Tap chi Nghien cdu va Phat triSn, so 4 (102). 2013
DA GABRO d THl/A THIEN HUE VA VAN DE KHAI THAC, Si/ DUNG
Biii v a n Nghia"
1. L^i noi dau
Gabro (gabbro) la nh6m da macma (magma), di.rgc hinh thanh do sii ddng cufng ciJa nhOiig khoi silicat nong chay. Ngifcfi ta chia da macma thanh 2 loai:
macma xam nhap (khi khoi nong chay dong dac d dudi sau nhu da granit, diorit, gabro) va macma phun trao (khi dung nham trao len mat da't mdi dong dac nhu da liparit, andezit...).
Da macma ra't pho bien tren Trai da't va tim thay or nhieu noi nhu chau My, chau Phi, chau A.. O Viet Nam da macma phan bo ph6 bi§'n d mien Bac, mien Trung, Tay Nguyen va m6t so noi khac. Tuy nhien su co mat cua da gabro d cac lanh th6 neu tren khong nhieu, dac biet d Viet Nam da gabro chi phan b6' han che d mot vai noi nhu Thanh Hda, Nghe An, ThUa Thien Hu§'..
O ThUa Thien Hue cac phdc he macma-gabro duoc nghien cUu tii kha lau, tap trung trong mot sd c6ng trinh ldn: Ban do dia cha't dai TrUdng Son va cao nguyen Ha Lao ty le 1/1.500.000 cua R. Bouret (1925), J. Hoffet (1993), Ban do dia chat Dong Duong ty le 1/2.000.000 cda J. Fromaget (1952), Ban do dia chat Viet Nam (phan phia Nam) ty le 1/500.000 cua Tran DiJc Luong, Nguyen Xuan Bao va imk (1983), Ban do dia cha't va tim kiem khoang san loat td Hue-Quang Ngai ty le 1/200.000 cua Nguyen Van Trang va nnk. Ban do dia cha't va khoang san nhdm td Nam Dong ty le 1/50.000 cua Vu Manh Dien (1988-1993)
2. Nhu:ng dac tn^ng cua da gabro u. Dac triing ve sti phdn bd
Trong pham vi ThUa Thien Hue dd macma phan bd rd't pho bie'n va da dang: Phdc he Dieng Bong (khu Tam Boi phia tay bac A Ludi): thanh phan chu ye'u la da plagiogranit; Phdc he A Bung (tay nam A Ludi): cd gabro nhUng khong phd bie'n; Phdc he Trd Bdng (phan bd td xk Hong Trung, A Ludi):
diorit thach anh, granodiorit; Phdc he Dai Loc (A Roang, A Ludi): granit biotit pocphy dang gflnai (gneis); Phdc h§ Que Son (khu vUc Nam Dong): gabro biotit, granit biotit; Phdc hd Chd V^n (phia bic Nam Dong, Phu Loc va Khe Day):
gabro pyroxenit, gabro hocblen; Phdc he Hai Vdn (phdn bd d Hai Vdn, Bach Ma, Mang Ca..): chu ye'u dd granit; Phdc he Bd Na (phan bd' d Ben Tuan, Song Bo): granit biotit.
Trong cac phdc hd ndu tren, dd gabro chu ye'u cd mat d Phu Lpc, Nam Dong vdi dien tich khong ldn, thudc phdc he Chd Van (v a T, cv) phan bd thanh nhdng
Trucing Cao dang Cong nghiep Hue
Tap ch! Nghiin cdu vS Phit trifo, sd 4 (102). 2013
dai nhd bao quanh khd'i granit Bach Ma thudc phdc hd Hai Vdn (v a T^ hv) ve phia bMc. Chung tao ndn dia hinh dang vdng cung dugc lien kd't vdi nhau tai mot sd' di^m nhd Xudn Ldc, Ldc Diln, Ldc An (Phu Ldc), Huong Hdu (Nam Ddng). Ngodi ra dd gabro cdn phdn bd' mdt vai dien tich nhd d dinh nui Bach Ma va khu vUc Apei, huygn A Ludi. Su phan bo' cua cdc the gabro nay diu lien quan de'n 2 hg thd'ng ddt gay chinh trong vung theo phugng tdy bdc-ddng nam vd a VI tuyd'n. Td dd cho tha'y chung dugc hinh thdnh td dudi sdu trong vd trdi da't vd dugc chuyen len nhd cdc hoat ddng cua ddt gay.
Theo chieu sdu dd gabro phdn bd thanh hai tang khd rd tU tren xud'ng;
- Tang tang lan dd gabro rat dac trung, phan bd' tren be mat cdc ddi thoSi, cd chilu day td vai mdt dd'n vai chuc mdt. Kich thudc cua cac tang ldn thudng ldn de'n ra't ldn vd tdp trung trdn bl mdt bao mdn ciia cdc tang da gd'c. Chat lugng da gabro tang lan kha td't, dg nguydn khdi cao. Day Id dd'i tugng quan trong de khai thdc, suf dung ldm nguyen lieu san xua't dd d'p ldt. Cac tang lan dd gabro dugc hen k i t vdi nhau bdi tdng da't mdu nau do, vdng cd thanh phan cat, set phong hda tU da go'c gabro.
- Tang dd gd'c gabro phdn bd d vung Ldc Dien, Ldc Hoa, huyen Phd Lpc vd Huong Hdu, huyen Nam Ddng tren dien tich khoang 18km^ Da gabro gdc Id ra vdi dien tich nho phat hien d vung tha'p, ven sUdn ddi, ndi, bl mat dd bi phong hda, bao mdn, nut ne manh. Phan ldn da gabro phdn bd dudi do sau vai chuc met tao ra do nguyen khd'i ldn, rdn chdc, mau tucfi sam. Thanh phan thach hgc la gabro amfibon hat ldn de'n nho. Day Id nguon tai nguyen tiem ndng (dat khoang 4 trieu m^) cd the dugc thdm dd, khai thac, sd dung trong thdi gian tdi.
6. Bgc triing ve thdnh phdn, mdu sdc
Khoi gabro khu virc nghien cdu dugc cau thdnh bdi 2 loai da chinh: gabro amfibon va gabrodiorit [3].
Gabro amfibon phdn bd phd bie'n trong khu vUc Phu Ldc nhu Ldc Dien, Lpc Hda. Dd cd mau den pha ddm nhd mau xdm trdng hoac tap hop thanh dom nho kilu hoa dau. Thdnh ph^n khoang vat chu ye'u tao nen da:'Hocblen 55-75%, Plagiocla 15-25%, Pyroxen 10-20%...
Gabro diorit phan bd' tugng dd'i phd bie'n trong khu vuc nghien cdu, tap trung d Lpc Dien, Ldc Hda (Phd Loc), Huong HOu (Nam Ddng). Da cd mau xam den, xam tro, xen cac hat nhd mau xdm trdng. Thdnh phdn khoang vat chinh cua da: Hocblen 29-45%, Plagiocla 40-60%, Pyroxen it gap 3-5%.
Dac trung cua da gabro la ty le khoang vat sam mau tdng (hocblen, pyroxen, olvm...), ham lugng hda hgc SiO, giam (<52%) nen da thudng sIm mau, CO mau den, den xen nhdng dd'm nhd mdu trdng... Dac trUng do tao nen sd khac bigt so voi cdc da xung quanh mau sang nhu dd granit cd ham luong SiO.
>65% (thugc phufc he Hai Van). '
Tap chi Nghien ctfu va Ph^t triln, sd 4 (102). 2013
c. Ddc tritng ve tinh chat ca ly, dg nguyen khoi vd tinh trang tri ciia dd gabro
Tinh chat c(J ly la mpt trong nhChig chi tieu quan trong trong vi^c xac dinh d6 ben cua vat lieu xay ditog nhtf lUc n6n, ILTC uon cong, life 5n m6n,.. m^ ckc th6ng so quan trong la cu&ng do khAng n^n, CLT&ng dp khdng keo, cu&ng do chiu nen,. Da gabro dufOc hinh thanh do quA trinh n6ng chdy ciia khd'i silicat trong long dat roi dUtfc dong ciJng thanh dk. Nhiftig A\i(ti nhiJng tkc dong cua tiT nhien nhu nhiet do, dp suat.. dk gabro it bi bien doi, bi§'n dang. Bdi vay da gabro thtf&ng CO dp bin, d6 ciJmg \6n. Theo ke't qud nghign ciJfu cho thay dk gabro Phu Lpc c6 CUdng d6 khdng n^n cao nha't 2.084kG/cm2, thap nhat ^.485kG/cm^
trung binh 1.835kG/cm^ [3]. Dd gabro Phti Lpc, Nam D6ng co tinh chat cd 1^
ddp Ung ygu c^u lam nguygn ligu san xuat dd 6'p ldt vd san xuat vkt lieu cao cd'p khdc. D6 cung la ddc trung ccf bdn cua dd gabro vl phuung dien chat lUcfng, tinh cha't ccf ly ma it co nguon nguyen lieu ndo sanh dUcfc.
Tinh trang tri cua dd gabro (c6n goi la sufc to diem cua dd): San pham dd gabro hien dang dupc suf dung rat pho bie'n trong vigc trang tri cdc cong trinh xdy dung. Tinh trang tri ciia da gabro dUtfc the hien rd't da dang nhUng tdp trung d mpt so' ye'u to' chinh nhU: mau sac, van hoa va do bong cua san pham.
Da gabro Phu Lpc, Nam Dong deu co mau den, xdm den pha d6'm trang nho phdn bo' deu, ldm cho dd c6 mau trang nha, nhieu hat tinh the hocblen, pyroxen sdp xep, dan xen, tao ngn dU&ng net sac sao vdi ve dep tif nhien von co cua no. Dp bong cua san pham gabro phu thupc vao nhieu ye'u to' nhU cong nghe, thig't bi, chat lUpng cua dd nhu: thdnh phan thach hpc, khoang vat, do cUng...
Dd gabro cua khu vUc nghign cUu c6 do bong khd tot. Sau khi gia cong, ddnh bong d mUc dp binh thu&ng (dp bong dat >70%), ng'u ky thudt ddnh bong tot, dp bong dat 100%.
Ve dp nguygn khoi ciia dd gabro khu vUc nghien cUu: Do nguyen khoi dupc hieu Id the tich cac khoi da ton tai mpt each tu nhien ma trong d6 khong c6 mpt khe nut nao. De danh gia do nguyen khoi cua da ngUcfi ta thu&ng sii" dung phUtfng phdp nghien cufu khe nUt. Vdi cdch xdc dinh nhU vdy cho tha'y da gabro Phu Lpc va Nam DSng c6 mufc dp nguygn khoi khong dong deu, chting thay doi theo dien va chieu sau phan bo'. Phan tren mdt gan cdc dUt gay dd thUcfng bi nUt ne nhieu do tac dpng cua qud trinh phong hoa (tU nhign), do tdc dpng ciia viec khai thac mo (con ngU&i) nen dp nguygn kh6'i thUcfng tha'p (dp nguyen khoi chu yg'u tu 0,l-0,4m^). Cdc khoi dd gabro d sdu it bi tac dpng hcfn bori qua trinh phong hoa (dupc quan sdt qua miu loi khoan) ngn dp nguygn khoi cao hcfn (e6 npi dat 5-8m3) [3].
Ben canh nhiJng Uu diem tren, da gabro khu vUc nghien cijfu co mpt so nhuac dilm nho do la: trong cdc miu dd gabro thUcfng chufa cac khodng vat nhom sunfua nhU pyrit, chancopyrit, asenopyrit... khi bi oxy hoa tao ra mdu nau ban tren bl mat da. O mpt s6' noi nhU Lpc Hoa, Ldc Dien dd gabro thUcfng bi cdc da mach sdng mau xuyen c^t va de lai nhOng vet trdng loang 16 tren be
Tap cW NghiSn cdu vi Fh^t trifa, sd 4 (102). 2013
mat dd. Tuy nhien nhdng nhugc diem neu tren cd the khdc phuc dugc bang cac phuang phap khdc nhau nhu phugng phap hda hgc, co hoc...
3. Van de khai thac, sut dung
Da gabro hign dang dUOc khai thdc, sdn xua't chd bie'n d mdt sd noi tren dia bdn tinh Thda Thien Hue nhu Phd Lgc, Hue.,ThUc te cho thay da gabro da ddp dng phan ndo nhu cdu xa h^i, gdp phan phdt trien kinh td'chung cua tinh. Tuy nhien cdc CO sd khai thdc, sdn xud't che bie'n vdn con nhd, hidu qua kinh td thu dugc tU nguon tdi nguydn nay chUa cao, quy trinh, ky thuat khai thdc cbn nhieu han che. Bdi vay, va'n dl khai thac, chd bien, sd dung da gabro can phai dugc nhin d gdc dd ddy du hgn dd Id hieu qua, tid't kiem, an toan va bao ve dugc mdi trudng sinh thai. De dat dugc muc tieu dd can phai cd sU quan tam chung cua cdc ca'p quan ly vd cac don vi san xua't, trUdc mdt can lam tdt cac cdng viec sau:
- Cdn tien hanh dieu tra, tham dd mdt cdch bdi ban hon dd'i vdi dd gabro nham khoanh dinh dugc cdc than khoang ca tren mat va dudi sau dat chat lugng, ddnh gia dugc trd lugng dua vdo khai thac cd hieu qua. Dong thdi phai dieu chinh quy hoach (hoac xay dung mdi) cho tdng giai doan dUa tren cac vung triln vgng, loai trU cdc vung kem triln vgng, cac vung dl tac dgng xa'u den mdi trudng sinh thai.
- Vide khai thac mo phai dugc xay dung, thiet ke' theo quy dinh, trdnh tinh trang noi thuan Igi khai thac trudc, noi khd khdn khai thac sau gay lang phi tai nguyen va tdn tha't kinh te. Mdt trong nhiJng va'n dl khai thac md hien nay can chd y dd Id vdn dl an toan md phai dugc dam bao dung quy dinh, mpt so' yeu to' nhu gdc ddc bd moong khdng qua ldn, chilu cao tang phai dUgc thiet ke hgp ly, phdn tdng rd rang.. de tranh tinh trang sat Id bd moong, gay nguy hiem cho ngUdi lao ddng va tai san dun vi. Trong khai thac mo phai dac biet quan tam vl nguIn nhan lUc. Nguon nhan lUc phai dugc dao tao chuyen ngdnh nhu giam dd'c dilu hdnh mo, cdn bg ky thuat, cdng nhan khai thac mo...
- Trong san xua't, che bie'n dd gabro tren dia ban tinh da dat dugc nhilu kd't qua td't, san pham cua dd gabro CO ban ddp dng dugc nhu cau, thi hieu cua khach hang trong va ngoai nUdc. Tuy nhien can da dang hda cac san pham, dl tan dung he't dugc cdc nguon nguydn lidu tU dd gabro. Han che nguon thai trong qua trinh khai thdc, chl" bien.
- Van de mdi trudng trong khai thac md phai dugc chu trong de dam bao tinh bin viing, tranh lam suy giam he sinh thai (nha't la rugng Ida, rimg td nhien, rCtng trdng). Mgt trong nhttng va'n dl mdi trutag hi td'n that nhilu nhat khi khai thac da gabro Id phai pha bo hang chuc hecta cay trong tU nhien hoac nhan tao, phdi boc di hdng tram nghin met khd'i da't phu, lay len hdng tram nghin de'n hang trieu mdt khd'i da... Bdi vay bao ve mdi trudng trong va sau khai thac khoang san la vd'n de khdng the thieu. Mgt trong nhttng bidn phap
Tap chi Nghien cu'u vl Phat trien, so 4 (102). 2013
quan trpng do la dSi mdi cong nghe, thiet bi, trong cay xanh, dieu chinh quy hoach, thay doi nhdn thufc, hanh vi cua con ngU&i do'i v6i moi trU&ng„,
4. LcTi ket
Da gabro la nguIn tdi nguyen quan trpng cho phat trien cong nghigp vdt lieu xay dUng, ddc bigt trong san xua't, che big'n dd op ldt. Bdi vay viec khai thac, che'bien, suf dung tdi nguyen dd gabro can phdi dUpc quan tam theo hUdng phat triln bin vflng, hieu qua.
B V N TAI LIEU THAM KHAO CHINH
1. Nguyin Vdn Chi^n va nnk. Th$ch hgc, Nxb Giao thflng-Vdn tdi, 1999.
2. Vo Mgnh Dien vd nnk Bio cio do ve dia chat vi tim kiem khoing sin nhdm td Nam Ddng, 19 1^ 1/50.000(1988-1993),
3. Nguyin Van Hiep vd nnl<. Bao cao ket qui dinh gii di gabro huyen Phu Lqc, ThUa Thien Hue. 1998.
4. Biii Vdn NghTa va nnk. Bdo cdo de tdi "Xay di;ng h6 sd khoa hpc ve tai nguydn khoang san CO khd nang dua vdo khai thdc sis dgng", Hue, 1996,
TOM T A T
Da gabro la mpt trong nhij'ng ngu6n tai nguygn quan trpng cho phat trien nganh cdng nghiep vat It?u xay di/ng 6 tinh ThCfa Thien Hue. Bai vi^t trinh bay c^c dac trung cua dd gabro ci tlnh Thifa Thien Hue, bao gom ddc trUng ve su phan bo; dac triJng ve thanh phan, mau sdc; dac trung ve tfnh chat cO ly, do nguyen khoi va tlnh trang trf. Bai viet cung neu len cac khuyen nghi ve viec khai thac, san xuat va che bien da gabro mpt each hieu qua, an toan, tiet kiem tdi nguyen va bao ve moi trudng smh thai,
ABSTRACT
THE PROBLEM OF EXPLOITING AND USING GABBRO IN T H Q A T H I E N H U E P R O V I N C E
Gabbro is one of the important resources for the development of building material industry in Thira Thi^n H u ^ Province. The article presents the characteristics of gabbro In ThC/a Thien Hue Province, including characteristics of the distribution, composition, color, mechanical and physical properties, material block and decoration. The article also suggests recommendations on how to exploit, produce and process gabbro effectively and safely in order to save resources and protect the ecological environment.