTONE; somiconsolidated and calcareous. Unit Is mostly oxidized. Qokyl!!t Farmq!lon-Miocent SANDSTONE CONGLOMERATE, SILTSTONE and CLAYSTONE; semiconeolidoted and calcareous. Corbonot11 of micrite, sporitl and calcareoue cloy. Sandston• Is pink, gray, light brown, very fine-to coorse-gralned, subangular to subroundtd, moderately well sorted, consisting of quartz, chert, feldspar, sedimentary and volcanic rock fragments. Traces of Iron OKidll, heavy minerals and occasional pyrite. Conglomerate Is rounded chert pebblll and cobbles with sand and clay matrix. Clay varies between dominantly montmorillonite and dominantly mixed Ioyer wltn minor kaolinite and Illite. Unit Is mostly oxidized. Basal 6 1/2 feet of conglomerate overlain by sandstone and clay-rich sandstone. Basal conglomerate composed of unsorted clasta 1/4 Inch ~i.!titf,~~~-J to ~ lncn diameter of chert and quartzite In o fine sand/siltstone r:; matrix. Sandstone fin11 upward from slightly conglomeratic medium sandstono to fine sandatone. Clay-rich sandstone contains limonitic cloy clash and oxidized plant atema. Care displays epigenetic oxidation and represents the upper portion of bed -load alluvia I channel fill. Cotahaula Formation-Miocene CLAYSTONE, SILTSTONE, SANDSTONE and CONGLOMERATE; semlconsolldotod, light brown and calcareous. Claystone varies botweon dominantly mortmorlllonlte to dominantly mixed layer with minor kaolinite and Illite. Siltstone Is slightly tuffaceous. Sandstone Is very fine-to medium-grained, subongular to oubrounded, moderately well sorted consisting of quartz, chert, volcanic rock fragments and feldapar. Trace amounts of Iron oxides, pyrite and organlco. Unit Is mostly oxidized. conglomerate overlain by fine sandstone with minor stringers of fine conglomerate. Baaol conglomerate composed of rounded clasts 1/4 Inch to 4 lnchll In diameter of chert and volcanic rock In a tine sandst0r11 matrix. Sandstone Is craubedded .OCM and retlecta lithotype• prtlent In basal conglomerate. Minor green (nduced) clay blebs and organic mattar occur near top of uctlon. Wtok eplo-tlo oxidation. Oepoalltd at the upper portion of bad-load alluvial channel till. Hole locat10r1 llt1 In a major ~~~~~ l sand belt ntor tha axla of the Gueydan (Calahoula) fluvial system. 3000- t; Interpretive Lithologic Log of Hole OG-2 Hole OG-5 o- .·::.·.·::.·:::.·.·.· :::::.:.J...:·::::. Surficial Deposits-Holocene Unconsolidated v1ry fine to medium grained, calcareous sand . ··: :::::. -.:L' caliche. Oxidized throughout. ·::::. '..:L.:'.". •. ·: Goliad Formation-Pliocene SILTSTONE, CLAYSTONE and SANDSTONE; semiconsolidated and calcareous. Sandstone is very fino grained, rounded to subrounded and moderately well eorted. Base is gypsiferous. Unit is mostly oxldind except base which is reduced. Gomma 2x Bockgrouncl Fleming Formation-Miocene SILTSTONE, CLAYSTONE, SANDSTONE and GYPSUM; semiconsolidated and calcareous. Unit is mostly oxidized except upper half which is slightly reduced. - 7.·7.::.~·7:X:·:::·. ::.·:::: ·.·.·:: :: .l~,.~·.. ·...t..t..~ ··-··-··- Oakville Formation-Miocene SANDSTONE, SILTSTONE and CLAYSTONE; somlconsolldated and calcareous. Sandstone is very fino to medium grained, subangulor to well rounded and madoratly well sorted. Unit Is mostly oxidized. :: ..-:-:::.::.-:-:;:·.;::- 2000-:ii~~ Gamma 3x Background Catahaula Formation-Miocene SANDSTONE, SILTSTONE and CLAYSTONE; semiconsolidated, slightly tuffaceous and calcareous. Sandstone is very fine to medium grained, subangular to subrounded and moderately well sorted. Unit it mostly oxidized except bottom of hole which Is partial! y reduced. Interpretive Lithologic Log of Hole OG-5 Hole OG-6 o- -.'-I·_._ .··:-:--~:-::. .-.:.:: ~ Surficial Deposits-Holocene II . -· l F'liiiQraln, very calcareous sand and caliche . I. -:~· ...... :+.-: . ~. J ::::~·i:. ,· ;~ .Goliad Formation- Pliocene SANDSTONE, SILTSTONE and CLAYSTONE; semlconaolidated and calcareous. Sandstone Is very fine-to medium-grained, aubrounded to rounded and moderately well sorted. Gypaiferous basal zone. Unll Is mostly oxidized ..cept for bose which Is slightly reduced. Interbedded ailtstone and claystone overlain by medium to fine sandstone. Siltstone Is clay rich and churned. Claystone Ia churned and contains fino sand and sill grains along fractures. Sandstone contains hematite, magnetite, and rounded to Irregular shaped clay clasts 114 inch to I Inch in diameter. Syndepoaltional oxidation. Deposited as floodplain grading up Into crevasse splay. Fine, churned, oxidized sediments typify floodplain aequence. More abundant sand in fining- up aoquences with mud clasts and ripple lamination suggest Influx of stdiment during flood events. Flemino Formation- Miocene SANDSTONE, SILTSTONE, CLAYSTONE, minor GYPSUM and CONGLOMERATE; semiconoolidatod and calcareous. Sandstone Is fine-to medium-grained, aubroundod to well rounded and modorotely well sorted. Conglomerate Is rounded chert pebbles and coarse-grained sand. Unit is oxidized except for upper portion which is slightly reduced. Gamma 2K 8ookQrDU11d Oakville Formation -Miocene SANDSTONE, CLAYSTONE and SILTSTONE; oemicoaolldoted and calcareous. Sandstone Ia fine-to medium-grained, subrounded Ia woll rounded and moderately well sorted. Unit is oxidized. 20 PPMeU 2000- ~~~~~-::::~~ -:t~:tt'-i:~~7:;~t- .-::_-:·~.::::_:.:.-::::c:..~c JAiternate beds of medium to fine sandstone, clay-rich siltstone and _-:-:-:-:-:-:-:::-:-::: claystone. Sandstone contains hematite grolnt, limonite grains, and --~-:-:::::::~-:-::=:.-:-:::: rounded clay cloll ttrlngers. Siltstone contains some clay matrix, ·-·~i~""'i-:.i-.----c::ii poulblt laminations and caliche blebs. Claystone contains caliche .. =: :=::=. clattt, contorted to broken lamina (rlpup clattt f) and burrows. ·.. ..:,:,--;-::-..;;,.-;-::- ..;.;.:; Sequenctt tend to fine upward. Syndepotltional oxidation. Consists of _;~i:;~";..;·:;:;;:.:;:;.-:;,;~ l ~nvasu tplay or minor trl~utorr depo~lts. Diagnostic features .~:,:. ..:,:,:.:..:..·,:,_;:..:.. 1nclude alternating lltholog1"• f1ne gra1n sizes, numerous zones of *t~~ mudclaots, pedogenic caliche nodules, and limited root mottling. 2'100- J Bau of Dakvi lit appro•lmately 200 feel Interpretive Litholooic Log of Hole OG -6 Hole OG-10 0- ...... :::::.J.: .. ·:: .. ~~asw.Tl.'~m~r.CLAYSTONE and CONGLOMERATE 1 llmlconsoll dated and calcareous. Sandlfone It generally medium-grained, tubrounded and well sorted. CCII ~~N~~b'IJ'~,,fL'!;ht~f'and CLAYSTONE;IImlcontolldatod and calcar~ous. Sandttone Is generally llne-grolned, oubrounded and moderately poorly -ltd. Upper 314 of unit lo partially reduced. ~~~~M~62r.~:~;S~~W~,ntAYSTONE and CONGLOMERATE ;tomlconsolldatod and calcareous. Sandotone It fine- to coarn-aralned, generally subrounded and moderately well sorted. Co!IQiomerate Is very coarto sand to gravel-size chert clasts. Unit Is partially reduced. il~B'~E~~~~~~~o~r:n'3 SANDY SILTSTONE, semlconaolldated, calcareous and slightly tuffaceous. Sandstone Is fine to coarse-grained generally subroundod ond moderately poorly sorted. Unit Is oxldlzod. Interpretive Lithologic Log of Hole OG-10 Hole OG-12 0- Surficial Deposits-Holocene Unconsolidated very f1ne to medium oroined, calcareous sond and caliche. lV~~.~~Rv~t~~i?and SANDSTONE; semiconsolidated and calcareous. Upper and lower portions of unit ore gypsiferous. Sandstone is fine-to medium grained,subangular to subraunded and generally well sorted. Lower half of unit is mostly reduced. f~~~:0ot"c't~:!~:.!o~~:~~ ~~~~:~~~~o~~s( ~ft~ct~/_'~~~m~~~~~x 7a~"d't c_c,.c,_,, c.'"- Siltstone has clay-rich matrix and contains pyrlte.lt Is occasion ally cross laminated and/or rippled. Claystone contains abundant microcrystals afpyrito,lndlcative of epigenetic sulfidic alteration. Deposited as flood plain -~~~~~]' and possibly eolian units? Fleming Formation-Miocene CLAYSTONE, SILTSTONE and SANDSTONE;semiconsolidatod and calcareous. Unil is partially reduced lhroughout. Gamma 311 Bock!Vound 2000- Rll'lft~-t~E, CLAYSTONE and SANDSTONE;semiconsoli dated and calcareous. Sandstone is fine-to medium-CJ"ained, subongular to ...... well rounded and moderately well sorted. Unit partially reduced throughout ...... 0 churned claY,stone; syndepositional oxidation. Floodplain environment. Catahoula Formation-Miocene SILTSTONE, CLAYSTONE and SANDSTONE; semiconsolidated, calcareous and slightly tuffaceous. Unit is oxidized and reduced. Interpretive Lithologic Log of Hole OG-12 Hole OG-16 o- :.:.: ::.:J..·::::: Sllrflclal D!potitt·HIIIoc- Medoum eraln.d, very calcanout Mind and calicllll. 1 !m"'s· ~~~. SU.TITONE,SILTSTONE and CHERT PEBBLE CON GI..OMERATi; temioantalldated ancl coloareout. Sandstone Is llno·lo modlum tralnocl, 9111orally auloraundecl and mocllnollly wolltorlod. Unit is oxldlzod. Ookvlilo Formatloto·Mioaono SANDSTON!, ClAI'ii'bNt, SILTSTONE and CHERT PEBBLE CONGLOME RATE; tomiOOIIIOIIdcrtod and calcarecoua. Sandstone Is tlno·to coorao-tralnod, tono~ally aubrtOindod and modlrallly wollaortod. La- half of unit Is oiiQiotly tulia-•, partially r.ouc.d and pyritic . ... --.. •· "-·-~·_... clayatono with Indistinct llllrrowa and raro blobs ot rlducod ayndopaaltlanal oxidation. Ooposltod at maulvo floodplain Interpretive LitholoQic Lo9 of Hole OG-16 Hole OG-17 o- Surficial Deoosils-Holocono Unconsolidated very fine to medium grained calcareous sand and caliche. Goliad Formotian-Piiocono CARBONATE, SILTSTONE,SANDSTONE, and CLAYSTONE; semiconsolidoted and calcareous. Carbonate is micrite and sporite. Sandstone is generally fine grained, subroundod and moderately well sorted, consisting of quartz, chert, feldspar, volconw rock frogments and minor heavy minerals and pyrite. Cloy stone is dominantly montmorillonite. Lower two-thirds of unit is unoxidized. ~~Ji'~§lJ'IJE:~cJlR'IlNlfef'stLTSTONE and minor SANDSTONE; semiconsolidated, highly calcareous. Cla~stone is dominantly montmorillonite; carbonate is micrite end sparite. Sandstone is very fine-to coarse-grained, angular to subrounded a!ld generally moderately well sorted; consisting of quartz, chert, feldspor and minor heavy minerals. Unit is partially gypsiferous and mostly unoxldized. Oakville Formation ... Miocene SILTSTONE, SANDSTONE, CARBONATE and CLAYSTONE; semi consolidated and calcareous. Sandstone is very fine-to medium-grained, sub angular to. sub rounded and generally moderately well sorted; consisting of quartz,volcan1e rock frooments, chert, fe.ldspar,minor amounts of h~avy m.inerals and iro~ oxides. Carbonate is micnte and sparite. Claystone 1s dom manti~ montmonl lonite. Unit is mostly oxidized. 2000-. Sandy siltstone and mudstone overlain by medium to fine scndstone. Sandy siltstone has a clay matrix and contains abundant cloy clasts. Mudstone/claystone is silty and burrowed. Sandstone is parallel to cross laminated and contains wood frag ments, caliche clasts, ond abundant clay clasts I inch to 2 inches in diameter Probable weak epigenetic ,oxida1ion within syndeposi1ionally oKidized finer-grained r~~~~~-l sediments. Environment:thlck,well-developed crudely upward-fining coarse miKed load or bed load channel fill overlying oxidized floodplain and splay sequence O of silt and mudstone. Bose of Oakville approximately 250 foot Interpretive Lithologic Log of Hole OG -17 Hole OG-17A 0- Surficial Deposits-Holocene Medium grained, calcareous sand and caliche. 1 ~i ~%~i'6'~l,t~I~~~~E and CLAYSTONE; semi-consolidated and calcareous. Sandstone is fino-to mediurn-groinod, sub angular to rounded end moderately well sorted. Unit is mostly oxidized. Fleming Formation-Miocene SANDSTONE, CLAYSTONE and SILTSTONE; semiconsolidaled and calcareous. Interpretive Lithologic Log of Hole OG -17A Hole OG-18 0- ...... :: :..1.:'. :·::: . :..1.:".: ·. :: ·:.1.:: ······-······· :.:... :..:.:::::-i.;...::·. - ···~.L.t····...;.~.···--········ :~~~:~~;.:~·:-~~ ------~-::::-:::::~~-::~~~ -:;..:_.:._:.:-'p;_~..:._.:,:.- --==-=-=-==-=~.;:-=-=...,.,-:r-. .,...-.-:-:-,"";':-, Goliad Formation-Pliocene -:-:-":'.':-:"':'":"'.".·.-:""':"':"" sANDSTONE, SILTSTONE,CLAYSTONE and GYPSUM; semi consolidated and calcareous. Sandstone is generally flne-Qrained, subrounded and moderately well sorted. Unit is mostly OKidized eKcept at base where it is reduced and pyritic. Thin interbeds of fine sandstane,siltstone, claystone, and gypsum. Gypsum beds predominate in lower 27 feet. Core becomes sandier up section. Sandstone is cross laminated to porollel laminated. Siltstone has a clay matri• and contains floating gypsum crystals c 1/8 to 3/4 inches long, molds of gastropods, pelecypods, ostracods, and some pyrite. Claystone is terrigenous to micritic Individual bods range from< I to 4 inches and ore highly dessicated. Gypsum beds are 1/8 inch thick and exhibit wavy (algal ?l lamonations. Slightly sulfidic to gley reduc tion . . Environment: coastal playa lake. Gypsum (bedded and intrastratal rosettes and laths), micrite, fine scale lamination, abundant dessication cracks, end intrafor mational rip-up clasts all Indicate this unique coastal plain environment. Gamma 2 1/Zx ladl.grOWid IIQ,Sr onom~.;:;.:;JIE':!:~~ 1 ~ 1LT~~E;c't!~~;E~ANDSTONE and GYPSUM; semiconsolidoted ond calcareous. Sandstone I$ generally fine to medium-grained, subrounded and moderately well sorted. Unit is mostly oxidized. I Gomma 3x and 2ll. lloo~round ~~6~Tb~f,§~~~s~b~t":nd CLAYSTONE; semiconsolidated and calcareous. Sandstone is generally medium-9rained, subrounded and moderately well , sorted. Unit is mostly unoxidized and pyritic. ·· -::-..::..:-::-~:-:J Fining upward sequence of very fine sandstone, Siltstone, and claystone over- .. --::-...:P:=.. lain by fine sandstone. Very fine sandstone is well sorted and massive. Silt- .. --:-:-...:.:.:::-...:.:.-::- stone is clay rich and churned. Claystone is sandy and also churned. Overlying ·..:,..;_,:.:.._:..:_:..:_.:..:_~:..._:. fine sandstone contains limonite, hematite, magnetite, and occasional pebbles -:;-:7"-.--:-:-7-:-:-.-:7 less than 1/4 inch in diameter. The sandstone is cross laminated and rippled. -' """-:':::":::_-:"::~: Syndepositional oxidation. Environment: Nondiagnosfic-passibly minor channel ,·:·:·~~·.::=·::-,_fill or splay/floodplain sequences. Catahoulo For motion-Miocene Interpretive Lithologic Log of Hole OG -18 Hole OG-20 o- Surficial Deposits-Holocene Unconsolidated very fine to medium Qrained, calcareous sand and caliche. Goliad Formation-Pliocene SILTSTONE, SANDSTONE and CLAYSTONE·, semiconsolidated and cal- ~::li"io~~::~~ ~~ ~~'i'lr~ll~ ~~~~~~~~i~en':! ~:,w~r~~·~e~~~.~~dn"ctrate- contams scattered pynte. Fleming Formation-Miocene SiLTSTONE, SANDSTONE and CLAYSTONE; semi consolidated and cal careous. Sandstone is fine-to medium-grained, subangular to well round ed and moderately well sorted. Unit is partially oxidized and partially reduced and contains scattered pyrite. ~===~r...J Dominantly siltstone with occasional interbeds of claystone and mioor fine sandstone units. Siltstone is churned and conto1n1 clay blebs and plant remains. Claystone is h iQhly churned/burrowed. Sandstone is well sorted and floating clay clasts and very minor hematite and = mollnB.Tite.~~l!or~roon ias~ndopositional 011idation and possible minor epi Envoronment: Thin chonnel-fi II and splay sands over a thick sequence of floodplain mud and siltstone '!lith thin distal or aeolian sands. · Oakville Formation-Miocene SANDSTONE, CLAYSTONE and SILTSTONE; semiconsolidated and co 1- careoua. Sandstone is very fine-to medium-<;~rained, subanoular to well rounded and generally moderately well sorted. Unit is partially oxi dized and partially reduced and contains scattered pyrite and organic carbonaceous material. ...... 0 \.0 Catahoula Formation-Miocene SILTSTONE, CLAYSTONE and SANDSTONE, semiconsolidated calcareous and tuffaceous. Unit penetrated is mostly oxidized.!' Interpretive Lithologic Log of Hole OG - 20 Hole OG-22 0- Surficial Deposits- Holac- Mtdium grained, very calcareous sand and caliche. I -';""t"" 1- -~-1 ± l llflh'-rf+HH, ++d'i - . ! Go!jqd Formotion-pliacp SANDSTONE,CLAYSTONE, SILTSTONE and GYPSUM; aamiconsolidattd and calcareoua. Sandatone is fint·to mtdium gralned ,subongular to will roundtd and well sorted. Unit is mostly oxidized. I j IH·f1. +++.!ltt+H+·''I:+H+H I l 'lr-. II+H+-1-I'v++IH-tH-1+~ Fleming Form f-~t+l-! ~- ! ~ i I ! I l:i 1!500-=OCM ~~~+1+!1-1-H++tt ;1_ ~:}. ~:~ ... - I 1 ' 1'1t-l I:H-Hf-H-r:-t+HI···I . t;· iL "II···· ~u.·.,-"' .. '-"'"'h'I·T·'-"',:. Catahoula Formatton-Miocene CLAYSTONE ,SILTSTONE and SANDSTONE; llmiconsolidated, oaloorsou• and llightly tuffooeoua. Unit penetrated it primarily reduced ond pyritic. Interpretive Lithologic Log of Hole OG-22