Geodynamic processes and mechanisms of the formation of hot dry rock in the Gonghe Basin

doi:10.13745/j.esf.sf.2023.2.63

Abstract

Abstract:

Hot dry rock of the Gonghe Basin is the first hot dry rock drilled in China, but its formation mechanism is still unclear. Based on previous data, combined with our thermophysical property testing and geochemical, geophysical investigation results, this paper discusses the genesis and geodynamic evolution of hot dry rock in the Gonghe Basin: (1) A series of tectonic activities, such as late collisions between the Indian and Eurasian plates and related post-collisional events lead to deep dynamic processes in the northern Qinghai-Tibetan Plateau, including tectonic uplift, asthenosphere upwelling and thermal intrusion. Under the combined effects of gravitational energy amassed by tectonic uplift and resulting gravity buoyancy, lateral extrusion stress in the northeastern margin of the Qinghai-Tibetan Plateau, mantle drag force, and thermal intrusion of the asthenosphere, crustal and mantle fluids flow from southwest to northeast along weak lithospheric layers (zones) in the Tibetan Plateau and Gonghe Basin. (2) Weak lithospheric layers (zones), such as plate (block) suture zones, plastic rheological ductile shear zones or high conductivity, low velocity bodies, and deep, large strike-slip fault zones and fault intersections, are channels for mantle melt migration to the Earth’s crust. (3) Geological heterogeneity of the Earth’s deep structure leads to nonuniform accumulation of heat produced at depth in the shallow crust. Heat flow is disturbed by groundwater activity and sedimentation/denudation in the shallow lithosphere, lithospheric deformation in the deep lithosphere, and magma convection in the aesthenosphere, while deep-heat flows laterally toward high-thermal conductivity granites, resulting in uneven heat distribution from deep to shallow in the lithosphere. This paper makes a breakthrough from the previous understanding of the genesis of hot dry rock in the Gonghe Basin based on a single factor and a few heat-control factors, and expounds a comprehensive genetic mechanism of hot dry rock, from heat source, heat migration driving force and channel, to reservoir and cap (layer).

Key words: Gonghe Basin, hot dry rock, comprehensive genetic mechanism, geodynamics, crust-mantle-sourced channel fluid

CLC Number:

P542.5
P545

ZHANG Baojian, LEI Yude, ZHAO Zhen, TANG Xianchun, LUO Yinfei, WANG Guiling, GAO Jun, ZHANG Dailei. Geodynamic processes and mechanisms of the formation of hot dry rock in the Gonghe Basin[J]. Earth Science Frontiers, 2023, 30(5): 384-401.

Figures/Tables 16

References 80

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钻孔位置	钻孔编号	地理坐标		孔深/m	孔口海拔/m	花岗岩埋深/m	井底温度/℃
钻孔位置	钻孔编号	经度/(°)	纬度/(°)	孔深/m	孔口海拔/m	花岗岩埋深/m	井底温度/℃
共和恰卜恰河谷	QR1	100.61	36.29	967.0	2 786	627.29	70
	R1			1 203.48		未揭露	83.08
	DR1	100.61	36.24	1 453.58	2 776	1 354	87.6
	DR2	100.60	36.24	1 852.38	2 796	1 440	98.6
	DR3	100.62	36.26	2 927.26	2 806	1 340.25	181.17
	DR4	100.62	36.30	3 102	2 889	1 402	182.32
	DR5	100.61	36.28	1 501.6	2 860	1 490	86.7
	GR1	100.65	36.25	3 705	2 863.8	1 350	236
	GR2	100.69	36.23	3 003	2 648.7	940	186
贵德三河平原及扎仓沟	R1	101.41	36.03	450.64	2 207.00	未揭露	43
	R2	101.41	36.04	1 709.56	2 206.00	1 490.55	97
	R3	101.38	36.04	2 701.20	2 213.00	1 400	103.74
	RK1	101.40	36.03	603.43	2 207.48	未揭露	64
	ZR1	101.30	35.97	3 050.68	2 510.8	0	151.3
	ZR2	101.31	35.97	4 721.60	2 465.52	592.07	214(4 609 m)

钻孔位置	钻孔编号	地理坐标		孔深/m	孔口海拔/m	花岗岩埋深/m	井底温度/℃
钻孔位置	钻孔编号	经度/(°)	纬度/(°)	孔深/m	孔口海拔/m	花岗岩埋深/m	井底温度/℃
共和恰卜恰河谷	QR1	100.61	36.29	967.0	2 786	627.29	70
	R1			1 203.48		未揭露	83.08
	DR1	100.61	36.24	1 453.58	2 776	1 354	87.6
	DR2	100.60	36.24	1 852.38	2 796	1 440	98.6
	DR3	100.62	36.26	2 927.26	2 806	1 340.25	181.17
	DR4	100.62	36.30	3 102	2 889	1 402	182.32
	DR5	100.61	36.28	1 501.6	2 860	1 490	86.7
	GR1	100.65	36.25	3 705	2 863.8	1 350	236
	GR2	100.69	36.23	3 003	2 648.7	940	186
贵德三河平原及扎仓沟	R1	101.41	36.03	450.64	2 207.00	未揭露	43
	R2	101.41	36.04	1 709.56	2 206.00	1 490.55	97
	R3	101.38	36.04	2 701.20	2 213.00	1 400	103.74
	RK1	101.40	36.03	603.43	2 207.48	未揭露	64
	ZR1	101.30	35.97	3 050.68	2 510.8	0	151.3
	ZR2	101.31	35.97	4 721.60	2 465.52	592.07	214(4 609 m)

编号	岩性	热导率 λ/(W·m^-1·K^-1)	体积比热容 Cρ/(MJ·m^-3·K^-1)	热扩散系数 α/(10^-6m²·s^-1)	含水率/%
1	粉砂岩	1.295 7	1.505 6	0.860 6	0.76
2	砾岩	1.374 0	1.458 5	0.942 1	1.45
3	灰色砂岩	2.440 5	1.751 3	1.393 4	1.48
4	深灰色粉砂岩	2.265 5	1.770 0	1.279 7	0.43
5	灰黑色粉砂岩	1.954 2	1.424 1	0.670 0	0.8
6	灰色变质泥岩	1.328 7	1.759 6	0.755 4	2.45
7	青灰色砂岩	1.407 0	1.478 0	0.951 9	0.72
8	千枚岩化变质板岩	1.390 4	1.483 2	0.937 5	2.47
9	变质砂岩	1.542 7	1.484 8	1.039 6	0.03
10	灰色板岩	1.684 0	1.481 6	1.136 6	0.28
11	粉色变质砂岩	1.983 7	1.539 0	1.289 0	0.80
12	灰色变质砂岩	1.635 7	1.496 2	1.093 2	0.13
13	新近纪黄色黏土岩	0.612 1	1.529 7	0.400 1	2.21
14	新近纪黄色黏土岩	0.387 2	1.338 8	0.289 3	2.43
15	新近纪黄色黏土岩	0.341 1	1.388 0	0.245 7	1.72
16	新近纪黄色黏土岩	0.214 2	1.341 7	0.159 7	3.14
17	新近纪黄色黏土岩	0.325 9	1.540 0	0.211 6	2.00
18	细粒花岗岩	3.262 3	1.823 7	1.788 8	1.31
19	花岗岩	2.443 8	1.824 4	1.339 5	1.76
20	花岗岩	2.915 0	1.661 8	1.754 1	0.16
21	花岗岩	2.656 8	1.835 3	1.447 7	1.46
22	花岗岩	3.016 1	1.895 9	1.590 8	0.21
23	灰色花岗闪长岩	3.177 2	1.702 1	1.866 6	0.32
24	灰色花岗岩	2.079 4	1.560 5	1.332 5	1.08

编号	岩性	热导率 λ/(W·m^-1·K^-1)	体积比热容 Cρ/(MJ·m^-3·K^-1)	热扩散系数 α/(10^-6m²·s^-1)	含水率/%
1	粉砂岩	1.295 7	1.505 6	0.860 6	0.76
2	砾岩	1.374 0	1.458 5	0.942 1	1.45
3	灰色砂岩	2.440 5	1.751 3	1.393 4	1.48
4	深灰色粉砂岩	2.265 5	1.770 0	1.279 7	0.43
5	灰黑色粉砂岩	1.954 2	1.424 1	0.670 0	0.8
6	灰色变质泥岩	1.328 7	1.759 6	0.755 4	2.45
7	青灰色砂岩	1.407 0	1.478 0	0.951 9	0.72
8	千枚岩化变质板岩	1.390 4	1.483 2	0.937 5	2.47
9	变质砂岩	1.542 7	1.484 8	1.039 6	0.03
10	灰色板岩	1.684 0	1.481 6	1.136 6	0.28
11	粉色变质砂岩	1.983 7	1.539 0	1.289 0	0.80
12	灰色变质砂岩	1.635 7	1.496 2	1.093 2	0.13
13	新近纪黄色黏土岩	0.612 1	1.529 7	0.400 1	2.21
14	新近纪黄色黏土岩	0.387 2	1.338 8	0.289 3	2.43
15	新近纪黄色黏土岩	0.341 1	1.388 0	0.245 7	1.72
16	新近纪黄色黏土岩	0.214 2	1.341 7	0.159 7	3.14
17	新近纪黄色黏土岩	0.325 9	1.540 0	0.211 6	2.00
18	细粒花岗岩	3.262 3	1.823 7	1.788 8	1.31
19	花岗岩	2.443 8	1.824 4	1.339 5	1.76
20	花岗岩	2.915 0	1.661 8	1.754 1	0.16
21	花岗岩	2.656 8	1.835 3	1.447 7	1.46
22	花岗岩	3.016 1	1.895 9	1.590 8	0.21
23	灰色花岗闪长岩	3.177 2	1.702 1	1.866 6	0.32
24	灰色花岗岩	2.079 4	1.560 5	1.332 5	1.08