KI^U K^T TH^M DIA

Tuyin tip cac cdng trinh nghiin cdu Dja chit va Dja vit ly biin - Tap IX 135^

CAC KI^U K^T HACH Fe- Mn TH^M LUC DIA

VI£T

NAM VA

N G U 6 N G 6 C

THANH TAO CHUNG.

Ngd Vdn Qudng, Phqm Qud'c Hiep, Le Dinh Nam Phdng Dia hod khodng sdn-Vien Dia chdt vd Dia vat ly bien

TOM TAT

Bdi bdo dua ra ki't qud tdng hgp phdn tich cdc diem qudng Fe, Mn d them luc dia bien Viet Nam dugc phdt hien tic cdc chuyin tdu khdo sdt nghien citu cua CHLB Nga, CHLB Dice vd Viet Nam tic nhiing ndm 1980 din ndm 2000. Theo hinh dang, kich thudc, todn hd cdc ki't hqch Fe, Mn dd biii dugc chia thdnh 5 kieu, vd tuong itng phdn bd d cde vi tri khdc nhau ciia them luc dia. Bdi bdo cdn gidi thieu thdnh phdn hod hgc vd ly gidi ngudn gd'c thdnh tao cua cdc ki't hqch. Trin ca sddd ddnh gid trien vgng cda chung vd kii'n nghi ddu tu nghiin citu tiep theo.

I. M 6 DAU

Hien nay tren thi gidi da phdt hien ra nhilu md va dilm qudng sat-mangan d phdn thIm luc dia va day biin bien dai. Mdt trd lugng khdng Id qudng sat- mangan kilu kit bach phdn bd trong bode dudi tdng trdm tich da dugc xac dinh d day biin Thai Binh Duong, Bdc Bdng Duomg va Ai Dd Duong.

Tuy nhien, vi nhilu ly do khac nhau, md d vung biin Viet Nam mdi rai rdc cdng bd nhiing phat bidn dd'u hieu cua cdc thanh tao qudng Fe- Mn nay. Dac biet la nhdng kit qua hgp tdc nghien cdu khao sdt cua cac nha dia chd't Viet Nam vdi Nga va Ddc td nhiing nam 90 trd lai ddy da khang dinh vung biin Viet Nam thuc su cd tilm nang khodng san Fe- Mn. Trong khudn khd bdi bdo nay, tdc gia tdng hgp, phdn tich cdc kilu thanh tao qudng Fe- Mn b vung biin Viet Nam, lam co sd cho viec xdc minh ngudn gd'c thdnh tao va du bdo triln vgng, tilm ndng cdng nghiep cua chdng.

n . CO s d TAI LifeU NGHlfeN CtlU VA BAN CHAT K^T HACH Fe- Mn 6 DAY BIlEN

Ngudn tdi lieu vd mdu dugc sd dung nghien cdu td cdc chuyin khao sat cua cdc tau Vulcanolog, Gagarinski (1980-1990) cua Nga, Sonne (1996- 1999) cua CHLB Ddc va cdc chuyin khao sat biin Ddng dinh ky (1998-2000) cua Viet Nam.

Cac mdu dugc phdn tfch chi tilt vl thdnh phdn vdt chd't, nhu phdn tich dd hat, hinh thdi cd'u true, phdn tfch khodng vdt vd hod ca ban.

Dugc bilt kit hach qudng Fe - Mn cd cd'u tao hinh cdu td dxyt va hydrdxyt Fe, Mn, kich thudc ngang cua cdc kit bach dd td vai phdn chuc centimet din vai met, thdng thudng dao ddng td 1 din 20cm.

Khodng vdt chinh tao nen kit bach theo P. Bemcov la: veriadit, prilomelan, hydrogrotit vd montmorilonit. Ham lugng trung binh cua cac nguyen td trong thdnh phdn kit hach (tfnh theo %) tuang dng: Mn 20 (40-8%); Fe 16 (26-2,5%); Co 0,33 (2,5- 0,2%); Ni 6,6 (2-0.2%); Cu 0,35 (1,6-0,03%); Pb 0,35-0,2; Zn 0,08-0,4.

III. CAC KI^U QUANG Fe, Mn 6 THEM LUC DIA BIEN VI$T NAM Cac tfch tu kit hach Fe, Mn dugc phdt bidn trong trdm tfch bl mat vung thIm luc dia biin Viet Nam chu ylu tdp tmng d khu vuc cda sdng Mdkdng, sdng Hdng va biin Tdy Nam Viet Nam (hinh 1) [ 1 ].

101* 102«

Hinh 1: Sadd phdn bdcdc diem qudng Fe - Mn. (Thu nhd td ty le 11500.000) Dua theo hinh thai, kfch thudc va dac dilm cua ke't hach trong cac trdm tfch, cd thi phdn chia kit hach Fe, Mn b thIm luc dia biin Viet Nam thanh 5 kilu nhu sau:

Kilu 1: Kit hach garit hinh trdn dIu. Loai nay thudng cd dang hinh cdu, b l mat nhan bdng, mau td'i xdm hodc den vdi kfch thudc phd biin 3-8mm, cd cd'u tao ddng tdm

Tuyin tip cac cdng trinh nghien curu Dja chit va Dja vat ly biin - Tip IX 137 vdi cdc ldp sdt cd mdu tuong ddi td'i, xen ke vdi ldp set sang mdu hom. Kilu nay chu ylu cd trong trdm tfch b l mat gdn cda sdng Mekdng.

Kieu 2: Kit bach set-gatit hay siderit dang cdt mau tfm- sang, hay vdng nhat vdi kich thudc phd biin 5-20mm. Chdng duoc phdt hien d trong trdm tfch sdng biin d vinh Bdc Bd.

Kilu 3: Ke't bach cd binh khdng dIu, gdc canh, hay bi mai trdn tihig phdn, mdu tim, tim- sang vdi kfch thudc td 2-3mm din vai centimet. Loai nay chfnh la trdm tfch cat dugc gan kit bdi gotit vd hydrdgatit. Kit bach kilu nay bat gap d phdn nudc ndng cua chdu thd sdng Mekdng keo dai.

Kilu 4: Kit bach cd hinh gdc canh khdng dIu, bd rdi. Dd la hgp phdn gatit- hematit mdu dd- mdn hdu nhu khdng cd phdn ldi vdt chd't silicat. Chung gap trong thanh phdn cua vd phong boa laterit bien dai hay gdn dd trong trdm tfch luc nguyen.

Kieu 5: Kit bach cd dang vd mdu ndu hdng bao bgc ldi dd bazan, hoac cacbonat.

Ham lugng Fe, Mn d loai nay kha cao FcjOj : 8,03-27,53%, MnO: 3,29-13,39%. Dilm cd mdu nay phdn bd d biin phfa tdy qudn dao Tmdng Sa (toa dd 10''04'19"N;

l i r i l ' l d ' E va 8°48'42"N; 109°39'26"E)

Theo ddc dilm thanh phdn vdt chd't, cd thi chia kit bach sat thanh hai loai: kit bach gotit trong trdm tfch holoxen biin hay sdng biin va kit bach gotit-bematit trong cac thanh tao luc nguyen.

Kit qua phdn tfch chi tilt thanh phdn hda hgc kit bach Fe - Mn d vung tbIm luc dia biin Viet Nam dugc trinh bay d bang 1 vd bang 2.

Bdng 1. Thdnh phdn hod hgc ke't hqch loqi gotit So' tram

vamiu 1 2 3 4 5 6 7 8

Ham Fe

13,99 18,20 17,48 28,84 26,39 20,54 18,55 38,17

Mn 1396 3755 3533 4972 1896 3038 4300 1973

Zn 102,0 109,8 135,5 137,7 108,2 140,2 155,0 138,7

Cu 26,2 29,6 34,2 42,0 37,4 33,2 31,5 57,0

ugng nguyen to'*

Cd 1,08 2,11 2,03

<1,31 2,58

1,81 2,65 3,44

Co 30,7 33,8 39,3 45,9 25,8 19,3 33,0 49,5

Ni 46,0 51,7 48,1 47,2 47,7 39,9 71,5 53,8

Pb 45,1 52,8 63,3 104,9

90,2 60,4 50,0 75,3

Mn/Fe 0,0100 0,0206 0,0202 0,0172 0,0072 0,0147 0,0232 0,0052

Bdng 2. Thdnh phdn hod hgc ket hqch loqi gatit-henamit.

So' tram vamSu

9 10 11 12 13

Fe 43,28 45,43 41,20 51,97 39,24

Mn 128 129 138 894 1017

Zn 47,7 64,0 43,0 469,0 302

Ham lugng nguyen io*

Cu 20,7 32,5 18,0 195,5 185,3

Cd 2,77 3,55 3,15 5,00 3,68

Co 2,1 7,0 7,5 89,4 74,8

Ni 20,1 24,0 21,5 61,5 73,6

Pb 121,0 117,5 111,5 268,2 148,5

Mn/Fe 0,0003 0,0003 0,0003 0,0017 0,0026

*Ham lugng Fe dugc tinh bang %, cac nguyen td cdn lai nhdn vdi 10 %

IV. M O T V A I NHAN DINH \ i N G U 6 N G 6 C THANH TAO CAC LOAI KET HACH

Fe - Mn 6 KHU VUC NGHlfeN CtJtJ

Phdn Idn nhiing kit hach nghien cdu phdn bd' d trong cac trdm tfch biin gdn bd, mac dd cd nhilu kilu hinh thai tdn tai khdc nhau, song chdng tuomg ddi dom dieu vl thanh phdn khoang vdt va thanh phdn boa hgc. Dd'u hieu ddc trung khac cua cdc kit bach la ham lugng Mn rd't thdp (Mn/Fe td 0,0003 din 0,0232).

Nhu vdy, cd thi nhdn dinh rang phdn Idn ngudn Fe, Mn cua kit hach ngbidn cdu dugc mang ra td luc dia vd ldng dgng d day biin. Qua trinh thdnh tao kit bach Fe-Mn d ddy chfnh la qud trinh ngung keo hodc kit tua cua hydrdxyt sdt rdi lang dgng d ddi tilp cdn gida nudc sdng va nudc biin. Nhdn dinh nay cung phu hgp vdi nhCrng yd'u td' tu nhien khdc nhau, nhu khu vuc cd khf hdu ndng dm, qua trinh phong boa boa hgc xay ra manh me tren luc dia, vdt lieu luc nguyen d dang boa tan va cac hat keo dugc nudc sdng mang ra biin mdt khd'i lugng Idn, gap dilu kidn ly-hda cua mdi tmdng thudn lgi se kit tua, ldng dgng thdnh tao trong dd cd cac loai kit bach Fe-Mn.

Cdc kit hach Fe-Mn d phdn thIm luc dia biin Viet Nam cd nhilu kilu vdi nhilu hinh ddng, kfch thudc khac nhau cd thi dugc ly giai bdi su phdn bd' va anh hudng cua cdc dilu kien thdnh tao dia phuong da dang.

Theo tinh todn [6] kit bach dugc thdnh tao rdt chdm, chdng phat triln vdi tdc dd khoang vai milimet sau tridu ndm. Chinh vi vdy, nhdng nod kd't hach cd kfch thudc Idn la nhdng noi td'c dd ldng dgng trdm tfch ndi chung nhd. Nhdng ddng chay ngdm dudi biin cung anh hudng rd't manh tdi kich thudc vd hinh ddng cua kit hach, ddc biet la dd mai mdn.

Rieng ngudn cung cdp vdt lieu dl thdnh tao kit bach Fe-Mn kilu 5 cd thi cd su xdm nhdp cua nhiet dich, ndi Ida hien dai dudi nudc, bdi ldi cua kit bach la dd bazan, va noi phdn bd cua dilm qudng tuomg ddi xa luc dia.

V. K^ T LUAN

Tdm lai, td nhdng diln giai, phdn tfch d tren cd thi dua ra mdt sd nhdn dinh sau:

1. 6 phdn thIm luc dia biin Viet Nam da phdt hien 5 kilu kit hach Fe-Mn Chung phdn bd chu ylu d phdn ngodi cdc cda sdng Idn (sdng Hdng, sdng Me Kdng va biin Tdy nam). Sd ft la d vung biin sdu phfa tdy qudn dao Tmdng Sa.

2. Mac dd kit bach Fe-Mn phdt bien cd cdc kilu khac nhau vl kfch thudc, hinh ddng, song chdng phdn Idn cd ngudn gdc td luc dia. Dilu nay dugc minh chdng bdng vi trf phdn bd va su dom dieu vl thanh phdn cua chdng.

3. Nhihig kit qua trdn ddy mdi chi la budc khdi ddu dinh hudng cho cdng tdc tim kilm, ddnh gid kit hach Fe-Mn b vung biin Viet Nam. Cdn ddu tu nghidn cdu sdu va he thd'ng hom dl cd thi phat hien ra nhdng tfch tu qudng Fe-Mn cdng nghidp trong khu vuc ddy tilm ndng ndy.

(Cdng trinh dugc hoan thanh vdi su hd trg tai chfnh cua chuang trinh nghien cdu co ban).

Tuyin tip cac cdng trinh nghien curu Dja chit va Dja vat ly biin - Tip IX 139^

TAI LifeU T H A M KHAO

1. A.C. Astakhov va nnk. 1991. Thach ludn va su triing hgp pha cua cdc kit bach sdt phdn phfa tdy biin nam Tmng Hoa. Tap chi "Thach ludn va khoang san cd fch", Vien Han ldm Khoa hgc Lien Xd. Matxeova. (ban tilng Nga).

2. Nguyin Dinh Dan. 1992. Ddc dilm phdn bd mdt sd ylu td dia boa trong trdm tfch tdng mat thIm luc dia Nam Viet Nam. Tuyin tdp nghien cdu biin IV trang 125 132.

3. Ngd Vdn Quang va nnk. 1997. Anh hudng cua qud trinh phong hda nhiet ddi dm tdi ddc dilm thdnh tao sa khoang ven bd biin nam Tmng Bd Viet Nam. Bdo cdo khoa hgc. Luu trd tai Vien Dia chd't vd Dia vdt ly biin.

4. Ngd Van Quang vd nnk. 2005. Nghien cdu tilm ndng khodng san Fe, Mn thIm luc dia biin miln Tmng Viet Nam. Bdo cao khoa hgc luu trd tai Vien Dia chd't vd Dia vdt ly biin.

5. Ngd Vdn Quang, Vu Thi Thu Anh, Pham Qudc Hiep. 2006. VI kha ndng phdt hien tfch tu kit bach Fe, Mn d vung biin miln Tmng Viet Nam. Tap chf Khoa hgc va Cdng nghe Biin, Sd 2 (T6)/ trang 116 - 1 2 3 .

6. V.I. Smimov. 1982. Dia chd't cdc md khoang san. NXB "Ldng dd't". Matxeova, (ban tilng Nga).

7. Dd Minh Tiep, Tdn Nd My Du. 2000. Budc ddu nghien cdu kit bach Fe- Mn vung biin sdu Ddiig Nam Viet Nam. Bdo cdo khoa hgc " Biin Ddng-2000". Nha Trang.

SUMMARY

TYPES O F IRON AND MANGANESE NODULES ON THE VIETNAMESE SHELF AND THEIR FORMATION ORIGIN

Ngo Van Quang, Pham Quoc Hiep, Le Dinh Nam

The article gives out general analyses of iron and maganese ore points on the Vietnamese shelf which were discovered through marine surveys of Russia, German and Vietnam from the 1980s to the year 2000. All of iron and manganese nodules found in this area are divided into 5 types in accordance with their shape and size;

they are relevantly arranged in different positions of the shelf. Moreover, their chemical components are presented and their origin of formation is clearly explained in this article. Those are scientific bases to avaluate the nodules'prospect and propose research planning hereafter.

Ngudi nhdn xit: TS Nguyen Tien Hdi Viin Dia chdt vd Dia Vdt ly Bien